I have been talking to a couple of people from east to west, and finally to KingMotorsports about getting a pre-fabricated bump steer kit for my ITR, but so far have not found anyone who can supply. As there must be thousands of lowered Honda suspensions, I am hoping someone knows where I could get a kit that at least puts me in the ballpark of zero bump-steer. Since all Honda's for the track will be lowered in the range of 1.5" plus or minus, a bump steer kit that corrects for that lowering would surely be better than none.

Here are some pics of the RTR setup for bump steer:







Kit consists of a rod end with a threaded sleeve to connect to steering rack for toe adjustment and a tapered spacer to distribute load to the spindle's steering arm and adjust tie-rod angle for bump steer control. Only thing to adjust depending on lowering value is height of tapered spacer.

I also found a product, the SRR Spherical Bearing for Steering Pinion, that does not adjust bump steer, but that might serve as a basis to start with, but I have not seen piece nor do I know of anyone using it:

http://www.srr.com.tw/index2.htm

(air jacks are cool!!!)

So where can one get a bump steer kit and how much, or is custom fab the only way to go?

 

those SRR tie rods are overpriced and dont serve any real purpose.

I too am looking into any bumpsteer issues I may/do have and how to fix the problem.

spherical bearings and a trip to the machine shop should fix any problems.

 

That RTR setup is VERY pimpy... keep us up to date on your progress... I am very interested.

Nash

 

So does everyone who drives lowered Hondas and Acuras on the track drive without correcting the bump steer? Judging by the size of the tapered spacer in the RTR kit, there is a very large error to be corrected in the toe curve as the suspension is lowered. People have been driving on these lowered suspensions for years. One would hope that there was a solution outside of the ones used by pro race teams. Perhaps some of the guys who fabricate parts need to make a product here.

 

The DC cars didn't have an outboard bump steer correction.

The guys that built all the neat stuff on the DC cars aren't in the business of making them for resale - unfortunately.

And the RTR kit ball center placement isn't That much off stock.

Scott, who is working on the other way to do it...<Fez voice on> "Jes, there ees another way to do it."

 

Is it possible to move the steering rack on an ITR to correct bump steer? That is the way I did it on my old 1970 Porsche, but that was super easy with a couple of longer bolts and some spacers between the rack and the car. I suppose if the steering rack can be moved, it might be time to look at some of the Mugen steering rack mounting bushings. But the fact that Mugen even makes bushings led me to think that it might be difficult to change the height of the rack in a similar manner to the Porsche. In the Porsche the steering rack is hard bolted to the car, with no rubber between the rack and the car. When I saw the RTR setup, I assumed they had considered the options and come up with their tapered spacer as the best solution (simplest perhaps). But I never saw the DC car setup.

There are two things to worry about, the first being tie-rod length which causes an arc, positive or negative in the toe vs. bump/rebound graph, a gross error, and is not adjustable without modifying rack end pivot or spindle steering arm positions, and the other is the angle of the tie-rod, which can be changed at either wheel end or rack end. This error is milder and if the tie-rod length is correct, which I am assuming Honda chose carefully to give a slight understeer for safety on a road car, an error in the height tilts a fairly straight line bump steer "curve" into toe in or toe out as the suspension moves in bump. If a car with double A arms that had zero bump steer is then lowered by changing springs and perch height, then the steering rack is lower than it was in the stock position (wheel is higher up in the wheel well). Thus when the wheel rebounds, the back of the wheel is pushed outwards (due to the arc traced out by the tie-rod being centered lower than the spindle) and toe-in occurs; whereas, when it compresses, the wheel goes into toe-out. This is all affected by the lengths and angles of the suspension arms. Things are quite different with McPherson struts, but I am not so concerned with those for the moment. In any case when I attended the race car setup seminar at AIM motorsports, they went on at length about bump steer correction in both front and rear suspensions and they demonstrated how to fix it. It seemed very important to them on their formula cars.

 

I made a kit for myself. cost me about $150 in parts not including labor. that turns into at least a $300 kit retail.

 

Wow, how'd you do it and what did you use? Would you mind taking pics?

Matt- who until today did not realize there were products to decrease/eliminate bump steer and is now intrigued by the concept.

 

my kit requires that you drill out the knuckle to turn the tapered hole into a standard thru hole for a 1/2" bolt (if i can recall)

you need a lathe to make the rest of the parts besides the heim joints.

 

Does anyone have any pictures or dimensions of a bump steer solution, or has anyone actually moved the steering rack?

 

I'm also trying to find a solution to bump steer on my integra. I was thinking about cuting and welding the stock ends into like an s shaped.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 600gixxer &raquo;</TD></TR><TR><TD CLASS="quote">I'm also trying to find a solution to bump steer on my integra. I was thinking about cuting and welding the stock ends into like an s shaped.</TD></TR></TABLE>

I think you might be risking life and limb with that concept.

 

sorry for such a noob question, but so when your Honda's lowered suspension is already pulling on the tie rod's inducing toe-out?(allignment to compensate) Then when you compress the suspension more you will induce more toe-out? Right? Hence "bumpsteer"?

Doing some sort of correction would reset it back to "zero" and the "zero" range isnt going to yield bump steer through full travel?

This seems pretty important.

 

I have not yet measured it on an ITR, but you are right about the concept. It depends a lot on geometry and the best way to predict what is happening is with a program like WinGeo3 or Susprog3D. When you lower any suspension, the steering rack should be moved back up as well to keep the tie-rods more or less parallel to the ground. If steering rack can't be moved, then tie rod ends are lowered. The formula guys are quite adamant about getting zero bump steer, so that is why I am surprised no one makes a kit for the Honda suspensions.

 

But what they did in those pics seems backwards? If your trying to keep the rack even and move the knuckle up(lowered car) cant you just flip the rod end upside down and put it on the bottom of where it attaches to the knuckle? I could be way off here lol

edit, in those pics the rod end looks horizontal&lt;sp but you have to consider the car is in the air and no weight on that suspension. I'm sure theres a very good reason that I cant grasp right now

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by johnjw &raquo;</TD></TR><TR><TD CLASS="quote">But what they did in those pics seems backwards? If your trying to keep the rack even and move the knuckle up(lowered car) cant you just flip the rod end upside down and put it on the bottom of where it attaches to the knuckle? I could be way off here lol

edit, in those pics the rod end looks horizontal&lt;sp but you have to consider the car is in the air and no weight on that suspension. I'm sure theres a very good reason that I cant grasp right now </TD></TR></TABLE>

bump for the same question

 

yaa bump I want answers

also I'm gonna go try it(flippeing it upside down), aslong as it doesnt hit my wheels

 

The hole in the knuckle is tapered, so you can't just flip it around. You could drill it out straight, but then you need a straight tie-rod end, or a bolt and heim joint replacement for the tie-rod.

 

bump

 

In the pic it looks as though the bushing has been raised, though surely you would want it to be lowered. For when the car is lowered say 1.5-2 inches the tie-rod is at about 35 degrees, when you really want it at 0 paralelll.

So either the rack goes up to compensate, or the tie-rod knuckle goes down, and say attaches underneath, like someone else said.

 

I think everyone looked at those pics and got all technical and geeky but now that I mentioned lowering the tie-rod end everyone else thought about it and decided that that would make more sense so they shut up *shrug shoulders* thats why this post is dead. Just cuz big teams build these parts we cant look at them and make our own without knowing what they did to modify the steering rack.

 

the steering rack doesnt necessarily have to be horizontal at ride height. whats important is what happens to toe during bump and droop. what you have to do is just measure toe change thru suspension travel and move the tie rod end to make your desired result. obviously realtime move their pivot point to get a desired affect. maybe it gives a greater amount of ackerman steering? maybe it takes away from straight line braking stability for that little bit more entry speed into corners? all these kind of questions needs to be asked. the end result is a faster lap time of course, no matter what the suspension does compared to theory.

theory only works perfectly on paper.

BSME

 

That would not change ackerman or affect it at all, and yeah your right I'm sure it works(why else would it be there). But I do see more bump-steer with that setup which would help stability when braking.

 

ackerman has to do with the two different radii that the front wheels have to follow around an axis.


OF COURSE CHANGING BUMP STEER AFFECTS ACKERMAN. what do you think we are talking about? when you are STEERING into a corner and the suspension goes thru BUMB and droop, there are toe changes.

in talking about bumb steer we are talking about a degree of ackerman.

http://www.auto-ware.com/setup/ack_rac.htm

 

Doods,

Technically:

Ackerman is toe change in response to steering input.

Bump Steer is toe change in response to suspension displacement.

So it's all toe change, but we should be particularly accurate with our terminology to avoid confusion and unnecessary argument.

Scott, who agrees with Shawn that step one is to measure your bump steer - this is not the place for just trying things.