Constantine

Matt,

You have a few problems going on for sure with the torque tube and possibly the TOB.

Take care of what are definite problems before chasing around other possibilities, like the transmission.

I converted a 86.5 automatic to a 5-speed, (the "Coke Car") myself and it came out without issues after the conversion. That's because I made sure all the items being put in were properly working, using some new parts and servicing the transmission and diff before installing them. Thankfully the transmission was not an issue.

HTH.

GregBBRD

Reality check....

The fact that all the gears are all good makes the transmission a great buy.

Finding a used, flawless 33 year old transmission does happen...but not very often.

I consider every single transmission I buy to be a "core". If they are rebuildable, I'm happy. If all the gears are intact, I'm elated.

Kiln_Red

Absolutely a great buy!

Not contesting that at all.. I always will feel out my warranty, though, when one is available. Many times I have redeemed partial or complete refunds while simultaneously retaining the part(s).

captainOCD

I was being optimistic that everything would be fine with it, but was hoping if it needed anything it was just something simple. I'd normally think bearings are something simple, but from what Greg said it seems like it depends which one. 3-4 grand is well outside of my budget for now though.

I still don't know how much gear mesh/rotating assembly noise is normal to be heard. I hate to keep taking the trans in and out, but I'm really wondering if I should get some better torque tube bearings and see if that's why the noise is carrying through the torque tube like that.

GregBBRD

I spent 4 weeks chasing a noise in an automatic transmission I rebuilt. Took the thing apart and changed pieces several times. Finally replaced all the internals. Replaced the axles, the wheel bearings (which were terrible...they had come loose at some point in time, destroyed the hubs, and then got tightened.) Still with the same noise at a certain rpm and load.

Turned out to be in the torque tube, even though the torque tube was perfectly quiet when tured by hand. One of the bearings was loose on the shaft and the shaft would "harmonic" at a certain rpm and load, making the noise.

I agree with Constantine (except for the part about the damper)....chase the known...you're going to have to fix those loose bearings, anyway.

captainOCD

Well I think that's what I'll go about doing first then. I'll get some new bearings, put it all back together (I'll get a new input shaft seal and top gasket for the trans too) and go from there. Seeing how well (<borat voice>NOT!</borat voice>) things worked out with these garage 9 bearings and inserts, Constantine's bearings might be the route to go here. The only reason I didn't get them before was the price, but I guess I got what I paid for.

GregBBRD

I'm guessing that the "garage 9" bearings have the same issue as the ones from 928 International. They measured one shaft and figured that all of the shafts had the same dimension. Turns out that the later automatic shafts have a larger OD by a few hundredths of a millimeter. Making the solid bushings that size means that they will be loose on the early automatic and manual transmission shafts, which is the current problem with the 928 International bearings and I would suspect the "garage 9" bearings.

I expect that 928 International will "solve" this problem quickly.....and soon there will be more economical bearings. (After all, the actual bearing part is only a few dollars.)

captainOCD

Do you think nylon would be a suitable material for the sleeves? I'll be back home in PA next week and will have access to my grandpap's lathe and lots of nylon.

Kiln_Red

IIRC from your video, there is an obvious bearing noise within the transmission. It is audible when you turn the input shaft by hand.

GregBBRD

Beyond my pay grade, without doing research.

GregBBRD

I agree with this. I think the noise is in the transmission, but I also agree the torque tube bearings are incorrect.

Might as well correctly fix the thing that just got "fixed".... it's got to happen anyway.

Mark Anderson

[QUOTE=GregBBRD;16089429) 928 International has some great looking new bearings, but they are too loose for a manual transmission shaft.
)[/QUOTE]
It is true that they do not fit well on the first 54 1978 cars. The shafts were slightly smaller. All other 1978-1995 fit properly

Kiln_Red

I assume the transmission is still out of the car. I wouldn't blink. Go through it and replace everything on an as needed basis. There is a bearing noise inside the transmission. Fix it. There is no point to reinstalling it as is. I defer on a product recommendation for the TT bearings, but you're going to have to go a different direction than what you have now.

One other thought... Are we totally sure that the input shaft bearing isn't your culprit??? If you are doing the seal, go ahead and do the input shaft bearing too.

Edit: ^^^Yikes! Input shaft bearing is pricey. ^^^

Might have to "hold the phone" on that suggestion as that could easily become expensive preventive maintenance. Not a budget-friendly idea.

captainOCD

The trans is out, and I'm not planning to put it back in until fixed.

I was doing some digging looking at parts diagrams and it seems like there are two needle bearings inside the input shaft. That's the area where I was hearing the noise with the stethoscope. That said noise could very well be travelling.

Attachment 1345113


I ran across this thread of someone tearing down a transmission. It looks like if the countershaft axle is removed (I'm going to have to see how I can keep all the gears on it from getting out of place) then the input shaft can be removed. This should give access to those needle bearings. It should also allow me to isolate the input shaft bearing from the rest of the trans to see if it's the noise (hopefully not for it's price).
https://rennlist.com/forums/928-foru...ml#post4161189

I do plan on removing the input shaft more along the lines of how the guy in this video did though because it seems that the above thread involved breaking out part of the bearing cage unless I missed something. Neither way seems ideal though since it's pulling on the outter race.


My hope is that if I can manage to get the input shaft out without knocking all the countershaft gears out of order or something like that, I can at a minimum narrow things down. Ideally I'd find that it's those needle bearings in the input shaft, replace them, and call it good. If it needs more I'll have to go from there.

Kiln_Red

Didn't realize the bearing for the input shaft was shared with 5th gear. That complicates things a bit from a labor perspective. I've never gone inside the manual gearboxes on a 928. What is the cost for the counter shaft needle bearings?