All the Way Into 915 & Comin Out (Long)

[Jim Sims]

After some delays to fit in basketball games, finals, dates and get some parts ordered and delivered, we tackled the differential and seals of my sons's 915. We carefully cleaned, noted thickness and stored shim that was under shaft retaining flanges. We then cleaned the outside of the diff. case (transmission housing) probably to excess but all the pockets in the ribbing are now devoid of dirt and are a dull gray. The drive flanges/shafts (put two screws in flange holes and use a bar to hold flange while loosening center retaining bolt) and side cover came off readily. The differential was lifted out and put aside for cleaning. Noted gear tooth mesh marks and etched number on ring gear matching it to pinion shaft. Being careful not to disturb the bearing race and not nick or mar the magnesium of the housing the old drive flange/shaft oil seal in the housing was knocked out with a brass drift. The oil seal in the side cover was more stubborn and wasn't moving with the brass drift method. We put the side cover in a shop press and using the back end of a spindle nut wrench (KD tool 2467) we had on hand as the pusher (2-3/8" diameter) we pushed out the old seal without difficulty or damage to the cover and without disturbing the race. We used 1" schedule 40 PVC pipe (1-5/16" actual OD) to make a tool to push out the old input shaft seal in the bell housing. We tried pounding on it but the seal was tight and the PVC pipe was cushioning some of the force of the hammer blows. Into the shop press again, still using the PVC pipe as a pusher and out the seal popped without much more effort. If one has a shop press the PVC pipe has the advantage that it is soft and will not mar the metal seal mounting surfaces. Then several hours of cleaning were required; the oil/mud/tar "adobe" on the backside of the drive flanges was a pain to get off - it had to be scrapped off with a piece of wood. Cleaned and chased all the housing stud threads. After everything was cleaned and dryed of solvent all the steel bearing races (pinion and input races in diff. housing were tight), roller bearings, gear teeth and shaft seal surfaces were given a coating of Swepco 201 gear oil and covered. Tomorrow we'll put in the new seals and start reassembling as far as we can - still waiting on new thrust washers for the pinion and input shafts. Having a good time! Cheers, Jim & Brad

[old_skul]

Oh, for a digital camera for you guys! Sounds like you're having fun. Good luck!

[Jim Sims]

Three new seals (two axle/drive flange and one input shaft) are now in transmission (differential) housing and side cover. We found it was easier and much more controlled to press them into place after coating with Swepco. This is compared to pounding them in with a pusher disk and hammer - we had to replace one of the axle/drive flange seals after it was over driven and the rubber static sealing surface (OD) was torn. Then we carefully reinstalled the cleaned and lubricated (again Swepco 201) differential assembly (we didn't take it apart) after coating the tapered roller bearings and races with a light coat of Swepco 201. We mounted the transmission (differential) housing on an engine stand with the side cover opening upward. We didn't want to drop the heavy differential assembly onto the tapered roller bearing and races as we installed it. A piece of 1-1/4" schedule 40 PVC pipe was projected upward through the axle drive flange hole on the oppposite side to support the differential assembly as it was lowered onto the bearing race. This was quite helpful as there is not a good way to hold onto to it (we didn't want to hold onto the upper tappered roller bearing) as it enters the housing as there is very little clearance for one's fingers on the sides. We next installed the side cover (new cover o-ring wetted with Swepco was already in place and the housing o-ring mating surface was wetted with Swepco), installed the cleaned bearing washers and prevailing torque, all metal, OEM lock nuts for the side cover and torqued them to 10 ft-lbs and finally to 17 ft-lbs in a criss-cross pattern. While we were torquing the nuts we were spinning the diffferntial assembly to ensure the bearings weren't binding. Next we wetted the axle/drive flange running and seal surfaces and the inside lip of the seals with Swepco and then installed the axle/drive flange. Then the axle/drive flange securing bolts (ours had washers) were torqued to 20 ft-lbs; torque was reacted with a bar working against two screws inserted into tapped holes in the drive flanges. Several of the tapped holes in the drive flanges were a bit tight so all of the tapped holes were chased with a thread restoring tap (not a cutting tap).

We then cleaned and reassembled 2nd through 5th synchro assemblies/gears (new synchro rings and brake bands for all and a new synchro hub or dogteeth for 2nd). Except for the 2nd gear dogteeth, assembly was very easy; only strong fingers and a pair of snap ring pliers are required. It took longer to clean the parts than to assemble them. Dogteeth were heated to about 250-300F with a hot air gun and then quickly moved to the 2nd gear assembly on a hyraulic shop press. Taking care that the hub splines between the dogteeth and gear were aligned the new dogteeth were readily pressed on. Measured OD of synchro assemblies; all within spec.

Cleaned all the parts (retaining identity and axial orientation) and shafts for input and pinion shafts; now just waiting on more parts to be delivered! It seems UPS now takes a couple of days longer to move shipments than before September 11th.

So far the worst part of this rebuild job is cleaning and the most troblesome is determining and rounding up parts.

There are apparently several (like four) stages of possible upgrades of the early (1973) 915 1st/2nd synchro/slider mechanism based on our research through catalogs, websites and inquiries of PCA. In the future we will post a list of the these upgrades with the required part numbers for critique and review by others on this board.

Cheers, Jim and Brad

[RoninLB]

Wonderful presentation, superior.

[Early_S_Man]

Jim,

Did you replace the 'stretch' bolts for the output flanges?

[Doug Zielke]

Jim,
I printed-out your excellent instructions for my files. Thanks for posting them.

[Jim Sims]

Warren,
For the time being we reused the original M10x1.5 DIN 8.8 "stretch" bolts for the output flanges (axle flanges). They can be replaced at anytime up until the transmission is reinstalled into the car. This is one detail we've been trying to get cleared up. They are indeed called stretch bolts but are also called out other places in the factory shop manual and parts catalogs as "expansion" and "elastic" bolts. I ran some stress numbers out on them and the specified torque (20 ft-lbs for our type of bolt with the washer under the head) only stresses the bolt to about 2/3's of yield strength (2/3's of 660 MPa) even if one assumes minimum thread friction due to oily threads. The design of the bolt is interesting in that the threaded section is upset and the shank of the bolt is forged down to a diameter such that the effective tensile areas of the shank and the threads are about the same. I'm tending to believe this bolt acts as some kind of spring element in the joint and is not really used in the same manner as a "stretch" connecting rod bolt. We were also unable to find any notes in the factory shop manual or other repair manuals about not reusing them. The factory shop manual was explicit about noting that other fastener elements in the transmission such as the shaft retaining plate lock washers and pinion shaft flange nut were not to be reused. Perhaps we just missed the information about the M10x1.5 "stretch" bolts. We'd really like to understand these bolts.

Warren or John Walker do you have any other references besides the factory shop manuals and technical specifications booklet that cover this issue? Are these bolts really only used once?

Thanks, Jim

[Jim Sims]

I have been informed by PCA that the M10x1.5 DIN 8.8 bolts used to secure the output flanges (axle flanges) in the 915 transmission final drive may be reused. Also, the use of Loctite on their threads is not recommended. Jim

[Jim Sims]

Today we assembled the input shaft; most of it was straight forward; just sliding on the cleaned old parts or new parts in the reverse order of disassembly. We had not removed the radial roller bearing that is mounted next to the first gear pinion (this is the gear machined into the input shaft itself) but cleaned it in place. A couple of parts were a little tight so they were briefly warmed with a hot air gun to gain a little clearance; this worked well for several parts (the 3/4 spider and forwardmost ball bearing race. The rearmost ball bearing race was still a little tight even after heating so we used the hydraulic shop press and a 1-1/2" copper pipe coupling fitting to push it into place. As the needle bearings, the roller bearing and their races were installed we applied a small amount of Swepco 201 to the race surfaces, rolling elements and cages; we took care not to get this oil on the cleaned press fit surfaces. Then we pressed on the rear most radial roller bearing using a 1-1/2" PVC pipe coupling to bear against the inner bearing race. Using a Snap-On 1-5/8" flare nut crow foot wrench we tightened the flange nut to 114 ft-lbs (reduced from 123 ft-lbs to account for the additional leverage provided by the crow foot wrench offset). We placed the clutch end splines of the input shaft in the splines of an old clutch disk mounted in a vise to react the torque. 114 ft-lbs is a good amount of torque; on the first attempt the Snap-On wrench spread and slipped on the nut. We put a strip of fine sand paper between the wrench and the nut and put a c-clamp across the wrench to reduce the spreading. This worked and we reached specified torque. I think a better tool for tightening this flange nut could be made from a 1-5/8" 3/4 " drive socket with a drive fitting welded on the side; the Snap-On flarenut crow foot wrench didn't have enough cross-section to keep its shape under the torque loading. We also noted that the new flange nut had a bit of thread locking compound on a portion of its threads. We didn't dimple the the nut flange to lock it; we'll do that later.

We cleaned up and installed new seals in the tranmission front cover. The seals for the shift rod and the speedometer drive output plus the o-ring on the side fitting which secures the speedometer drive cross shaft were replaced. Of course, the difficult part was prying out the old seals; the factory manual instructions of prying with a small screwdriver only provided a hint. Brad and I recall the stories of replacing the shifter shaft seal in situ with a little hook tool and the shifter shaft in place. We salute those of you who have done this! We found that prying with a little screwdriver (wood under the shank for a fulcrum and to protect the front cover) only managed to bend the screw driver and tear the rubber lip of the seal. Instead we used the screwdriver as a little chisel on the top of the seal to drive the seal radially inward (distorting the metal core of the seal no doubt) and a bit downward; doing this several places around it's diameter broke the seal free and it then came out readily by prying with the screwdriver. No damage was done to the bore in the housing. The new seal was coated lightly with Swepco 201 and pushed into place by hand.

We were able to remove the the speedometer drive shaft seal by placing a small screwdriver under the inside of the seal and prying upward with a steady pressure. We didn't remove the little clip and take out the speedometer drive fitting Instead, we cleaned it in place, flooded it with Swepco 201 and installed the new seal wetted with Swepco. This seal couldn't be pressed into place all the way with one's fingers; we used a small socket and a soft faced hammer to tap it into final position.

To replace the the o-ring in the side fitting securing the speedometer cross-shaft we first removed the inside snap ring. Then we pushed on the gears of the cross-shaft with our fingers to attempt to push the side fitting outward. This didn't work due to the resistance of the tightly fitted o-ring and limited clearance (also limited finger strength) for one's fingers. In order to avoid marring the housing and the fairly delicate speedometer cross-shaft gears we made a prying tool out of a plastic tent peg (we bought a bag of these to make non-marring wedging and prying tools as required - since they're intended to be pounded into the ground they're quite tough). This worked well and the side fitting pushed out. Everything was cleaned up, the new o-ring wetted with Swepco 201 and installed. The cross-shaft assembly was pushed and tapped gently back into place and the inside snap-ring reinstalled.

We also suffered a couple of set backs. One was the input shaft bellhousing oil seal in the transmission (differential) housing. The edge onto which this seal registers is very slight and doesn't give a good indication when the seal is in the correct axial position plus we neglected to measure the seal position when we initially removed it. In the process of trying to ensure we had it in the proper position (we were checking using the input shaft) we managed to overdrive it and tear the outer diameter sealing surface. It has been removed and will be replaced. We have marked a length of 1-1/2"of PVC pipe with the exact driving distance so next installation we know when to stop pressing.

The second problem was found while cleaning the 5th/reverse idler assembly. We finally removed the needle cages and noted to our dismay that one of the needle rollers was missing. It appeared impossible for the needle to go inward and the cages had been inside the idler since removal from the transmission. Although, we suspect the needle has been missing for sometime (like for years!) we did search for it though all our bags and boxes but had no luck finding it. The idler shaft and outer race show no damage but we'll have to get a new needle cage (probably two since they're paired). That's enough! Cheers, Jim and Brad

[Jim Sims]

After a long "hiatus" due to waiting on parts (we finished cleaning all the other parts while we were waiting) we resumed assembly. We resolved our first gear synchro hub (dogteeth) parts problem and assembled the first gear synchro with a new synchro ring, a new brake band and the old energizer and anchor blocks. The pinion shaft was then assembled without the need for the shop press; we simply heated all the parts (including the new thrust washers) with a hot air gun and they just slid on. All the bearings and bearing running surfaces were lightly coated with Swepco 201 but we kept the "press fit" surfaces clean of oil. Next, we replaced the input shaft seal (after coating it with a bit of Swepco) for the second time; again we used a hydraulic shop press pushing on a piece of 1-1/2" PVC pipe to set the seal. However, this time we carefully measured and marked the PVC pipe to ensure we didn't push the seal too far. The transmission housing (differential housing) was remounted on the engine stand for convenience of reassembly. Brad reached in through the shaft openings in the transmission housing with a long cotton swab and lightly coated the small differential gears with molybdenum disulfide grease (we used Lubro Moly assembly lube LM3010). We retrieved the single metal pinion shaft shim that we had carefully removed, cleaned and stored and put it back in place on the transmission housing. Then we finally locked the flange nut on the input shaft by denting in the thin part of the nut flange with an old center punch which we had ground down to a rounded point; the input shaft was supported on wood blocks on the work bench to ensure it wouldn't be bent by the hammering on the punch. The 1st/2nd speed selector fork rod was inserted back into the transmission housing followed by the 1st/2nd shift detent (a new part; we replaced all but one of the shift detents), its spring and the retaining bolt with a new sealing washer (from the gasket kit). The detent retaining bolt was then torqued. Then the 1st/2nd speed selector fork was slipped around the 1st/2nd operating sleeve on the pinion shaft. The pinion shaft was inserted into the transmission housing so that the the pinion gear just rested on the bearing race. At the same time the 1st/2nd selector fork is being guided onto the 1st/2nd selector fork rod (note that the clamping bolt has to be removed from the shift fork so it can slide along the rod). Then the input shaft is brought up along side the pinion shaft and they are meshed together and inserted into the transmission housing together, each into their respective bores/bearing races. The input shaft has to be guided through the bell housing oil seal and the pinion shaft has to be meshed into the differential ring gear. Also, the bearing retaining (or clamping) plates have to be kept oriented so they can be slid onto the transmission housing studs. It really is helpful to have two people for this operation given all the things that have to be positioned and held. Then new lock washers were put on the bearing retaining plate studs followed by the hex nuts. Then the hex nuts were torqued; not all of the nuts could be accessed with a socket or crowsfoot wrench so about five of them were tightened by hand feel. The 1st/2nd selector fork bolt was then "snugged up" but not fully tightened. Then a detent was "dropped" from the top of the transmission housing into the mostly vertical detent bore. This is the detent between the 1st/2nd and 3rd/4th selector fork rods; it is "trapped" between the rods. Before we reinstalled any detent parts we cleaned out the detent bores plus cleaned all the detent parts (springs, retaining bolts, etc.) and everything was lightly coated with Swepco. The interference fit plug that seals this vertical detent bore was then tapped back in place at the top of the transmission housing. Then the 3rd/4th speed selector fork and the shift guide were loosened on the 3rd/4th speed selector fork rod. Note that the clamping bolts have to be removed so the fork and guide can be slid along the rod. Then the fork is placed around the 3rd/4th operating sleeve and the rod is inserted into the transmission housing. Then the fork and shift guide are positioning approximately back into place; there are grooves in the shift rod for the clamping bolts that help re-establish these positions. Then the clamping bolts for the fork and shift guide are "snugged up" but not fully tightened. The 3rd/4th detent, spring and retaining bolt with a new seal were then installed and the retaining bolt torqued. Next we adjusted the selector forks but I've written enough for tonight. More to follow. Cheers, Jim & Brad

[Jim Sims]

Upon assembling the pinion shaft and input shafts together we also noted the slight axial offset of the mesh of the 1st gear set and to a lesser extent the other gear pairs that tbitz reported. Upon close examination one could see the polishing from the gear contact so it's apparent these gears had been meshed and running with this offset prior to disassembly.

Adjusting the 1st/2nd and 3rd/4th selector forks/shift guides.

We found the section of the factory shop manual covering this operation incomplete and with inconsistent nomenclature; we had to refer to our disassembly notes, the Haynes and Bentley manuals and the exploded diagrams elsewhere in the factory manual to make sense of the procedure. A plastic version of the P360a plate or template was installed on the shafts and selector fork rods. This template emulates the front wall of the gear housing for shift fork adjustment purposes, correctly positioning the shafts and the 1st/2nd and 3rd/4th selector fork rods. Then the thrust washer (item 31 per the main assembly exploded diagram), the 5th gear with its synchro hub assembly (includes needle cage and race), 5th and reverse speed sliding gear (5th/reverse operating sleeve) and guide sleeve (this is the equivalent of the spider) were installed on the pinion shaft followed by pinion shaft flange nut. The needle bearing and running surfaces (races) received a light coating of Swepco 201 oil. Then the castellated nut was put on the front end of the input shaft. Next the transmission shafts were locked against turning. This was done by engaging 5th gear (moving the 5th and reverse speed sliding gear over the synchro ring of the 5th gear)and by engaging 1st gear (at the same time) by sliding the 1st/2nd speed operating sleeve over the first gear synchro ring. This procedure means special tool P37a is not required; in fact the P37a tool wasn't required at anytime in our rebuild. Then the castellated input shaft nut was torqued to 94 ft-lbs (1-1/16" socket used) and the pinion shaft flange nut (36 mm socket) was torqued to 180 ft-lbs. 1st gear was then disengaged.

Next the 1st/2nd speed selector fork rod (this is the one with the integral shift guide) was turned all the way to the left (driving direction left) and then slightly back the other way so that the flat portion (in the middle of the shift guide section) is "almost vertical". We assumed this is to ensure there is some play to avoid the shift fork applying a constant radial load the operating sleeve. The 1st/2nd speed selector fork was then positioned to put the 1st/2nd speed operating sleeve exactly in the center of the 1st and 2nd gear synchro rings. We used a dial caliper to measure this positioning. Then the fork clamping bolt was tightened to 18 ft-lbs; note there is spring washer under the heads of these clamping bolts . This procedure was repeated for the 3rd/4th speed selector fork. Then the 3rd/4th speed shift guide was adjusted axially along the 3rd/4th speed selector fork rod so that it's vertical shift guide faces lined up with the vertical faces of the integral shift guide of the 1st/2nd speed selector fork rod. The 3rd/4th speed shift guide clamping bolt was then tightened to 18 ft-lbs. We ensured there is .080" to .120" (2 to 3 mm) gap in the vertical direction between the shift guides. We rechecked the "almost vertical" positioning of the flat portion of the 1st/2nd speed selector rod during this measurement; we measured about a .100" (2.5 mm gap). It is apparently important that this gap exist to avoid interference problems. Shifting was checked by moving both operating sleeves (1st/2nd and 3rd/4th) by hand to ensure the gears would engage. 1st gear was engaged again and the castellated input shaft nut and the pinion shaft flange nut were loosened and removed. 5th gear was disengaged, then the 5th reverse gear parts and the P360a plate removed.

The 5th/reverse shift fork was adjusted later after the gear housing was installed.

After we finished adjusting the shift forks and shift guides we compared the new positions of the shift forks and shift guides to the original positions measured at disassembly. Most were within .005" (0.13mm) of the original position; one was different by .007" (0.18 mm).

More to come.
Jim & Brad

[Jim Sims]

This is the next to last installment in this "essay"; I have used these posts as a means to document our repair. They are long but I wanted to record all the details and things we noticed. Sorry about the length.

Disassembling, cleaning and assembling gear housing:

The gear housing was supported open end down on three 2x4 wood block pieces (to lift it off the studs) on the work bench. The two steel roll pins retaining the detent system parts were driven downward with a pin punch. Ensure the pin punch is smaller than the bore of the roll pin hole and that the straight section is long enough to ensure the flare of the punch doesn't contact the hole as the pin is driven down. Our housing is magnesium and one doesn't want to damage or widen the pin bores to the point the roll pin would be loose. Then we drove out the detent hole plug (also called half-round dowel pin) at the top of the housing using a small chisel; the chisel was carefully driven under the head of the plug and then it was used to pry the plug out. Remove the two roll pins before removing the plug. This detent system is under spring tension; if the plug is out when the upper roll pin is driven out there is a possibility of some of the internal parts "flying out" and becoming lost. Next we removed all the detent parts except for long detent (the one with the narrow middle section). This long detent hung up one one of the cross-hole edges and we didn't want to force it past (again the issue of soft magnesium); we decided to clean and lubricate it in place. The 5th/reverse speed selector fork shift rod was removed. The entire housing (including the detent system bore) was cleaned with mineral spirits and allowed to dry. All the housing stud threads were chased and cleaned with mineral spirits. The housing gasket sealing surfaces were carefully cleared of the old paper gasket material. Paint stripper (rinse the area well afterward with water and then mineral spirits) was used to soften and loosen the gasket remanents. Plastic putty knifes and wooden "Popsicle" sticks (my wife is a Kindergarten teacher) were used to scape the gasket surfaces. No metal scrapers were used as the magnesium is too soft. The bearing races were given a light coat of Swepco 201 gear oil. We noted that the bearing races were still tight. Special tool P366 is specified to reassemble the detent system. We made a substitute from a length of fiberglass reinforced plastic rod .312" or 8 mm in diameter; our rod is 14" long but one could get by with a 9" long piece. This rod fit the detent system bore perfectly and being plastic helped prevent damage to the soft magnesium. We drilled a 7/64" (~2.75 mm) diameter x 7/8" deep hole in the center of the rod from one end. This makes the end of the rod into a tube. We used a hand drill; we had to do it twice for the first time we were not centered and broke through the side - we cut off the damaged part and started over. Then we took a fine jeweler's type hack saw and cut the rod across a diameter, axially down to the bottom of the hole. Then we cut from one side to the axial cut. This leaves only half of the tube part on the end; the substitute P366 tool is made. The detent parts were cleaned and lubricated with Swepco 201; we installed a new short detent. The detent system bore was lubricated with Swepco and again put on the work bench on the wooden blocks. The 5th/reverse speed selector fork rod is reinstalled; ensure that the two smaller adjacent grooves on the rod are installed under the detent bore. The long detent was positioned so that its "waist" aligned with the lower roll pin hole; one can look in the roll pin hole with a flashlight to check this alignment. The lower roll pin was then driven in place using a pin punch and hammer. Then the helical coil spring was installed from the top of the detent system bore followed by the pin and alumimum sleeve. Then the substitute P366 tool was used to push on the side of the aluminum sleeve opposite the upper roll pin hole; this pushes down the sleeve and compresses the spring. The aluminum sleeve must be pushed down to a position below the upper roll pin hole so the upper roll pin can be driven in to secure it. We looked in the upper roll pin hole to determine this postion and then marked the top end of the plastic rod to note the position. Then the upper roll pin was driven into place. The short detent was installed and the bore plug (half-round dowel pin) hammered back into place.

One more installment to come. Jim and Brad

[bigchillcar]

jeeez,
and i couldn't even get my old man to 'throw a football' with me! i feel like i got shafted! say, jim, if you're in your sixties more or less, i could use a new dad...
9114102267

[Jim Sims]

Not quite old enough for that bigchillcar. But I know the feeling; didn't have too many positive interactions with my father after age 14. After seeing what happened to some of our younger cousins (drugs and alcohol), my wife and decided to try and do things differently with our children. There's no getting around the requirement to spend time with them; this is how they will learn to do things and learn their values. This takes lots of time, not the "10 minutes of quality time a day" bull****. We're rebuilding/restoring a '73 911T as one way to spend time together. It's not cheap but then one can buy a lot of Porsche parts for the cost of only a few weeks of drug/alcohol rehab. Keeping busy with something interesting and motivating equals less time to get into trouble. See if you can link up with some Porsche people in the Little Rock area; check with the PCA. I recall Porsches to be sparse in Arkansas; I worked as a Petroleum engineer in the late 70's in El Dorado but they're likely around. We have a little group of Porsche guys in my community and there is often a "tech session" going on in the garage/driveway of one of our senior members every weekend (at least when the skiing is poor). Jim

[Bill Verburg]

Similar project,

[Jim Sims]

Next to last and very long installment.

Installing gear housing:

The gasket mating gasket sealing surfaces of the transmission (differential) and gear housings were cleaned of any oil and the paper gasket installed dry on the transmission housing studs. Per instructions from PCA we installed our paper gaskets dry as all of our gasket surfaces were unmarred; PCA said for rougher gasket sealing surfaces it was permissible to very, very lightly coat the paper gaskets with silicone rubber sealant. After a week or so under 3 liters of Swepco 201 there are no signs of leaks or weeping. Then the selector shaft (this is the shaft that has the pivoting side lever with the ball like feature on the end and that will protrude out the front cover to connect to the shift coupler) is placed within the gear housing and they are installed together onto the transmission housing and over the shafts. All of the running/ contacting surfaces on the 3rd/4th shift rod, selector shaft and it's side lever and the bearing races in the gear housing were given a light coating of Swepco 201 oil before the gear housing was put on the tranmsission housing. Ensure the back end of the selector shaft goes into its bore in the transmission housing and that the ball end of it's pivoting side lever is placed between the vertical faces of the shift guides. The positioning of this pivoting side lever can be checked and adjusted by looking/reaching through the opening in the bottom of gear housing for the guide fork/cover. Also ensure the front end of the 3rd/4th speed selector fork shift rod is aligned to go into its bore (we believe the factory shop manual calls this bore a "ball sleeve" due to the detent function) in the front of the gear housing. The washers and nuts were installed on the transmission housing studs and tightened to 17 ft-lbs. The sealing surfaces for the guide fork cover were cleaned of oil and the paper gasket installed; we rolled the transmission over (it's on an engine stand) to an upside down position to make this easier. The guide forks (mounted on the cover) and the cover were installed ensuring the forks capture and guide the pivoting side lever of the selector shaft; again all of the contacting surfaces were given a light coating of Swepco 201. The washer and nuts were installed on the guide fork cover studs and tightened to 17 ft-lbs. We then righted the transmission.

Installing and adjusting 5th/reverse gears:

The idler gear shaft was installed into its bore in the front of the gear housing and turned until it engaged the pin in the housing; don't put the rubber o-ring in the groove on the front end of the idler shaft yet (the to be installed needle cages, etc. won't pass over it). Then the fixed gear of the 5th gear set was installed (small flange facing the gear housing or rearward) on the front end of input shaft followed by the reverse speed fixed gear and castellated nut. Next, the 5th speed thrust washer was lightly coated with Swepco 201 and placed on the front end of the pinion shaft followed by the 5th speed free gear with its synchro hub assembly (includes needle cage and race) with the syncro ring side facing forward away from housing - again all running surfaces lightly coated with Swepco 201. Then the guide sleeve (equivalent to spider) and flanged nut were installed on the front end of the pinion shaft. Next, the thrust needle bearing (looks like a washer with radially oriented rollers), two needle bearing cage assemblies with spacer ring between them and idler gear (gear with straight teeth is forward) were installed on the idler shaft followed by the thrust washer - all running surfaces coated with Swepco 201. Take care one doesn't lose a needle out of the cages; the needles at the cage seams can easily fall out. Also, the thrust radial needle bearing can shift forward off a step in the idler shaft (this can happen if one pulls the idler gear forward for some reason) and then prevent the idler gear from reseating properly to the rear; make sure this doesn't happen. If the thrust bearing falls off, it can't just be pushed axially back onto the step with the idler gear; instead the idler gear has to be pulled forward to access the thrust bearing and reposition it. If it is no longer possible to do this, for example if one is further through the procedure and the input and pinion shaft nuts are torqued preventing forward movement of the idler gear, then the axial thrust bearing can be put back into correct position on the step using wooden "tooth picks" from the sides. Next the 5th/reverse sliding gear (or operating sleeve) was installed along with it's selector fork (5th/reverse speed selector fork); again running surfaces were lightly lubricated with Swepco 201. The selector fork clamping bolt was removed to permit it to slide along the 5th/reverse speed selector fork rod; leave the clamp bolt out until the castellated and flanged shaft nuts are torqued. Then we engaged first gear using the selector shaft (roll to driving left and push rearward) and also engaged fifth gear by pushing the 5th/reverse sliding gear (operating sleeve) over the 5th gear synchro hub assembly. This locks the transmission up to permit final torquing of the input and pinion shaft nuts (special tool P37a isn't needed). The castellated nut on the input shaft was torqued to 94 ft-lbs using an 1-1/16" 1/2" drive socket and the pinion shaft flange nut was torqued to 180 ft-lbs using a 36mm 1/2" drive socket. Don't install the roll pin in the castellated nut nor dimple the flange nut yet as one may have to still "back-up" and redo something. We then released fifth gear by pulling the 5th/reverse sliding gear (operating sleeve) forward off the 5th gear synchro hub assembly and also released first gear by pulling the selector shaft forward into neutral. Then the 5th/reverse speed selector shift fork clamping bolt (along with its spring washer) was installed but not tightened. Then we ensured the the 5th/reverse speed selector shift fork rod is in neutral position (rearmost detent groove in rod under the detent in the gear housing). The idler gear was then pushed rearward against the fixed 5th speed gear (the one on the input shaft). Then the 5th/reverse speed selector shift fork is pushed forward against the 5th/reverse sliding gear (operating sleeve) removing all play between them in the forward direction. Move the fork and sliding gear clamped (by hand) together to obtain .040" or 1 mm axial (front to rear) clearance between the straight gear teeth on the idler gear and the straight teeth on the sliding gear. Then while holding this position the 5th/reverse speed selector shift fork clamping bolt was snugged; the .040" clearance was then rechecked and then the clamping bolt was tightened to 18 ft-lbs. We checked the position of the shift fork relative to the measurements made at disassembly and we were with in .007" (0.18mm) of the original position. We then reinstalled the roll pin located in the 5th/reverse speed selector shift rod just forward of the shift fork. We were not sure of the function of this roll pin; it may limit forward motion of 5th/reverse speed selector shift rod while shifting into reverse as there is no detent in this direction. A 2 x 4 board was jammed under to 5th/reverse speed selector shift rod to brace it against the floor while tapping in the roll pin. The roll pin was tapped in from the right side until it reached the far side of the rod; the balance of its length was left protruding from right side of the rod. Next, the o-ring on the end of the idler shaft was lubricated and installed; this o-ring seals the shaft in the front cover. The roll pin was then installed in the input shaft castellated nut; after torquing we found that the cross drilled hole in the shaft and the slots in the nut lined up allowing installation of the roll pin. The factory shop manual is silent about what to do if the castellated nut slots and cross-drilled shaft hole do not line up. Based on our experience with wheel bearings we would loosen the nut after torquing to the next aligned slot. The thin flange of the pinion shaft flange nut was then dimpled into the groove in shaft using a center punch with a rounded point. There will have to be one more short installment - ran into character limit! Jim

[Jim Sims]

Last installment (really)!

Installing front cover:

The gasket sealing surfaces were cleaned of oil and the paper gasket installed on the gear housing studs. The selector shaft and the end of the 5th/reverse speed selector rod were coated with Swepco 201 oil. Then the front cover was installed onto the gear housing feeding the selector shaft through its bore and seal. Also, we ensured the reverse idler shaft and the 5th/reverse speed selector shift rod aligned with their bores in the front cover. There was a slight resistance as we pushed the cover into place; this was the o-ring on the idler shaft being compressed into its bore. Once the o-ring is compressed the front cover "snaps" into place. The nuts and washers were installed on the gear housing studs along with the wiring and cable support brackets. We installed a new tranmission ground strap on the lowest stud on the right side. We found we had to "nibble" a bit of the soldered end of the new strap with a end cutter tool to permit it to clear the side of the front cover. There is a large flat washer on either side of the ground strap but no smaller washer under the nut; we also applied silicone dielectric grease to all the contact surfaces of the ground strap and it's washers. The nuts were then tightened to 17 ft-lbs. The actuating pin for the backup light switch was lubricated and installed with the small end forward or towards the switch. Then the back up light switch was installed and torqued to 22 ft-lbs. We then replaced and lightly lubricated with grease the plastic bushings in the throttle bell crank on the side of the gear housing. Then the drain plug in the bottom of the transmission housing was tightened to 17 ft-lbs and the transmission turned on its side so that the filler hole in the side of the gear housing faced upwards. Three liters of Swepco 201 80W/90 gear oil were measured and poured into the transmission with the aid of a funnel (no oil appeared at the transmission housing vent hole which is and should be facing forward). The side filler plug was installed and tightened to 17 ft-lbs. Then the tranmsission was rolled once in both directions to an inverted position with the transmission vent hole covered with a finger. We then installed a temporary T-handle on the selector shaft and shifted through all the gears. Shifting was a little stiff but all gears were reached without problems. T-handle was removed. Done until clutch installation time! Cheers, Jim and Brad

[dhamilto]

Mmm, I was hoping that I could just open up the transmission, pop on a new 2nd gear synchro, and close it up again!

But really, how much of this would I have to go through to change 2nd gear synchro and what tools would I need? Would the wear be immediately obvious if I opened here up, or is disassembly required to inspect properly? I was contemplating opening her up to see if its a fix that I can make, rather than just sending it straight to a shop without knowing what needs to be replaced.

Thanks,

83SC

[pwd72s]

All of above? Illustrates well why I make a phone call, one that says in a nutshell: "Gordon? HELP!" Of course I pay...but to my mind a skilled and experienced mechanic who does things right is worth what I pay. We've all read the engine rebuilding horror stories on this board...poor suckers who read the ads, then went to one of the "assembly line" rebuilders. I thank my lucky stars to have a relationship with Gordon. (You NW guys will know who I mean...)

[Jim Sims]

To renew the 2nd gear synchro parts, both shafts (input and pinion) have to come out. You can somewhat inspect the external appearance of the dogteeth (synchro hub), part of the synchro ring and part of the operating sleeve by just going in as far as removing the gear housing. However to really look at all the wear points one has to do further disassembly. Some things will be obvious but even having things apart and looking at say an operating sleeve and determining whether it is too worn takes experienced judgement. Given our transmission had 144,000 (or more?) hard miles on it we just replaced the standard recomended parts: synchro rings, brake bands, operating sleeves (1/2 and 3/4), the worn 2nd gear dogteeth, one shaft nut and some lock washers and the gaskets and seals. We also replaced some other parts that looked questionable or worn. Not all of the special tools are needed but some are or least their homemade substitutes. A big vise or an hydraulic shop press is needed along with some big wrenches, sockets and torque wrenches. The worst part of the job is the cleaning, then the waiting on the parts after you figure out what is needed. After doing one transmission I am highly skeptical of the $999 rebuilds; I also understand why people find needle rollers on the drain plug magnet after a rebuild. It will be much easier and faster next time and when it comes time to rebuild my '76's transmission I intend to do it myself. Cheers, Jim