ThirdPedal

My car's had a faint popping sound from the front suspension since I bought it. It only happens when weight is transferred fore and aft...either accelerating lightly or coming to a complete stop. I can also replicate it when the car is parked by pushing down on the fender and it seems to be on both sides. The entire suspension system has been upgraded by the PO within the last 3 years (I have the documents). It has a Welmeister FSB, Racer's edge Caster Blocks, camber plates, Welmeister 250lb springs, Koni inserts, and new control arms.

The PO acknowledged the front popping sound saying it started after the FSB was installed. I took that as fact and went about my business. The problem seems to be a bit more frequent now, so I set out to fix it. The sway bar bushings looked great, the endlinks were fine, and all connections were tight. To test, I disconnected the front sway bar and went for a drive. Sure enough, the noise persists.

Since I can replicate the noise by pushing on the fender. I started holding onto components and bouncing the suspension with my ear close by. I think I've narrowed it down to the caster blocks, and I wanted to get your much more seasoned advice before I went tightening things.

The two bolts that attach the blocks to the body are torqued just fine. However, it seems as though the bolt that holds the control arm to the block might be loose. First of all, does this seem feasible? If so, what should the torque spec be? Is it possible instead that the bushings inside the caster blocks have gone bad? Thanks for your help!

odurandina

yes. but what did you see when you checked the bushings ?

xschop

The M10 x 1.5 locknuts inside the rear control arm area of the frame well are spot-welded from the factory and easily bust loose. You can check by loosening the caster bushings (if they are good) by the M10 bolts and see if they shake around inside.

ThirdPedal

Haven't inspected them yet. I was hesitant to jack up the car and start loosening things for fear of knocking something out of alignment. I assume any adjustments should be made with the suspension loaded...but with the Weltmeister springs, the ride hight makes adjusting things difficult while it's on the ground. What should be the proper procedure for inspecting the bushings, or are my fears of messing with alignment unfounded?

Are you referring to the two bolts that hold the blocks to the frame? If so, that could make sense. If this is my issue, aside from spot welding again, what might a fix be?

Thanks for the help guys!

968workaholic

If the bolt that goes through the control arm and the castor block is loose, then your castor is porbably out of spec. Try tightening the bolt up and see if your noise changes/goes away.

xschop

Yes those two M10 caster block bolts thread into nuts that are spot-welded to the inside of the frame rail. I was able to repair my passenger side while the engine was out for the V8 swap last year. I chopped a square section out of the top of the frame rail to get a Mig welder in there with new M10 x 1.5 flange nuts. It is important to use flange nuts because the flange on the nut is readily able to weld to the frame rail sheet metal without blow-thru. The reason for the failure is worn ball joints that resulted from worn/bad strut from P.O. I'm sorry if this has happened to you.

xschop

I've got a MS paint drawing of of the caster block dimensions from my control arm swap and IIRC the sheetmetal was @14-16 gauge in that area. Going with that, if I had to do this fix from underneath the car on a lift, I would cut the spot-welded nuts/sheetmetal out with a 3 1/2" cut-off wheel or plasma cutter and build a plate that looks like this and weld it to the bottom frame area of the control arm with the flange nuts completely welded on their perimeter to the same gauge sheet. Of course install it with the nuts inside the frame rail. That 68mm c2c dim is accurate the rest can be fudged....HTH

ThirdPedal

Well, I don't know if it's loose. It looks like in order to tighten it, I'll have to raise the car. I was worried about knocking something out of alignment in doing so, but you make a good point that if that's the problem, it's out of alignment anyway. I was just curious as to what the chances are that this bolt is loose. It's pretty beefy, and doesn't seem like something that would loosen on it's own. Which makes me concerned about:

I really hope this isn't the case, but I'll have to raise the car to check and see. Thanks for the diagram BTW. If it turns out the nuts are loose, that'll be my weekend project.

ThirdPedal

Well, the plot thickens. I jacked the car up and checked the torque on the control arm to caster block bolt, and both sides were as tight as could be. Then, I checked the caster block to frame bolts (loosened them and the control arm bolts), and checked for play and nothing. While I had the control arms off, i took a look at the bushings in the caster blocks, and they look brand new. Good news that nothing is broken, bad news I can't identify the clunk/pop.

While I was at it, I rechecked the wheel bearings and ball joints, and there is no play in the wheels. Checked the tie rods for play (why not) and nothing. I can't find anything loose or worn in the front suspension. I'd swear it was all new if the clunk didn't persist.

To explain the issue one more time, it only occurs on fore/aft movements at the moment I start to accelerate or right when I come to a complete stop. It also seems to increase in frequency as it warms up. It makes no noises when I hit bumps or turn. It's not the sway bar (still disconnected), control arm connections (caster block and the connection in front of it), ball joints, tie rods, or wheel bearings. Is there anything I could be missing?

If this is something I have to live with, then so be it. I just want to make sure my car is safe not only for daily driving, but for autocross and the occasional HPDE.

xschop

Your missing two things, The strut mounts are cheesy on these cars and collapse over time (can be checked by the large rebound washer if it rests past the stop rings)
Also not sure what year your car is, but the Early strut screw caps are what keep the strut cartridge from clunking around, make sure they are screwed down tightly. And if you have custom springs, check their seating on the strut bodies.

ThirdPedal

Ooops, I did check the strut mounts, and deemed them improbable because they're just 3 years old, and I held my ear to the mount (camber plate on top), bounced the car till it popped, and it sounded like the sound was coming from somewhere on or around the control arm. Definitely not the top. My car is an 88 951 BTW.

The car has 250# Weltmeister front springs, and they seem to be seated fine. However, they are progressive springs, and when resting, the bottom coils sit on or close to one another. I'm wonder if that might be it?

xschop

Large X-member bolts to frame tight? Also the top camber bolt can rotate under vibrations and leave lateral slack betwen the cam bolt head and strut. It can clunk back and forth I have experienced this before. Also if the inner tie rod socket is worn, and then if not that, I've seen pinion gears Fubared, but your steering wheel would have a pissload of play if that were the case, then there's the steering shaft U-joints that are clocked wrong from the factory and can have play transmit into the suspension. Sure is alot of crap to check on LOL.

ThirdPedal

Ooooo new stuff to check! LOL

I checked the top camber bolts, and while they seemed tight, in checking them, there seemed to be some tension to where I would turn them to tighten them and they would immediately return to the position they were previously in. Not wanting to break anything, I left them be because I suspect the noise to be coming from below. I'm still learning the ropes with this thing...is that normal?

My steering is really tight and the noise does not happen at all when steering. I think it's something I can rule out.

I'm trying to think of everything in the front suspension that moves when the suspension is compressed (only slightly). The inner tie rod socket is a possibility though. there's no play in the tie rods, but something could still be worn. I'll have to check that with my new batch of stuff tomorrow.

Thanks for all your help with this!

xschop

Those cam bolts can seem tight and still slap back and forth against the strut protrusion where they adjust. I recently had this happen after installing my modded struts. And lastly an unseen problem could be the outer tie-rod soket worn and slapping in it's pocket. I replaced mine with heim-joints and the one on the passenger side had a nice tick to it along with the mushroomed, ball-joint which destroyed the alloy control arm pocket all due to a completely worn strut.

ThirdPedal

I'm really starting to suspect the cam bolts. In theory, those would be subjected to the forces that would make the noise, and if they can make noise when tight, that might just do it. If they are the culprits, do you just live with it, or tighten them further? I'm going to check on those while I'm under there checking the x-member bolts and control arm sockets. BTW, where did you find the heim joint replacements for the control arm sockets?