klunk sound when braking and accelerating

[dmede808]

I'm getting a klunck noise whenever I brake hard or accelerate after a hard stop. I can also hear it when I back up and stop hard.

Per some suggestions from others I have checked my exhaust pipes, motor mounts and drive shaft. all seem to be ok. that is I cant move any of them by hand and hear that noise. I jacked up the front end and took both wheels off. The rotors seemed solid, nothing loose, no funny noises. I didn't try to tighten any of the u-bolt nuts but they all look solid and no signs of them moving.

Is this just a brake noise or do I keep looking? Any help is appreciated.

Dave
1987 fj60

 

[Doc]

Did they just 'look' solid, or did you grab onto them and pull and push with some weight?

 

[lovetoski]

From your post, it happens on both braking and acceleration, going forwards and backwards. Unless I'm not thinking clearly, only something in the suspension could clunk under all of these conditions. So, this tends to rule out anything driveline related.

Sometimes when I'm kinda stumped I try to eliminate things that are easy to check. In your case I'd check to make sure that the following are torqued to the right values: shackle bolts, u-bolts, steering knuckle nuts, and brake caliper bolts. It's a good idea to check these every so often anyway, and in this case your clunk could come from one of them.

If none of these eliminate the clunk, then (still going on the "it's gotta be in the suspension theory") I'd check the spring bushings. These can become severly worn over time. The OEM ones are rubber, and are a pain in the ankle to replace. Poly bushings are the way to go.

To check them I think I'd jack up the frame, let the axle hang loose, then jack the axle seperately. I'd use a crow-bar (or similar) to reef on the spring bushings to see if there is wierd movement.

That's all I can think of right now...

Best Regards,

 

[hj60]

If none of these eliminate the clunk, then (still going on the "it's gotta be in the suspension theory") I'd check the spring bushings. These can become severly worn over time. The OEM ones are rubber, and are a pain in the ankle to replace. Poly bushings are the way to go.

To check them I think I'd jack up the frame, let the axle hang loose, then jack the axle seperately. I'd use a crow-bar (or similar) to reef on the spring bushings to see if there is wierd movement.

Another thing to do is get a buddy to repeatedly turn the steering wheel ~1/4
turn in each direction (motor off) while you get under the rig and just start looking
at and grabbing steering and suspension components.
It'll be fairly obvious if something's out of whack.
Then jack the rig up by the frame so the wheels are about 2" off the ground. Have
your bud wiggle each front wheel top to bottom and side to side while you're
under there grabbing parts.
Finally, while the rig's in this position, get a prybar or something and use it to pry
up on each front wheel. Not too much. Just enough to see if there's any worrisome
movement.
If suspension's causing the clunk (and it probably is) you'll probably find it this
way.

 

[CardinalFJ60]

loose spare?

Just throwin' some things out there....could a loose spare be the culprit?

 

[dmede808]

thanks for those reasponses. i pulled on everything that i could but that doesn't exactly replicate the forces found while driving. i think the idea of just re-tourqing everything i can is a good one.

it is not the spare. its nice and tight and im pretty sure of where the sound is coming from.

it happens on accel only after a hard brake and soemtimes happens during a hard brake and will sometimes happen on a back up hard brake. this tell me that it is either a suspension problem or the brake caliper bolts. so i'll start there.

thanks guys.

 

[tradarcher]

"CLUNK" Sound

The output shaft from the tranny (t-case input shaft) is worn on the splines for the main gear. This probably explains the loud CLUNK when you shfit from D to R or let of / speed up and some of the driveline slop. The wear on the tranny output shaft is pretty common on shafts with V cut splines.

 

[wheelinwarren]

I just went through the same thing and it was the u bolts the springs were old and rusty which made play in between the leaves I hade to replace the u bolts as they usally just snap off when you try to adjust them

 

[lowtideride]

u-joints u-joints um u-joints?

 

[jwest]

Before you do anything, lube the drive shafts and u-joints.

I like to have the suspension fully extended when I grease the shafts.

.