Thumping sound from Rear when Braking

[burningskulls]

Hello,

My car just recently started making a thumping sound from the rear wheels when braking. It doesn't do it all the time. I would say around 50% of the stops I come to, and it doesn't vary between hard and normal braking. It is a whump-whump-whump sound that seems to increase in speed as the car comes to a stop. It is definitely coming from the rear and most likely the rear passenger side. Does anyone have any ideas of what this could be? I have a 1992 coupe. I searched but could only find a lot of instances where a thump happened when shifting. Thanks for any help you can provide.

Micah

[rainier]

i think i have the same problem as you on my s14

[element240]

are the calipers loose?

[that180guy]

check your rotors. the wear on the rear rotors might be uneven.

[idlafie]

Hello,

My car just recently started making a thumping sound from the rear wheels when braking. It doesn't do it all the time. I would say around 50% of the stops I come to, and it doesn't vary between hard and normal braking. It is a whump-whump-whump sound that seems to increase in speed as the car comes to a stop. It is definitely coming from the rear and most likely the rear passenger side. Does anyone have any ideas of what this could be? I have a 1992 coupe. I searched but could only find a lot of instances where a thump happened when shifting. Thanks for any help you can provide.

Micah

Thumping sound from the rear wheels could be either from 1). a blown shock, or 2). worn rear subframe bushings.
Check your rear shocks for any leaking fluid around the shock pistons. See if there is any greasy or oily type dirt clinging to the shock tower. Try bouncing your rear end up & down by hand a few times & see if it stops as soon as you let go of the car. Next time you fill up your car with gasoline, see if the rear end drops drastically from the weight as you fill up your gas tank. Also check to see if you have any abnormal tire wear which may be due to a blown shock. Last but not least, put your car up on jackstands, raising the rear tires off the ground. Grab a tire in your arms & see if you can move the tire up & down. If your shock is blown, then you probably can. The shock act as a dampner & should not be easy to move. If it's blown, then it will move up & down rather easily.
If your shocks turn out to be okay, then your thumping sound is more likely due to your rear subframe bushings. On S13's & S14's, the rear suspension is bolted to the unibody frame of the car at four boltdown points. These boltdown points use rubber bushings which help to insulate & isolate the rear suspension by helping to reduce the amount of road feel transferred thru the frame...kinda like a pillow or cushion. When these rubber bushings start to go bad, then your rear suspension will start to clunk around everytime you brake. See the attached website for an explanation. (Don't let the 300ZX information fool you..the 240SX shares the same type suspension setup...the fix used for the 300ZX can also be used on the 240SX).
http://www.capitalzoftexas.com/techtips/
Easiest way to check to see if your rear subframe bushing are shot is to take your car out for a spin. Find a nice flat even-surfaced road. Drive at a certain speed for a certain distance, then start gently tapping your gas pedal. If your subframe bushings are shot, every time you gently tap yourr gas pedal, you'll hear a corresponding thumping sound from your rear end.
Anyhow, hope this helps...
ID
'95 SE with shot rear subframe bushings....repaired with Gregg Dupree subframe spacers.....see http://www.specialtyz.com/suspension.htm for additional. :rawk:

[sxse240]

Okay, I'm in the same boat. Clunking rear end when coming to a stop. I put in SPL subframe spacers/collars and now I just hear the noise better, along with some gear noise from the diff. While I was under there, I found that I had snapped one of my anti-roll bar end links. Half of it was just dangling from the bar, with all the other pieces missing. So, I thought for sure that must have been the problem. I replaced both links with Energy Suspension pieces and took it out for a ride and it STILL clunks.

I've searched this and other boards and it looks like there's about half a dozen of us who've tried all the usual fixes with no success. I'm spending today under my car until I can figure it out. First guesses are diff bushings, followed by u-joints, then tightening every bolt back there. I'll let you all know what I find.

To recap:

Rear end clunking noise
Installed subframe spacers
Replaced broken end link
STILL CLUNKS!!!

[Demik]

u got one of lukes welded diffs

[aznpoopy]

i have a similar problem that just started up a week ago. i get a whooshing noise during braking that slows as the tires slow. i thought it was related to the brakes as i had just replaced pads and rotors and i know my rear calipers are a bit screwed up.

[sxse240]

Spent some quality time under my car today and was able to diagnose my noise as a badly worn or broken passenger outer CV joint.

Sucker sounds awful. I figured it out by putting the rear end up in the air and getting under it while my brother shifted as fast as he could between first and reverse.

Time to look read up on it in the FSM and start searching for parts. If the entire right axle needs replacing, it looks pretty expensive. Hope you guys don't find the same problem with yours.