Clunk in driveline

A little background. 67 coronet 500 3834bbl. Engine and trans rebuilt along with 323 suregrip and u joints. All done in 2010, by professionals, installed by me. Beginning of season last year I was noticing a clunk as it shifted through the gears, trans had a shift kit installed. Didn't give it much thought. Greased ujoints checked fluids all seemed good. Noise remains. This year weather was nice. Took it out and noise is worse. Checked diff fluid, low. Pulled third member out nothing out of ordinary found. Reinstalled with additive same problem. Pulled pan on tranny. Nothing but clean fluid. No debri in pan. Checked ujoints when shaft was out seemed ok no resistance found. All mountings seem tight. Worn but not moving. I'm out of things to check. I have a short video but not sure how to post if even possible. One thing I found today while running it was the driveshaft is extremely warm near the tail shaft of trans, but at the differential is cool. Help!

could be a number of things as you know, but seeing you have some heat at the shaft front u joint, any binding/stiffness at the u joint-yoke when you had it out?...is it possible the driveshaft is too long/short?, how much fore to aft engagement of the yoke into/out of the tranny tail shaft/spline?, 3/4" is about ideal...how much spline of the yoke is in the tailshaft?

I thought about that, but I've had the car for about 10 years and haven't changed anything. I didn't notice the clunk until just recently. I didn't find any binding or resistance in the front or rear joints. It make the loudest noise when shifting to second gear around 20. Isn't is a duffle shift where second is a clunk and the drivetrain jerks

Just to add, when if first started it to check the new fluid, I didn't seem to feel it so I though it was the problem. But as it got warmed up it it was there.

Although you mentioned the front of the shaft was "heated/warm", may just be heat transfer from the tranny, exhaust?...

Have you looked at the converter/flexplate bolts, inspection cover for any signs of contact?

Sometimes we make changes that we think have no effect on problems, and neglect to mention them when asking for help, have you made any suspension mods? a different pinion yoke perhaps? transmission yoke change during the rebuild? I'll assume you checked the rubber tranny mount?

I haven't changed anything. I pulled of the inspection cover because I though I had a drain on the converter. Looks as clean as when installed.

Did you turn the driveshaft by hand to narrow down the location of the noise?

Did you try to push up on the rear of the trans to see if the mount is separating?

Did you look around the trans tunnel, fore and aft, to see if there are any witness marks? Do the same with the exhaust.

Inspect the rear suspension as it make be the source due to loading and unloading as you shift.

Get someone to hang their head down low out of the passenger door to hear where it's coming from is my best suggestion, narrow the location down.

Sounds like a u-joint or a mount.. but could it be from an entirely different untouched part of the drivetrain? Anything like play at the drive axles, wheel bearings, anything like that?

Not sure I'd be too distracted by what's warm vs cool - both ends of my driveshaft definitely get warm during a drive.

- Art

Don't overlook your motor mounts, especially the rubber biscuit mounts that came on the '67's. Here's the easy way to test them. Open your hood and start your engine, you should be able to see the engine or air cleaner through the gap between the raised hood and bottom of the windshield. Now put the trans in low gear and power brake the engine for just a few seconds. If your left side motor mount is bad you will see the left side of the engine raise up a good bit from the torque. Now do the same thing in reverse and watch the right side. I've seen them so bad the engine torques until the exhaust bangs off the floors. The rubber insulators will appear good until you put the torque to them, give it a try.

I would pull the shaft & check that the front yoke/ ujoint moves smoothly back & forth in both planes. pull the rear ujoint caps & how much end play the front yoke has into the trans (I like no more than 3/4"). extension housing rear bushing play. If all good I would swap in another pig (non sure grip/any ratio) what ever you have laying around to confirm/elim that. is the backlash OK on the one that is in there?

Driveshaft turns with no problem. Trans mount is good. No movement nothing seems to move except when it shifts second you can see the diff move as it clunks

Motor mounts are good replace them when I did the motor. Used Schumacher mounts.

I will pull it out again tomorrow and check. I really appreciate all of your ideas and suggestions everyone, I have a short video, can it be posted on moparts

Moves how? yes you can post a video (not sure how but others will help you).

I think if you could see it, it might help narrow it down

Try e mailing it to fmd@twc.com and I will see if I can post it for you if you want.

Did you check backlash on the rear-end? If the ring gear is set wrong or has a lot of wear it will clunk. You can do quick check by unbolting the driveshaft from the pinion yoke and see how much play is in the yoke. It should measure between .006 to .010


I'm getting a clunk on my D200 when it's put in reverse but haven't had a chance to look at it.

Ring and Pinion specs

Just a quick update. Pulled the driveshaft checked ujoints again. Small resistance but. Ow grinding found. Greased and reinstalled. While in neutral, rotating driveshaft back and forth I hear a clanking in the tail shaft section. I know the rear springs are worn so I put c clamps on the leafs to simulate load in the car while driving, but that didn't help( cars is off ground). I hear the clunk noise in the car on passenger side, and sometimes while shifting from drive to reverse.
Something else I just discovered, while rotating the passenger side wheel back and forth I get some play before the drive will turn and hear gears meshing? Drivers side is not so pronounced. Is this normal? Trans is in neutral

That is what Sherlock Holmes, Lieutenant Kenda and Columbo would (likely) call a (serious) clue(s). The clanking sounds real serious & I think that is what you are hearing when it shifts, if you can hear it now with what you are doing just imagine what is happening when the load is released on a shift. & thirdly the ujoints should move SMOOTHLY in there plane of travel (both ways in front yoke) back & forth.

I agree with you. So what would you do next? I'm at a standstill right now. Short of pulling the trans out and having it rebuilt or tore down to see if it's the prob. Or again pulling the third member out and have that looked at. Frustrating. Should you hear a gear noise when rotating the tire back and forth. Is it also normal to hear a noise out of the tail shaft area on the trans while rotating the shaft back and forth. Things I don't really have much experience with. Is it possible to post a video on moparts?

If you upload to YouTube and create the video there, then paste the link here...
- Art

If you are talking about the diff case, "play before the drive will turn and gears meshing" - then this sounds like what my diff felt like when I thoroughly checked my drivetrain for a clunking grinding sound this summer and nothing was wrong with the diff (my prob turned out to be the pass side rear wheel bearing, just FYI).

As mentioned by someone above - If you grab the rear wheel and you can move it up/down or front/back, then you might have a bearing problem there, not related to your tailshaft noise.

Best,
- Art

rear wheels off the ground/in neutral either bearhugging a wheel & rotating it forward and backward how much play are you estimating you are feeling/hearing in the rear end? further up .006-.010" was posted as a normal "backlash" dimention or just grab the pinion yoke by hand & rotate it back & forth. Up front I ain't a tranny guy but I would do the same thing & others will advise further & didn't we cover checking the ext housing bushing wear? I ain't thinking the ujoint(s) are causing the clunking but if one or both of em are binding/not moving smoothly they will wear out fast (you said they were a bit tight but no looseness correct?) & then clunk. this might be a combo of the R&P backlash and something going on in the trans but from prior I'm leaning (barely) toward the trans. post that video with good sound & keep the ex noise out of it as much as you can.

With the car in the air, grab the front driveshaft yoke at the front u-joint and see if it will move up and down inside the trans end. Any up and down movement of the shaft inside trans is too much and indicates the tailshaft bushing is bad.

Onto the rear end. Hold, or have someone hold the tires from turning, trans in neutral, see how much the driveshaft can turn in both directions before it is stopped by the wheels. How much can it turn, total of both ways?

One more thing you need to check on the rear end. You stated you could hear a noise on one side of the car, On that side of the car, put a socket with a ratchet on the U bolts holding the axle to the rear end and see if the u bolts are loose. The torque on the u bolts is not very high, but the nuts should at least be snug and resistant to tightening. Looks u bolts will let the rear axle rock on the spring and give you a clunk. If they feel loose, look up the specs and torque all the nuts to spec on both sides.

Let us know what you find. Gene