Bumpsteer etc....
#16
Rennlist Member
The ER ones are a tight fit and you need to grind the knuckle slightly to get them on. I actually cracked one the first time I installed them by forcing it on without grinding enough material away. To ER's credit they did replace it for free.
#17
Addict
Rennlist Member
Rennlist Member
I have one semi-similar to what's pictured above: I just developed it for the 928: what's the thread entering the steering rack for the 944? 928 is M16x1.5.
Mark
Mark
#18
Rennlist Member
Thread Starter
Pics of your version Mark?
#20
Rennlist Junkie Forever
If you drop the tie rod at the wheel (moving it more towards parallel with the ground) without moving the A arm pivot point "up", you no longer have a parallel A arm-to-tie rod relationship which is worse.
TonyG
TonyG
#21
Rennlist Member
You move the tie rod down at the wheel to restore the parrallel relationship with the control arm which you have also moved down at the wheel with pins.
#22
Rennlist Junkie Forever
Not gonna happen.
I would never use a longer ball joint pin to space the control arm away from the spindle.
The loads on the ball joint pin change from a 100% sheer load to something completely different.
That's asking for problems.
TonyG
#23
Rennlist Member
Fine. If you don't use longer ball joint pins, you don't need to drop the tie rod and the relationship between the two stays stock regardless of how you raise or lower the suspension.
Lots of people use them though. I have the Racers Edge ones, three years of racing on slicks and so far no problems. Maybe they are coming....
Lots of people use them though. I have the Racers Edge ones, three years of racing on slicks and so far no problems. Maybe they are coming....
#24
Rennlist Junkie Forever
Lots of people use them though. I have the Racers Edge ones, three years of racing on slicks and so far no problems. Maybe they are coming....
I'll take the bump steer (especially since there is so little of it due to the fact that track cars have spring rates so high, there's not much wheel travel to begin with... and thus not much bump steer to content with).
TonyG
#25
Rennlist Member
I think there is something to be said for restoring the control arm geometry when you have a very lowered car though. Pins might not be the best engineering solution to solve the problem, agreed, but something is needed.
I can tell the difference with how the car feels with changes in front roll centre, having tried several different setups to change the angle of the front control arms and ride heights. I think with stiff springs changes in roll centre location are more noticeable than less.
I know it's only anecdotal, but in my case I am confident the car handles better with the arms dropped where they are, and there are improvements in steering feel to be gained from bump steer adjustment. I'm guessing that even on a car without extended pins, bump steer could be subtlely improved by moving the rack mounts.
I can tell the difference with how the car feels with changes in front roll centre, having tried several different setups to change the angle of the front control arms and ride heights. I think with stiff springs changes in roll centre location are more noticeable than less.
I know it's only anecdotal, but in my case I am confident the car handles better with the arms dropped where they are, and there are improvements in steering feel to be gained from bump steer adjustment. I'm guessing that even on a car without extended pins, bump steer could be subtlely improved by moving the rack mounts.
#26
Rennlist Member
Thread Starter
Anyone got any half decent pics to illustrate what this all means? I have a decent idea but I think it would be beneficial for others reading the thread.
#29
Rennlist Member
See how the red, tierod, and blue, control arm ends move on different arcs? Because one is at an angle to the other, as you go further in the travel, the arcs diverge more. When the arcs diverge, the steering knuckles will have to pivot a little bit so nothing binds up. This pivoting of the steering knuckle turns the wheel a little bit - this is bump steer.
If the control arm and tierod are parallel, then the paths of the arcs stay a constant distance from each other, and keep the wheel pointed at the same angle while it goes through the suspension travel.
I don't have an exact measurement, but I'd say my 944 is 2-3" lower than stock. It's low enough I have to drive the front onto wood blocks to get the lift arms under it... and my lift is low enough to go under a stock GT3 with no problem.
#30
Wasn't sure as I don't track except on my daily commute. If I were tracking I would build a set of drop spindles with bolt-on wheel bearings and get rid of the stub shaft.
Modding the X-members, I've found that an exact 0.75" A-arm bolt relocation allows for an inexpensive solution to the Tie-rod drop at the knuckle...
Modding the X-members, I've found that an exact 0.75" A-arm bolt relocation allows for an inexpensive solution to the Tie-rod drop at the knuckle...