Rear End Stick Problems (944) Bad Oversteer.
07-21-2003, 02:31 PM
#1
Drifting
Thread Starter
Rear End Stick Problems (944) Bad Oversteer.
Hey guys. AutoXed the 951 last weekend and had serious issue keeping the rear end from coming around after braking, and into the turn.
Now before I start getting driving lessons here, let me say right up front this is a car-specific problem. 3 Drivers and the same issue.
I used to have the rear severely lowered, and just raised it - perhaps I went too far (like right back to US spec). I've been battling this issue with this car for quite a while now, but it seemed exacerbated this last event.
I am running stock 89 M030 suspension and swaybars, Kuhmo Ecsta Supra 712s, and -1.5 degrees camber in the front, -1.25 in the rear (used to run -1.5 in the rear, but I was having traction problems-wheelspin due to the open diff). Toe is very close to zero, on the toe-in side, front and back.
Any suggestions? I feel like the car should be more nuetral, even on street tires. We're going to run Yoko A032R (I think that's it) next time around, but I'd like to correct the problem before patching it....
Now before I start getting driving lessons here, let me say right up front this is a car-specific problem. 3 Drivers and the same issue.
I used to have the rear severely lowered, and just raised it - perhaps I went too far (like right back to US spec). I've been battling this issue with this car for quite a while now, but it seemed exacerbated this last event.
I am running stock 89 M030 suspension and swaybars, Kuhmo Ecsta Supra 712s, and -1.5 degrees camber in the front, -1.25 in the rear (used to run -1.5 in the rear, but I was having traction problems-wheelspin due to the open diff). Toe is very close to zero, on the toe-in side, front and back.
Any suggestions? I feel like the car should be more nuetral, even on street tires. We're going to run Yoko A032R (I think that's it) next time around, but I'd like to correct the problem before patching it....
07-21-2003, 03:26 PM
#2
Nordschleife Master
I would take a close look at the rear ride height. Make the car level (put a level on the doorsill if you want to go crazy).
I've read that the rear being lower will cause understeer and higher will cause oversteer. I am not 100% sure about this, though.
My car, when it had stock suspension had a tendancy to understeer if anything.
I've read that the rear being lower will cause understeer and higher will cause oversteer. I am not 100% sure about this, though.
My car, when it had stock suspension had a tendancy to understeer if anything.
07-22-2003, 07:44 AM
#5
Race Director
What size tires are you running front and rear?
You may need more tire in the rear to help you dial out some oversteer, if it is as massive as you say.
I know my 968 M030 rear sway bar is 3-way adjustable, is yours? If so, what setting do you have it on? Also: check the front swaybar to ensure it is not loose.
Your camber settings are ideal for a street/autox compromise: I don't think that's giving you any problems.
Does your car exhibit ANY understeer, especially in the slower, tighter corners?
-Z-man.
You may need more tire in the rear to help you dial out some oversteer, if it is as massive as you say.
I know my 968 M030 rear sway bar is 3-way adjustable, is yours? If so, what setting do you have it on? Also: check the front swaybar to ensure it is not loose.
Your camber settings are ideal for a street/autox compromise: I don't think that's giving you any problems.
Does your car exhibit ANY understeer, especially in the slower, tighter corners?
-Z-man.
07-22-2003, 02:03 PM
#6
Drifting
Thread Starter
OK - front swaybar mounts are good, rear swaybar is non-adjustable (89 turbo S bar) Tire sizes are the standard sizes for the 17" 993 cup replica wheels, 255 or so in the back...
I'm bring the back down a hair, and realigning after corner balance to some toe-out in the front and rear to improve my slip angle (per Mr. Richman's suggestion). Adam also reminded me this morning that since I didn't re-align after I raised the rear, I really don't know how it is setup back there!
True that...
Next event will be on stock Turbo S Clubsport wheels with Yokos, so I should have more grip - and I may increase my negative camber all around by another .25 degree...
I'm bring the back down a hair, and realigning after corner balance to some toe-out in the front and rear to improve my slip angle (per Mr. Richman's suggestion). Adam also reminded me this morning that since I didn't re-align after I raised the rear, I really don't know how it is setup back there!
True that...
Next event will be on stock Turbo S Clubsport wheels with Yokos, so I should have more grip - and I may increase my negative camber all around by another .25 degree...
07-26-2003, 08:03 PM
#7
Drifting
Thread Starter
Bah! one of my rear clubsports has a one inch crack in the edge. Anyone know where I can get a cosmetically-challenged but straight and true replacement?
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08-02-2003, 10:08 PM
#8
Drifting
Thread Starter
UPDATE: Corner Balancing...
I put the car on the scales and this is where it was:
FL: 792# FR: 766#
RL: 726# RR: 762#
LX: 1555#
RX: 1493#
After adjustment, I ended up with: (with driver)
FL: 775#827# FR: 775# 786#
RL: 743#799# RR: 751#777#
LX: 1526# or 50.1% 1605# or 50.3%
RX: 1518# or 49.8% 1585# or 49.7%
It is getting better, but I think the rear is a tad too high, and the front way too low on a ride height issue. I will be at least raising the front and re-corner balancing tomorrow. Then, on to the alignment rack to see what the current alignmnet values are (or aren't).
More to come!
I put the car on the scales and this is where it was:
FL: 792# FR: 766#
RL: 726# RR: 762#
LX: 1555#
RX: 1493#
After adjustment, I ended up with: (with driver)
FL: 775#827# FR: 775# 786#
RL: 743#799# RR: 751#777#
LX: 1526# or 50.1% 1605# or 50.3%
RX: 1518# or 49.8% 1585# or 49.7%
It is getting better, but I think the rear is a tad too high, and the front way too low on a ride height issue. I will be at least raising the front and re-corner balancing tomorrow. Then, on to the alignment rack to see what the current alignmnet values are (or aren't).
More to come!
08-03-2003, 06:43 PM
#9
Drifting
Thread Starter
ok, final numbers: (without and with driver...)
LF: 777#(825#) RF: 778#(795#)
LR: 716#(783#) RR: 733#(755#)
LX: (1580# or 50.0%)
RX: (1579# or 49.9%)
the car sits almost square, within 3mm in the rear (driver's side high), within 7mm in the front (driver's side low). I was told the driver's side fender was replaced, so I'm assuming this is as good as it gets.
The car is a lot higher front and rear than what I am accustomed to running, with ~ 10mm rake from rear (high end) to front, as measured on the door sills. I typically make them level.
The front spring perches are ~1/2 inch from the bottom of the threads (I actually raised them almost that amount today because I want some suspension function up there!).
I am running 1989 944 turbo M030 suspension, stock everything (~180# spring rate).
I have between 13.25 and 13.5 inches between center of wheel (or spindle) and top of arch up front, per PCA specs (13" minimum for ball joint safety)
Still need to align this thing...
LF: 777#(825#) RF: 778#(795#)
LR: 716#(783#) RR: 733#(755#)
LX: (1580# or 50.0%)
RX: (1579# or 49.9%)
the car sits almost square, within 3mm in the rear (driver's side high), within 7mm in the front (driver's side low). I was told the driver's side fender was replaced, so I'm assuming this is as good as it gets.
The car is a lot higher front and rear than what I am accustomed to running, with ~ 10mm rake from rear (high end) to front, as measured on the door sills. I typically make them level.
The front spring perches are ~1/2 inch from the bottom of the threads (I actually raised them almost that amount today because I want some suspension function up there!).
I am running 1989 944 turbo M030 suspension, stock everything (~180# spring rate).
I have between 13.25 and 13.5 inches between center of wheel (or spindle) and top of arch up front, per PCA specs (13" minimum for ball joint safety)
Still need to align this thing...
08-11-2003, 09:23 AM
#10
Drifting
Thread Starter
ALright! I got my alignment and ride heights set, and the car performed WONDERFULLY this past weekend.
We had a Solo II at Carolina Motorsports Park, on the Autocross section of the track. Mr. Richman and I co-drove the car, he took first in class for B Stock (also beating all the A stock drivers) I didn't do so well, but my times dropped dramatically every run as I got used to the track speeds, the tire grip, and over my apprehension of the previous rear-end preoblems.
Neither of us had difficulty controlling the car this time around (and we both did last event)
The alignments specs I went with are these:
Front toe: 0.06 toe in 0.06 toe in
Camber: -1.50 -1.50
Caster: +2.79 +2.90 (that was as close as they would come)
Rear Toe: 0.18 toe OUT 0.19 toe OUT (for a better tire slip angle)
Camber: -1.34 -1.37
Tire temps showed the front tires to be even all across (must have the camber right) - the rears could use some more negative camber, but with an open diff, I am giving up contact patch during acceleration with any more negative camber, so this is the compromise I settled on.
We ran Yoko A032Rs, on the Turbo S rims sizes with 36psi up front and 31 psi in the rear, cold.
I hope this helps someone ese, as I can't seem to get good car setup information from the lists! (and I know there are others out there that USE the cars as they were designed)
We are battling wheelspin like crazy now, even with a low boost condition (only 8 psi, and it comes in LATE LATE). Either I have to source a cheap factory LSD unit, or we are going to play with a bigger front swaybar (I'd have to go to the 30mm bar at this point) to keep the inside rear tire down....
We also had a braking problem, prolly due to rotor glazing.
We had a Solo II at Carolina Motorsports Park, on the Autocross section of the track. Mr. Richman and I co-drove the car, he took first in class for B Stock (also beating all the A stock drivers) I didn't do so well, but my times dropped dramatically every run as I got used to the track speeds, the tire grip, and over my apprehension of the previous rear-end preoblems.
Neither of us had difficulty controlling the car this time around (and we both did last event)
The alignments specs I went with are these:
Front toe: 0.06 toe in 0.06 toe in
Camber: -1.50 -1.50
Caster: +2.79 +2.90 (that was as close as they would come)
Rear Toe: 0.18 toe OUT 0.19 toe OUT (for a better tire slip angle)
Camber: -1.34 -1.37
Tire temps showed the front tires to be even all across (must have the camber right) - the rears could use some more negative camber, but with an open diff, I am giving up contact patch during acceleration with any more negative camber, so this is the compromise I settled on.
We ran Yoko A032Rs, on the Turbo S rims sizes with 36psi up front and 31 psi in the rear, cold.
I hope this helps someone ese, as I can't seem to get good car setup information from the lists! (and I know there are others out there that USE the cars as they were designed)
We are battling wheelspin like crazy now, even with a low boost condition (only 8 psi, and it comes in LATE LATE). Either I have to source a cheap factory LSD unit, or we are going to play with a bigger front swaybar (I'd have to go to the 30mm bar at this point) to keep the inside rear tire down....
We also had a braking problem, prolly due to rotor glazing.
08-11-2003, 10:34 AM
#11
Race Director
Two questions/points:
1. Tire temps: your tire temps should get slightly hotter towards the inside of the tire, due to the camber. (At least that has been my experience on the TRACK in DE's.) The camber allows the edges too cool a bit during the straights. Not sure how much it would cool down in autox, but you should see this. -1.5 & -1.3 degrees of camber are only 'slightly' agressive, but a good setting for a dual purpose street/autox car.
2. Bigger front sway bar: why? You didn't mention anything about still having oversteering issues, and a bigger front will just give you more understeer. I am not sure if this will help with wheelspin. Since my 944S2 doesn't have LSD either, I also battle the wheelspin issue!
Just my $0.42,
-Z-man.
1. Tire temps: your tire temps should get slightly hotter towards the inside of the tire, due to the camber. (At least that has been my experience on the TRACK in DE's.) The camber allows the edges too cool a bit during the straights. Not sure how much it would cool down in autox, but you should see this. -1.5 & -1.3 degrees of camber are only 'slightly' agressive, but a good setting for a dual purpose street/autox car.
2. Bigger front sway bar: why? You didn't mention anything about still having oversteering issues, and a bigger front will just give you more understeer. I am not sure if this will help with wheelspin. Since my 944S2 doesn't have LSD either, I also battle the wheelspin issue!
Just my $0.42,
-Z-man.
08-11-2003, 07:41 PM
#12
Drifting
Thread Starter
Yeah, we were thinking that weight transfer to the outside front corner might be an issue, but that wouldn't contribute to wheelspin on the exit, now would it? So, the front swaybar angle is out, exactly as you were suggesting - it could only hurt front end stick...
The car is a daily driver, and the compromise settings seem to be working really well. There really aren't any straight sections in the autoX courses I am used to, so the tires (at least the front) seem to even out temp wise when the handling is right, so the mild camber angle seems to be good for the stock suspension, at least thusfar.
As I said earlier, if I had LSD, I'd certainly add some camber in the rear!
The car is a daily driver, and the compromise settings seem to be working really well. There really aren't any straight sections in the autoX courses I am used to, so the tires (at least the front) seem to even out temp wise when the handling is right, so the mild camber angle seems to be good for the stock suspension, at least thusfar.
As I said earlier, if I had LSD, I'd certainly add some camber in the rear!
08-12-2003, 10:00 AM
#13
Race Director
Keith: just a side note: My wife and I will be vacationing on the Outer Banks next week. Are there any autocrosses near there coming up?
I'll be driving a "mental rental," but it would still be fun to dice it up!
-Z.
I'll be driving a "mental rental," but it would still be fun to dice it up!
-Z.
08-12-2003, 10:33 AM
#14
Racer
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Z-Man what part of the outer banks will you be in? I think Keith said that there would be the 24hr auto-x here that weekend. But depending on what part of the OBX you will be in you could still be 8hrs from here.