Trans started slipping between 2-3 last night and after draining some fluid out, found it dark and somewhat milky. So pulled the whole pan and found a good amount of medal debris / shavings. Was rebuilt just under 2 years ago and has just over 6k miles on it at this point.

Any thoughts if a fluid and filter change will be enough to remedy the slipping issue or am I outta luck on this build?

 

Oh man that doesn't sound good or look good.

My fear has always been having any part of the powertrain rebuilt and it going bad in a fraction of the time that the factory components lasted.

Two schools of thought on the fluid replacement. Replacing fluid can hurt the transmissions operation on well used ones. Or have no negative effect at all. But thats in regards to long term usage. Under 2 years and 6000 miles is a different story. However the damage seems like long term usage. My gut tells me changing the fluid will kill it completely... Hope i'm wrong. Would be awesome if you have a long term warranty on it...

 

Well the old fluid's out and I'm waiting on a new filter to put the pan back up with new fluid. I'm already resigned to it being likely toasted, for whatever reason.... And unfortunately, though built by what was indicated to be a good local shop, only 12 months warranty. I'll be contacting them just the same, but not expecting much of a response except 'outta warranty, outta luck"...

May throw some Lucas slip-fix into it just to keep it mobile long enough for a run to whatever shop I select next.

Soooo, yeah...

 

Understandable.

Warranties usually seem to work out that way, close but no cigar... Great that you are assuming the worst and hoping for the best. It minimises the pain and annoyance. And definitely try all the supposed snake oils. They work, 40 years of driving for me and loving the oldies I have tried plenty of them. If they don't work, things are just too far gone.

 

This will give you an idea of where the problem is.

 

You won't make it worse by putting in fresh fluid and seeing what happens. That's not a horrible amount of material, but that is a lot of shavings. My rough guess is a bushing or thrust washer is getting chewed up - usually either bad clearances (which should kill it pretty quickly) or fluid flow problems. Double/triple check you fluid cooler to ensure it's not clogged. I always run a filter on the return line from the cooler - the black magnafine filter is awesome and available under several brands (e.g. Raybestos), usually under $30.

 

Are you still in contact with whoever rebuilt it?

 

The current trans just has the stock lines running into the radiator, no separate cooler or filter. It's been in the car just under 2 years with just over 6k miles. The shop who built it is a local family-owned place and generally appearing well thought of in terms their expertise. But their warranty is 12 months, so I'm not expecting any remedial assist on their dime.

Flushing the cooler lines will be a absolute at such time the trans gets redone (or just outright replaced) and I guess I'm in for another converter as well. I might subsequently plumb a filter into the mix going forth.

GS thanks for the attachments - I'll check 'em out.

 

Have you read the line pressures?
The line pressures are an immediate way to pin point the circuit leak. A slip is more or less a leak.
If that's planetary, support, friction/steel or torrington etc shrapnel, no amount of snake oil or fresh fluid will fix it.
Read the line pressures.
Is the drive shaft the right length?

 

Agreed as to there not being a snake oil fix in its future - something's destroying inside so it needs to come apart for any real fix to be contemplated. Old fluid's dark-ish and a bit milky with visible glitter, so it's done.

When this happened, the car also suddenly wouldn't idle in drive anymore - hoping to temporarily get that back so maybe I can at least get the car to my local trans shop under its own power.

I run an aluminum stock diameter driveshaft that was built locally a few years ago using the prior steel shaft for a size template - the steel shaft that came before it was made by the same shop in 2017, in direct duplication from the OEM driveshaft I provided back then for it to be patterned from. The driveshaft had never been an issue that I know of but I do recall the trans installer commenting he thought it should be about 1/2" shorter to give the yoke a bit more play on the tail shaft (although no fitment issues specifically indicated). I'm not currently aware of it bottoming out on anything inside the tail shaft that might be causing damage.

Pan's off and old fluid drained, will get it back together by week's end hopefully for further eval.

 

Perhaps not, but it's still a pretty low-mileage failure. If the shop wants to maintain their good reputation, they should be willing to at least take a look at it -- if nothing else it could help point you down the right road.

 

If the driveshaft can be installed without monkeying around with the rear end then it's not too long. Too long and the driveshaft can push into the trans output shaft when the suspension compresses (rear end generally gets closer to the trans as the suspension compresses) causing bad problems. The driveshaft should never put forward/backward pressure on the output shaft.

If that radiator is very old then the cooler circuit could be messed up or have trash in it. Definitely need to clean it out whenever replacing the trans. The trans cooler line is relatively low pressure (certainly under 50 psi, probably around 10-ish?) so it's normal to cut the return tube and splice in a filter with some bits of rubber hose and hose clamps. Putting a little flare or bubble on the line adds an air of professionalism but isn't strictly necessary.

It's absolutely necessary to rebuild or replace the converter whenever there's trash found in the pan. There will be a similar amount of trash hiding inside the converter waiting to kill the next trans.


Does it also slip in reverse? If so then the direct clutch is dying.

 

Yeah, that's the tough part - if they agreed to look at it but not rebuild it under warranty, I'd see no immediate point to bringing the car back to them for anything. Once it was apart again in their shop, then I'd essentially have no choice but to go another round with their work, which if it was faulty, wouldn't inspire my confidence in their repairs.

I do plan to stop by there to let them know and see what they say, but not holding my breath there'll be any offer of a gratis repair if determined to be their work product issue.

 

Rad is a newer Be Cool aluminum unit so I'm good there. I don't recall any driveshaft fitment issues with the car being essentially on the ground / all 4 wheels but I plan to recheck that once I get the pan back up on the trans, to measure the yoke clearance extending from the tail shaft and whether it's bottoming into the shaft before clearing the rear yoke for install. It was essentially patterned directly from the OEM shaft I pulled from the car when I first bought it in 2016. The OEM shaft was a 2-piece unit which I presumed to have been original to the car based on fit and aged appearance appearing in context to the rest of the chassis components.

I'm running the same size wheels and tires all around, so no substantial front to rear imbalance issue that would be seemingly causing shaft angle or mount issues.

And I will definitely be replacing the TC - not worth banking on a flush to clean out old debris.

 

As far as drive shaft length goes trust BUT verify before running it with a fresh trans.

See Dennys measurement diagram:
https://www.dennysdriveshaft.com/p-3...o-measure.html

I had the same situation with a new shaft made to replace the two piece out-of-phased OEM.
Then I was hunting down a vibration and found that shaft had excessive run out.

The third shaft was made too long and took out the number matching TH400.
Denny whittled me a brandi new aluminum shaft to go behind the rebuilt trans.

The internal destruction from the oversized shaft was significant. I came real close to destroying the "numbers" case.

 

I've actually been reading up on that a bit tonight - while I don't have any noticeable speed vibrations (I rarely run the car past 80 mph, typically no more than 75) I do want to closely check the DS further once I get the pan back up and all 4 wheels back on the ground. Then I can cleanly measure the c-to-c as well as the front yoke spacing between the points of fully bottomed forward within the tailshaft and residual room left after installing the DS into the rear yoke.

I've read that if the visible front yoke surface length measures between 3/4" to 1" after the DS is fully installed, then it's properly fitted...

Will have to see how that goes.

 

So, interim update - I replaced the filter and fluid after the pan drop - at least for now the car idles properly again and shifts thru the gears without issue parked in my garage. Have not road tested yet as I'm saving that for the trip to a different local trans shop I trust more to check it out further. They're looking to get me in sometime next week so until then I'll stay parked.

I also took the driveshaft out for review and decided based on its fitment measurements that having it shortened 1/2" would be a reasonable adjustment to give it more mounting clearance between trans and rear, in addition to more yoke movement flexibility room up front behind the trans. Reinstalled that today and happy with the adjustment.

Still prepared for ultimately bad news but at least for now all in one piece again

 

About the driveshaft maybe being too long... I had a vibration, in my '71 Cutlass Turbo 350.Rreplaced the U joints and found ATF leaking out rear seal, when removed I found yoke and rear bushing was worn. Replaced the rear seal and bushing and yoke. I found that every yoke I could find was 1/2 " longer than the original one! Everything else was fine for dimensions but it was 1/2 " longer! Maybe that is why your set up is too long? I looked and looked and never did find a yoke like my worn original- (or was it original- I can't say for sure!) I ended up putting it together by setting the joint together with out caps and then sliding on caps. Now I have maybe 1/4" clearance when rear end is at ride height. Seem to be OK since was done about 4 years ago, but I don't like it.

 

Yes - that was exactly the issue on my current aluminum driveshaft - 1/2" longer yoke length than the one on the steel driveshaft that they built for me back in 2017 in duplication of my original one.

The yoke on my steel driveshaft was newly installed at that time, so possibly between then and now they became unobtainium (or maybe they already were even then and my local shop simply still had one left in stock)?

 

Yeah maybe you can get a original used one on here and not have to shorten driveshaft, if you think it is a problem. Not sure about if mine is OK or not, I'll be following, thanks for posting.

 

I ultimately had the aluminum shaft shortened this week by the local shop who previously made it for me - it's now 1/2" shorter than before in identical overall length match to the prior steel shaft I still have packed away from the swap.

Now a seemingly perfect overall fit to the car as was the steel shaft. So now just working on getting my car into the trans shop in the coming week for a teardown.

 

The more you drive it, the more destruction will occur. Have it flatbedded.
You could save the trans case and or expensive hard parts from rapid unintended disassembly.

 

Much appreciate the thought but It's a 5 mile drive on all low-speed local roads so I'm just gonna roll the dice at this point. My preferred shop guy that I'm going to has another BOP TH350 on hand if needed for core parts or a total swap out.

I did have the car flat-bedded home the night this occurred and kudos to the AAA driver for their great service aside, still not my first choice for this subsequent limited distance run. Going in Monday for the autopsy, which works out well since I'm off work for MLK Day and can hang there as needed.

 

Don't know if it matters to you, but putting in another trans will not match #'s of course. Don't know if yours is the original anyway. My Olds doesn't have the #'s matching trans, It is from a '73. Prolly was a rebuilt unit for a quick fix back in the day...

 

Nope - matters not. Just a CS that had appeared to have already had a trans replacement at some point in its prior history - I remember figuring out somehow from internet searching the numbers that it might have come from a '71 Buick vehicle, probably just a shop swap from decades before my time in the car.

 

Yup. It was a rude awakening for me 20-some-odd years ago when the shop's "rebuild your trans" actually meant "grab one from the pile of pre-built cores on the floor that looks like it'll fit".