transmission bolt re-tap and gasket question

[BGman]

I was replacing the ground strap for the transmission and found that the bolt securing the ground strap has been over-tightened and has stripped from the trans housing. For reference, this is a 3" long bolt that is on the bottom of the rear plate of the tranny - goes through the intermediate plate - and tightens into the transmission housing. Essentially, it holds on the rear plate by sandwiching the intermediate plate.

Let me start by saying- I have never taken apart the transmission on my 914.

However, it appears that the gaskets probably need to be replaced on either side of the intermediate plate (lots of buildup).

What am I getting myself into by removing the rear and intermediate plates, re-tapping the housing for a larger bolt, and replacing both the paper gaskets either side of the intermediate plate?

Can this be done pretty easily- or are things going to fall apart once the intermediate plate is removed (which is how it appears in Chiltons)?

[red-beard]

Bolt???

No bolts should be there. There are studs all the way around the outside of the rear cover which do what you say. The studs are secured into the tapped holes with locktite and then a nut holds the cover on. The typical thing that happens is a stud and nut rust together and the stud backs out.

If someone replaced it with a bolt, you did probably strip the threads. You could tap and rethread with an overside stud, but then you'd need to drill the intermediate plate larger as well.

A cheesy fix would be to JB weld the stud into place. You might try loctite first.

For a rundown on what you can do after pulling the cover...

see http://home.san.rr.com/pb914/rebuild/

[Dave at Pelican Parts]

If you do pull the intermediate plate, make absolutely certain that you count the number of "gaskets", and note the color and measure the thickness of those "gaskets". They are actually shims to set the ring and pinion engagement, and are pretty important.

The different thicknesses are color-coded, but the colors can be tough to tell after years of fading or having transmission fluid leak through them. Double-check things by measuring the thickness and by noting the color.

--DD

[BGman]

yep- its a bolt. You are probably right, someone backed the stud out and replaced it with this bolt. Where can I get a replacement stud? Or oversized replacement stud?

My initial reaction is to lean towards the cheesy jbweld idea....

So, removing the intermediate plate is not a big deal as long as I pay attention to the gaskets?

[Dave at Pelican Parts]

See the article that Red-Beard linked to. (And wrote!)

--DD

[BGman]

Yup- it is a bolt. I guess you are right that the stud was lost and the PO just tried threading in a bolt that probably did not match the threads.

Thanks Red for the link, that is an excellent resource for someone like me. It looks like, if I am careful, that I can in fact pull the intermediate plate, replace the gaskets, replace the stud, and get it back together without having it all fall apart. Thanks for the advice on counting the gaskets (shims).

FYI, the tranny did run fine- I have no problems with shifing or gear wear that I know about. Few more questions-

1. Where do I find a replacement stud - standard or oversized? What would be an oversized one that would work? (type/length)
If they are easy to come by- I guess I would rather fix it correctly and tap a new one into the case.

2. If I did this, is there any other parts inside the tranny that I should replace regardless (since I have it all apart). For example, Is it silly not to replace all of the studs at the same time?

Thanks guys- I appreciate the help.

[red-beard]

Hmmm. Just about any fastener place. Pretty common, 8mmx1 I think. Length, not exactly sure, but I'd say between 75 and 100mm.

You would drill and tap the hole to 10mm. Then drill the intermediate plate to just over 10mm so the stud will work.

An alternative is a used case. I have _TONS_ of them.

[BGman]

Just for closure on this thread....

I first tried to JBWeld the stud in place- It did not hold....just pulled free as soon as I started to torque it. I just did not want to have to go through drilling the intermediate plate.

I then drilled/tapped the case for a 10mm stud and then found that the hole through the intermedite plate was large enough to pass it! Everything went back together fine.

All in all, I had it apart/together about half a dozen times. Eventually, I became pretty good. I learned that if it does not all slide back together- pounding on it is not going to help. I spent a lot of time moving the gears slightly until all of the teeth mesh....when they did, it just all fits and closes.

Red-Beard's article is fantastic! Everyone should print and save in your "for future reference" 914 folders (c-mon, I know you all have them). Thanks for taking the time to write it.

By the way- I looked for real studs, but could not find any locally that were long enough. I ended up using high grade all-thread and cutting to length. According to the industrial fastener shop, the kind I bought is 2 steps stronger than what you normally find at home depot/lowes.
-greg

[red-beard]

Well, this is good to know. More fodder for the fire! I'm glad we could help.

[Zeke]

Why did no one mention a heli-coil? I use these on all stripped bolt/stud holes.

[norustscott]

zeke, not sure. twas my first thought. end result would be the same iwththe same effort...maybe even cheaper than helicoil/timesert.

[mike95125]

Helicoil - My first thought too to keep stock stud width.