The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

Suspension groans after k member swap - suspect a arms?

Duane Black

Curbs go brrrppp
485
314
Exp. Type
Time Attack
Exp. Level
5-10 Years
Durham, NC
so as mentioned, this is a groan.

I just put a bmr k member in so the tie rods and a arms were loose and even off the car.

Install went well, and I put the old a arms back in after a few years, a few miles (96000), and a few track events (like 20), i suspect distrubing those bushings made them groan.

It doesnt groan over bumps or even pop. I can jump up and down on the struts and no noise. You can shake the tire ir kick it any way you want, no noise.

Sitting still, you can move the wheel and there’s no noise.

Taking off straight occasionally gets a groan.

The best time to hear it is say making a right turn from a stop sign. A groan each way. It seems more pronounced in rights.

It also is more audible at low speeds.

The last time strut mounts went bad on me, they popped iver things like speed bumps and sounded different. This is a groan rather than a pop.

Any other suspicions?

Edit: i nut and bolt checked everything. Although the a arm bolts were loose, tightening them didnt help. If anything it got worse actually
 

Duane Black

Curbs go brrrppp
485
314
Exp. Type
Time Attack
Exp. Level
5-10 Years
Durham, NC
Any cares to try again? Put the energy suspension bushings in today. No great change in noise, maybe in my imagination. I’ve also emailed Kelly at BMR since ut showed up after disturbing the set up on that install.

It did seen tougher to get a groan out if it after driving a few miles with polyurethane a arm bushings in but i think it’s my imagination. So what would be the next guess? Ball joints feel good on the ground without 3441 lbs of car on it. Still cant make a noise or feel anything wrong without physically moving the car. I sprayed live in the strut towers and didnt seem to do anything, may try again
 

Duane Black

Curbs go brrrppp
485
314
Exp. Type
Time Attack
Exp. Level
5-10 Years
Durham, NC
I don't know that I'd call it metal on metal. It could be. However, it doesn't sound like any metal on metals I've heard that I can recall. It sounds a little like a creaky door hinge, which I guess is technically metal on metal? It is also covered up enough by other noises that my attempts to record it were in vain. Is it possible a bad hydro bushing and a new polyurethane bushing make the exact same sound?

Someone suggested it could be a ball joint - as in when it went back together, there may have been a little rusty spot on a ball joint that wasn't rubbing before and that's what it is.

My thought for the strut bearing was that I know it rotates with the strut so it could be that. The most mysterious of all is how I haven't figured out how to replicate the sound with the car parked. I'd be all over strut bearings if it made noise on bumps or if I could jump on the strut tower and make the noise.

And in addition to all of this, yesterday evening while driving home on new bushings and 60 degrees, the noise seemed way less pronounced than driving to work this morning when it was 40 degrees. It could be my imagination. The car may just miss Florida.
 
369
146
Exp. Type
HPDE
Exp. Level
5-10 Years
Waco, TX
Hubs good? Sounds like it could be a wheel bearing groaning in the cold grease it thick and when it warms up it's a little looser making it a little free-er.
 
369
146
Exp. Type
HPDE
Exp. Level
5-10 Years
Waco, TX
Depends really, turning can add load to the bearing. It's easily checked and depending on miles on them and how hard they've been driven could be due to change.
 

TymeSlayer

Tramps like us, Baby we were born to run...
3,765
2,666
Exp. Type
HPDE
Exp. Level
3-5 Years
Brighton, Colorado
Reason I asked is because I have the BMR K-member with their A-Arms, A-arm and radiator supports with FRPP bumpsteer and had this issue when making sharp turns at low speed. I greased up everything I could and the sound (definitely metal to metal) went away. Even though the parts weren't on the car that long, I assumed something dried up. Although I never actually diagnosed what was going on and saw no obvious signs of wear, greasing all the fitting did the trick.
 

Duane Black

Curbs go brrrppp
485
314
Exp. Type
Time Attack
Exp. Level
5-10 Years
Durham, NC
So far so good. My car is lighter and on skinny 200 tw tires. With the a arm brace, I dont anticipate issues. The front end definitely goes where i point it. The polyurethane a arm bushings on my stock a Arms helps feel the tires. On re71r, it was rare that you point the tires somewhere and they not go. With hankooks rs4, I occasionally point and it doesn’t go, but it’s not a arm, you can just feel the front tires sliding w/o bite. I’ve heard of a 4000 lbs roush car cracking a weld and Kelly at Bmr admits to issues early, but nothing recently, especially wity the z brace and a arm brace
 

ChrisM

Mostly harmless.
1,101
1,270
Exp. Type
HPDE
Exp. Level
3-5 Years
SoCal
@Fabman runs the BMR front setup (or at least he did, probably still does if he hasn't built something better) and reported an issue early on (like, years ago), but it was quickly rectified and hasn't had any since, and his car is a monster.
 
5,152
5,688
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
@Fabman runs the BMR front setup (or at least he did, probably still does if he hasn't built something better) and reported an issue early on (like, years ago), but it was quickly rectified and hasn't had any since, and his car is a monster.

Yup, I had one of the early radiator supports that failed where the sway bar mounts up. BMR sent me a revised part that has been perfect ever since. I highly recommend the optional supports BMR offers, especially the one that ties the K member to the Rad support, it really ties things together nicely. I give that part credit for the continued good service that I have had with this setup. I wouldn't run one on track without it.

1385683_10151898634768535_1955828941_n.jpg
 

Duane Black

Curbs go brrrppp
485
314
Exp. Type
Time Attack
Exp. Level
5-10 Years
Durham, NC
I got a frankenstein setup. Steeda radiator support with the bmr z brace, k member, and a arm brace. I also run rs4 vs re71r so its not apples to oranges. But, the car now feels more capable than the tires under it.

I got polyurethane bushings on stock a arms, koni front struts, stock rear. I may have a watts link and strano bars soon
 
5,152
5,688
Exp. Type
W2W Racing
Exp. Level
20+ Years
Pleasanton: 1/2 way between Sonoma and Laguna Seca
I used to jack my car up by the stock k-member, very convenient location, tough to jack it up by the subframe and still get a jack under it. Any luck with jacking up on the BMR piece?

I put the jack under the crossmember where the rack bolt is.
I have the nut on top instead of on the bottom like the one pictured above.


Sent from my iPad using Tapatalk
 

TMO Supporting Vendors

Top