supernow bumpsteer kit - steering angle spacers for grip driving
 

hey all. thank you for reading and discussing my post with me.


i bought a supernow bumpsteer kit a while back for my NA to eliminate bumpsteer. i was just wondering if anyone could discuss the pros and cons of the spacers for grip driving? these could include steering rack ratio speed change, extra weight on the steering rack/unsprung, increased wear on the steering pump, different allignment change during turning?

i got the kit to get my toe change under suspension travel down to a few thousandths, so i am really trying to get to the nitty gritty. i just dont know if i need the steering increase or if there are benefits for non drift, non turbo, too.

and lastly, spacers sort of allude me. im running under the assumption they go between the tie rod and the rack (or maybe at the end of the tie rod), and you have to adjust the toe so its not toed out upon install. then, i am assuming that the rack has more rod to push each wheel outward at full lock?

thanks all!

russ

The FC suspension doesn't have bump steer... Not sure what exactly you are trying to eliminate...

Why would you think this would change the steering rack ratio or affect the pump at all. Those are separate systems unrelated to the height of the tie rod end.

Have you ever measured how much toe changes under suspension travel? I don't remember that ever being a problem on the FC other than at the rear where people swap the stock bushings for solid.

FYI - you can get quality race engineered products for the FC here: http://www.awrracing.com/store/index.php?cPath=1_5

the fc suspension does have a good amount of bumpsteer when you lower it and change the geometry. the toe change will be reduced (hopefully elimited) under suspension travel using this kit. the pump has to do more work per movement of the steering wheel because it is pushing the wheels out further, faster. i have heard of people overheating their stock racks due to this (drifters), and know one that runs two stock rack coolers now. and again, this is unsprung weight and changing the lengths of the steering control arm (toe control arm).

i have measured toe change on new cars and it can be horrific (and i belive i had talked to tony at awr about his quest to eliminate toe change as well). i do have solid bushings in the back from awr as well.

I've wondered about the use of "super angle kits" (SAK) for grip driving as well. The theory being that if turning the steering wheel to full lock with the kit nets more wheel travel, then the wheel must turn through the range of motion faster than stock, because it has more angle to travel through as you go to full-lock.

Example with random values: Without the kit a 1/2 turn of the steering wheel might net you 20% of the available stock angle, but with the SAK, a 1/2 turn of the steering wheel would net you 20% of the MODIFIED steering angle, which would be 28% of the STOCK steering angle, effectively quickening the steering ratio.

The only question is how these angle kits affect Ackerman and the negative affects it would have on slip angles/wear on the front tires.

i immediately googled ackerman and learned something new about steering/suspension/tires. thank you

I'd say leave well enough alone, I see no real advantage to this for track driving and it'll just lighten your wallet some more. (BTW, it'd be sprung weight, since it's attached to the chassis)

well i have them sitting in my garage so it wont lighten my wallter anymore than it already is

Fatten your wallet by selling them then.

angle kits do NOT quicken the steering ratio. they simply move the steering stops, so the steering wheel will rotate further.
one downside to the spacers is you have to space the wheels out to clear the sway bar at full lock. this probably isnt an issue for grip driving, but if you spin out or whatever, the wheel will bang into the sway bar. spacing it out means less room in the wheelwell for tire.

i would say you're best off running a 2-hole rack (slower ratio than 3 hole) with a steering quickener. i believe the common quickener is 1.5:1, so that would yield a final rack ratio around 12:1, which is great. you get the fast steering, and dont have to worry about wheel spacing or any of that crap.

PS pump coolers are easy and cheap. find any generic PS cooler off ebay (probably better to get one form a large vehicle) and plumb it into the low pressure return line with some hose clamps. my cooler cost me 9 bucks and does great in autox.

lol what is a 2-hole rack/3-hole rack? and what is a steering quickener?

The 2 hole race was the 17.4:1 engine rpm sensititve power steering rack and pump, and the 15.2:1 speed sensitive rack and pump is the 3 hole setup.

A quickener is just a gearbox that multiplies the input from the steering wheel to the rack.

no questions just do what i say!!

haha