knfeparty

I haven't seen instructions on Clark's and I haven't seen anyone mention it here. That probably means it isn't possible. But the parts exist.

I have an original tranny in my 89 NA (153k) that the PO let the fluid leak down too far. After replacing the fluid (full of silvery...chrome, probably, but no metal whiskers fortunately) the transmission has quieted down except for that in fifth gear, with the clutch out, decelerating, it squalls loudly. I've seen parts like "5th gear needle bearing" that sound like the culprit. I bought this car to learn how to work on cars, so the fact that it sounds like a huge project just to get the trans in and out of the car isn't a problem. But actually taking the transaxle apart? I don't want to ruin a 90% usable transmission, but at the same time I don't want it to hand grenade on me unexpectedly while driving, which I think would be possible even if I didn't use 5th and it never made noise.

924RACR

Don't be silly, if course it's doable, and parts are readily available.

It's also a very complicated project, worse IMO than an engine rebuild as far as technical complexity. Yes, I'd be concerned about making things worse; that's why I'd suggest you consider getting a spare to swap in while rebuilding at your leisure. Or just rebuild the spare?

Factory manual IMO is required.

Really, the important question is: what's the most complicated job you've done to date?

knfeparty

It sounds like I don't need to do it unless I get a spare tranny. One is out there, but it's a hefty tag to buy it and get it here, and it's from a wreck so who knows if it works? Is there going to be any danger of further damage? The first 4 gears and R work fine.

Luis de Prat

Had mine rebuilt last year when the 3rd gear blew up. Cost around 1.200 Euros to have done, parts included, although it was an easy decision since it's a limited slip. Parts are available but they're extremely expensive.

knfeparty

everything is intact except apparently the bearing for a single gear (5th)
If I did it myself, I would probably replace just that to keep things simpler and cost low

924RACR

From what I've seen over this side of the Big Pond, parts aren't too bad; I rebuilt mine a few years ago, dropping in an LSD as well (with experienced help, of course), got all the bits from EBS Racing.

Mike C.

Really isn't that bad (relatively speaking) if you aren't going to change the ring & pinion. Here's a link to my rebuild but keep in mind that a lot of what I had to do was driven by the need to re-shim the pinion and differential bearings because I put in new R&P gears. See page 3 for photos.

https://rennlist.com/forums/showthre...ission+autopsy

Legoland951

5th gear replacement is much simpler than any other part of working on the transmission. It only requires the removal of the rear of the transmission to swap out 5ths. Many spec guys change out the 5th to the shorter gearset so they would probably be able to tell you where the nearest shop is.

knfeparty

legoland, you just made my day. So all I would have to do would be to unbolt the transaxle from the diff and swap out fifth gear/its bearing, meanwhile leaving the diff and everything forward of that in the car? It goes into 5th fine, so I think the gear is physically okay. Because if that is true, that would be wonderful beyond words. Totally wonderful.

Dave951M

5th is the easiest gear to get to. You'll still want to drop the tranny to be able to get the rear housing off. Call Jim Burton over at Eurowerks, he might have a spare laying around if a local Rennlister doesn't.

knfeparty

A spare tranny or a spare 5th gear? I was going to get the fifth gear bearing from pelican parts. If I'm going to rebuild this sucker, I'm not going to spend money on a whole 'nother tranny unless I happen to find a '89 LSD, which is next to impossible since the '89 tranny was unique. I don't know if I can get the car high enough to drop the tranny out. Can I get the transaxle out any other way, maybe by taking the bumper off or something? I need to replace those shock things anyways, since one got kinda smushed somewhere down the line...

Mike C.

Get a pair of car ramps. This will give you plenty of clearance. As for raising and lowering the transaxle, I would recommend one of those transmission holder adapter brackets for your hydraulic jack. Otherwise, you'll need a helper to heft it....

tifosiman

If you have some decent jackstands (or a pair of ramps as mentioned), you can get the back up high enough. The bumper isn't what is in the way, it is the spare tire well.

Oddjob

153k is getting up there in mileage for a trans, especially if it was not properly maintained (low oil level, probably didnt change fluid often enough, etc).

There really isnt any chrome plated components in the transmission. All the gears and shafts and bearing races are steel, and the synchros are brass - so what you are seeing is flakes from the bearings and gears. Also there are two separate magnets inside the trans that collect the big bits of metal, so thats is possibly why you didnt see "whiskers" in the drained fluid.

The 5th gear set is noisy on the 944 series cars, and its not uncommon to get more transmission noise when in 5th, especially when unloaded - coasting or idling down. The 5th gear set is on the outboard side of the gear carrier (steel transmission case section), covered by an aluminum cap. It is also outboard of the rear pinion shaft bearing. I think for these reasons, there is more audible vibration when 5th gear is engaged.

Also, the 5th drive gear on the end of the pinion shaft is very close to the rear face of the gear carrier. As the pinion bearings wear out, and allow more play in the pinion shaft, its possible that the pinion shaft can move forward enough for the 5th gear plate to actually rub against the gear carrier housing. I have seen this on a trans, there was a wear mark on the gear carrier where 5th had been rubbing against it.

I would not expect the needle bearings to be the problem - those typically do not wear out (but anything is possible). My guess is that your pinion bearings are worn and possibly the big ball bearing on the end of the input shaft (in the alum cap housing behind 5th gear), allowing for some play/movement in the shaft assemblies - which you are hearing in 5th gear.

At this point, before you start buying replacement parts, or spare transmissions, I would find someone knowledgeable with these cars (but someone who is Not trying to sell you something, so probably not a mechanic), take the car for a drive to see if the noise is unusually bad, or if its just the typical 944 trans gear noise.

At some point, the transmission will need to be rebuilt (they dont last forever), but it may not be necessary in the near future.

If you do decide to work on the trans, you will absolutely need the factory service manual, transmission section. No other source will have the info that you need.

knfeparty

Thanks for the advice, oddjob. I've heard that the 944 is noisy in 5th, but this is a really loud squall and there is no way that this is anything that isn't tearing up some metal. I already have some ramps; good to hear that will get it high enough. But I don't really have some place that I can leave it to work on for that long, especially if I'm going to have to pull the transmission apart and THEN order parts, which always takes over a week because I'm in NC and all the 944 parts dealers seem to be in CA. Well I've got someone lined up to drive it. I've been waiting for weeks for my mechanic (we promise fast service, no matter how long it takes) to do the timing belt/water pump, but when that gets done maybe I'll drive it to someone who knows what's what in NC and feels like giving up some free advice. Maybe Jim Burton at EuroWerks or Clark Fletcher himself.