captainOCD

I didn't run the motor with the driveshaft disconnected because I can hear the noise just turning the driveshaft. There's not enough room to slide the driveshaft all the way out of the transmission without dropping the clutch, so I guess that's what I'll be doing next to isolate it to just the torque tube to isolate as Greg said. I can also feel a bit of play and even hear a slight clunk when working the end of the driveshaft up and down.

(Note this isn't the normal position of the driveshaft, it's pulled partially out of the transmission.)


I'm gonna have to take some more stuff apart to tell for sure, but so far it seems likely to be these bearings I bought being junk.

skpyle

Ouch, that hurts.

Keep on going, what you are doing is worth it.

captainOCD

Redoing stuff sucks. At least now I can replace the leaky trans input shaft seal I forgot to before.

belgiumbarry

perhaps a stupid thought , but i assume you have to align the bearings all in the same direction , so entering the drive shaft you can't move a bushing or bearing ?

captainOCD

I got the torque tube pulled (which you can do without removing the clutch or front bellhousing it turns out). There's still a bit of looseness to the driveshaft, but the noise I've been hearing is definitely coming from the transmission.

Driveshaft engaged with the trans, then pulled out from it (you'll see where it spins more freely).


And turning the input shaft to the trans. Trans in neutral. No slop in the input shaft.


So I guess I'm kind of at a loss as far as where to go from here. The trans shifts great with no noise, crunching, or grinding, so apart from whatever bearing is making noise, it probably doesn't need much. It's probably something that can't be determined without taking it out of the car and looking at it more closely, but I'm going to go ahead and guess that it probably isn't going to be something easily accessible.




Yep, that's how you have to do it.

Kiln_Red

Shake it off. You've made lots of progress on a pretty short timeline. It shouldn't be too much of a surprise to have some kind of issue after an invasive project such as this. To some degree, the parts themselves were unknown commodities. Now you know what you have and there's a lot to be happy about.

It sounds like a transmission rebuild may be in order.

GregBBRD

Well, those bearings are way too loose on the torque tube shaft....no way you should be able to pull the shaft back and forth with two fingers. The shaft moving inside the bearings makes a differect kind of problem....a harmonic noise as the shaft flexes and turn into a "wave" under load, allowing it to move inside the sleeve inside the bearing.

Do yourself a favor and buy a set of Constantine's bearings, which are currently, the only solution. (Be sure and put the damper back in.) 928 International has some great looking new bearings, but they are too loose for a manual transmission shaft. Hopefully Mark will be correcting this, in the near future, and have a more cost effective replacement part than Constantine has.

That's a noisy transmission, no doubt. Hopefully, it's "only" 5th gear bearing that is bad.

Porsche made a different bearing for the '85/'86 model transmissions, with bigger ***** and a larger OD. The outer race is also "thinner" which can be a problem (see below.) It's a much sturdier bearing than the '78-84 transmissions had, so I bore almost all of those transmissions to accept the larger, bigger, more stable bearing.

However, it is very common for the '85/'86 transmission cases to go "out of round" and "pinch" the larger, sturdier, but thinner bearing, which will distort the bearing and cause bearing noise/failure. This is pretty simple to determine if it is an issue, when the transmissuon is apart. Simply install a new bearing onto 5th gear and install it into the case. If it sounds like the bearing in the above video, it needs to be repaired. (Which is difficult to do.)

Constantine

Three Super Bearings were designed to replace the vibration dampener and are very affordable for their benefit over any other solution. They were over-engineered for their given application at the beginning and have been constantly refined.

Adding in the old vibration dampener, even with new aftermarket rubber holders, is adding a potential problem back in for no reason.

Been doing this for about 20 years now (how time slips away) and no problems with them.

Unfortunately when owners try other methods, this is usually the result. The TT is a bit more complicated than most believe.

captainOCD

I didn't think much about the driveshaft being easy to move before, but the looseness I can feel now does have me concerned.


As for the transmission, it's out now. I didn't really expect to be able to visually see anything wrong and indeed didn't.



Poking around a bit with a stethoscope in places I could get it (not the shaft down below, pardon the redneck speak) it seemed loudest near the syncro near the input shaft, but the bearing pressed into the case at the input shaft looked fine and I was not able to hear any noise with the stethoscope on the race of it.



Otherwise, the internals of the trans all still seem in good shape. My untrained eye didn't see any unusual wear on gears.




Going from input to output end.












So I guess my question towards those who rebuild transmissions, cough greg, looking at the pictures and assuming it does just need some new bearings, how big of a bill is that to get done? I've seen people throwing around numbers like 3-4 grand for a trans rebuild, but I get the idea those are in worse condition than this one is.

Constantine

Matt,

Did you have the noise before you rebuilt the TT and replaced the TOB?

If not, would concentrate on reviewing both those areas again.

The drive shaft should be tight inside the TT bearings. Delrin inserts is a very poor method to rebuild TTs and this is one problem with them.

A loose drive shaft in the TT is a bad problem and could result in damage to the clutch and the drive shaft at least.

captainOCD

I only had this transmission and torque tube in the car for a week. It was an auto before that.

GregBBRD

The "average" rebuild runs between those two numbers...sometimes less (rare) and sometimes more.

It's all about parts. You don't have buy too many $450 5th gear bearings or $200 synchros to get the cost up.

Kiln_Red

Matt,

From the other thread, didn't you mention a 90-day warranty?? Time to cash in?

captainOCD

There is, but I paid $1800 ($1900 ish with tax) for all the parts (trans, torque tube, clutch, pedals, etc). So even if I took the trans back to him and he said it was worth $1200 of that (he didn't break down the stuff by part) I don't think I'm gonna find another one of these transmissions for $1200 that doesn't need some work done to it.

captainOCD

Something I was thinking about last night, and perhaps this is what you were getting at Constantine, is this even an abnormal sound/noise to hear from the transmission? This is the first time I have really looked at the internals of a manual transmission (quite different from turbo 350s I've worked on with my dad).

The gears meshing definitely isn't going to be silent, is this just normal gear meshing I'm hearing that was being amplified by the torque tube due to these bearings with delrin sleeves? I know noises travel and make them hard to track, but when in the car the noise never sounded like it was coming from the transmission, always from the torque tube or bellhousing (using a stethoscope).

Here's another video of spinning the transmission. In neutral, then first, reverse, and last fifth. Oil has been drained from the trans.