Rear Brake slapping click/clunk noise. What the heck (3 Viewers)

[dbbowen]

Really didnt want to make a thread about this, but here i am. Ive disassembled and reassembled the brake assembly about 8 times in the past 3 days.

Ive got a FF fzj80 rear axle under my 60 series that i can not for the life of me pinpoint this weird slapping clunk. It seems to do it at a rate of one slap a wheel rotation, and it seems to only do it once the brakes have warmed up. Ill put the brake assembly back together and think its good and once i drive a few miles and it all heats up, its back to slap city.

The rear axle was fully rebuilt. All the bearings in the diff are brand new. All the wheel bearings are brand new. The rotors are brand new Napa rotors. The calipers are reman napa calipers. The pads are OEM toyota green pads. I reused the parking brake shoes because there was a ton of meat left on them, but they are OEM shoes. All of the internal springs and pins and stuff are new. Parking brake tension crank thing tensioned as outlined in the FSM, bell cranks adjusted as outlined in FSM. Hand brake adjusted per FSM. Even the Driveshaft is a brand new tom woods driveshaft with new ujoints and slip yoke and its greased.

When the brake starts slapping i can give my hand brake one or two clicks and the slapping goes away and is silent again.

I couldnt really find much on search besides @ZIFFFZJ80 s post about it. Hes got a video on it and mine is making pretty much the exact same noise.

What is this weird brake clunking?! Video inside

forum.ih8mud.com

This s*** is driving me crazy. Has this happened to anyone else? is there some remedy that I dont know of?

Clunk is coming from the passenger side of the rear axle like inside the brake assembly. Theres no abnormal wear on any of the parts that i can find

 

[jonheld]

When the brake starts slapping i can give my hand brake one or two clicks and the slapping goes away and is silent again.

Sounds like the rotor/drum is loose or not seated correctly.

 

[dbbowen]

Man, that is what i was thinking, but when i install the Rotor its able to seat all the way flat against the wheel mounting surface and then the lug nuts from the wheels hold it down into place. Unless im missing something. When the rotor is just on the axle with no caliper it is able to move some as the holes are bigger than the wheel studs

 

[jonheld]

Man, that is what i was thinking, but when i install the Rotor its able to seat all the way flat against the wheel mounting surface and then the lug nuts from the wheels hold it down into place. Unless im missing something. When the rotor is just on the axle with no caliper it is able to move some as the holes are bigger than the wheel studs

Put the rear on jack stands, remove the wheel and put a couple of lug nuts on the studs to hold things in place. The lug nuts should be able to make contact with the drum. See if you can move the drum or see if the sound is still present.

 

[dbbowen]

Put the rear on jack stands, remove the wheel and put a couple of lug nuts on the studs to hold things in place. The lug nuts should be able to make contact with the drum. See if you can move the drum or see if the sound is still present.

I can recreate the noise with the rear jacked up and the wheel still on and wheel off with the rotor on, but once i remove the rotor the noise goes away. Something is either hitting the rotor or the backing plate inside. It sounds like its coming from inside of the drum

 

[satchel]

Very strange. Only thing I can think of to help is maybe get a stethoscope to help narrow down the location.

 

[dbbowen]

I’m going to try and swap the rotors side to side to try and see if the rotor is not machined right. I’ve already had one defective Napa caliper out of the box. It wouldn’t surprise me if the rotor isn’t right

 

[Kernal]

@dbbowen : Can you post up photos of your emergency brake components on the affected side? Maybe one with the brake handle down, another with it pulled??

 

[dbbowen]

@dbbowen : Can you post up photos of your emergency brake components on the affected side? Maybe one with the brake handle down, another with it pulled??

I need to go out and grab some photos. Yesterday i swapped the rotors from left to right and on my test drive it seemed to make the noise go away. Which is puzzling to me.


That being said, when i did my axle swap, the first week or two this noise wasnt there. It just started happening last friday. Im wondering if it will happen with the new "fresh" rotor. Ill try and grab some photos today

 

[vipergrhd]

I know you mentioned the rear diff. is a recent rebuild, did you have new axles too? If not check your axle flange if it's bent slightly. I think your rotor could be out of round too if axle flange is ok.

 

[dbbowen]

I know you mentioned the rear diff. is a recent rebuild, did you have new axles too? If not check your axle flange if it's bent slightly. I think your rotor could be out of round too if axle flange is ok.

huh, so the donor truck was in a front end collision but it was pretty minor. That makes me wonder about the rear axle. How would you go about checking to see if the flange is bent? The rear axles are original. I put RCVs and lockouts on the front and that is a whole different can o worms haha


I swapped the rotors thinking the one was out of round. Before i swapped them, if you took the wheels off and put the lug nuts on... when you spun the hub it would spin, hit a spot that felt like the brakes got tighter, then would make the slap noise, then go back to spinning more freely. It got tight and slapped in the same spot every time. I figured it would do the same on the driver side but now the noise is seemingly not there. My test drive was during rush hour so i wasnt really able to really get the brakes hot so I should know for sure on my next drive

 

[vipergrhd]

If you removed the rotor and put it in drive you might see it wobble, if you can't get a dial indicator and put it on the flange face it doesn't take much runout to make the rotor wobble and causing the rotor to rub on the shoe or the pads.

huh, so the donor truck was in a front end collision but it was pretty minor. That makes me wonder about the rear axle. How would you go about checking to see if the flange is bent? The rear axles are original. I put RCVs and lockouts on the front and that is a whole different can o worms haha


I swapped the rotors thinking the one was out of round. Before i swapped them, if you took the wheels off and put the lug nuts on... when you spun the hub it would spin, hit a spot that felt like the brakes got tighter, then would make the slap noise, then go back to spinning more freely. It got tight and slapped in the same spot every time. I figured it would do the same on the driver side but now the noise is seemingly not there. My test drive was during rush hour so i wasnt really able to really get the brakes hot so I should know for sure on my next drive

Also check the finish of the drum if it's rough cut the tendency is to pull the shoe off the backing plate like a screw effect. Hope this helps.

 

[dbbowen]

If you removed the rotor and put it in drive you might see it wobble, if you can't get a dial indicator and put it on the flange face it doesn't take much runout to make the rotor wobble and causing the rotor to rub on the shoe or the pads.

Also check the finish of the drum if it's rough cut the tendency is to pull the shoe off the backing plate like a screw effect. Hope this helps.

The screw effect seems exactly like whats happening. I talked to my local napa, they are a local franchise so they are significantly than the corporate stores. They have a mill and said if the noise comes back they will just machine the inside of the drum portion and see if that fixes it

 

[COYS]

I had this noise. When warmed up hwy speed it’d make this insane clanking noise and truck would vibrate violently.

Turns out the star adjustment on the rear parking brake was the issue. I had to loosen it so when warmed up there’s enough clearance so the p brake components wouldn't touch. But what sucked is the parking brake action wasn't as tight (required way more clicks).

 

[dbbowen]

I had this noise. When warmed up hwy speed it’d make this insane clanking noise and truck would vibrate violently.

Turns out the star adjustment on the rear parking brake was the issue. I had to loosen it so when warmed up there’s enough clearance so the p brake components wouldn't touch. But what sucked is the parking brake action wasn't as tight (required way more clicks).

huh you dont say. When you say loosen it, do you mean basically make the pads further away from the rotor? ive been doing the opposite and making the pads tighter trying to stop it from clanking haha

 

[COYS]

huh you dont say. When you say loosen it, do you mean basically make the pads further away from the rotor? ive been doing the opposite and making the pads tighter trying to stop it from clanking haha

Yea so when it heats up there's more clearance. But by doing this your parking brake lever will require more clicks or such was the case for me.

 

[dbbowen]

Yea so when it heats up there's more clearance. But by doing this your parking brake lever will require more clicks or such was the case for me.

man if its that simple im going to lose my mind haha. Ive taken it down completely and put it back together using the FSM more times than i can count now

 

[ppc]

huh you dont say. When you say loosen it, do you mean basically make the pads further away from the rotor? ive been doing the opposite and making the pads tighter trying to stop it from clanking haha

The disc brake pad clearance can't be adjusted. When the brakes are applied the pads clamp the rotor. When the brakes are released the pads get retracted by the runout of the rotor to the point they have very little clearance which is perfectly normal provide the pistons in the caliper are not frozen. To me your description sounds like the hand brake shoes are causing the problem and have not been properly adjusted or the shoes are not floating on the backing plate due to corrosion etc.. To adjust the the hand brake you need to constantly apply the hand brake as you adjust to "center" the shoes on the diameter. Once the pad drags you need to back off a few clicks of the adjuster. If you don't do this properly the hand brake will drag, heat up and expand causing more drag.

 

[COYS]

man if its that simple im going to lose my mind haha. Ive taken it down completely and put it back together using the FSM more times than i can count now

I literally bought every single parking brake factory part including the cable to get my parking lever action FSM tight.

The insane vibration after truck had a chance to warm up made me suspect the worst like a busted axle. I even tried to hold the lever on the way back to the shop to burn through the pad (I.e. break in per FSM) to no avail.

It was only after we backed off via the adjustment screw that truck drove normally, but with a sloppy lever and sht hold. I drove around tail tucked for a while until I was able to find time to drop off my 80 at Valley Hybrids where Georg's crew were able to work their magic to get my parking brake action to acceptable levels (+hold) sans stupid vibration/noise.

Good luck, pal!

 

[robnicko]

The thing to remember with the parking brake on these is that they should only hold after 7 clicks. They are not like a passenger car park brake that holds after a couple of clicks. The reason for this is to allow for suspension travel when off roading which if adjusted too tight will activate the PBrake when flexing as the cable gets pulled.

When I adjust mine i back off the star nuts so theres alot of play, pull the lever up 7 clicks and then adjust the star nut at each wheel to the point where it just starts to bite. Have done this always and never had an issue plus the PB holds just fine. Still has the original PB shoes too

another tell tale sign of overtightened PBrake is when you have the wheel and caliper removed if you cannot slide the disc rotor off easily