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Clunk in the rear

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MarkA

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I have had this clunking in the rear at each wheel when the direction of torque changes. It shounds like it is comming from the area of the drums. I thought that it was worn hubs. So I did some work to the rear of the car since it really needed it for other reasons.

Well, now I have new Daytons, new hubs, new knock-offs, new lug nuts, rebuilt rear end (all new bearing and seals), rebuilt shocks, new shock links, and some new paint (the new paint was for speed!). After all of that, I still have the clunking when reversing up a hill. It is never both sides at once. One side usually follows the other.

I did not replace the radius arm bushings. Will they make a clunking sound? The only other thing I can think of is something wrong with the spider gear assembly in the diff or worn splines on the axles.

What do y'all think?

Mark
 
Excess lash in the spider gears is certainly a possibility...

Are the U-bolts that secure the axle to the leaf springs tight?
 
The u-bolts are tight and all of the rubber is new. It does seem that the inside wheel clunks before the outside wheel when backing and turning at the same time. This doesn't always happen when backing and it does happen when moving forward and changing speed abruptly (stomping on and off the gas). I had the diff rebuilt by a guy who knows British rear ends (he is a dirty old man!) and he said that everything was in great shape and gear lash was set perfectly. But since every morning starts with a backing out of the garage and back up the driveway a bit, I hear it all of the time and it is driving me crazy!

Mark
 
Well Mark, Did it clunk before the diff was rebuilt??--Keoke
 
Yep, the clunk was there before I started any of the work. I really thought it was worn hubs and/or wheels. That was the main reason for new wheels and hubs. I rebuilt the diff since it was howling so much. I change the rear axle bearings since I found they were worn when I was removing the diff. I had the shocks rebuilt since they leaked faster than I could get oil into them. I replaced all of the rubber and bushings since I was in that neck of the woods.

I was really hoping that this clunk would have gone away! I guess I could next fix the radio and just keep it turned up...

Mark
 
Before I go too far, I am going to try something I should have checked before posting... I am going to back off the knock-offs a little, set the parking brake, and check for any lash in the hubs by trying to turn the wheels by hand and by pushing the car back and forth. Even though the hubs and wheels are new, you never know!

Mark
 
Are you sure that the axle really is attached solidly to the springs. Brackets solidly attached to the axle, U bolts tight, spring center bolts intact?

Also front of spring eye bushings & mounts in good condition & tight?

Main spring leaves intact, not broken?

Radius arm bushings & mounts very solid on both ends?

It sounds like the axle housing is moving in relation to the chassis or springs.

It could even be the shock mounts or link anchors being loose.
D
 
Well Mark, Dave listed a bunch of things to check. Also have a good look at the universal joints if they havent been replaced. If the noise is in the diff, you can simply jack up the rear end and gently rock one wheel back and forth . You will feel the play and can hear the clunk.---Fwiw--Keoke
 
Hi Mark,
Just to eliminate things, maybe check the truck for loose items. Battery & tray, spare tire, screw drivers etc.
 
Mark,
Since you seem to have a BJ8--have you unbolted the radius arm bolts and checked the holes in the axle brackets and in the forward attachment points?

I was at Kurt Tanner's shop a while ago looking at a pre-restoration car and these holes were worn into ovals in both cases. I remember this because I was taking pictures for my own project of adapting BJ8 radius arms to my BN6.

SteveG
 
The radius arms are the only thing I have not changed out. I was kinda thinking I should at least check them. I will look at them today.

Mark
 
I has a simliar noise and after changing lot's of parts,...it ended up being a U-Joint.
I replaced them both.
Patrick
 
Hi Patrick,

I did replace the U-joints with all of the other work. The noise is comming from each side of the rear axle.

Mark
 
I measured the backlash in the wheels. With the knock-offs lightly snugged, I can move the wheel 1/16" as measured at the tread of the tires. Is this normal for new hubs and wheels? I thought that it should be tighter than this.


Mark
 
This 1/16" at the tread would translate to much less at the splines. I would say that it is well within the acceptable range.
D
 
Although it doesn't necessarily sound like if from the description, are the shock mounting bolts loose, they tend loosen up over time. Although I think with this you would get he noise more over bumps than start/stop.

Wire wheel hubs bolted down tight as well?
 
Everything is tight with new hubs and hub bolts. I just got the entire rear end, including suspension, put back together a month ago with everything new or rebuilt, except the radius arms. I noticed today that I do get the clunk when going over large bumps/holes in the road. With the original/old wheels, the clunking is much worse which leads me to think it is backlash in the splines.
 
MarkA said:
I noticed today that I do get the clunk when going over large bumps/holes in the road. With the original/old wheels, the clunking is much worse which leads me to think it is backlash in the splines.
Click to expand...
If it were backlash in the splines, it should be easy enough to detect. If you keep a very slight throttle on when going over the bumps, it will remove the backlash in the splines & no clunk.

I've never really had splines so loose that they would cause a klunk when going over bumps.

Loose shocks will rattle when going over the slightest bump.

With some springs, if they have double wrapped ends, the overwrapped eye can fit loosely enough to cause an annoying rattle on light bumps.

You earlier said that it was particularly noticeable when backing up a hill. This would put reverse torque on the axle locating parts. Thus I mentioned the radius arms & possibly front spring eye bushings.

You have my sympathy. Clunks/rattles underneath can be very hard to locate since it only happens under actual road conditions.
D
 
May I suggest you take the rear seat pans out and have someone in the passenger side see if they can pin point the location of the sound better? I've done that before to comfirm loose shocks.
 
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