Well I pulled the tranny (again) to work on my leaky rear main seal. Good news is that the RSM I put in last month was bone dry

Bad news: My refreshed tranny is leaking from the input shaft (with a brand new seal ).

Ok, I did a search and found lots of info bout how to remove the seal with the gear stack in place. But, no real mention of how to install with the gear stack in place. Will the new seal simply slip over the input shaft and into the seal pocket?

I am doubtful because when I installed this seal last time (with the gear stack removed) I had a hard time getting the seal to seat all the way down.

Questions:
1. Any special techniques to installing the seal with the input shaft in place?
2. Should the seal sit completely flush with the housing? (I could never get my previous one to sit complete down...)
3. Any thoughts as to why my new seal is already leaking (other than the excessive pounding I gave it going in )
4. Saw an old comment from Brad about the pivot balls leaking???? I need to recheck mine when I get home...(sorry, not really a question).

Oh and yes, I lubed the new seal last time.

thanks

i've not done this on a Porsche trans/diff, but all the descriptions refer to the infamous "tubular drift.' (IOW - pipe.) find a bit of pipe that just fits over the mainshaft and that oughtta do it for you.

One of the common problems with the input shaft seal on a 901 transmission is knocking the garter spring off the seal when installing the gear stack. If the seal doesn't look damaged from the outside, then pull the side cover off the diff. Look at the main shaft where it comes through the diff area. I bet you find a garter spring spinning around the main shaft..........

Ok, had a short day at work. So I got home pulled the old seal out....

let me say that the technique of "punching" in one side causing the other side to pop out is brilliant. That and of course the "hook type" seal puller.

But, the circular spring was still in the seal, which leaves me still wondering why this new seal was leaking???????

Let talk about seating depth!!! Should the seal be completely flush with the tranny case? As I mentioned, the old seal was NOT flush.

Upon close inspection of the input shaft, I notice that it tapers inward as the shaft meets the splines for the clutch disk. This tapered part is also noticably NOT smooth. It has a rough (but uniform) finish. Farther back the shaft (toward the inside of the tranny), the finish changes to a very smooth one.

The transistion from rough to smooth finish occurs right at the spot where the seal should sit. If my seal was not completely on the smooth part, could this cause my leak?

Come on folks!! help me out!!

Also, should I use a sealant on the OD of the seal?

QUOTE (jr91472 @ Jul 25 2005, 02:39 PM)

The transistion from rough to smooth finish occurs right at the spot where the seal should sit. If my seal was not completely on the smooth part, could this cause my leak?

Yes!!!

I use a piece of PVC pipe to drive the seal home... I think 1" worked..

On my seal I noticed that the part of the seal that actually rides on the input shaft is at the BACK of the seal if you are looking into the bellhousing. The part that rides on the input shaft in the front is just the dust seal.

QUOTE (jkeyzer @ Jul 25 2005, 02:11 PM)

On my seal I noticed that the part of the seal that actually rides on the input shaft is at the BACK of the seal if you are looking into the bellhousing. The part that rides on the input shaft in the front is just the dust seal.

yes, I just noticed that as well. That tells me that even though the seal wasn't completely flush, the "sealing surface" at the back was still on the smooth surface.....

QUOTE (jr91472 @ Jul 25 2005, 08:44 AM)

Will the new seal simply slip over the input shaft and into the seal pocket?   Questions: 1.  Any special techniques to installing the seal with the input shaft in place? 2.  Should the seal sit completely flush with the housing? (I could never get my previous one to sit complete down...)

Yes it will slip right over. Here is what I posted on tat2'd:

That tranny seal can be tough. Use a piece of lead pipe a bit smaller than the outer edge of the face of the seal to gently and slowly tap it into place. Stop every few taps and observe it to verify it's moving evenly. Sometimes just before they are "seated" flush, they will tend to flange out on you. If that happens, discard it and try another one.

If your shaft is worn at the seal spot, you can unscrew the spring inside the seal, snip off a bit and twist it back together to produce a tighter grip.

We used some adhesive on the outer surface of my last seal. Doesn't seem to leak a bit. I forget what we used, but can look it up for you if you like. PM me.

Mine is seated flush to the face of the tranny.

QUOTE (TimT @ Jul 25 2005, 02:03 PM)

I use a piece of PVC pipe to drive the seal home... I think 1" worked..

I also used a piece of PVC pipe to tap the seal into the bellhousing case. Worked fine.

thanks to everyone who chimed in!

I started out using the pipe from my floor jack (gently tapping). Got it about 3/4 the way in. Then found some PVC with a larger diameter to finish it off. I did notice some slight "flanging" as Joseph mentioned.

Once seated, I applied a layer of gasket sealer to cover the seal/tranny mating surface all around. I suspect that it was this area where my previous seal was leaking.

Next I removed the pivot ball for the T/O fork, slathered with more gasket seal and re-installed just for good measure.

Tranny is still out of the car, so I will probably spend the rest of the day contemplating the "flanging" and consider driving over to Zims, getting a new seal and starting over. Or maybe I will just let it ride.......

somedays, this car make me crazy.....

Seal installations are always tough for me too, I never have the right size driver to do it right... Same for wheel bearings, just ask Jenny...

I went through 2 input shaft and 2 drive flange seals before I got mine in right.

Zimms has then in stock for 3.99 ea. Think I'll buy a couple.

Ok, took another shot at it....

flanged or not flange????

another.....

high temp RTV gasket maker.....

".....going crazy with the cheese whiz..." - Beck

If you use some brake cleaner and towels to clean up the tranny it will be more obvious where it is leaking next time (if there is a next time, I hope not).

That RTV isn't goign to do much. I would have put a very thin layer around the outside of the seal before installing it.

QUOTE (jkeyzer @ Jul 27 2005, 10:28 AM)

That RTV isn't goign to do much.  I would have put a very thin layer around the outside of the seal before installing it.

My last one we applied sealer around the outside before inserting the seal.

Photos can be misleading, but the seal itself looks okay to me.

You don't want to hear this, but I'd pull it out and do it.... one more time... around the outside... with a VERY thin coating.

good luck!!!

You don't think I drove all the way over to Zimms and only bought 1 seal do you?

thanks for the tips everyone

At the breakfast today, Jenny brought up a point I'd never thought of... Her and Aaaahndy both had problems where the pilot bearing in the flywheel had been removed (probably when a machine shop lightened the flywheel), and never replaced. Evidently this allows the input shaft to move around just enough to make the seal leak. Both she and Aaaahndy cured their persistant transmission leaks by installing a new pilot bearing.

Have you checked your pilot bearing?

--DD

makes sense....

turns out my problem was a poorly installed seal (by me) while I had the tranny apart.

so far, the new one is golden.

thanks

On the pilot bearing issue. There is also a small split bushing behind it in the crankshaft. It provides protection against the pilot bearing being recessed into the crank too far. I tried to find one last year and they were NLA. I ended up making 1 out of iron pipe. Somewhere there is a diagram showing where the pilot bearing should sit relative to the flywheel. It should leave just enough space for the felt washer between the pilot bearing and the 5 hole washer (something like 2.3 mm).

I know Brad commented on the pilot bearing sitting too far into the crank.

Dave