|
|
SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS! |
Post Reply |
|
Thread Tools | Search this Thread |
01-27-2014, 10:14 PM | #1 |
Private First Class
16
Rep 175
Posts |
Need help diagnosing a suspension noise
Recently installed a set of AST 4100 coilovers and now hear a loud popping sound from the rear when going over big bumps at speed. It seems like it's worse on the driver side rear. It's not all bumps, but just occasional and it's loud. The set was bought used with only 5k miles and they seem to all be working with no leaks. I feel like it's something simple, but can't figure it out.
I had a friend whose a tech at a bmw Indy shop do the install. Its the z4 m specific kit with spherical RSMs and hyperco 5.5" 650 rear springs. Anyone have experience with this? All suggestions for solutions would be much appreciated! Also called Vorshlag and they are not sure either without seeing the car. |
01-27-2014, 11:27 PM | #3 |
Private First Class
16
Rep 175
Posts |
|
Appreciate
0
|
01-28-2014, 12:34 AM | #4 |
Midlife Crises Racing Silent but Deadly Class
1820
Rep 5,337
Posts
Drives: 2006 MZ4C, 2021 Tesla Model 3
Join Date: Oct 2007
Location: Welcome to Jamaica have a nice day
|
Spherical RSMs make all sorts of noises.
__________________
Sitting on a beat-up office chair in front of a 5 year old computer in a basement floor, sipping on stale coffee watching a bunch of meaningless numbers scrolling aimlessly on a dimly lit 19” monitor.
|
Appreciate
0
|
01-28-2014, 12:57 AM | #5 |
Private First Class
16
Rep 175
Posts |
|
Appreciate
0
|
01-28-2014, 10:14 AM | #6 |
Midlife Crises Racing Silent but Deadly Class
1820
Rep 5,337
Posts
Drives: 2006 MZ4C, 2021 Tesla Model 3
Join Date: Oct 2007
Location: Welcome to Jamaica have a nice day
|
I know exactly what it is. The rear springs are caught on the collar and won't rotate, and there's torsional energy stored up when they compress. When you hit a bump, the stored up torsional energy all of a sudden releases, creating that "PING!" sound that reverberates throughout the chassis. And once they settle back down, the spring occasionally get caught on the collar and wash, rinse, repeat.
I used to get the same noise on my GC kit, but only after I lifted up the car and put it back down (springs fully unseated and reseated on perch) and only after I hit a big bump after lifting up the car. Then I put a couple of thrust sheets (they're thin little plastic rings sandwiched between thin aluminum rings that allow the springs to rotate freely) and haven't had the same noise since.
__________________
Sitting on a beat-up office chair in front of a 5 year old computer in a basement floor, sipping on stale coffee watching a bunch of meaningless numbers scrolling aimlessly on a dimly lit 19” monitor.
|
Appreciate
0
|
01-28-2014, 05:42 PM | #8 |
Second Lieutenant
13
Rep 279
Posts |
As referenced above most likely either the spherical RSM's or lack of thrust sheets. I have the 4150's with thrust sheets and RE RSM's and they are silent. Could be something else, but those are your most likely culprits.
__________________
06 Alpinweiss Z4M R Anthracite Apex EC-7 9F/9.5R, 245/275 Super Sport's, 17" Kosei K1 255/40r17 Direzza II, SS Lines, Pagid RS29, Ate SuperBlue, VT Comp. MM's, RE trans. mounts, AST 4150, Swift springs, Vorschlag camber plates, RE RSM, H&R swaybars, spherical rtabs, SuperFlex poly fcabs, StrongStrut Braces, Euro Headers, Stromung exhaust, ESS Tune, Eventuri intake |
Appreciate
0
|
01-28-2014, 07:04 PM | #9 |
Midlife Crises Racing Silent but Deadly Class
1820
Rep 5,337
Posts
Drives: 2006 MZ4C, 2021 Tesla Model 3
Join Date: Oct 2007
Location: Welcome to Jamaica have a nice day
|
Not sure if I'd use lube there, it's bound to attract dirt and gravel and cause the binding problem to get worse.
I would try thrust sheets and see if that helps. If not, change out the adjustable perch with an adjustable, articulating weight jack.
__________________
Sitting on a beat-up office chair in front of a 5 year old computer in a basement floor, sipping on stale coffee watching a bunch of meaningless numbers scrolling aimlessly on a dimly lit 19” monitor.
|
Appreciate
0
|
01-28-2014, 11:14 PM | #10 |
Private First Class
16
Rep 175
Posts |
Never heard of thrust sheets. Where's a good place to get these? The set was bought used with under 5k miles. The previous owner never had these issues and didn't need any extra components.
|
Appreciate
0
|
01-29-2014, 12:07 AM | #11 |
Second Lieutenant
13
Rep 279
Posts |
Hi there!
http://www.swiftsprings.net/products...rsal/misc.html $50 or so for both sides. They go above and below the spring. Rear shock mounts are also suspect. I was steered away from the spherical mounts because of the noise issues. The RE mounts are tits! If the previous owner didn't have any noise issues are you sure everything is installed/torqued correctly? Swaybar endlinks reconnected? I have been really happy with the fact that my AST coilovers/Vorschlag camber plates are so quite.
__________________
06 Alpinweiss Z4M R Anthracite Apex EC-7 9F/9.5R, 245/275 Super Sport's, 17" Kosei K1 255/40r17 Direzza II, SS Lines, Pagid RS29, Ate SuperBlue, VT Comp. MM's, RE trans. mounts, AST 4150, Swift springs, Vorschlag camber plates, RE RSM, H&R swaybars, spherical rtabs, SuperFlex poly fcabs, StrongStrut Braces, Euro Headers, Stromung exhaust, ESS Tune, Eventuri intake |
Appreciate
0
|
01-29-2014, 09:44 PM | #12 |
Private First Class
16
Rep 175
Posts |
Thanks for all the suggestions. I'm going to take it to a shop that is a licensed vendor of ast suspensions and see what they say. The thrust sheets seem cheap enough to try as well.
|
Appreciate
0
|
01-31-2014, 06:36 AM | #13 |
Lieutenant General
2280
Rep 12,565
Posts
Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT
iTrader: (99)
Garage List F15 X5 xDrive35i [8.75]
E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.20] |
Hpa should also sell the thrust sheets
|
Appreciate
0
|
03-07-2014, 10:26 PM | #15 |
Midlife Crises Racing Silent but Deadly Class
1820
Rep 5,337
Posts
Drives: 2006 MZ4C, 2021 Tesla Model 3
Join Date: Oct 2007
Location: Welcome to Jamaica have a nice day
|
That's where I got mine.
__________________
Sitting on a beat-up office chair in front of a 5 year old computer in a basement floor, sipping on stale coffee watching a bunch of meaningless numbers scrolling aimlessly on a dimly lit 19” monitor.
|
Appreciate
0
|
03-09-2014, 09:57 PM | #16 |
Private First Class
16
Rep 175
Posts |
Shop is saying the ast 4100 can't go too low because the adjuster is hitting something and needs to be modified. I could have my wording mixed up here, but anyone else have an issue with lowering restrictions?
|
Appreciate
0
|
03-10-2014, 10:21 AM | #17 |
Lieutenant General
2280
Rep 12,565
Posts
Drives: Z4 M, X5, GX460
Join Date: Apr 2008
Location: CT
iTrader: (99)
Garage List F15 X5 xDrive35i [8.75]
E86 Z4 M [10.00] F10 550i (Retired) [9.17] F25 X3 xDrive35i (R ... [9.43] E82 135is (Retired) [9.50] E85 Z4 M (Retired) [9.41] E90 328i xDrive (Re ... [9.25] E86 Z4 3.0si (Retired) [9.20] |
It's quite the opposite, AST41's were meant to run low and if anything can't go too high else they will "top out"
|
Appreciate
0
|
Post Reply |
Bookmarks |
Thread Tools | Search this Thread |
|
|