Side shift rebuilding
 

Well, I finished another one of these buggers, this time a side shifter....

It looked like it had been in an oil bath for sometime. After dissassembling, I scrubbed the case. And I mean scrubbed. I did find what was potentially a tranny leak - the little pivot for the the clutch fork was loose. Yeah, the one no wrench fits on. I had to get a deep socket 14mm and grind it's OD to make it fit. Makes me wonder if this tranny had been pulled apart before.

Other issues: Not much oil left and what was there was sludge. I cleaned sludge from _every_ component. A surprising amount of magnesium "rust" on the outside. 5 studs had to be replaced. The ball and cap part of the sideshifer had rust, as did the shift fork rod (out side part).

Internally: Other than the sludge, the actual tranny shafts were in nearly perfect condition, _except_ one of the pinion bearings on the intermediate plate, was shattered....

I cleaned out the sludge, and reassembled the shafts. The shift forks are different on the sideshifter. And it's weird that as you move the shift fork selector rod that the opposite gear is selected. The gears are ordered (drive side to Passenger side) 1/R-2/3-4/5 but when the selector is all the way to the drivers side, it is contacting 4/5.

Seals: The hardest seal to replace always seems to be the little selector rod seal. Clamp the sideshift selector down and use a long screwdriver. I found that pressing very hard into the seal, then hitting the screwdriver shaft to pop the seal out helped. All the rest are straight forward.

Word to the wise: Don't mess with Texas! I mean, don't mess with the differential. I was playing with the internal gears on the differential (sludge removal). I moved the internal gears somehow. Unfortunately, I rotated them and the parts that connects to the drive shaft no longer pointed in the correct direction. I had to dissasemble the thing to get it apart. NOTE: You do not have to remove the helical gear to take it apart. Just pop the roll pin out of the middle. That helical gear and it's multitude of locking tabs cost me lots of time.

Oh, if you're going to do one of these jobs right, you do need a few "special" tools:

The usual suspects: Tool to remove the dog teeth and the shaft alignment rig.

30 mm deep socket! I found a wheel bearing 1/2 drive at my FLAPS for $6.00!
14 mm deep socket, ground down at the tip. ($ 2.99)
19 mm deep socket - but a 3/4 SAE seems to work very well (castel nut)
Snap ring pliers (removing the circlips on the gears)
narrow punch for the various roll pins.
4 and 6 mm allen sockets
17 mm "allen" for the drain and fill plugs (the 914/6 tailshift used a 17 mm standard)
8 mm 12 pt for removing the drive shafts
A no mar brass hammer is a god-send.

Lessons learned: Tighten the castle nut on the pinion shaft before putting into the casing. As with the tailshift, shift the 4/5 slider into 5th before dropping the gear assembly into the tranny casing. Use _lots_ of penetrating oil on all of the external casing cover nuts. This should minimize the number of pulled studs. If the torque does not go up when re-installing the case cover and differential cover nuts, you have stripped the threads and need to replace the stud. Clean clean clean! Clean the threads on everything as much as possible! Diesel fuel _is_ a good inexpensive solvent. Clean the casing on top of one of those 12 qt covered oil pan things. Use lots of solvent. Brass brushes of various sizes, an old tooth brush and a very stiff brush where the bristle are in line with the handle. You will need to tap many components apart and back together (I SAID _TAP!!!).

Now to actually install one!!!!!!!!!!!!!!

James

PS: And wash those coveralls once in a while.....

Excellent info!! What manuals are you using, if any? How hard would it be to change gear ratios? 1st, 2nd and maybe 3rd.

Some are harder to change than others. Let me look at it again. Each gear is actually 2 gears, 2nd gear is part of the shaft. 1st would be tough, since it's mate also runs reverse and that setup is unique. The rest of the gears have to be matched, since the shaft centers can't move. So 3rd, 4th and 5th should be changable. Changing them would just be accomplished by just wapping those gears as you assemble the shafts.

The actual rebuilding of the shafts is pretty straight forward. I'm using the full 914 shop manuals. They have fantastic exploded view diagrams.

James

I have been afraid to do a rebuild on mine after hearing about
resetting the backlash correctly after pulling the intermediate plate. I was told that a porsche dealer shop had to reset this
accurately? How do you get it reset?

Also, where do I get those special tools?:confused:

3rd, 4th and 5th gears are easy to change. Just buy a gearset in the ratio that you want and install. Price range from about $350 to $550 for a gear set. First can also be changed easily, however the last time I saw a price on a non stock 1st gear set, it was about $700. Second gear is the trick, since the input shaft gear is made on the shaft you have 3 options. You can buy a new input shaft with a different ratio second, $$$$$., buy a 904 input shaft which uses an interchangable second gear or have second gear ground off and a new gear welded on. Chris Fisher at PowerhausII does that for about $750.

On the special tool list you left off a 32mm deeeep well socket to torque the nut on the input shaft. You can either buy one for about $40 or I had a machine shop cut one in half and weld in a piece of pipe to make a 13" deep well. You can also use a 32mm crow's foot, but they you have to calculate the torque offset.

Hargray, as long as you keep track of the shims/gaskets in between the intermediate plate and the tranny case, you don't have to re-set the ring and pinion lash. I believe that the shims are color-coded, but it's probably a good idea to measure them as well just in case!

Some of the specialty tools can be purchased through Pelican Parts. Others are fairly standard tools available through your local tool store.

--DD

I used the BACW "Big @ss Cresent Wrench" for that. You certainly could weld up a tool for this, but I don't plan on making a living at these trannies. A 32mm Crows foot would be the easiest tool to buy, except 32mm Crows feet don't grow on trees......I'll see if Home Desparate has one at lunch time, when I buy a new 10 mm tap :(

I do need to get a 13 mm crows foot, for the exhaust nuts......And a new 1/4 universal drive. Snapped one yesterday too....

I second Dave, the 2 really special tools can be purchased from Pelican. If you have the spare $25, I'd also reccomend an inexpensive hand press. It would be easier on everything than hitting the dog teeth removal tool with a hammer. Although, a hammer works fine.

A BAS (Big @ss Screwdrive) is also helpful when you need to torque the 30mm nut. I found wedging it between the 1st gear slider rod, a stud and reverse, worked really well. Select the tranny into first for this (Position of the reverse gear on the slider is better!).

The shims on the Pinion shaft are set at the factory to adjust for the slight variation in the thickness of the components. Unless you are changing an actual gear on the shaft, you will not have to measure. I think this is the "big scary deal" that everyone talks about. As long as you are not replacing an actual gear (very unlikely unless the transmission is TRASH! In which case, forget rebuilding it), you won't have to do this.

James

The gasket color code is:
Light Brown 0.004"
Green 0.006"
Dark Brown 0.008"

Since the gaskets get oil soaked, it is sometimes hard to tell the color. It is good to measure them any way. They are kind of hard to measure since they get compressed from the installation.

There are also shims between the pinion gear and bearing. Do not change these or they will upset the mesh also.

As long as we are throwing around tranny tips - here are a couple:

Save an old clutch disc (even one from a VW bug works!) and use the center for a holding tool for the mainshaft. Weld a bar to the hub and you have a nice vice adapter that the mainshaft will slide into.

When loosening and tightening nuts and bolts on the shafts you can lock the transmission by selecting two gears at the same time. Once the shift linkage is out of the way you just push the sliders of two gearsets together (2nd and 4th for example) and the shafts can't turn in relation to one another.

James