Effect of lower control arm relocation brackets on handling?

[BuickMike]

I was looking at the UMI Performance rear lower control arm relocation brackets so I can increase my anti-squat value, but am curious if doing this will hurt my cars handling.

My current suspension setup is geared more for handling at this point:
All poly body bushings
1LE front LCA bushings
UB machine tubular upper A arms
Power Performance 1/2" longer upper and lower ball joints
2nd gen Blazer spindles (11" rotors with dual piston calipers)
SPC springs
Stock rear control arms - all boxed with HR Parts poly bushings
2nd gen blazer rear swaybar mounted to frame (poor man's pro touring bar)
stock front swaybar with poly bushings and endlinks


I really want to get the tires to plant better, but not if it negatively affects my handling. Does anyone use these on a street car? Experiences?

 

[toofastforyou]

I was looking at the UMI Performance rear lower control arm relocation brackets so I can increase my anti-squat value, but am curious if doing this will hurt my cars handling.


I really want to get the tires to plant better, but not if it negatively affects my handling. Does anyone use these on a street car? Experiences?

I used to have some "relocation brackets" (plates) on my GN and they did help planting the tires during a launch and I've never felt any effect on handling. They do work, but are kinda "old school" now that some adjustable control arms are available allowing you to adjust your pinion angle ('cause that's what the relocation plates really do...) :redface:

Claude.

P.S: If you want a set of these brackets (or plates), I have a new unused set I could sell 'ya! :wink:

 

[turbo nasty]

I used to have some "relocation brackets" (plates) on my GN and they did help planting the tires during a launch and I've never felt any effect on handling. They do work, but are kinda "old school" now that some adjustable control arms are available allowing you to adjust your pinion angle ('cause that's what the relocation plates really do...) :redface:

Claude.

P.S: If you want a set of these brackets (or plates), I have a new unused set I could sell 'ya! :wink:

They relocate the IC not pinion angle. I have driven a cutlass with them and the only draw back I had was the arms/brackets stick down more and are closer to the ground

 

[Alky V6]

Theoretically, the more the lower control arms are away from horizontal with the ground, the worse the handling, as far as cornering. It has to do with the control arms starting to rearend steer the car during cornering. You can probably imagine that when a car goes into a corner, say a left turn, normal body roll will lessen the ride height on the right side of the car and will raise ride height on the left side of the car. When this is happening, the right lower control arm is attempting to go closer the horizontal with the ground, while the left side lower control arm is trying to go further from horizontal with the ground. If you can imagine the changing angles of the control arms, then you will see that the horizontal lengths of the control arms, front to rear are changing when the car rolls in a corner. The right side will be longer and the left side will be shorter. This will tend to cause an oversteer in the turn due to the rearend attempting to steer the rear of the car away from the turn.
When the lower control arms can be set closer to horizontal to the ground, the rearend steering effect is less in a turn.

 

[Alky V6]

The best way to change the IC with a stock suspension, with handling remaining a concern, is to change the upper control arm angles, IMO. Either raise the rear of the UCA or lower the front of the UCA.

 

[BuickMike]

Thanks for the info Donnie. Makes sense. If the LCA's are at more of an angle, then that angle will change more rapidly when the spring is compressed. So you're saying that raising the rear location points on the UCA's will do the same thing?

 

[Alky V6]

Thanks for the info Donnie. Makes sense. If the LCA's are at more of an angle, then that angle will change more rapidly when the spring is compressed. So you're saying that raising the rear location points on the UCA's will do the same thing?

Because the UCAs are located more centrally compared to the LCAs, any body roll that occurs in a turn will have much less affect on the true front to rear lengths of the UCAs, affecting rearend steer less.

 

[Pronto]

My friends 70 GTO had bad wheel hop. He had some UCA "no-hop" bars put on. Relocation brackets that moved the bushing location up with an S shaped bracket piece. No diffence in handeling the I ever felt but it did stop the wheel hop.

 

[Alky V6]

Shock stiffness can also help with tire chatter. I found that a stiffer compression setting helped take care of some tire chatter I would get on a hard burnout. It could also be a sign of worn out shocks, and/or control arm bushing material with too much deflection.

 

[charlief1]

Donnie's put the info out as to which to move. What most don't think about is that the rear suspension is triangulated. This boils down to simple geometry really. Out of all the triangles the isosceles triangle has equal sides. I know this may sound silly but think about it as if you're dragging one corner behind you. The triangle end is the axle and depending on where the point is will depend on the load the axle can produce. This will effectively move the IC location foward or backwards, up or down, to change the way the car behaves at launch or even around a corner. Moving the uppers will effect the handling of the car in a corner less than moving the lowers because of where the arms are pointing to. You move the IC not only rearwards but down towards the CG of the car. If you move the mounting point of the lowers at the axle you move the IC rearwards but up away from the CG of the chasis.

 

[BuickMike]

Thanks for all the great replies. This is all great info! As you all can tell I want to have my cake and eat it too. Maybe I'll look around for some used anti-hop bars and try them out.

 

[charlief1]

If you use the ones that go on top of the axle they have a tendancy of breaking the ears off the axle. You can get off set bushings for the axle though. I got mine from speeway motors.

 

[BuickMike]

I saw those. They only offset 1/4" though, right?

 

[charlief1]

They don't off set them much but if you don't want to buy some other parts and put them on they're the easiest way to change the IC without changing the way it handles in a corner. The other cute thing about them is it still is legal if you go to one of the Buick races, since it doesn't change the "stock" mounting position.:biggrin:

 

[BuickMike]

Are all 8 bushings the same? I can't remember. I guess I could put them all on. Since I need to adjust my pinion angle too I can only see myself getting about 3/4" more separation at most. Would that make a big enough difference? I'm not too big on changing bushings since I recently replaced them all with HR Parts bushings.

 

[charlief1]

All the bushings that mount in the arms are the same, the 2 in the axle are different.

 

[KevinB]

Baseline suspensions makes the kit to lower the front if the upper control arms. I think they are a vendor here too

 

[BuickMike]

Baseline suspensions makes the kit to lower the front if the upper control arms. I think they are a vendor here too

I like everything about their UCA and relocation kit...except for the price LOL. I see they sell just the buckets, but say that they will not work with any other arms. Why sell them likethat then?? Maybe I'll just make my own buckets out of 3/16" steel, figure out where I want the arms, set the pinion angle and control arm relocation point where I want it, and drill a hole to mount.

 

[charlief1]

His board name is kevinS if I remember right. You might want to PM him.

 

[Alky V6]

I like everything about their UCA and relocation kit...except for the price LOL. I see they sell just the buckets, but say that they will not work with any other arms. Why sell them likethat then?? Maybe I'll just make my own buckets out of 3/16" steel, figure out where I want the arms, set the pinion angle and control arm relocation point where I want it, and drill a hole to mount.

Kevin's buckets and UCAs make it so much easier, though. That's what I'm using in my car. If you want to change the IC just a little, you can quickly remove the buckets, plug and weld up the old holes, and redrill your new ones, then reinstall the buckets, readjust the UCAs to get the pinion angle back to spec, and done.
It is so nice being able to do the hole relocations on the bench on simple buckets.