348 Transaxle

Hi Brothers - In the last couple months, I've read many threads on the topic of 348 gearbox problems, and reviewed a couple of the main ones today. For those who haven't seen some of my posts, I purchased my 348TS in January, and although the gearbox was in good shape, the mechanic mentioned it was "developing some of the usual noises" during the PPI.

A friend and I can hear a very slight amount of whine at times at very light throttle in upper gears, and since I'm doing a preventive major service now, I want to check and correct any gearbox problems now also. I drained the oil, and didn't see any real evidence of metal, but that was just from an initial look.... no magnetic plug in the case. I want to confirm some things and ask some questions after reading the threads on the topic. Hope FatBillyBob, Ernie, and others can comment...

From posts, it seems a big problem are the 4 side (maybe just 2 on one particular side) ring nuts/bearings, with ring nuts coming loose. In the manual, these seem to be parts 22,27,48, and 51. Seems that I should check bearings at each of these points and then tighten and stake the ring nuts. What torque to use on the ringnuts? Any other cautions to be aware of?

Also, I see 2 other ring nuts listed in the manual... 17, and 90 (I think that's all of them). Have these ring nuts also been found to be a problem? I guess my plan is that if I find no signs of real problems in the gearbox, to just remove ring nuts, check and replace bearings if needed, then torque and stake the ring nuts. Then just drive it unless other signs or noises come up in the future. One thing I have never done on a vehicle is gearbox or gear work. Any other recommendations on doing this?

A previous neighbor and Fchat member used to track his '89 348 a lot, and had 2 blowups. He ended up having it rebuilt with 355 parts (not sure what parts), and no more problems. Anyone know if 355 box bearings are a replacement for what we have in the 348? Any other experience with retrofit of 355 parts in the gearbox?

Thanks.. since this may be a critical path if parts are needed, I want to get a start on this. I'll also, of course, be checking the clutch (dual-disk), triple seals, and servo/bearing. I appreciate any help!!

 

Forgot another thing I wanted to ask... the subframe is out, and if I do remove the gearbox, it seems that the engine is only supported on the subframe by the 2 engine mounts. Is the engine balanced well by itself on these 2 mounts? Seems the gearbox is a stressed member, and I don't want the engine to tip, or overstress the mounts (especially with the price I've seen posted here). I guess I could just use wood blocks with a stand or something to support the rear of the engine. I just want to make sure I know what to expect when removing the axle. Thanks again.

 

Based on what I've read in most of the major 348 gearbox threads, I wasn't sure if the factory staked any of the ringnuts at all. But
when I removed the covers on my gearbox today, here's what I found... all nuts tightened and staked.

So does the factory stake most of these, and is it just some unlucky owners who have unstaked ring nuts?
Mine's a '92, VIN 90690.
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Didn't see any metal when I drained the oil in the gearbox, and inside it looked really clean! Found a few metal specs in the strainer, and they were magnetic, so were steel flecks, and I suppose are gear wear surface flecks. I'm not a gearbox expert, but it seems to look pretty good to me overall Interested in any input from those who have seen a lot of these boxes... Thanks.
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I have a question on the gearbox oil pump, which I haven't inspected yet. I seem to remember that there was a factory oil pump upgrade at some point, and also the oil pump bearing has been mentioned a lot here. Any details on what I should expect to find, or be concerned about on this pump? Thx. again.

 

Hey- thanks Daniel! Actually, I have read some threads saying that 348 gearbox failures may be due to the "oil pump bearing"... and I was thinking it was upgraded at some point. Anything to watch for there? Seems too simple to really be a problem, though.

Thanks for mentioning the engine oil pump, though. I did want to check the tensioner there, since I've seen threads showing disasters from it failing. Are the new tensioners pretty bulletproof? I'll take a look at it all when I get back to the front, and post pics and Q's then.

PS - I saw the thread about your gearbox blowup. Sorry that happened

 

I'm hoping since mine seems in pretty good shape at this point, that I can just watch and listen close for any developing problems, and catch anything before anything really expensive happens... not that any work on the box will be cheap. PS - I also missed a shift once in the past 3 months since I owned the car. Was loud, but I hope using the Redline NS will help ease shifting so that I don't have to feel I have to force things before my foot automatically eases off the clutch. The RPMs drop off so fast, also, that it's hard to keep revs up to aid in shifting ... since consensus seems that it's best to shift at higher revs.

If you do rebuild a box, would be great if you could make a "How To" and post on club348 site.

 

Thanks Pap! I guess the nut staking WAS done at the factory. Anyone else find theirs staked the first time they were opened?