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Rear clunking noise (the checklist)

79mustang351w

Hard-core CEG'er
Joined
Nov 13, 2010
Messages
1,254
Location
Bucyrus, OH
Well I finally found the clunk that has haunted my car for way too long. And it wasnt the obvious swaybar endlinks or bushings in the control arms. Its something that some of you may be running into...and dont even know it.

My car suffered from a clunk due to the aftermarket E-brake cables I bought from O' Reillys Auto Parts. My car is lowered alot on Koni adj. struts and Ground Control coilovers...and the cables were binding on the plastic wheel well plastic liner. The driver side cable was just rubbing the cable ever so gently on the wheel well plastic liner. But the passenger side was tapping one of the rubber isolators (the two big rubber hunks on the E-brake cables that isolate it from tapping on the underbody) on the wheel well liner. It was binding so hard that the passenger brake caliper was moving enough to make the caliper tap and "clunk" metal to metal on the top tabs of the brake pad. Sounds crazy I know...but it can happen. I will provide a checklist of things to consider when looking for the "clunk" noise that seem to be common with age on these cars. My car also had a caliper spring and pin issue too...so the caliper was already loose compared to the properly done driver side. So that didnt help the matter either...but the cable was the main cause of all the damage and led to the spring and pin issue (I had previously fully rebuilt and powercoated ALL the calipers on the car with new seals and hardware and such).

There are some differences in the design of the aftermarket cables compared to stock...and if I remember correctly they dont have holders (or keepers to keep them from sliding in and out of the tab with the plastic bushing underneath the car "C shaped one"). So that means they can just slip through the mount freely (when they are supposed to stay locked in one place if I remember correctly). And the rubber isolators are a tad different than the stock ones too...maybe even the overall length. Cant remember for sure...I will know when I get some factory cables (on order). So I will edit this paragraph if I am mistaken.

But here is a checklist of some things to check and consider when trying to find the "clunk" noise in your car.

-Sway bar bushings and mounts
-Swaybar endlinks and bushings
-Control arm bushings
-Control arms being bent
-Toe arms being bent
-Hub bushing (the bushing that is in the rear wheel hub itself)
-If using a bigger aftermarket sway bar(check for clearance to the rear subframe...I had a shiny spot before on my Addco swaybar...until I fixed that clearance issue)
-check for the infamous cracked swaybar mount (common with the "hook" style bushing mount and single bolt design)
-also check that the swaybar pivots freely in the bushing (sometimes the "hook" style bushing mount will be bent and bind the bushing too hard on the swaybar) this will not cause the "clunk" but a squeaky annoying suspension! lol And it could bind hard enough to break the swaybar endlinks...so just something to consider
-check also that the strut mount top bolts are tight
-check the struts nut for proper torque
-check top strut mounts for wear or being completely broken (have heard of issues of metal to metal just from the rubber being worn too much...even if the mount wasnt broke like most)
-check struts
-check E-brake cables and brake calipers as noted above (especially with a lowered car...clearance can become an issue with the e-brake cables)
-check hub bearings (they can make all kinds of crazy noises)
-check that the strut is bolted tight in the rear wheel hub
-check that all control arm bolts, swaybar, and subframe bolts are properly torqued (any rear suspension bolts for that matter)
-check to make sure fuel lines are not loose or bent and banging on the top of the rear subframe
-if using aftermarket swaybar endlinks...make sure the heim end is not wore out.

I am sure there are more things I cant think of without being under the car. But this will give you some things to think about as you try to hunt down that annoying "clunk." Good luck in your fix... and feel free to PM me if you need any advice. My car has had MANY of these issues...and most times it was multiple ones at the same time.
 
I bought Raybestos professional grade #BC95736 from Rockauto for my car I'm putting back together. They look exactly like stock including having the rubber isolator with the fins on it. The cable is coated with plastic and it has the boot on the caliper end. I had cheap ones from a local auto parts store once and they froze up in the winter from water.
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Mine didnt freeze up....they just didnt mount the same in that clip like the factory ones and the ones you show. Those look like they have the same stoppers on the cable for that clip to hold the cable in place like the factory ones. I may get those...as the factory ones are WAY too overpriced. Thanks for the part number and post Denny.

I hope my post helps somebody fix their car. It has plagued me for too long...and it wasnt one of the obvious noises (swaybar endlinks or something that normally wears). I had thought it was the caliper before....but just didnt think it could rattle with that spring in their properly...but after that pin got worn and that spring cocked out of place...because of the cable...it made all sorts of ruckus. Got a new love for the car again after getting this noise fixed though!
 
Very good info.


While swapping over my new rear suspension, I found that my "right turn, over a bump, right rear clunk" is actually the lateral arms bushings are junk at the rear hub, and at the point where the arm bolts to the chassis under the rear doors.

It causes the arm to twist at static height almost to the point where the arm touches the knuckle. Then with the geometry of the rest of the rear end, plus the right turn and a bump, it causes the arm to tap the knuckle giving you a quick couple "clu clu clunks" until your turn and the bump are passed. Rarely making a clunk while driving straight.

I thought it was the rear koni shock, so I replaced it, not it. Then I thought maybe the upper strut mount, replaced it, not it....... My sway bar brackets are in place and not broken and my end links are in place, not broken.


If you have a "turn clunk" in the rear, check the twisting bushings and see if the arm is almost touching the knuckle ;)
 
Those lateral arm bushings are surprisingly flabby even when they're good. Upgrading to the Energy Suspension bushings on those gives a pretty significant improvement in cornering stability and transitional response.
 
Upgrading to the Energy Suspension bushings on those gives a pretty significant improvement in cornering stability and transitional response.

^ tell me more! Are these the bushings that need to be burned/cut out of the knuckles and the new ones pressed in?
 
Do you have Energy suspension bushings in those arms? Guess I forgot to mention that. Its well worth the investment and you wont have that "turn clunk" noise. At least I dont in mine now after installing the Energy Suspension poly bushings...and with the stiffness of poly bushings...you wont have that issue again.

Not gonna lie to anybody...getting the old rubber bushings and metal sleeves out involves the torch and some good ol' fashion "time spent" with the car...but its one upgrade I highly recommend...and not hard to do. Getting the new bushings in involves a little lubrication on the bushings (leave the sleeves out...they go in last, after the bushings are in place) and some pursuation. I pressed mine in with a vise.

I was just typing this out too when you two replied...lol.

Energy Suspension part #4.3154G for black or 4.3154R for red
 
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