High speed stability
12-02-2007, 09:15 PM
#1
Thread Starter
Join Date: Dec 2007
Posts: 6
High speed stability
Hello, I recently bought a 1988 5.0 notchback with 60 000 miles on it.
Everything on it is stock and original, original exhaust, shocks, etc.
I have this problem when driving on the highway. The car feels like it wants to turn in on itself around corners. In other cars I've owned the car resists going into a turn. The wheel centers itself when you let it go. In this mustang as you turn the wheel there is no resistance and the car will keep turning by itself, in fact you have to counter steer in some instances because it just wants to keep turning. I think I can feel the back wheels steering straight making the back end steer opposite the front wheels. It becomes noticable above 45mph. It's freakin scary, the other day I was going about 100mph and the car almost went sideways around a gradual curve in the highway. Dry roads and everything, not accelerating.
I checked the camber and toe myself using a piece of 2x4 (meaured with vernier calipers for constant thickness) that fits in my rim and then using a level for the camber and a laser pointer for the toe. I had a helper mark the laser pointer against a wall 125 feet away. The camber appears to be 0 degrees but it's hard to tell since it's hard to find a level surface. It's close to 0 anyway.
The front has 0.68 degrees total toe in.
The rear has 0.11 degrees total toe out.
The only mistake I made when doing the toe measurment was I took the readings after backing the car slowly into position, I should have driven forward slightly to load the steering components in the forward direction instead, not sure how much of a diff it would make though. Front toe might be 0.5 degrees total instead.
Anyway, it's definately not toed out in the front which is what I was expecting given the steering problem.
Anybody have any ideas? The shocks don't seem worn out, the car doesn't bounce over speed bumps. It jiggles when pushed side to side and the back end has side to side jiggle over speed bumps. I think it's just the tires though. I currently have 215/65/15 Blizzak WS-60's on the car for winter. The sidewalls are not as stiff as a summer 50 series tire. I've had these tires on other cars though and did not have any highway driving problems. The only difference I ever had was that the steering isn't as responsive. The car also had this problem with the tires that came with the car which were some crappy 235/60/15's. Could it be those torque struts on the back axle? Maybe they are worn out? Rear control arm and sway bar look ok. I'm out of ideas!
Everything on it is stock and original, original exhaust, shocks, etc.
I have this problem when driving on the highway. The car feels like it wants to turn in on itself around corners. In other cars I've owned the car resists going into a turn. The wheel centers itself when you let it go. In this mustang as you turn the wheel there is no resistance and the car will keep turning by itself, in fact you have to counter steer in some instances because it just wants to keep turning. I think I can feel the back wheels steering straight making the back end steer opposite the front wheels. It becomes noticable above 45mph. It's freakin scary, the other day I was going about 100mph and the car almost went sideways around a gradual curve in the highway. Dry roads and everything, not accelerating.
I checked the camber and toe myself using a piece of 2x4 (meaured with vernier calipers for constant thickness) that fits in my rim and then using a level for the camber and a laser pointer for the toe. I had a helper mark the laser pointer against a wall 125 feet away. The camber appears to be 0 degrees but it's hard to tell since it's hard to find a level surface. It's close to 0 anyway.
The front has 0.68 degrees total toe in.
The rear has 0.11 degrees total toe out.
The only mistake I made when doing the toe measurment was I took the readings after backing the car slowly into position, I should have driven forward slightly to load the steering components in the forward direction instead, not sure how much of a diff it would make though. Front toe might be 0.5 degrees total instead.
Anyway, it's definately not toed out in the front which is what I was expecting given the steering problem.
Anybody have any ideas? The shocks don't seem worn out, the car doesn't bounce over speed bumps. It jiggles when pushed side to side and the back end has side to side jiggle over speed bumps. I think it's just the tires though. I currently have 215/65/15 Blizzak WS-60's on the car for winter. The sidewalls are not as stiff as a summer 50 series tire. I've had these tires on other cars though and did not have any highway driving problems. The only difference I ever had was that the steering isn't as responsive. The car also had this problem with the tires that came with the car which were some crappy 235/60/15's. Could it be those torque struts on the back axle? Maybe they are worn out? Rear control arm and sway bar look ok. I'm out of ideas!
12-02-2007, 09:17 PM
#2
5th Gear Member
Join Date: Oct 2005
Location: Ohio USA
Posts: 4,616
RE: High speed stability
ORIGINAL: rob76
Hello, I recently bought a 1988 5.0 notchback with 160 000 miles on it.
Everything on it is stock and original, original exhaust, shocks, etc.
I have this problem when driving on the highway. The car feels like it wants to turn in on itself around corners. In other cars I've owned the car resists going into a turn. The wheel centers itself when you let it go. In this mustang as you turn the wheel there is no resistance and the car will keep turning by itself, in fact you have to counter steer in some instances because it just wants to keep turning. I think I can feel the back wheels steering straight making the back end steer opposite the front wheels. It becomes noticable above 45mph. It's freakin scary, the other day I was going about 100mph and the car almost went sideways around a gradual curve in the highway. Dry roads and everything, not accelerating.
I checked the camber and toe myself using a piece of 2x4 (meaured with vernier calipers for constant thickness) that fits in my rim and then using a level for the camber and a laser pointer for the toe. I had a helper mark the laser pointer against a wall 125 feet away. The camber appears to be 0 degrees but it's hard to tell since it's hard to find a level surface. It's close to 0 anyway.
The front has 0.68 degrees total toe in.
The rear has 0.11 degrees total toe out.
The only mistake I made when doing the toe measurment was I took the readings after backing the car slowly into position, I should have driven forward slightly to load the steering components in the forward direction instead, not sure how much of a diff it would make though. Front toe might be 0.5 degrees total instead.
Anyway, it's definately not toed out in the front which is what I was expecting given the steering problem.
Anybody have any ideas? The shocks don't seem worn out, the car doesn't bounce over speed bumps. It jiggles when pushed side to side and the back end has side to side jiggle over speed bumps. I think it's just the tires though. I currently have 215/65/15 Blizzak WS-60's on the car for winter. The sidewalls are not as stiff as a summer 50 series tire. I've had these tires on other cars though and did not have any highway driving problems. The only difference I ever had was that the steering isn't as responsive. The car also had this problem with the tires that came with the car which were some crappy 235/60/15's. Could it be those torque struts on the back axle? Maybe they are worn out? Rear control arm and sway bar look ok. I'm out of ideas!
Hello, I recently bought a 1988 5.0 notchback with 160 000 miles on it.
Everything on it is stock and original, original exhaust, shocks, etc.
I have this problem when driving on the highway. The car feels like it wants to turn in on itself around corners. In other cars I've owned the car resists going into a turn. The wheel centers itself when you let it go. In this mustang as you turn the wheel there is no resistance and the car will keep turning by itself, in fact you have to counter steer in some instances because it just wants to keep turning. I think I can feel the back wheels steering straight making the back end steer opposite the front wheels. It becomes noticable above 45mph. It's freakin scary, the other day I was going about 100mph and the car almost went sideways around a gradual curve in the highway. Dry roads and everything, not accelerating.
I checked the camber and toe myself using a piece of 2x4 (meaured with vernier calipers for constant thickness) that fits in my rim and then using a level for the camber and a laser pointer for the toe. I had a helper mark the laser pointer against a wall 125 feet away. The camber appears to be 0 degrees but it's hard to tell since it's hard to find a level surface. It's close to 0 anyway.
The front has 0.68 degrees total toe in.
The rear has 0.11 degrees total toe out.
The only mistake I made when doing the toe measurment was I took the readings after backing the car slowly into position, I should have driven forward slightly to load the steering components in the forward direction instead, not sure how much of a diff it would make though. Front toe might be 0.5 degrees total instead.
Anyway, it's definately not toed out in the front which is what I was expecting given the steering problem.
Anybody have any ideas? The shocks don't seem worn out, the car doesn't bounce over speed bumps. It jiggles when pushed side to side and the back end has side to side jiggle over speed bumps. I think it's just the tires though. I currently have 215/65/15 Blizzak WS-60's on the car for winter. The sidewalls are not as stiff as a summer 50 series tire. I've had these tires on other cars though and did not have any highway driving problems. The only difference I ever had was that the steering isn't as responsive. The car also had this problem with the tires that came with the car which were some crappy 235/60/15's. Could it be those torque struts on the back axle? Maybe they are worn out? Rear control arm and sway bar look ok. I'm out of ideas!
Bet you cant bounce your front end
put your hands on the front bumper real fast and try to push down
12-02-2007, 09:35 PM
#5
6th Gear Member
Join Date: Apr 2007
Location: California
Posts: 10,468
RE: High speed stability
Yeah, it sounds like you have a fair bit of positive caster. Gives you more neg camber when you turn the wheel, which is good for handling. It'll also increase steering wheel effort at lower speeds and more positive caster will also decrease return to center of the steering wheel. What you described about the rear sounds like loose roll oversteer, but it could be that your front alignment is so out of whack that it's causing the sensation. Take it to an alignment shop and see where you're really at, especially on caster. Also, what's the condition of the rear suspension? With the car jacked up and weight off the rear, can you move the axle housing side to side, or is there anything obviously wrong/worn with the rear suspension?
12-02-2007, 11:01 PM
#7
Thread Starter
Join Date: Dec 2007
Posts: 6
RE: High speed stability
I thought there was no adjustment on the caster adjustment on these fox body mustangs.
My measurements are accurate to within 0.1 degrees. I'm a physicist so I know how to measure such small angles
I'm not going to pay $100 for an alignment if I don't have to.
If I knew the factory Toe angle I would be able to say whether I have to too much or too little toe. The only other clue is that when I accelerate hard off the line the rear end goes out to the right a little and then a little to the left. This is without any wheelspin. I assume this is some kind of torque steer as the axle twists. It just does it a little. Not too much.
The shocks are fine because when you bounce the car up and down it goes back to it's default position without coming back or without any further oscillations. Of course brand new suspension would be tighter but It wouldn't be making the car dangerous to drive. My Neon had original suspension with 150k miles on it and it felt rigid/controlled and tracked great right up to 120mph.
My measurements are accurate to within 0.1 degrees. I'm a physicist so I know how to measure such small angles
I'm not going to pay $100 for an alignment if I don't have to.If I knew the factory Toe angle I would be able to say whether I have to too much or too little toe. The only other clue is that when I accelerate hard off the line the rear end goes out to the right a little and then a little to the left. This is without any wheelspin. I assume this is some kind of torque steer as the axle twists. It just does it a little. Not too much.
The shocks are fine because when you bounce the car up and down it goes back to it's default position without coming back or without any further oscillations. Of course brand new suspension would be tighter but It wouldn't be making the car dangerous to drive. My Neon had original suspension with 150k miles on it and it felt rigid/controlled and tracked great right up to 120mph.
12-02-2007, 11:14 PM
#8
Thread Starter
Join Date: Dec 2007
Posts: 6
RE: High speed stability
When I shake the car side to side at the back the axle doesn't seem to have any obvious play in relation to the body. However maybe it does front to back on one side which could be causing wonky rear end steer.
12-10-2007, 04:37 AM
#9
Thread Starter
Join Date: Dec 2007
Posts: 6
RE: High speed stability
So I lengthened one of my tie rods by about 1/64 of an inch or so, and it now drives great on the highway. I actually went even beyond that and test drove it making about 5 adjustments and trying it out. When it was more toed out (I estimate at around 0 toe) it was just too hairy to drive above 70mph. Taking tight curves felt like I was driving an F1 car or something as it was wanting to dart around which was kinda scary but made for quick steering otherwise. Anyway I toed it back in and now it feels pretty good on the highway. It doesn't randomly change direction and the wind doesn't make it dart about. It sails around curves. I'd estimate the toe on it right now to be about 0.4 degrees total or about 1/16 of an inch each side.
I believe the problem I had originally was I had too much Toe (0.7 degrees) and it didn't want to start turning the car until you had turned the wheel quite a bit at which point it would really pull suddenly to the side. (which was a bit scary at highway speeds!)
It still doesn't want to center the wheel by itself at lower speeds. At highway speeds it kinda wants to center itself now but not otherwise. I think maybe the rack or the ball joints are stiff. How do you test the rack?
I believe the problem I had originally was I had too much Toe (0.7 degrees) and it didn't want to start turning the car until you had turned the wheel quite a bit at which point it would really pull suddenly to the side. (which was a bit scary at highway speeds!)
It still doesn't want to center the wheel by itself at lower speeds. At highway speeds it kinda wants to center itself now but not otherwise. I think maybe the rack or the ball joints are stiff. How do you test the rack?
12-10-2007, 09:47 AM
#10
2nd Gear Member
Join Date: Oct 2007
Location: Ft. Lauderdale FL
Posts: 337
RE: High speed stability
My car feels like crap at high speeds aswell.
I replaced
Inner and outer tierod ends
Ball joints
Wheel bearings
Shocks and struts
Got an alignment...
Next i'm going to replace the steering rack because my car wants to turn more then it wants to go straight, i understand your feels like an f1 car comment, it DIVES into the turns around 40mph but wants to "wander" back and forth in a lane trying to go staight, it sucks. I'm also debating replacing the k-member with the tubular one because i my alignment guy said my front end wasn't 100% straight because my drivers wheel is 1/2 inch to far back in the wheel well, i don't know if its a bent control arm or the k-member, phuk it, i'll just replace it all and not worry about ordering more parts.
I replaced
Inner and outer tierod ends
Ball joints
Wheel bearings
Shocks and struts
Got an alignment...
Next i'm going to replace the steering rack because my car wants to turn more then it wants to go straight, i understand your feels like an f1 car comment, it DIVES into the turns around 40mph but wants to "wander" back and forth in a lane trying to go staight, it sucks. I'm also debating replacing the k-member with the tubular one because i my alignment guy said my front end wasn't 100% straight because my drivers wheel is 1/2 inch to far back in the wheel well, i don't know if its a bent control arm or the k-member, phuk it, i'll just replace it all and not worry about ordering more parts.