josh99ta

iTrader: (1)

Swapped the DeCrapons out for Bilstein HDs, did the Upper Mount Mod while I was at it, and threw in some poly sway bar endlinks. Those were the only changes to the suspension. Now over road irregularities and bumps I get a loud sound from the front suspension. It's not really a clunk or anything, more than anything else it just sounds like something is ajar up front.

A few notes...

UMM - I had a shop cut the upper mounts, and their cuts weren't 100% perfectly straight across where the shock rod meets the bottom of the mount. Could this be causing the noise?

Shocks - The Bilstein HDs didn't have a nub at the top for me to cut off. Instead they have an allen head hole in the top of the shock rod. Because of this I didn't cut anything off, and I also didn't drill through my shock towers for clearance. I have no way to verify clearance as the front of my car is pretty low and I can't get my hand in there. Could this be causing the noise?

The car rides very nice now. Noticably more suspension travel, the car feels more planted through dips and more composed all together. Over bumps it does ride a bit more stiff, but you can feel that it's the better shock valving over the stock DeCarbons. Overall I really like how it feels, just wish it didn't sound like crap over bumps. It's hard to take a drive with the radio off because it sounds so bad.

99Bluz28

iTrader: (35)

As long as the mount was cut at the correct angle it shouldn't be a problem, but I couldn"t say for sure without some good photo's.

FYI, with the UMM you need to cut the end of the shaft shorter. Cut the shaft shorter and carefully grind some flats on it.

josh99ta

iTrader: (1)

That's the thing, where most shocks have a nub at the top that sticks up the Bilsteins do not have that. It's threaded all the way to the top, and has an allen head opening in the top where the nub would be. I believe that the overall height of what sticks up is shorter on the Bilsteins in comparison to other shocks (ie: the Bisteins are threaded to the top, and those threads stop where most other shocks threads stop). I can't verify this 100% for sure, but I think it is correct.

One is probably cut pretty close to the correct angle, the other is probably jacked up a little. The noise is equal on both sides though. I will also say that I did add a smaller washer up top, but with or without washer it doesn't seem like the upper mount can tilt either way simply because the spring sits up into the mount and keeps it pretty solid from rocking back and forth as the write-up says is necessary. It seems like this would also be a problem without the UMM mod, but there is no way I have beast-strength to make it rock against the tension of the spring.

Is it possible that the Bilsteins are just that loud operating? Seems like another set of Bilsteins I had on a F-Body were noisy too, but that was so long ago I can't really remember. It seems like the sound is too loud to be just that I would think though. I did pick up extra noise in the rear too after swapping in the Bilsteins in the back also.

99Bluz28

iTrader: (35)

I would double check that there's no slack in the upper mount, and everything is tight, and the shock shaft isn't contacting the metal in the upper control arm mounts (the part that sticks into the upper mount recess).

josh99ta

iTrader: (1)

I'm trying to imagine how I'd check all that with the whole suspension put back together, the wheel on, and the weight of the car on whole front suspension so that it is loaded. I'll try to check each side with the wheel at full lock in the opposite direction and see what I can come up with. I know I ran the nut on top of the shock down pretty far, but maybe I could have taken it down even further. I felt like that's something I didn't want to overtighten. Was that a mistake in my thinking? Should that upper nut be run down as far as possible?

I'll check out this stuff this afternoon and report back later today.

Faze

[QUOTE=josh99ta;12615594]...I know I ran the nut on top of the shock down pretty far, but maybe I could have taken it down even further. I felt like that's something I didn't want to overtighten. Was that a mistake in my thinking? Should that upper nut be run down as far as possible?[QUOTE]

This gets my attention. I assume you used a spring compressor when you assembled the spring/shock/mount assembly, right? The torque on that nut is not that tight (I don't have the spec in front of me) but it has a definite stopping point. If you didn't tighten it, and there is slop in the assembly, you can expect noise.

99Bluz28

iTrader: (35)

Yes, you don't want any slack that would allow the shock shaft to slide up/down in the center of the upper mount, which would create noise.
IMO, maybe you either didn't put a tall enough spacer on the shock shaft and have slack , or you didn't tighten the nut far enough down on the shock shaft. Plus there's still the possibility you still need to cut the shock shaft down shorter.
To check it you're going to need to jack the car up and remove the wheel/s (you can do one side at a time) and secure the car with a jack stand/s. You need to carefully look to see if there is any gap between the bottom of the upper mount and the metal bump-stop retainer directly below it, now put your jack under the lower control arm and start lifting the arm up while watching the above area for evidence of any slack. If after doing this you see no evidence of any slack, then your next move is removing the shock/spring assembly.

Good luck!

twitchtwice

iTrader: (12)

do you have the stock bushings in the stock lca's?

josh99ta

iTrader: (1)

Looks like I'll have to remove the assembly. I think I could run the nut on top of the assembly tighter, but I put them on with an impact gun, and they're ran down pretty far. I'm sure they can be tightened further though (using the impact, not sure if I could get them any tighter by hand).

The spacer is the right size. I removed the center section of the part I cut off and relocated it to the top side of the assembly.

I could see needing to cut the shaft shorter, as I had no way to verify the height. I know that it's threaded all the way to the top though. I may have to remove both assemblies and drill holes through the strut towers for clearance. I don't want to cut into the threaded section and not be able to get the assemblies apart again.

Stock bushings in stock LCAs. No noise before, swapped out the shocks and did the UMM and immediately got extra noise.

jmilz28

iTrader: (13)

Didn't you end up cutting the stock shocks on this car or did you decide against it?

z28bryan

iTrader: (7)

Yeah.. did you do what Faze is talking about?

josh99ta

iTrader: (1)

The Bilstein shocks are threaded WAY down. Way past what stock DeCarbons are and past what Konis are from what I've seen (these are the only three shocks I've used before on F-Bodies). I'll probably pull the assemblies out and crank the nuts down as far as they'll go with the impact just to ensure that's not it. I'll probably also drill a hole through each strut tower just to ensure the top of the shock rod isn't hitting, and work out some way to cover it up on the top side. Probably go ahead and do the wire tuck mod on the passenger's side and hide the trunk release on the driver's side while I'm at it.

pjb

iTrader: (2)

you have to compress the springs when you put it together. the shock must be fully seated up into the upper shock mount. the top nut is not enough to compress the spring. it will get tight but the whole assembly will have slop in it. most people find this out after they put it all together and then have clunking noises. if thats the case you have to start over and do it again (this time the correct way).

josh99ta

iTrader: (1)

I did compress the springs while putting together the assembly. I've put together close to a dozen F-Body front suspension assemblies over the years and never had clunking issues before with any of the others, and since the machine shop wasn't as precise as I would have liked them to have been with the cuts on the upper mounts I was wondering if that could have been the issue. Will report back when I have time to pull the assemblies and retighten them, as well as verify everything else under there (probably after the holidays).

99Bluz28

iTrader: (35)

Good luck , and keep us posted.

josh99ta

iTrader: (1)

Will do. I admittedly didn't tighten down the upper nut as much as I have in the past because I had no shock "nub" to cut off, and I didn't want to drill through the strut tower if I didn't have to, and I didn't want it banging into the strut tower. Maybe out of reservation I was really easy on it and didn't tighten it down nearly enough. I was trying to figure out a way to have my cake and eat it too, and it probably just didn't work out. Lucky it's a quick and easy fix. I love F-Body suspensions. So easy to pull apart and put back together. Just glad I didn't get an alignment already. Might even do the !wire mod while I have it all apart. Planning on wrenching on it Saturday so should have some results by Saturday evening.

pjb

iTrader: (2)

the nut doesn't really need to be torqued down real hard, but it is critical that the spring be compressed enough to let the upper shock mount sit all the way down on top of the shock. tightening the nut will not pull the mount all the way down by itself because the springs are too stiff to compress that way.

by "nub" do you mean the unthreaded flat part at the top? I'm not familiar with the UMM, but if you need to shorten the shock shaft would it matter if you removed the "nub" or part of the threaded end? (if you're saying yours are threaded all the way up).

josh99ta

iTrader: (1)

The nub must be removed or it'll hit the shock tower (which may be what the noise I'm getting is). The Bilsteins are threaded all the way to the top, and I didn't want to cut into the threaded part in case I wanted to remove the spring or needed to service the assembly at a later date. So without cutting any length off the top of the shock shaft where the nub would have been, my only other option is to drill a small hole through the strut tower to allow the shock rod clearance.

pjb

iTrader: (2)

run a nut (or even 2) down the shaft. cut the desired amount off the shaft. turn the nut(s) back off the shaft and it will clean up the cut threads. use a thread chaser if needed.

josh99ta

iTrader: (1)

That's the thing. With a second nut run down it, you can't cut off enough unfortunately (I don't think). It would have to be a really thin nut. I did think of trying it but the nuts I had were too thick to accomplish it.