Thickness of sealer and the affect on bearing pre load.

[q2418130103p]

For years I have been trying to fix the clacking noise my transmission makes whenever the clutch is released, a noise which I can now hear even when in gear, which I assume is a result of the extra sound transfer I get as a side affect of solid mounts.

Anyway, one thing I thought of the other day was the thickness of the sealer used to put the transmission back together. I rebuilt the transmission last year, pre loaded the bearings, and sealed the case back up with a black permatex type stuff. And probably used way more than I should have.

It seems to me that the thickness of the sealer could actually throw off your pre load. Is this possible? I am not convinced myself since the pre loads are usually around 5 - 10 mil, and the sealer probably can't be much more than 1 mil. Since there are 3 sealing surfaces that would be 3 mil of additional case length. So if you had your pre load as loose as possible to begin with, 5 mil, it would now be 2 mil.

[Ninja Performance]

Doesn't matter how much you goop on. If you torqued the cases together correctly, the film of sealant on the mating surfaces will be the same no matter how much you used.

-Chris

[q2418130103p]

So what do you suppose is the thickness of an rtv seal? Maybe it would be smart to be a transmission together with something like three bond 1194 which is very thin and basically gets painted on.

[Chris@Rvengeperformance]

the factory did in fact use a very thin anerobic sealant. RTV black or gray works well though. When I've taken these apart after sealing them this way the rtv layer is so thin it isn't even there in some spots. The case pushes it out until only the low spots basically get rtv of much thickness.

[q2418130103p]

Welp sounds like it doesn't make a difference then.

I think I am still going to crank this transmission open again though and check for obvious signs of wear. I cracked it open last time to replace all the syncros, and a couple of the bearings (both input bearings, and a couple taper bearings). My goal was to solve the clacking, get smoother shifting, check for wear potentially causing excessive backlash. With solid motor mounts it seems slack in the drive train is very easy to feel, since there is nothing to dampen shock when the slack is removed except the tires and your butt. I end up getting a sizable bang and a slight metal to metal noise which I assume is the sound of teeth making violent engagement.

I succeeded in only 1 of my fixes, the syncros. I didn't find any noticeable wear that would cause excessive backlash (and I previously replaced the prop shaft carriers, transmission output shaft and tc input sleeve and checked the backlash in the rear diff already). And I made the clacking noise WORSE. The noise is evident whenever the clutch pedal is let go. I know that this is a common problem, however I dont think most people are able to hear it while driving, especially evident under heavy load low RPM. I can get it to go away at idle if I press the clutch pedal half way and slow let it out. But I always get to listen to it while on the highway.

I was thinking maybe my pre-loads were loose with gasket material as the cause... guess not.

[q2418130103p]

fyi, the sealer called for in the service manual (MD997740) is actually Threebond 1216 which is silicone based.