How to diagnose a bad strut?
#1
How to diagnose a bad strut?
I've been chasing a noise which sounds an awful lot like a loose fastener somewhere in the front passenger-side suspension of my car. It happens over rough pavement, but only small irregularities, larger bumps don't cause any sound. It's been getting steadily worse over time and it's not insulated at all from my ears since I use the MM upper strut mounts with the metal spherical bearing. To this point I haven't had any issues with NVH, even with these mounts.
There is realistically only about 4K miles on these struts, but much of it under pretty harsh conditions (autocross/track events). The only highway miles are to/from events.
The front suspension is MM upper strut mounts, FRPP springs, Tokico D-Spec struts, Steeda front sway bar, and Mr. Strano's sway bar end links.
At one point I had:
- Double checked the torque of all fasteners involved. (Upper strut mounts, strut to spindle bolts, sway bar end links, sway bar chassis brackets, lower ball joint pinch bolt, etc.)
- Swapped the sway bar end links for the OE end links (better NVH isolation)
- Done the ball joint test from the FSM
- Checked for play in the wheel bearing
- Checked for interference of the spring to the strut tower
And still the noise persisted. But, I finally found a test that replicates the sound. With the car sitting on the ground, if I grab the top of the wheel and "monkey" it real hard, I can replicate the sound. It's the same if I remove the wheel, raise the lower control arm, grab the top of the strut near the spring perch and monkey it. With the lower control arm in full droop, it doesn't make the noise. I don't see any evidence of fluid leaking from the strut and the driver-side strut does not make this sound.
I haven't yet removed the strut assembly, but even when I do, I'm not sure exactly what I'm looking for. My theory is that something is breaking down inside the strut and it is starting to fail but I don't have a lot of outward indication of this other than the monkey test.
Anybody know what Tokico is going to want to hear when I call them on the phone and ask them to warranty the strut?
There is realistically only about 4K miles on these struts, but much of it under pretty harsh conditions (autocross/track events). The only highway miles are to/from events.
The front suspension is MM upper strut mounts, FRPP springs, Tokico D-Spec struts, Steeda front sway bar, and Mr. Strano's sway bar end links.
At one point I had:
- Double checked the torque of all fasteners involved. (Upper strut mounts, strut to spindle bolts, sway bar end links, sway bar chassis brackets, lower ball joint pinch bolt, etc.)
- Swapped the sway bar end links for the OE end links (better NVH isolation)
- Done the ball joint test from the FSM
- Checked for play in the wheel bearing
- Checked for interference of the spring to the strut tower
And still the noise persisted. But, I finally found a test that replicates the sound. With the car sitting on the ground, if I grab the top of the wheel and "monkey" it real hard, I can replicate the sound. It's the same if I remove the wheel, raise the lower control arm, grab the top of the strut near the spring perch and monkey it. With the lower control arm in full droop, it doesn't make the noise. I don't see any evidence of fluid leaking from the strut and the driver-side strut does not make this sound.
I haven't yet removed the strut assembly, but even when I do, I'm not sure exactly what I'm looking for. My theory is that something is breaking down inside the strut and it is starting to fail but I don't have a lot of outward indication of this other than the monkey test.
Anybody know what Tokico is going to want to hear when I call them on the phone and ask them to warranty the strut?
#2
I installed the MM camber plates on my GT500 with Ford Racing lowering springs and seem to have a noise in the front suspension similar to what you describe. Sounds like a light dull thump when I get going at low speeds and over speed bumps, but I never hear it while driving at speed even over rough/irregular surfaces. I believe it's on the passenger's side. I'm thinking I may not have completely removed the rubber band that's used to keep all the camber plate parts together prior to installation.
Even though I installed lowering springs, I used MM's standard spacer configuration and not the one for recovering bump travel.
Let me know what you find - if anything.
Even though I installed lowering springs, I used MM's standard spacer configuration and not the one for recovering bump travel.
Let me know what you find - if anything.
Last edited by 6-Speed; 11-10-2009 at 10:01 PM.
#3
Might be related to the front lower control arms. There is a new TSB that just came out - TSB 09-24-16 that replaces the LCAs if confirmed to be the source of front end noise.
Here's a link at Team Shelby:
http://www.teamshelby.com/forums/ind...howtopic=51279
Here's a link at Team Shelby:
http://www.teamshelby.com/forums/ind...howtopic=51279
#4
It's definitely not this TSB. To close the loop on this one, the conclusive test was swapping the passenger side strut to the driver side (including using the driver side spring and upper strut mount) and vice versa. After I did this the noise moved from the passenger side to the driver side. While I'm not too happy about having to deal with the Tokico warranty, at least it happened at the end of the season. And, there's nothing worse than not knowing the root cause.
While this might be a good opportunity to make the switch to Koni yellows, it's rather poor timing since it seems they are currently unavailable.
While this might be a good opportunity to make the switch to Koni yellows, it's rather poor timing since it seems they are currently unavailable.
#5
Just to confirm, did you keep the endlinks on the same side, or did you move them with the strut?
I had a similar noise that was driving me crazy. Turned out it was the endlinks (Strano's)--those rod ends can, and do, gain some play in them and start to rattle. Just something else to check (it's an easy fix with a new rod end).
I had a similar noise that was driving me crazy. Turned out it was the endlinks (Strano's)--those rod ends can, and do, gain some play in them and start to rattle. Just something else to check (it's an easy fix with a new rod end).
#6
Yep. I took the sway bar out of the equation and removed it along with end links. Driving the car without the front sway bar wasn't as bad as I thought it was going to be BTW. Somehow I had visions of the car spinning wildly off the road the moment I turned the steering wheel.
#7
I think it's pretty clear that you have a bad damper.. or at least a guide failing. I'd get it warrantied (or try, good luck). And when the Koni's are back, change to them and sell the D-specs (there will always be a market for them).
And as was stated, it's not the endlink, though I admit that they can make some noise because we use rod-ends for strength, and rod-ends can make a little bit of racket when they wear, but they are also much stronger than ball and socket type ends.
And as was stated, it's not the endlink, though I admit that they can make some noise because we use rod-ends for strength, and rod-ends can make a little bit of racket when they wear, but they are also much stronger than ball and socket type ends.
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