Eric at Speed Direct says there is sufficient adjustability in the Steeroids RP to adjust for 0 bump steer.
Anyone know how to do this?

 

He sh ould know what bump steer is, but from talking with Pete79L82 here, that comment would say he doesn't...there is no available adjustment on that system for bump steer, I suppose it was minimized in the design of the center adaptor plate, and at any rate, it was not one of my considerations when doing my system....and it's NOT a problem now that it's modified....
so I say it's a non issue, in reality...

GENE

 

Gene I think bump steer is a major problem and no bolt on steeroid steering system is going to be withoug bump steer and ackerman effect. For one thing the steering arms are all wrong for rack and pinion steering. They should be curved and ours are straight.
I could go into this but it gets longs and boring for most but regardless of where you mount the rack, behind, in line with or in front the rack will introduce ackerman and curved arms are suppose to help cancell some of the affect.
I tested a new mustang last week and at 3 inch lift it still had 3/4 inch toe in. The ONLY car designed without bump steer from the factory is VIPER. It is designed with 0 bump steer. The only one.
Gene I would like to see you really measure bump and give me figures at 1, 2 and 3 inch lift and 1 and 2 inch down.

 

Norval,
Can these measurements be taken by a rookie without sophisticated instruments?
Thanks,Will

 

Anyone can take measurements. The crudest way is to take a tape measure, hook it in one tread of one tire then measure across the front to another tread on the opposite tire. Try to do it as high up as possible, you are trying to get the center of the tire in front. Write this measurement down and mark the spots on the tire for the next measurements.
They must all be taken from the same spots.
Jack the car up in the center exactly one inch. I measure from the ground to a spot on the bumper. Take another measurement from the same spots on the tire.
Do this for 1, 2 and 3 inches up and write all dimensions down, remember all readings from the same spot on the tire and try to get as high as possible for the 1st reading and reuse these spots over and over. A friend would really be helpful.
What ever reading you are getting is actually only 1/2 the total toe in because the rear toes out an equal amount.
So if you get 1/4 inch less then original on the 1 inch rise the total toe is 1/2 inch for only 1 inch bump up.
Down is impossible for most.
For me at home I have a strong, absolutely paralled, level hoist where the car is driven on and level side to side and I can work comfortable from under neath so it is easy taking readings.
I also have a hook that screws into the car and a place on the hoist to pull it down 1 or 2 or 3 inches accurately.
Anyway the bump up will give you an idea of toe on bump up as when you launch and the car goes sideways.
Guys remember a year ago when I complained about the car going crazy on launch. All that is gone with work on the steering.
I do have the proper bump gages with dial indicators but a ruler gives you an idea at this rough stage.
Good luck and let me know if you do it. I would also like to hear from others that try it. I want to compare.


[Modified by norvalwilhelm, 9:50 AM 8/21/2003]

 

Years ago I took a 1/8th stainless plate and rolled it to match the curve of the crossmember under the front of the motor. I welded this stainless plate to the underside for future jacking. I did not want to damage, scratch the original frame. This plate has had hundreds of lifts from my 3 ton jack over the years.
At the same time I welded a large nut onto the plate for toeing or pulling the car down for whatever reason.
I have a large eye that screws into this nut for pulling the car down to bump steer checks.
Here is a shot of the plate.

 

Norval, I don't deny for a second the bump steer problem, but after moving the inner tie rods UP about 1.5 inches like Pete suggested, well the problem was greatly cut down, as noticed by jacking up the front end....I have not taken measurements....tell you what, for some reason of course with the driver's tie rod being shorter by about 2 inches the toe is more noticeable on the driver's side....garage full of furniture repairs now, so can't set up too easy to get anything done....maybe tomorrow....

GENE

 

Gene the first thing that is done for pump steer is lower the outer tie rods. In your case you moved the inners up. That is the same thing as moving the outer down. That is a normal modification and knowing what I know now would do that right away.
Unless you actually take measurements eyeballing is not good enough. You need to put numbers to the values.
Steroids also does not address the length of the tie rods. I went through 4 different lengths and mounting locations and hit a good one on the 3rd attemp. The 4th try with still another 1 or a total of 4.1 inches longer then stock and the bump steer was getting worst.
So 2.1 inches longer then stock was improving and 4.1 was going too far and the bump steer was increasing again from the lowest reading with 3.1 increase in tie rod length.
It is also important if possible to keep both tie rods the same length. IF POSSIBLE.
Gene take measurements and the driveway is good enough.
Have a good day and it looks like you and I are the only ones who really get worked up about this. Twin Turbo must be still sleeping.

 

Please allow me to say a few things here. It was never stated that 0 bump steer is attainable but the point is that our system is easily adjustable , unlike the stock tie rods. With respect, Gene, you don't know what you are talking about. Our tie rod ends can be adjusted nearly .7" total at the steering arm. The importance of adjustability is very great due to the large number of contributing factors affecting the bump steer curve of a particular car. The curve will vary car to car due to factors such as alignment, ride height, frame and bushing compliance and others. That is why it is important to measure your specific car and adjust it accordingly.

In all reality measuring toe change when the car is not moving and the suspension isn't being loaded isn't an accurate representation of what the steering and suspension systems are encountering in the real world. Granted, it is the best most can do under the circumstances but its merits beyond getting the setup in the ballpark are debatable. I'm not saying that performing this task is pointless. I'm saying that there is more to it. Rarely is a car in the static, wheels straight situation that is measured. As soon as you turn the wheel things change (the amount they change depends on many of the same factors that affect bump steer). During cornering is the time that toe steer and ackerman issues begin to affect things much more.

 

In all reality measuring toe change when the car is not moving and the suspension isn't being loaded isn't an accurate representation of what the steering and suspension systems are encountering in the real world. Granted, it is the best most can do under the circumstances but its merits beyond getting the setup in the ballpark are debatable.

When we take our cars in for an alignment they always do it with the car static. They set caster, camber and toe with the car just sitting there. We need a place to start.
99% of our driving is in a straight line and this is where toe is set for, the straight line. But most of our driving is done with the wheels moving up and down over the road surface, over a hill, down in a valley . Our wheels are rarely actually static while rolling along.
This is where bump steer really comes into play.
We have only one way to design/test pump steer and that is with the car stationary and the suspension put through it's range of travel while the change in toe is measured. There is certain adjustments that are required to fix the problem and by plotting out the toe change it will tell you , shorter/longer tie rods and raise/lower the inner/out tie rod. These movements can be gotten from a chart in any good suspension book or a GM manual.
In my GM corvette manual they give sample bump steer curves, plot them out and tell you the fix for the problem.
To me it is alot easier for me to fix the present stock steering setup then to go to steroids. I don't know enough about them, I wouldn't know how to go about making large adjustments to the tie rod lengths and I wouldn't know how to change the steering arms to curved ones to cancel ackermans.
The raising or lower of the tie rods ends seems to be the only thing I would know how to do.
If a new stock mustang still has 3/4 inch of bump steer at 3 inches rise and that is factory engineered I certainly couldn't do better.
Wait a minute my 28 year old modified system is already alot better :) :)

 

First off, apologies to Steeroids, I did not know adjusting the outer tie rods height was possible....
on my setup, I had to refab the inner mount to raise the tie rods....at any rate, I see Norval's comments his post above to be correct,....
I am going to measure the toe in and jacking the car....in a minit...

GENE

 

Norval, guys, well I went out in my HOT and SWEATY garage, I don't have natural a/c like Norval has up there in never never land,... :D :D

but I set up the strings on the jack stands again.....and noted the monofilament lines said the same thing as they did last time I called it a hault on alignment.....1/8 inch differance from front to back of rim on each side...
meaning 1/8 inch toe in on each side....

bumper height 19.5 inches at nose peak center....

raised the car to 20.5 inches.....gained 1/16 inch per side toe in...making 3/16

raised the car to 21.5 inches....gained another 1/16 inch...makeing 1/4 inch
raised the car to 22.5 inches......gained another little bit, but still closer to 1/4 inch....hummm...odd....oh well....
raised it another inch to 23.5 inches....now it's really toad in, sucker ready to jump now....about 3/8 inch

raised it another incyh to 24.5 inches....tires still on the ground...lowered suspension by an inch you know due to heavy springs...so that it's gettingmuch worse...about 1/2 inch differance perside....

with wheels in the air, don't even bother to look.....

I need a few fat friends to weigh the car down...stand on the engine I guess for any other measurements....

but like I said, it's not so bad...certainly NO WHERE NEAR as bad as it was before Pete's advice....

far as I"m concerned...job done....I guess...

oh crap, here we go again....just what I need, another project.... :auto: :auto:

GENE

 

Good for you Gene and go screw yourself with my natural air conditioning in never never land. :) :) It is in the 90's here, dry and hot. I am doing my part without air and it is 81 in the house and the air is still.

You don't need to measure off strings, just measure off the tire front and rims do not tell the story.
You have a 15-17 inch rim and the tire od is 24-26 so you are not actually telling the proper toe without equaling the od of the tire.
Also 1/8th per side as off the rim is way way too much. That woud translat to at least at least 1/4 inch and alot more after taking the od of the tire.
Raising the car 1 inch you get 3/16 on the rim per wheel or 3/8th total plus plus because again of the rim measurement. That already exceeds my worst measurement
Gene just try it by using the tap across, hooked on one tire and to the other tire at the highest height possible. Mark the spot and do it from the same spots. The strings are not needed nor is rim measurement right.

Gene your initial toe should be reduced.
Any steering system is adjustable at the outer tie rods because they do not belong to the steering system. It it supplies heim joints for the outer tie rod a simple stud or 2/8th bolt and spacers will work. If the spacer exceeds 1 inch tack weld it to the arm for stability.

 

Gene, no problem. I just wanted to set the record straight.

Norval, the alignment is designed to be set with the car static. As you know, without modifying the suspension points you can't change the camber or caster curves. You have to start somewhere and a basic, static setup is a good beginning but only a beginning. As I said, getting the bump steer in the ballpark with a static check is fine but it is just the beginning. There are more factors involved and it is far more complicated than just a simple straight-ahead bump steer measurement.

I don't deny the benefits of having a zero (or as close as practical) bump steer curve as measured in the traditional sense but there are trade-offs being made that affect dynamic toe steer. The steering system and the suspension system are working together (and sometimes opposite) to allow the car to handle both in a straight line and a corner. The interaction is somewhat complicated because of all the factors involved. These interactions require quite a few trade-offs when deciding what performance criteria is more important.

It seems that we are arguing somewhat different points. I agree with you that the traditional measurement addresses bump steer issues in straight line driving. My point is more to what happens when you begin to corner. That is where toe steer is affected by ackerman, suspension geometry, chassis roll, frame and bushing compliance, etc. I feel that this area needs equal consideration.

In regard to the new Mustang, not only is it a 25 year old chassis, it (as with most cars) has many trade-offs that yield such effects. I would say that cost of manufacture is the most important performance criteria that Ford is designing to.

 

Norval, sorry, got you beat, we got rain about 90% of the time and humidity to match at 95% on a dry day.... :D :D :boxing :hurray:

I just haven't the energy to jump under the car and measure what with all the arthritis...it's sorta hard to do....no help this time of day...
maybe this weekend....i can get wife to do the jack while I lay under the car....

GENE

 

Speed Direct you would make a good polatician. You haven't said anything you can really latch onto and you have muddied the waters.
For the stock system I say mill 1/4 inch slots in the cross shafts and it will give you 5 degrees positive caster without shims and set the camber at negative .75 degrees
Add 1 inch blocks or shims to the outer tie rod, increase tie rod sleeves to 13 inches and move the center tie rod 3.1 inches per side closer to the centerline of the car and at the same time move the inner tie rod to the top of the center link. Set toe at 1/6 inch.
There I have made solid number recommendations to the normal crowd now you made the same solid recommendations for the purchasers of the steroid system.

 

Norval;
You have given a lot of great info here on the forum, not the least of that pertaining to bump steer.

I have started a R&P install of my own, the mounts are mocked up, I'm just starting the linkage from the steering shaft to the Rack ( the three U-joints from Flaming river came today) and the tie rods are still unconnected.

My plan is to get a mount tacked up for the rack, then build an adjustable tie-rod mounting plate to measure bumpsteer. It will be interesting to see if I duplicate your findings.

Have you ever measured bump steer with the wheel turned? I think it would be interesting to see a 3d graph of bumpsteer vs steering angle, it is something I plan on doing. I doubt there is anything that can be done once the information has been gathered, but I like to know that kinda thing.


I wonder if Mr Speed Direct is just concerned about looking bad in the eyes of the lurkers around here. We all know they have a fine product but some of us want better than fine and others just like to build stuff ( me).


I do wish that companies would publish specs about their products. Remember the good ol days when they would actually publish specs like bumpsteer charts, ackerman angles, camber graphs....Oh well

 

what is bump steer again, i forget, age thing...lol

 

:withstupid:....only I'm 23....so no excuses!! :lol:


[Modified by SuprJames, 6:06 AM 8/22/2003]

 

Bump steer is the change in toe in/out occuring when the wheel moves up and down over the road....making the tires tread twist as if cornering, when in fact it's not....hard on tire tread, and handling gets tricky also...

Norval, on a trip over the bridge I love so much near me here, I have started looking at various vechicles at speed, and it's amazing what I see from the front ends.....tires going in every direction it seems, looking like a swing axel from a Ford truck say, then the strut cars, then the double wishbones, which are the only ones going straight up and down....
man, I swear, it's turning into a hobby now, looking at suspensions in action....

OH, the bridge is getting a bit of age on it now, and so i'ts not as smooth, the undulations of the road surface make suspensions work harder, so the action if much more noticeable...

kGENE