Need advice on how to troubleshoot handling issue
07-26-2007, 12:17 AM
#1
Staging Lane
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Need advice on how to troubleshoot handling issue (Warning: those of you expecting to read about troubleshooting modded or improved handling setups, you'll be disappointed... this is a fully 100% stock vehicle 
)
Been a while since I last posted here, still fighting the handling/stability problem that has plagued my WS6 for close to 2 years now.
Here's the current situation:
Sometime in late 2005 the local road crews removed a small 4-5 inch wide taper joining two sections of pavement in my neighborhood, the taper having served to connect one section of road with only one layer of pavement to the rest of the road with the final 2 layers already on it. As luck would have it, I came along before the second layer got put down, and hit that ~4 inch "barrier" at ~30 mph. Since that very moment of impact, my steering has exhibited a lot of kickback over gentle bumps and plenty of tramlining on even what seems like smooth roads!
Within moments of the "impact" I had the car on an alignment rack and everything looked exactly like what I usually spec'ed for this car, with the exception of toe being off a small amount (can't remember how much, nor in what direction).
This "impact" was hard enough to (in my opinion) kill the original 7 year old battery through the shock.
So far, anyone who's taken a look at the car hasn't found a single reason for this behavior, and one GM dealer "expert" even went so far to claim all F-cars did this... which enraged me because for 7 years my car was as controlled and comfy as a Cadillac (well, at least compared to the raw feel of my GTA).
What's been done:
==============
Swapped shocks (for stockers, albeit the "new" part number on the physically smaller De Carbon shocks
), sway bar end links, rotated tires, alignment, changed one tie rod end with a *small* amount of play at the BJ end.
My usual alignment:
===============
camber around -0.1 degree (just enough to preload suspension, in my opinion)
caster around 4.4 (although I think the car has been at 3.9 at some point, and as high as 4.7 or so)
toe: 0
Tires:
=====
Yokohama AVS Sport in stock size. About 15000 miles on the tires at the time of the "incident" and they had behaved perfectly well until that very moment. The tires are currently showing some definite feathering on the insides!
So with some vacation time coming up, I need to plot out what I'll be tackling, and I'd appreciate any advice. Here's what I've thought of so far, please feel free to comment or shoot down as you see fit.
1. tightening up the steering rack preload (the bolt up front), perhaps the rack gear took a beating during that incident?
2. stock replacement lower front control arm bushings (did the 1998 WS6 cars come with 1LE bushings?). Several shops have checked the bushings (on the vehicle) with a crowbar test, and claimed the bushings were okay, however I wonder how F-body savvy these guys were to begin with... maybe large wide tires require better bushings to maintain steering control?
3. complete replacement of lower control arms incl. bushings. Could the impact have bent something in a way that wouldn't show up on an alignment rack? Is there a way to check that the tie rods remain at proper geometry as the control arms move through their arcs?
4. Could the upper arms have been bent with this sort of impact? if so, could both upper and lower arms have been bent in a way as to keep all the alignment numbers untouched but affect the steering geometry during suspension movements? Should I even worry about the knuckle?
5. could the joint in the steering column be a source of headache here? I've seen references to the steering column being a source of steering kickback, but how much slop is considered acceptable?
I could be wrong but I almost get the impression the steering effort has increased somewhat (or perhaps I'm simply fighting the wheel more). I'm sure the tire feathering has something to do with this. Road imperfections also seem harsher and more transmitted through the wheel.
The car's ride height appear to not have changed at all, and I compared this with a reading I happened to take by chance several weeks before the incident. However, visually I can't shake the feeling that the tires are tucked further under the fender... sort of like if you stand beside the side mirrors and look down at the top of the fenders, it's almost like the tires are more shrouded by the fender lip. One would almost think the camber was off in a big negative way, but things all read out normal on the alignment rack.
I'm even prepared to revert to replacement F1 tires in case it would be due to the Yokohamas, but it doesn't explain why the Yokos were okay for the first 2 years of use. As for the shocks, if I can get the stability back, I may spring for Konis in an effort to dial in the shock behaviour I was perfectly happy all along with the original shocks (I know, I'm weird I guess... but they did fine on our crap roads).
Some photos of how the car sits as of about 2-3 weeks ago coming up:
)Been a while since I last posted here, still fighting the handling/stability problem that has plagued my WS6 for close to 2 years now.
Here's the current situation:
Sometime in late 2005 the local road crews removed a small 4-5 inch wide taper joining two sections of pavement in my neighborhood, the taper having served to connect one section of road with only one layer of pavement to the rest of the road with the final 2 layers already on it. As luck would have it, I came along before the second layer got put down, and hit that ~4 inch "barrier" at ~30 mph. Since that very moment of impact, my steering has exhibited a lot of kickback over gentle bumps and plenty of tramlining on even what seems like smooth roads!
Within moments of the "impact" I had the car on an alignment rack and everything looked exactly like what I usually spec'ed for this car, with the exception of toe being off a small amount (can't remember how much, nor in what direction).
This "impact" was hard enough to (in my opinion) kill the original 7 year old battery through the shock.
So far, anyone who's taken a look at the car hasn't found a single reason for this behavior, and one GM dealer "expert" even went so far to claim all F-cars did this... which enraged me because for 7 years my car was as controlled and comfy as a Cadillac (well, at least compared to the raw feel of my GTA).
What's been done:
==============
Swapped shocks (for stockers, albeit the "new" part number on the physically smaller De Carbon shocks
), sway bar end links, rotated tires, alignment, changed one tie rod end with a *small* amount of play at the BJ end.My usual alignment:
===============
camber around -0.1 degree (just enough to preload suspension, in my opinion)
caster around 4.4 (although I think the car has been at 3.9 at some point, and as high as 4.7 or so)
toe: 0
Tires:
=====
Yokohama AVS Sport in stock size. About 15000 miles on the tires at the time of the "incident" and they had behaved perfectly well until that very moment. The tires are currently showing some definite feathering on the insides!
So with some vacation time coming up, I need to plot out what I'll be tackling, and I'd appreciate any advice. Here's what I've thought of so far, please feel free to comment or shoot down as you see fit.
1. tightening up the steering rack preload (the bolt up front), perhaps the rack gear took a beating during that incident?
2. stock replacement lower front control arm bushings (did the 1998 WS6 cars come with 1LE bushings?). Several shops have checked the bushings (on the vehicle) with a crowbar test, and claimed the bushings were okay, however I wonder how F-body savvy these guys were to begin with... maybe large wide tires require better bushings to maintain steering control?
3. complete replacement of lower control arms incl. bushings. Could the impact have bent something in a way that wouldn't show up on an alignment rack? Is there a way to check that the tie rods remain at proper geometry as the control arms move through their arcs?
4. Could the upper arms have been bent with this sort of impact? if so, could both upper and lower arms have been bent in a way as to keep all the alignment numbers untouched but affect the steering geometry during suspension movements? Should I even worry about the knuckle?
5. could the joint in the steering column be a source of headache here? I've seen references to the steering column being a source of steering kickback, but how much slop is considered acceptable?
I could be wrong but I almost get the impression the steering effort has increased somewhat (or perhaps I'm simply fighting the wheel more). I'm sure the tire feathering has something to do with this. Road imperfections also seem harsher and more transmitted through the wheel.
The car's ride height appear to not have changed at all, and I compared this with a reading I happened to take by chance several weeks before the incident. However, visually I can't shake the feeling that the tires are tucked further under the fender... sort of like if you stand beside the side mirrors and look down at the top of the fenders, it's almost like the tires are more shrouded by the fender lip. One would almost think the camber was off in a big negative way, but things all read out normal on the alignment rack.
I'm even prepared to revert to replacement F1 tires in case it would be due to the Yokohamas, but it doesn't explain why the Yokos were okay for the first 2 years of use. As for the shocks, if I can get the stability back, I may spring for Konis in an effort to dial in the shock behaviour I was perfectly happy all along with the original shocks (I know, I'm weird I guess... but they did fine on our crap roads).
Some photos of how the car sits as of about 2-3 weeks ago coming up:
07-26-2007, 12:38 AM
#2
Staging Lane
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Just tried to find some comparison photos of my car from way back when, and how the car looked about 2-3 weeks ago... try as I might, I can't really make out any appreciable difference in stance (but it's late, maybe I'm missing something obvious?).
1999
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2007
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2000
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2007
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1999
====
2007
====
Any advice greatly appreciated.
1999
====
2007
====
2000
====
2007
====
1999
====
2007
====
Any advice greatly appreciated.
07-26-2007, 07:01 PM
#4
Staging Lane
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Sorry. Wanted to avoid the barrage of "Check your alignment" replies. I already wasted a lot of time and money on sway bar end links and shocks and other things that in the end didn't need replacing after all (thanks to the many armchair "experts" on another board), so as a sign respect for the more knowledgeable members here, I wanted to make sure to provide as many pertinent details as possible.
So here's the Coles Notes version:
============================================
Hit a patch of irregular pavement at 30 mph and all of a sudden my steering went weird. Lots of kickback, lots and lots of tramlining, and a possible increase in steering effort. No apparent change in alignment specs from what I was running for years.
See above first post for a breakdown of what was attempted and what I intend to do.
Any advice on what to focus on first would be greatly appreciated.
==============================================
Hope this helps summarize my problem. Any recommendations or comments (especially if they've gone through this same thing, or have accumulated a good understanding of our suspensions) would be greatly appreciated... you'd be helping out a fellow devoted F-fan return to 100% enjoyment of his ride.
So here's the Coles Notes version:
============================================
Hit a patch of irregular pavement at 30 mph and all of a sudden my steering went weird. Lots of kickback, lots and lots of tramlining, and a possible increase in steering effort. No apparent change in alignment specs from what I was running for years.
See above first post for a breakdown of what was attempted and what I intend to do.
Any advice on what to focus on first would be greatly appreciated.
==============================================
Hope this helps summarize my problem. Any recommendations or comments (especially if they've gone through this same thing, or have accumulated a good understanding of our suspensions) would be greatly appreciated... you'd be helping out a fellow devoted F-fan return to 100% enjoyment of his ride.
07-29-2007, 09:28 AM
#6
Have you checked for play in the front wheel bearings? That's my first thought.
Or, these cars are known to bend spindles easily. However, if the alignment specs are still the same or have been readjusted, I'm not sure what effect a bent spindle would have on it all. It may act like normal, or it could cause issues, but I'm not 100% sure how it would act, so I can't say for sure.
Or, these cars are known to bend spindles easily. However, if the alignment specs are still the same or have been readjusted, I'm not sure what effect a bent spindle would have on it all. It may act like normal, or it could cause issues, but I'm not 100% sure how it would act, so I can't say for sure.
07-29-2007, 09:28 AM
#7
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Were the front control arms inspected for play? On a
beater of mine I drove for years with the upper control
arm bushings missing. That made for some interesting
differences in steering geometry, accelerating vs decel
and left/right which would shift abruptly. I was still able
to align it well enough (judging purely on tire-wear basis)
but the handling was poor.
With an impact like that I would suspect something in
the hard linkage might have gotten bent (or worse) and
even if you adjust tire alignment the geometry may be
odd. Or sloppy.
beater of mine I drove for years with the upper control
arm bushings missing. That made for some interesting
differences in steering geometry, accelerating vs decel
and left/right which would shift abruptly. I was still able
to align it well enough (judging purely on tire-wear basis)
but the handling was poor.
With an impact like that I would suspect something in
the hard linkage might have gotten bent (or worse) and
even if you adjust tire alignment the geometry may be
odd. Or sloppy.
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07-29-2007, 03:23 PM
#8
Staging Lane
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Originally Posted by trackbird
Have you checked for play in the front wheel bearings? That's my first thought.
Or, these cars are known to bend spindles easily. However, if the alignment specs are still the same or have been readjusted, I'm not sure what effect a bent spindle would have on it all. It may act like normal, or it could cause issues, but I'm not 100% sure how it would act, so I can't say for sure.
Or, these cars are known to bend spindles easily. However, if the alignment specs are still the same or have been readjusted, I'm not sure what effect a bent spindle would have on it all. It may act like normal, or it could cause issues, but I'm not 100% sure how it would act, so I can't say for sure.
I had not thought of the spindles. I'm actually surprised to hear of the car's rep for bending spindles... they look beefier than the upper A-arm, that's for sure!
I thought the upper arms would be the first to go before the spindle. I'll have to have a closer look to see if there is any way a tire impact at that angle could bend the spindle and yet keep my alignment specs bang on (no pun intended).Thanks for the lead. Will price spindles on Monday (
logging into my bank account to check how bad I can take the hit).
07-29-2007, 03:37 PM
#9
Staging Lane
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Originally Posted by jimmyblue
Were the front control arms inspected for play? On a
beater of mine I drove for years with the upper control
arm bushings missing. That made for some interesting
differences in steering geometry, accelerating vs decel
and left/right which would shift abruptly. I was still able
to align it well enough (judging purely on tire-wear basis)
but the handling was poor.
With an impact like that I would suspect something in
the hard linkage might have gotten bent (or worse) and
even if you adjust tire alignment the geometry may be
odd. Or sloppy.
beater of mine I drove for years with the upper control
arm bushings missing. That made for some interesting
differences in steering geometry, accelerating vs decel
and left/right which would shift abruptly. I was still able
to align it well enough (judging purely on tire-wear basis)
but the handling was poor.
With an impact like that I would suspect something in
the hard linkage might have gotten bent (or worse) and
even if you adjust tire alignment the geometry may be
odd. Or sloppy.
Well, the front control arms were inspected for play by Zeke's (the speed shop subcontracted by SLP to do the specialty F-cars up here when they were produced) and also by a reputed high performance shop specializing in race Porsches. Both had no concerns over the lower bushings, don't recall them checking the upper bushings though. Maybe I'll go dig in there this evening in my garage and check that out (nice excuse to grab my crowbar since I'm on vacation now and nowhere near a coworker
).I'm still torn between going all out and replacing all 4 arms and bushings or just trying the bushings first. Not being equipped with a spring compressor, I'll have no choice but to farm that job out (probably to Zeke's) so I have to factor in the labor time of bushing R&R versus replacement of the whole mess (didn't consider spindle too... damn).
I was starting to lean towards bushing R&R under the thought that maybe the bushings were allowing a change in scrub radius due to compression of the bushings (and subsequent horizontal shift of lower A-arm under load) and that was creating a torque on the wheels. I came to this conclusion based on the fact that it seems WS6 bushings were rated harder than normal bushings and it seems the wider tires were the factor (ie. shared with 1LE), and I'd read about random pulling/steering kickback during braking, something my car appears to exhibit since the incident. But now you've added the concern that maybe something hard is bent.
(gotta figure out what could bend without affecting any of the three main alignment specs)
The insides of my tires are really getting chewed/feathered to heck.
BTW, I really appreciate you guys sharing your thoughts and experiences on this. It's really helping me figure this out. I don't give up easily in anything I try, and I WILL nail this sucker down.
This car has been too good all these years to let it suffer like this. Again, thank you very much. 