bumpsteer in mustang 1969 promotors sports kit

[juit]

I have all stock

did the uca 1 inch drop & got worse

the car is aligned to uca drop settings

I bought a Pro motorsports bump kit clone

but the guy told me that Im gonna need to cut a screw

before modifying anything permanent how can I know that I really need the kit?

my steering is in good cond I even replace my mechanical steering with a new one

when Im in low or hi speed the car wanders a lot in uneven roads

in new hi way road the cars drives awesome at 75 MPH but when I hit a small bump or the road changes a lil the wondering starts again

Ill post pics of the kit once I get it



pics of the kit as promised





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[LSG]

Juit, what are the numbers that to which your front end has been aligned ? I'm not aware of UCA drop settings......I know the specs to which I like to see a front set, but not everyone uses the same specs.....

Who did the UCA drop ? if the holes are too far forward, you'll have less caster, and the car will have a tendency to wander. Note that the tendency to wander is not the same thing as bump steer. And changing the UCA mount points does not change or affect bumpsteer.


and did you purchase a Promotorsports kit or someones copy of that kit ? if so, who made the copy ? Do you think you can be certain it is made correctly ? I don't know what screw you'd be cutting, but it doesn't sound right from here. LSG

[juit]

the car wanders when I hit road crowns or uneven road, if the road recently fix of new the car will drive awesome

I bought a template online and it had the alignment settings

the holes on 67-70 are just one inch lower if I recall

the alignment shop did the holes

it had bump steer before the holes but after they got a lil worse

I have 17 bullit rims installed

Ill receive the BS kit tomorrow
they were made in CNC so I think it will be a decent copy 2 local mustang club guys have them installed & love em but they didnt do the UCA drop they just lower their mustang with lighter springs

[bartl]

Can't remember..... what do you have for front spindles? Weren't you going to install a rack and pinion? Do you still have the stock steering box?

Bumpsteer is going to be affected by anything that changes the relationship between the inner and outer tie rod ends. Ideally, you want everything to be close to an imaginary line drawn between the outer tie rod ends. What happens when you compress or extend the suspension is the distance, in a lateral plane, between the inner and outer tie rod ends decreases, toe-ing the wheels out. This isn't so bad when the wheels are straight but messes up the geometry when in turns.

[LSG]

Juit, to what specs are the front pieces aligned. We need numbers. And what is 'made in CNC' ? What steering do you have? A UCA drop doesn't change bumpsteer, but if you have aftermarket steering, and you have lowered the car, THAT can affect bumpsteer. LSG

[juit]

have stock steering box
what I have read when you do the uca drop it changes the response in steering, if you have bump steering it will feel more, at least thats what I read in other forums and its happening


the kit is made on a CNC machine

[LSG]

Juit, in the front suspension, the steering linkage is supposed to move in an arc, almost identical to the arc in which the wheels move. This is why the steering linkage is down there next to your lower control arms. changing the inside mount of the upper arms doesn't induce or remove bumpsteeer. Moving the steering linkage up or down will, as will fussing with the lower arms.

My best guess is that your car was aligned, after the UCA drop, without enough positive caster. This will not increase bumpsteer, but it WILL increase responsiveness - you'll feel that the car wants to dart around, and the better camber curve will let you if you want to. If you had more positive caster, it would track nicer down the road. I like 8-12. Lots of folks think thats excessive and are very happy at 5 or 6. If you have the 3 degrees or less that most shops want to give you........you have my personal guanrantee that it will feel better with more. I don't think bumpsteer is your problem. How much caster do you have ? If the shop can't tell you, or if they just say 'we went with stock specs'.............they are explaining to you that they don't understand your stang and they don't know how to do it right. LSG

[juit]

Ill go to the shop today and see

[juit]

do I have to put neg or pos caster?

the BS kit looks pretty legit to me

[lemonshindig]

positive caster. I run like 2.5 degrees +.

[juit]

wold I need to re align the mustang after the bump kit?

[Lee12609]

You definitely need to realign after the bumpsteer kit although it doesn't sound like your problem.

It sounds like the car is tramlining, which most people have never heard of. Do a Google search and you will find out what it is and how to "help" reduce it. Lower your tire pressure a bit and see how it does.

Raising the caster will cause more high speed stability but will also make low speed turning require more effort. Any alignment shop will set to factory spec if not told to so otherwise, doesn't mean they are right or wrong. Just tell the technician you want a little more caster and he'll give you more if possible.

[dobrostang]

Personally, I would hold off on the bumpsteer kit and drive the car first. If you still have bumpsteer and all your other components are in good condition then I would address it after everything else is settled down. There are so many variables, ride height etc, the drop could actually have helped if bumpsteer was your issue. When I did my drop, it did not induce more bumpsteer.

Just a thought...

[juit]

will do that then first

it says on the directions that the kit was designed for 1 uca drop to help the steering smoothnes

[juit]

Did the caster they tight to the last thread to get as much as positive caster and just cut the half of it

I think that I will be needing the kit after all