Vintage Mustang Forums banner

1 - 7 of 7 Posts
G

·
Guest
Joined
·
0 Posts
Discussion Starter #1
heres my problem when accerating car front stays up until brakes are put on new shocks ball joints control arms upper control arm shafts seem ok one side alittle tight other loose can any one help cannot drive.
 

·
Registered
Joined
·
19,980 Posts
Use some punctuation please. You have one long, run on sentence and it's hard to fiquire out exactly what you've done.

One quess on your problem. If you replaced your lower arms, maybe you tightened the shaft bolt through the bushing with the suspension fully extended. This will ad a little extra, artificial spring rate via the bushing.

These bolts should be tightened with the suspension at normal ride height.
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #4
Update:

Here's what we did.

Replaced upper control arm shafts and bushing.
Replaced all tie rod ends and control arms.
New Shocks and springs.
Front end alignment done.


Without springs or shocks, the upper and lower arms can be moved freely through the entire range up and down without resistance.

Here's the problem:

Under acceleration the front of the car picks up and stays there. The front can be brought down by applying the brakes while in motion. If the car is still up while stopped, it will go down on its own if backed up gently. This was done both with and without the shocks and sway bar in place.

We have had many people look at the car and none have an answer for the problem.

Any help will be greatly appreciated.

Thanks.
 

·
Registered
Joined
·
5,196 Posts
Need more details:

What are the alignment settings the shop is using?

Stock or modified components (control arms, springs, etc)?
Type of brakes/spindles?
Shelby Drop?
Size and offset of wheels?

Problem sounds VERY similar to one I previously had, that's why we'll need to know EXACTLY what parts you are running!
 
G

·
Guest
Joined
·
0 Posts
Discussion Starter #6
I have used all stock parts including springs.
Disk brakes with stock spindles.
No Shelby drop.
Magnum 500 14" wheels with spacer behind rims.

This set-up was run for about 5 years without problems until the car was dismantled, totally refinished and then rebuilt. Now we have the front end that wants to go up and stay up.

I appreciate the help.
 

·
Registered
Joined
·
5,196 Posts
It's odd for this problem to show up with your combination of parts - usually wide wheels, tubular controls arms, or Granada brakes/spindles are involved......

What is happening, is that as your front end lifts, you are getting a bunch a toe-in, and positive camber. In other words, when viewed from the top, the tires point in at each other like this: / \ (toe-in), and when viewed from the front, the tops "tip out" away from each other like this \ /. Correct? Is this what you see when the front end is up???

What are your alignment settings? Many mechanics still try to align to the old settings, which don't work well with modern radial tires. You should be set to:
NEGATIVE 1/2* camber
POSITIVE 1-1/2* caster (2* - 2.5* if power steering)
1/8" Toe-IN

If you car is aligned with POSITIVE camber, I'd definitely begin there! You want 1/2* negative for street driving - tire wear will NOT be adversely affected.

The more caster, the better, although steering effort goes up with increased caster. Increasing caster WILL reduce the amount of toe change. The toe change, combined with too much positive camber is what is causing your problem.

Try running the front wheels without the spacers. How thick are they? Increasing the wheel offset too much thru the use of spacers can exagerate the geometry problems.

Finally, how much toe change do you have? Check the toe in at rest by comparing the width between the front and rear of the front tires. For instance, 56" between the fronts of the tires, and 56.5" between the rears = 1/2" toe-in (too much). Then, with the front in the "up position", measure again. If the is too much toe change, you might look into the Baer bumpsteer corrector kit. I added it to mine, and went from over 2" of toe change down to 1/8" of toe change - pretty dramatic difference....
 
1 - 7 of 7 Posts
Top