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Phantom "clunk" won't go away!


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Hey all, I was hoping for more suggestions. Per messages I read here in the archives months ago I replaced the front differential mount insulator. While I was at it I replaced the moustache bar bushings and sway bar bushings/end links I still want to replace the control arm bushings and plan on doing that soon when I replace the wheel bearings and install coilovers in place of the struts. The problem is there is still a clunk that sounds like someone it hitting the floor with a hammer when I go over some bumps in the road. It doesn't happen with all bumps and I cannot duplicate the sound in the garage bouncing the back of the car. Railroad tracks and expansion joints are by far the worst. I'm ready to take out the carpet and subfloor and get in back with a stethascope to try and corner the source of this sound. hmm, that or ride behind it on a creeper... nah, that won't work.. it's driving me crazy. The chassis in question is a 77 280z, the car is now like Dick goodmans 250 GTO

Thanx for any input!

Chelle

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Make sure that the nuts on the strut bearings are tight inside the hatch, and get a big pair of pliers between the coils on the springs and make sure the clincher nut on the strut tube is tight. In our VW, it used to pound over expansion joints when it needed the struts replace.

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Guest Anonymous

The last owner of my z had the exact same problem.

 

But i cant remember for the life of me what it was.

 

I think it was somethin like a plastic spacer that kept the rear diff from hitting the underside of the body....sorry thats not much help but all i can remember.

 

btw mine is a 77 280 2+2

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Hiya : )

did you see my post on the GTO's?

http://www.hybridz.org/ubb/ultimatebb.php?ubb=get_topic;f=8;t=000614;p=2

I'm a longtime fan/owner/builder of many of the GTO replicas. Currently I'm working on converting that car to right hand drive (just to be different) I have been an admirer of your car for some time as well.. it's beautiful : ) I'm in the Chicago area and am always open to visitors. Bring your car over the summer and we can take 3 of them out for photo ops.. I didn't build this one though I've done much of the modifying of it beyond the basic kit.. I'm also working on a few other projects including a chassis for a puckett GTO body and an original 1974 Lamborghini..

: )

Chelle

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Guest scca

check to see if a strut top nut is loose in the strut housing. this will make a good clunk when you hit bumps in the road. i have seen this a few times. peop0le who replaced struts didnt tighten the nut enough.

 

next would be u joints in half shafts.

 

lastly ring and pinion gear lash too much and you need a new diff

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Guest zthang43

I had that exact same clunk in mine; took me 3 years to find it! It was the pass. side strut pin; the one that connects the strut to the control arm. The pin and the metal sleeves in the bushings had both worn enough that they would make a clunk when I hit a bump a certain way. I replaced the pin and bushings and the clunk went away. (That's when I decided to start selling my strut pin puller, since those pins are such a pain.)

The only way I was able to find the clunk was when I was replacing the strut cartriges, and had the strut leaning out of the car. It was only attached by the strut pin, and at that point I could wiggle it back and forth and see a bit of slop. It only seemed like a little tiny bit of play but it was enough to clunk.

Hope that helps.

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Guest scca

speaking of the strut pin puller tool....

 

i tried it and it didnt work so well for me.. not sure if i somehow did something wrong but it pulled the threads off the end of the pin and by doing so ruined the nut that is the end of the tool...

 

how many others here have used it successfully..

i remember Terry saying he did.. this was a Cali car originally and a 75 280- i really expected the pins to just pop out

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Guest Anonymous

I got the nut on the end of the strut pin removal tool onto the pin and was not on far enough. Ruined the nut. Made up another one and a spare! I do not know how a person can get the strut pin off without the strut pin removal tool. I buffer/polished the strut pins after they came out. A little rust and impossible to move.

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Guest heinera

Mine made loud clap, clap, clap in reverse, and when downshifting at WOT. Turns out it was the drivshaft hitting the rear swaybar. I removed the swaybar and the loud noise hasn't happened since.

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Guest Anonymous

Have you checked the rubber under the spring? My car does the same thing and the lower spring rubber is all torn up. So I think that the spring is hitting the suspention assembly. When shifting, over bumps, and letting off the gas at high RPMs. Does this sound possible?

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You get another 2 cents worth.

 

When I bought my Z I noticed a clunking from the front end during the test drive. Figured it was a ball joint or wheel bearing and decided to fix it once I owned it. The front end checked out OK, so just lived with the mild clunk.

 

In subsequent upgrades I decided to install gas struts and new springs. It was then that I noticed the nut on the top of the strut must have been loose allowing the strut to flop around a bit. Worse yet, the movement had rounded out the normally D shaped hole and had worn over half way through the strut rod itself!

 

So yeah, a clunking could be caused by a loose strut nut. So try retorqueing the struts and if you get ANY significant movement out of the nut OR if this fixes the clunk, then DISASSEMBLE ALL 4 STRUT TOWERS TO MAKE SURE NOTHING IS ABOUT TO BREAK IN TWO!!! My problem was with the top of the strut, but obviously any problems with the bottom (rubber gone, strut pin, or the big nut holding the catridge in the tube) will cause the same problem.

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Guest Anonymous

Paid $100 today to find a bad rattle and clunking that has been a problem for 6 years on a 1974 260 Z. Had tried everything, and can't tell you how many hours I have been under the car, looking for the noise.

 

Seems the bolts in each end of the lower strut tube were loose, allowing the strut to move forward and back on hitting bumps, cracks, or what ever. Mechanic loosened the cinchs on the strut bushings, tightened the end bolts, re-tighten the end bolts, and bingo, noise gone.

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  • 4 months later...

chelle

 

I had a clunk in my stock 72 Z that I finally traced down to the nut on the right stub axle. I took the car to a garage where some serious torque could be applied to the stub axle nut. No more clunk.

 

Good Luck

 

Miles

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I forgot that I never posted the resolution to the phantom clunk! sorry!

I found the trouble - after replacing EVERYTHING else and still clunking I replaced the adjustable (pricey!) rear control arm bushings with non adjustable poly ones... and no more clunk!

Unfortunately that meant giving up on the adjustment, but I have a coilover kit on the car anyway - with adjustable upper mounts, so I guess the loss of that adjustment isn't critical.

Chelle

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  • 10 years later...

Noticeable clunk in right front strut, barely noticeable clunk in left front strut, both noticed when loosening lug nuts for tire change-no problems when driving.  But if it happens when I'm just breaking a lugnut free it has to be happening  I have tightened the gland nut as tight as I can with a big channel -locks, but I think the strut is loose LATERALLY inside the tube, like the diameter of the shock insert is a bit too small.  The strut has to have a little clearance so that I can get it in and out, but I wonder if I have a bit too much clearance.  I don't know the model number of my struts, but when I bought them a million years ago, they were the MR2 struts and I got them from Ground Control when I did my coilover conversion.  The strut rod has no machining at the top, only threads.  I bought the struts already sectioned from an SCCA IT racer that I trust.  Gonna get under the car and have somebody wiggle the lugwrench with me under it-just to be sure it isn't a TC rod or tie-rod, but I'm pretty sure it is the strut.  I don't know how I might shim be bottom, but perhaps it is at the top-I think the gland nut is stock 240z, not a Tokico gland nut if that matters.  Can't recall why I chose to use the stock nut and I don't have a Tokico gland nut on the chance that is the problem.  What tool do you guys use to tighten the gland nut?

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