Strange drivetrain noise in 95 RMW Help!

Hi there, new member of the forum but have been following for years. This summer my beloved 94 Caprice wagon blew her transmission, and after a long attempt to repair it, I gave up and bought a 95 RMW to replace it. Car has 101xxx on the odometer. Engine runs strong (LT1) and the transmission was suppossedly rebuilt, but I'm not sure about it. It at least has clean unburned fluid and an aftermarket TCI trans pan. The problem is that it makes a terrible "racka tacka" noise when the drivetrain is unloaded, mainly when coasting. It wont do it right away on a cold start, but after a trip around the block it starts to make its calling.

I replaced the driveshaft with a known good one (which has almost brand new u joints), checked the torque converter bolts, lugnuts, and heat shields for looseness. one heat shield has one bolt missing (sheared at the joint) but doesnt make a noise anywhere near this when moved. One muffler has a large hole in it (hence why it is so loud) but I secured any loose metal inside the muffler. Next step is probably to check the rear end oil level as the pinion has a small leak, but it doesnt sound like a typical rear end noise to me. This is driving me crazy, and I cant get it in the garage for another week or so, so I have been laying under it in the snow trying to figure it out. Not fun.

It only happens when warm(ish), speed is above about 20mph, and coasting or braking. I can sometimes make it hold the noise by matching the engine speed to the car's speed. Any ideas? Please?? Thanks!!!!!

Here is my YouTube video:  

https://www.youtube.com/watch?v=B4eJwVQ6p9A

1. Check rear end fluid.
2. Replace mufflers.
3. Get back to us.

Will do when I have time. I have a video, working on how to post it, as it appears I have to reduce its size to attach it, and per forum rules I can't post the link to YouTube for a week. its out there as "Strange Drivetrain Noise in 95 Roadmaster Wagon" on the Youtube...

https://www.youtube.com/watch?v=B4eJwVQ6p9A

Thanks guys

Garrett I edited your post and inserted your YouTube.

Tom

I had a problem with the trans shuddering when I was at a steady 45-50 MPH, and other steady speeds as well. It made the whole car shudder, like the engine was detonating. I got a tube of anti-shudder (yes this is for real) from NAPA, and it instantly fixed the problem. It comes in a small red tube, about 2 oz., and was about $10.

Awesome thanks Tom! I suppose it could have something to do with a shudder, but the car seems to ride smooth, just noisy. Did yours make any noise Fred?

Planning on getting under the car today if it warms up and possibly putting it on jackstands to see if I can replicate the noise in the driveway. Will let you know how it goes.
Thanks guys

Garrett

It probably would be a good idea to put your location in your signature.

Tom

Quick update: ran the car with the rear end in the air, and holy cow it's so much worse. sounds like a metallic jackhammer, will probably take a video soon. It is definently coming from the rear end, and sounds loudest at both wheels. I checked the rear end fluid and it was actually quite a bit high...not sure how that was even accomplished. Perhaps backlash or worn axle shafts? the play on the pinion side doesnt seem much different than my old caprice wagon which had 215xxx and no noise. may have to pop the cover off for this one.

Mine would rattle when I applied just a little throttle at about 45-50. It would also do it at up to 70-75. I thought it was the lockup clutch, but a friend of mine suggested the shudder stop, and it worked.

seems I found the issue...retaining pin for spider gears has been rattling around....lets see if the pics work

What a wonderful nasty/smelly job. Glad you found the issue though!

-Mike

That is almost as ugly as it gets. I have never seen anything like that before.

Now is the time to build a bullet proof rear. What ratio is it?

True track and shorter gears...or you can get one from the junk yard and just swap them.

Junk yard...cheap...rebuild...not cheap, but good.

Would have to check on ratio, but am almost sure it is a 2.56...anything else is somewhat rare in these things. I still have my 94 caprice wagon I might swap axles with, as there is nothing showing up the the local junkyards for a complete wagon axle....given this is my $950 soon-to-be daily driver, not really planning on throwing a bunch of money in it haha. If i find a good 91-93 wagon axle with a 3.23 or similar I might swap it in....the hunt begins...

Welcome to the site. That rear looks pretty awful, You could get away with just swapping the carrier, but that can be a lot of work. Luckily 8.5" 10 bolts are stoopid common, just not in wagon configuration.