Troubleshooting help: Clunk during braking

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Looking for diagnostic help. When I brake, I get a clunking (or slight popping) with a frequency of about the tires turning. I'm 90% sure its coming from the rear axle. Its more prevalent with light braking. The truck has a recent rebuilt rear diff (I did the pillow block and it might have been tight), new OEM drums, new-ish brake cylinders and pads (Cruiser Outfitters, IIRC), new leaf springs and u-bolts (RuffStuff).

I took the tires off a bit ago and looked the brakes over, everything looked ok, and again adjusted them. I know my driveshaft is worn, so I pulled that and went driving. The clunking (only during braking) remains, but I can feel it slightly less. I attribute that to the drivetrain not transferring the noise. That eliminates the driveshaft and transfer case (I think). The u-bolts are at a steading 100 ftlbs (weight off axle). So I don't think the axle is shifting on the new springs. The truck drives fine so I tend not to think diff. Nothing leaks (either brake or axle fluid) nor is anything contaminated with oil. The rear brakes are adjusted using the factory procedures. Fronts are disks.

The only other "odd" thing with the rear brakes is if I spin the wheels, they each drag a bit at a "high spot". Originally I had my old drums turned and they still did this. So I bought new OEM drums, but no change. No weird noises, vibrations, or leaks from the rear axle but I hope its not bent some how. The clunking is a more recent development, so I don't think its old damage, but anything is possible.

Could it be the diff loading up during braking if my pillow block is tight? Pull the drums off again? Drain the diff fluid for a looksey?
 

Pighead

Stop calling it an FJ
Joined
Aug 31, 2004
Messages
8,436
Location
Camino
That's a good one. As i read thru your post, you checked off all my top-of-the-head ideas.
You've re-torqued the U-bolts and not just the once?
I guess I'd have to lean towards bent axle (?)
Wag cuz youve ruled out cheap fixes
 

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
U-bolts have multiple retorques. Last three have shown no change in torque.

I did a search here first, it's clearly not a common problem. No way I came up with something new. Someone has seen this... Hopefully they chime in.
 
Joined
Apr 2, 2008
Messages
10,309
Location
Victoria, BC
First though was driveshaft ujoint or slip-joint… Are they all free from play when unloaded? I’m already doubting that’s the issue, but don’t want to rule it out without saying it.

Next thought is pinion gear missing a chunk (or ring gear). I think mine made a clunk when I let off the gas… went away with heavy braking and acceleration. But to be honest that was 18 years ago so the exact details are somewhat vague. What I do remember was it was cyclical and changed along with speed under specific circumstances, and big chunks of pinion gear in the bottom of the diff.

Third idea would be a bearing or race in the rear axle… but I’ve not had them make noise… even when one of my front races had broken in two. It’d be a harder problem to find… and you’ll only know you’ve found it after you do. I’m more grasping at straws on this one.
 

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Driveshaft ujoints are new, but the slip joint does have play. However, I removed the driveshaft, drove around, and the issue remains.

I was wondering about a (newly) broken pinion gear loading up too. I suppose the next logical step is drain the diff fluid and look for metal.
 
Joined
Apr 2, 2008
Messages
10,309
Location
Victoria, BC
You can always put it back in if it’s still newer and clean… likely the most you’ll need is a gasket or rtv to find out. If there aren’t chunks on the drain plug you likely don’t have bigger ones in the bottom of the differential.
 

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Rear diff plug out. Just peach fuzz. No chunks on the plug. So that’s good news. The diff gears have 2500 miles them (fluid drained and filled twice for break in). 1200 miles on the fluid that just came out.

First photo is as the plug came out. Second photo is with the fuzz wiped off. Third is of the fuzz on a towel. Nothing unusual to my untrained eye. But lacking any other ideas, I’ll pull the cover tomorrow or the day after and have a look-see.

5EDE798D-818D-4687-8819-00865180FA28.jpeg
A2DDC938-71A9-42C2-A275-CAB1196B44DA.jpeg
image.jpg
 
Last edited:

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Diff looks fine. No chips or missing teeth. I’ll mic out the pinion spacer tomorrow. That’s the one thing I did and Toyota had limited spacer sizes available. If anything it would be a bit tight, but there’s enough slop it can move around so it shouldn’t be binding.

After that, I’ll button everything back up and take another look at the brakes themselves. The only thing I can think of there would be a bent housing. But I haven’t done it and I’ve had the truck a long time so I’d think it’d have manifested before (unless the rear brakes were never really working).
 
Joined
Jul 11, 2013
Messages
1,417
Location
California
Diff looks fine. No chips or missing teeth. I’ll mic out the pinion spacer tomorrow. That’s the one thing I did and Toyota had limited spacer sizes available. If anything it would be a bit tight, but there’s enough slop it can move around so it shouldn’t be binding.

After that, I’ll button everything back up and take another look at the brakes themselves. The only thing I can think of there would be a bent housing. But I haven’t done it and I’ve had the truck a long time so I’d think it’d have manifested before (unless the rear brakes were never really working).
Do you have discs in the front ? If so a common clunk is the bolts holding the calipers backing out. I’d be willing to bet this is your issue.
 
Last edited:

SlapSmak

SILVER Star
Joined
May 16, 2010
Messages
324
And of course, you have jacked up the truck and yanked and pulled on the corners to see if you have a clunk while putting sideways pressure on components. and you checked the spring perches and bushings as well as the shock bushings? also, the rear body to tub bushings.
 

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Pinion spacer measures out at 0.06mm each size. That’s the minimum space allowed. So it it is in spec, even if just barely. New gasket being leak checked now.

All shocks and all suspension bushings are new and tight. Springs, ubolts, shackles, etc.

I’ll double check the front brake bolts, but to be clear it’s a “clunk clunk clunk” that I can hear and feel in the brake pedal as the truck slows. It’s not a single clunk as the brakes load up. Also, no pulsing in the brakes like a drum the needs turned.

Could it be the entire drum pad assembly moving if either the axle shaft or the axle tube isn’t true? The axle shafts slide in fine and the seals don’t leak.

The clutch has no effect, so that should eliminate the xfer (needs rebuilt) or trans. At least the trans for sure.
 

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Front calipers all tight. Stick-on wheel weights well free of everything. Truck makes no noise jumping on any corners or pushing on anything.

Pulled a drum (again) to look. Where the screw driver is pointing is a small lip. I ass-u-me that's a by-product of machining. I did notice when putting the wheel back on that there is an increase in brake drag. With my pinion spacer tolerance at a minimum, that forces the axles out (or doesn't let them come in at all) to the max extent they can. That should keep the drum as far as it can be outward. Can a brake pad be too wide? Drums are OEM. The wheel brake cylinders are from Cruiser Outfitters. I cannot find the receipt for the pads.

DAA0A476-3F1C-4F41-A34F-93DB9BBC6392.jpeg
B9E31D0C-8BF4-45E7-ABC2-4B48DC78B236.jpeg
2D19609E-32B6-431C-A2C6-2D27D5EECB83.jpeg
 
Last edited:

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
Wider to the point of being obvious? Or wider to the point of just subtly screwing you up?

Edit: Found the transaction. Brake pads from Cruiser Outfitters.
 

hobbes

SILVER Star
Joined
Feb 2, 2002
Messages
1,056
Location
SWFL
I'm circling back to close this thread out. I replaced the rear brake pads with OEM. That seems to have totally resolved the noise. I don't know why. I still have a bit of a "high spot" that makes no sense to me as I spin the tires. I adjusted the brake to about 7 clicks from locked on the "high spot". Everything seems to work great.

A final note: the shoes on there had a wear pattern that extended about 30% from each end after about 5000 miles of driving. The middle 40% of all four shoes really weren't making much contact. Not sure if that's normal or not.
 
Last edited:
Joined
Apr 2, 2008
Messages
10,309
Location
Victoria, BC
Some OEM type drums are thinner and can get warped. Mark’s Off Road had a write up about it and I understand sells drums that are less likely to warp. I ditched my last drums 20+ years ago so I don’t have any experience with the products advertised.
 

Users who are viewing this thread

Top Bottom