Headers cause Bumpsteer - Help !

[Fastkarz]

rthomas771 -
Front Addco part number ACO-835 is larger than stock(7/8")
Rear Addco part number ACO-264 is 3/4"

mav1970 -
I understand the shelby drop, just didn't want to mess with moving the upper arm mount location so I gave it more camber instead.


I think the P/S ram having that angle is the root cause of the bump steer.



I know there are other guys out there who have installed these Hedman Headers 88306 & Hedman drop bracket. What kind of bump steer problems are they having ?

[Joe Dirt]

Originally Posted by Fastkarz

rthomas771 -
Front Addco part number ACO-835 is larger than stock(7/8")
Rear Addco part number ACO-264 is 3/4"

mav1970 -
I understand the shelby drop, just didn't want to mess with moving the upper arm mount location so I gave it more camber instead.


I think the P/S ram having that angle is the root cause of the bump steer.



I know there are other guys out there who have installed these Hedman Headers 88306 & Hedman drop bracket. What kind of bump steer problems are they having ?

Might try revising your alignment specs

.5 to 1.0* negative camber

3.5-4.0* positive caster

.15 to . 25 toe in

Should make the world of differance jmho you have a tone of positive camber and way to much toe in no wonder it drives crazy


Mine didn't have bump steer with the same headers and a drop bracket fwiw

[mav1970]

Originally Posted by Fastkarz

I know there are other guys out there who have installed these Hedman Headers 88306 & Hedman drop bracket. What kind of bump steer problems are they having ?

Try what Joe Dirt suggested first. It won't cost you anything if you do your own alignments

[Fastkarz]

So the here are the specs and where I am at:
Spec is caster -1/2 +-2, i'm at +1 1/2
Spec is camber 1/4 +-1, i'm at +1/2

-If zoomzoomguy is right it sounds like I have my caster at the wrong end of the range and I should go negative

-But mav1970 said "I used to set my own caster/camber when I was building stock cars and you always went positive on the caster."

-Joe Dirt is saying I should go to 3.5-4.0 positive caster which is much more positive then what I have and I am inclined to agree


So which is it? Should I be more negative or positive on the caster ?


injectedmav said "My camber is slightly negative at -.5° and I have a slight pull when I hit lines in the pavement or grooves that run in the direction of travel"


I have +1/2 camber and i don't get tire screech in the turns. Should I go more negative?

Yeah mav1970 I see an alignment again in the near future. I just want a concensus from the guys on what they are running so I can make progress and not move backward.

Thanks again for all the help.
Sean

[Joe Dirt]

Originally Posted by Fastkarz

So the here are the specs and where I am at:
Spec is caster -1/2 +-2, i'm at +1 1/2
Spec is camber 1/4 +-1, i'm at +1/2

-If zoomzoomguy is right it sounds like I have my caster at the wrong end of the range and I should go negative

-But mav1970 said "I used to set my own caster/camber when I was building stock cars and you always went positive on the caster."

-Joe Dirt is saying I should go to 3.5-4.0 positive caster which is much more positive then what I have and I am inclined to agree


So which is it? Should I be more negative or positive on the caster ?


injectedmav said "My camber is slightly negative at -.5° and I have a slight pull when I hit lines in the pavement or grooves that run in the direction of travel"


I have +1/2 camber and i don't get tire screech in the turns. Should I go more negative?

Yeah mav1970 I see an alignment again in the near future. I just want a concensus from the guys on what they are running so I can make progress and not move backward.

Thanks again for all the help.
Sean

Your alignment is bad off follow my specs and the car will drive a ton better I do this stuff everyday I work in a shop that deals with solely brakes/suspension and alignments

Positive camber along with the toe in you have will make that car "bumpsteer" as the wheels are layed out at the top and pointed in at each other

You need NEGATIVE camber and positive caster to make it stable. And you need to reduce your "toe" in

[injectedmav]

You need NEGATIVE camber and positive caster to make it stable. And you need to reduce your "toe" in

Agreed. Even though I have the slight shift on uneven pavement, it's easily controllable and the combination of negative camber and more than 2° pos caster will go a long way in stabilizing the front end. 5/16" seems like a lot for toe. It's definitely the cheap fix. I settled on 2.5° positive caster because I didn't want to pull the UCA mount to add a shim. Tires are too big to get to 3.5° but that's what I would prefer.

[rthomas771]

rthomas771 -
Front Addco part number ACO-835 is larger than stock(7/8")
Rear Addco part number ACO-264 is 3/4"

I have always heard that you need 1/4" difference. It's possible you are experiencing oversteer.

[PaulS]

Caster specs were put together for bias ply tires - we run radials they need a more positive caster. So positive caster and zero to negative camber with minimum toe in will make the car very stable and reduce tire wear.