View unanswered posts | View active topics It is currently Tue May 21, 2019 7:03 am



Reply to topic  [ 13 posts ] 
 Steering Wheel Shimmy Under High Speed Braking 
Author Message
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Steering Wheel Shimmy Under High Speed Braking
So the old firebird is up to some of it's old tricks again.

Back in the winter I was driving the Firebird to work and I was getting a significant amount of shimmy in the steering wheel while braking at 100 km/h and higher...Nothing in the pedal, no vibrations or anything else while not braking. I figured it was a high spot on the front rotors, they were a couple years old, so I put on new pads and rotors....No change.
So I bit the bullet and took it to a local shop, they came back saying it was a tire issue.....At the time I was running some winter tires that were WAAY past their prime (like 10+ years old)....Running my hand across the tread surface I noticed that the fronts were worn sort of "wavy"....By this point we were into March, so I just swapped to my new-ish summer tires. Problem disappeared!! I drove it another month or so, then Christi started driving the car to work...All was good.

Now, about 10,000kms later I can feel the same kind of high speed braking shimmy in the wheel starting up again....It's not nearly as bad as it was, but still kind of annoying. I feel it ONLY in the steering wheel (no pulsating pedal) and ONLY while braking at 100+

I checked things out quickly last night and everything looks alright to me, no obvious abnormal wear on the tires, alignment feels good (only about 6 months old), etc.

Now, I do need to rotate the tires (summers), it's been on my list of shit to do, but it's kinda complicated because the rear rims have the larger hub hole, so I actually gotta get them re-mounted....Maybe related to this? Maybe not?

Does anyone have any ideas about what could be causing this?? I'd really like to fix it once and for all.


Thu Jun 27, 2013 8:32 pm
Profile
CCFBG Club Member
User avatar

Joined: Fri Mar 03, 2006 8:52 pm
Posts: 1164
Location: Drayton
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Did you use a torque wrench when changing wheels? Were the bearing hubs cleaned when the rotors were changed?

_________________
Image


Thu Jun 27, 2013 10:02 pm
Profile
Senior Forum User
User avatar

Joined: Mon Feb 01, 2010 12:26 pm
Posts: 217
Location: Ottawa
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Sounds like the tires are starting to wear abnormally again if the issue went away with changing them the first time. Did you ever run the current tires on a bad alignment?

My experience is that if they start to wear abmormally there's no stopping it even after fixing the alignment..

_________________
86 IROC
LQ4/T56/3.50 8.8 (next step..TC76)
Build thread: http://ls1tech.com/forums/conversions-hybrids/1819001-1986-iroc-turbo-lq4-t56-build-ac.html
Formerly 95 LT1 [LE2.2]/T56/4.11 9 Bolt..12.6@114MPH


Fri Jun 28, 2013 8:32 am
Profile
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
flame wrote:
Did you use a torque wrench when changing wheels? Were the bearing hubs cleaned when the rotors were changed?


Yes and definitely yes....My entire reason for changing them was to try and fix the simmy, so I was extra careful to make sure the mating surface was perfect.


Fri Jun 28, 2013 8:52 am
Profile
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
6speedIROC wrote:
Sounds like the tires are starting to wear abnormally again if the issue went away with changing them the first time. Did you ever run the current tires on a bad alignment?

My experience is that if they start to wear abmormally there's no stopping it even after fixing the alignment..


Could be....When I got the summer tires last year I drove for a couple months before getting an alignment because I noticed a bit of feathering starting on the out edge of the fronts....Got the alignment, toe was out a bit...feathering disppeared.

The rears shouldn't have any abnormal wear at all, so I guess I should try rotating them up to the front, and see what happens. Only thing I'd worry about is that something else is causing the tires to wear strange so I'd just end up ruining another set.


Fri Jun 28, 2013 8:56 am
Profile
CCFBG Club Member
User avatar

Joined: Mon Sep 01, 2008 9:01 pm
Posts: 1061
Location: Barrie
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Not sure what quality of rotors you put on when you replaced them last year, but perhaps the new rotors have warped already...there is some really crappy Chinese steel out there.

_________________
Image
1995 FORMULA

CURRENTLY INBETWEEN RIDES


Fri Jun 28, 2013 10:55 am
Profile
Senior Forum User
User avatar

Joined: Sun May 13, 2007 10:48 am
Posts: 984
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Loose wheel bearings possibly, worn out steering components, too much toe, not enough toe, could be lots of things

_________________
1987 IROC ww 99 LS1,TR224/112, STG2 heads ported by American Speed, P Gold springs, LS6 intake, SVO 30's, Ported TB, Comp Cromo Push rods, Katech Rod bolts, LS6 oil pump, T56, SW LT's, 8.8 hybrid rear 3.73, 275/40/17 MT ET streets, lots more
12.1 @ 112 mph 1.69 60'

89 R7U 1LE Players Challenge car all stock.


Fri Jun 28, 2013 2:17 pm
Profile
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Back in the winter I had the car up in the air and there was absolutely no play in the front end that I could detect...course things could have changed since then, I'll try to get some time to check again this weekend.
As far as the toe goes....I had it aligned at GM back in the Fall, and I am usually pretty good at picking up on crappy alignments (it's a pet peeve of mine) and I really not sensing anything abnormal now.

Anyone think it could have to do with the front shocks/springs? They're one of the few components that's still original on this car?

Car has just over 100,000km on it BTW.


Fri Jun 28, 2013 4:05 pm
Profile
CCFBG Club Member
User avatar

Joined: Tue Feb 28, 2006 1:42 pm
Posts: 2739
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Firm wrote:
Back in the winter I had the car up in the air and there was absolutely no play in the front end that I could detect...course things could have changed since then, I'll try to get some time to check again this weekend.
As far as the toe goes....I had it aligned at GM back in the Fall, and I am usually pretty good at picking up on crappy alignments (it's a pet peeve of mine) and I really not sensing anything abnormal now.

Anyone think it could have to do with the front shocks/springs? They're one of the few components that's still original on this car?

Car has just over 100,000km on it BTW.


Very doubtful its the shocks or springs Zack.

Check the lower control arm bushings. They're known to dry rott and take a hike on 4th gens. Your alignment you got back int he fall couldve masked the bushing problem/wear and doing the alignment could have corrected the alignment issue, but now the bushings could be that much WORSE that its causing the wheel to shimmy under brake dive.

Also check the torque arm mount on the drivers side of the transmission. If that mount has play in it, the car will have all kinds of wobblyness or 'shimmy' to it under braking.

_________________
2012 Camaro 2SS/RS - LS3/TR6060: BTR Cam, Long Tubes, 3" Catback, UDP, CAI Intake, Air Scoop, 3.91 Gears, Poly Diff Bushings, Toe Arms, Poly Subframe, Poly Radius-Rod bushings, ZL1 Suede Shifter, ZL1 Mounts, Arun Tuned - 475rwhp 443rwtq
11.97 @ 116 w/ 1.85 60'

Listen To Song Of My People!
Image


Sat Jun 29, 2013 4:15 pm
Profile WWW
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Thanks Jay, those are both new suggestions. How would I go about checking the LCA bushings?? Even the torque arm mount, what would I look for to know that it's bad??

I did rotate the tires today....no change, so I guess it's not tire related....Good news, cuz I don't wanna buy more tires!


Sat Jun 29, 2013 7:05 pm
Profile
CCFBG Club Member
User avatar

Joined: Sat Mar 19, 2005 8:07 pm
Posts: 4327
Location: The big town
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
If its in the wheel when braking, i would be checking the rotors with a dial indicator, new doesn't mean shit, i have a customer thats very hard on his brakes , full brembos and ebc., last 2 sets of front pads, glue let go and he can warp the rotors within a week of pushing them hard.

_________________
Image

9.06@155 mph, small block pump gas with 3.42's bird
8.14@166 mph, big block on 250 shot monza


Mon Jul 08, 2013 7:14 pm
Profile
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
I am leaning towards rotors too at this point. I just ordered some new parts and Jay and I are planning to change them this weekend. I'll report back once it's done.


Tue Jul 09, 2013 8:20 am
Profile
CCFBG Club Member

Joined: Wed Jul 09, 2008 9:16 pm
Posts: 1021
Location: Mississauga
Reply with quote
Post Re: Steering Wheel Shimmy Under High Speed Braking
Little update: Jay and I installed new rotors and pads yesterday. I've put about 200kms on it since and there's no sign of any shimmy! :)


Sun Jul 14, 2013 7:27 pm
Profile
Display posts from previous:  Sort by  
Reply to topic   [ 13 posts ] 

Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group.
Designed by STSoftware for PTF.