915 Rebuild (Part II) - Time for Assembly

[sc_rufctr]

Originally Posted by arbita1

Peter,

I'm pretty sure I have the pill locations straight. I'm looking for the orientation of the 3/4 shift rod. Which way are the recesses in the rod supposed to go.

The picture in the Bentley manual shows the smooth side of the rod only. So it's hard to tell exactly where those recesses go.

I'm guessing from this response you removed the shift forks from the rods.

The adjustment of the shift forks is pretty straight forward if not a bit tedious but take your time to get this just right.
As a suggestion you need to try and understand how the rods and forks for each gear pair are moved around inside the gearbox by the shift rod and the articulated arm.

Maybe the gear box gurus should chime in with some tips to help you because the last thing you want is to have to crack open a sealed transition to re adjust them.

[sc_rufctr]

These seem like a good idea to help you hold everything in place so you can adjust the shift forks and at $19.95 not a bad deal.

But how often will you use it? Maybe you could borrow one instead or if you choose to buy one, use it as a book end for your Porsche technical manuals...

[arbita1]

Yes. I removed the forks and will be re-adjusting them. I have the jig.

I figured it out. There are grooves on the rods for the fork pinch bolts. Basically those align the rod in the case to their proper orientation once the fork is installed on them. So I got that back together and put the jig on and started installing the 5th/reverse gear stuff so I can align the forks.

Question...I'm having trouble keeping the transmission still while torquing the output shaft nut to 181 ft-lbs. I had mounted my old clutch disc on the wall with some plywood and used that as my lock/holder. It worked well for the input shaft nut (but that was only 118 ft-lbs. )

I was thinking of just using my impact wrench...but I'm afraid of over torquing it. Any ideas?

[sc_rufctr]

I'm no were near this stage myself but I'm planning to mount my trans in an engine stand to do the final assembly.

I figured I could stand on the legs of the engine stand so that I can get that final 188 ft-lbs without too many problems.
I may even bolt a thick plank of wood between/on top of the legs to get a better foot hold.

Great to hear you're making progress and the shift rod issue is resolved.

[Peter Zimmermann]

Originally Posted by sc_rufctr

Maybe the gear box gurus should chime in with some tips to help you because the last thing you want is to have to crack open a sealed transition to re adjust them.

This adjustment is really difficult to convey because, although the book explains it, one has to learn how to do it. I do it this way, which is no guarantee that it will work for you - and I work with the trans on a heavy-duty stand.
1. Torque M/S & P/S fasteners with jig in place.
2. Place 1/2 & 3/4 sliders in neutral position.
3. Center slider for 3/4 mid-way between the two gears and snug the shift fork bolt (no need to torque it yet).
4. With the trans top facing up, look under the gear stack and find a vertical reference that can be seen while looking at the 1/2 rod/small fork (I use a casting line on the diff housing as my vertical reference).
5. Rotate the rod/fork counter clockwise until it stops, then move it clockwise until the flat surface of the fork is vertical - don't go past vertical. You'll probably have to do this a few times before you know that you have it right.
6. Taking care to not let the 1/2 rod turn, center the slider between 1 & 2, then snug the shift fork bolt. This is a little tricky, and seems like you need three hands - just work with it until you get all your fingers where they need to be.
7. NOTE: "SNUG" means tight enough so your adjustment can not change.
8. Verify that while centering the 1/2 slider the 1/2 fork rod position did not change.
9. Turn the trans upside down, and check the alignment of the 1/2 & 3/4 shift rod forks (the small, black ones). They should be lined up so the finger of the shift rod will be able to move smoothly from one to the other. Adjust if necessary by loosening the bolt for the small fork on the 3/4 rod.
10. OK, now you should have the brass 1/2 & 3/4 shift forks centered between their respective gears, and the smaller rod forks aligned with each other, as well as the small 1/2 rod/fork not turned past vertical.
11. Now the distance between the small forks must be set. This is perhaps the most difficult adjustment, because the manual is a bit imperfect. Push the two forks together, and check how close the flat portions of each fork (NOT the tips!) get to each other. Now, move them as far apart as possible and see how far apart they are.
12. At the closest point the forks should be about 1mm apart (they must not touch), and at the widest point the flat surfaces should be no more than 3mm apart. This is when experience helps, but if you can achieve about 2mm of clearance at the mid-point of your clearance motion you should be good to go.
13. Re-check your small forks to make sure they are still lined up and tighten the bolt for the small fork.
14. Turn the trans upside up, and use a large, flat-bladed screwdriver to test shift 1st-4th. After you have successfully shifted into each of the four gears, one at a time, re-check that both of your sliders are still centered between their respective gears, adjust if necessary, check the 1/2 rod/fork for vertical, then torque all three bolts to 18lb/ft.
15. Remove 5th gear and your jig, install your center housing with shift rod, and secure the housing with one nut. Install your end cover and secure with one nut.
16. Turn the trans upside down, and with the finger of the shift rod in position (centered in the two small forks) you should be able to rotate the finger (by turning the end of the shift rod) so that it moves smoothly between the 1/2 & 3/4 small forks.
17. If you have interference you will have to adjust the vertical position of the 1/2 rod/fork. If movement is smooth without tip contact you're good to go. Remove the housings/shift rod, and prepare the parts for final assembly.

I have to stress that standing over your shoulder watching you is really the only way to be sure that there is no communication problem. If you have trouble please post!

Originally Posted by arbita1

Yes. I removed the forks and will be re-adjusting them. I have the jig.

I figured it out. There are grooves on the rods for the fork pinch bolts. Basically those align the rod in the case to their proper orientation once the fork is installed on them. So I got that back together and put the jig on and started installing the 5th/reverse gear stuff so I can align the forks.

Question...I'm having trouble keeping the transmission still while torquing the output shaft nut to 181 ft-lbs. I had mounted my old clutch disc on the wall with some plywood and used that as my lock/holder. It worked well for the input shaft nut (but that was only 118 ft-lbs. )

I was thinking of just using my impact wrench...but I'm afraid of over torquing it. Any ideas?

DO NOT USE AN IMPACT - THAT'S AN ORDER !

Try this, go to Home Depot/Lowe's or the like, and buy a flat, steel bar, at least 1" x 1/4" x 4'. Set up your clutch disc on your M/S splines, and buy bolts and spacer material (quality stuff) so that you can bolt your flat bar to the installed clutch disc, AND to the diff housing using a bolt through one of the engine mount stud holes. Once everything is tight, put the trans in 4th gear, and "roll" the trans over until the bar is resting firmly against your bench top. You still might need a helper to hold the trans while you torque the P/S nut.

[arbita1]

The Bentley manual seemed pretty straight foward with the fork adjustment. It didn't seem that complicated. I'll go through it and compare it to Pete's instructions above.

Yeah...I think I'm going to have to lock it in a gear and put it on the floor and maybe have someone hold it done while I torque it. I had thought of the flat bar bolted to the clutch disc as well, so I already bought the flat steel. I'll give it a try.

[arbita1]

Pete's suggestion was on...I needed to lock the transmission in 4th gear. My home made I/S lock wasn't enough to resist the 181 ft-lbs of twisting force. With both locked I was able to torque it without much a problem. Would have been easier with a second set of hands, but I overcame.

I did the adjustment procedure and it seemed to go pretty easily. I haven't pulled off the jig yet because I want to take some photos for you guys to look at first...but I couldn't find where my wife put the camera last night.

I put the shift rod into the housing (obviously without the intermediate case on) just as a quick test. It seemed to move through the two forks without any interference. I'll double verify once I remove the jig using Pete's method.

Now I'm just waiting for my Curil T (ordered from Pelican with a few other goodies). I'm so close I can taste it.

[Peter Zimmermann]

Originally Posted by arbita1

I put the shift rod into the housing (obviously without the intermediate case on) just as a quick test. It seemed to move through the two forks without any interference. I'll double verify once I remove the jig using Pete's method.

Remember, placing the shift rod the way that you did does nothing - you need the intermediate housing and nose cover on to make sure that the rod is in the actual position that it will be in when the trans is functional. A little movement here, a little there, and you end up with a false test result. This is similar to trying to turn your diff without the side cover seated - it won't tell you anything but it can certainly scare you!

Glad to hear that you're making progress! Make sure that your 1/2 slider has its asymmetrical teeth facing 1st gear (that's the side of the slider that has a groove machined into the OD)!

[arbita1]

Is there a trick to getting the intermediate cover on with the selector rod in the case?

The little stub out thing that sticks off the rod prevents the cover from going on.

[Porsche_monkey]

Pic please.

Are you talking about the detent?

[Peter Zimmermann]

Originally Posted by arbita1

Is there a trick to getting the intermediate cover on with the selector rod in the case?

The little stub out thing that sticks off the rod prevents the cover from going on.

Put the shift rod inside the cover, and hold it in its approximate installed position while you slide the housing into place. This is good practice for you for when the gasket and sealant will be in place!

Put a little smear of lithium white grease on the tip of the rod where it will fit into the hole in the diff housing!

[arbita1]

Got it.

If you put the rod in the case and rotate it all the way counter-clockwise as far as it will go, the piece that comes off the selector rod which actuates the 5/R rod will clear the hole casting in the case that holds the 5/R rod. (If that makes any sense...so hard to describe this stuff when you don't have the correct terminology.)

Intermediate and end covers are on and the selector piece moves through the 1/2 and 3/4 lever forks clearly and past them for the 5/R too.

Now I'm just waiting for my sealant so i can get this thing back together.

[Peter Zimmermann]

Originally Posted by arbita1

Got it.

If you put the rod in the case and rotate it all the way counter-clockwise as far as it will go, the piece that comes off the selector rod which actuates the 5/R rod will clear the hole casting in the case that holds the 5/R rod. (If that makes any sense...so hard to describe this stuff when you don't have the correct terminology.)

Intermediate and end covers are on and the selector piece moves through the 1/2 and 3/4 lever forks clearly and past them for the 5/R too.

Now I'm just waiting for my sealant so i can get this thing back together.

Outstanding!

[Peter Zimmermann]

Matt: Tech tip...
When you apply your Curil T, use a clean sheet of paper from an 8.5x11" tablet, and lay the paper on a flat, clean surface. Put your gasket for the diff housing to intermediate housing on the paper, diff housing side up. Squeeze out a thin bead of sealant onto the gasket and spread as already discussed. Place the gasket on the diff housing and the Curil will stick it in place. Make sure it's lined up with the stud holes in the lower left corner.

Now apply a thin bead of sealant to the intermediate housing sealing surface, spread it evenly, put the shift rod in the housing, and hold it so you can see that the detent is "down." Slide the housing into position being careful to not tear the gasket where the two studs pass through it into the diff housing.

Repeat procedure for the nose cover.

[arbita1]

Originally Posted by Peter Zimmermann

Matt: Tech tip...
When you apply your Curil T, use a clean sheet of paper from an 8.5x11" tablet, and lay the paper on a flat, clean surface. Put your gasket for the diff housing to intermediate housing on the paper, diff housing side up. Squeeze out a thin bead of sealant onto the gasket and spread as already discussed. Place the gasket on the diff housing and the Curil will stick it in place. Make sure it's lined up with the stud holes in the lower left corner.

Now apply a thin bead of sealant to the intermediate housing sealing surface, spread it evenly, put the shift rod in the housing, and hold it so you can see that the detent is "down." Slide the housing into position being careful to not tear the gasket where the two studs pass through it into the diff housing.

Repeat procedure for the nose cover.

Perfect timing on this. I should be getting my order on Thursday.

[arbita1]

Here's a few crappy phone pics just for fun:

Overall -


1st/2nd Gear Slider Position


3rd/4th Gear Slider Position


Selector fork positioning

[arbita1]

My gasket set came with all these seals. I can't find a place for these. Where do these go?

[Peter Zimmermann]

Matt: Your picture #4, post #116, scares the heck out of me! It does not look like you have the small fork for 3/4 even close to where it has to be. I did a mock-up for you (see pics below) that might help, the last couple of photos show a piece of paper where your approx. 2mm of clearance should be:

[arbita1]

Oh wow! I think I measured the 2mm to the wrong spot.

Below is what I did.



Funny though the selector rod still seemed to move through without intereference. It reset it per your photos and take another picture for review.

[Peter Zimmermann]

Originally Posted by arbita1

My gasket set came with all these seals. I can't find a place for these. Where do these go?

Don't worry about them, they're for different year transmissions - speedo drive seal, seal washers for detent plugs, etc.)...