ls1zfast

I have heard guys mention a few times that having LCA relocation brackets has a negative affect on handling in a road race application. Someone explained it to me once but it either didnt sink in or I forgot... just wondering what info is out there about this topic.

Nick

EchoMirage

iTrader: (3)

it would only have a negative effect if the LCAs are at the wrong angle for road racing. for handling, youd want them as level as possible. for drag racing, youd want them (im not sure im not a drag racer) angled down towards the rear end. i think....i do more then just go in straight lines so im not sure.

z28bryan

iTrader: (7)

Picture how the LCAs attach between the body and the axle. Say they are normally angled down from front to back. Say the car leans to the left. The left side of the suspension compresses and the right side extends. As the left side of the axle moves up, the left LCA swings up, causing the horizontal distance to increase between the chassis and axle mount. As the right side of the axle moves down/away from the chassis, the right LCA wants to swing down, causing the horizontal distance to decrease.

So basically a turn causes one side of the axle to move forward and other side to move back, pointing the axle in a certain direction. When LCAs point down from chassis to axle, body roll causes the axle to point away from the turn causing oversteer. Just the opposite happens with the opposite angles on the LCAs

I don't see a bad thing with roll induced understeer. Aka the angle of the arms higher at the axle side after lowering my car. I don't get wheel hop and the car might be a bit more stable taking turns.

ls1zfast

Are you assuming the LCA bends, flexes, or stretches when put under compression or extension? IF not.... the HORIZONTAL distance between the rear axle and the subframe cannot increase or decrease, because the lca is a set length that does not change. The ANGLE will change but not the horizontal distance. Or am I missing something....?

I could see how lowering the mounting place on the axle would make the angle between the subframe and the axle more extreme on the side of the chassis that is unweighted during cornering (i.e. a much steeper angle from the subframe to the axle), in what way does this dramatic angle affect handling ability/predictability?

darknessxyz

iTrader: (22)

I don't really get what z28bryan means. I've my LCA relo bracket and mount my LCA to the lowerest point. So my LCA are pointing down from the chassis to rear axle. I don't drag and I run the mountians. I feel the rear end more settle after that. I've 1.2" lowering spring.

UMI Sales

iTrader: (1)

Hello
It doesn't really matter what type of racing you do either Drag, Auto X. The relocation brackets were designed to allow you adjust your lower control arms more parallel. And doing so eliminates any wheel hop and increases your traction performance. UMI Performance offer two versions a weld on and a bolt on! Below is a link.

http://umiperformance.com/products.php?category_id=125

If you have any other questions feel free to ask and I will be more than glad to help!
Thanks
Brad

Ironhead

Yes. Think of just the outside arm in a turn for a second.

If it is pointed down towards the axle, as with relo brackets, the distance from the axle to the subrame will increase as the body rolls. This is because as the suspension compresses the LCA will become more level, effectively lengthening it in comparison to when it was not level and angled down towards the rear.

Of course this has the effect of "steering" the axle towards the outside of a corner. End result - Roll oversteer.

If the LCA is level or angled down towards the front, the opposite will occur. The LCA effectively shortens. Roll understeer.

z28bryan

iTrader: (7)

I swear I responded a 2nd time to this thread. Damn me for forgetting to hit reply.. doh!

ls1zfast

I am seeing what you and Bryan are talking about. If you drew a vertical plane between where the subrame and the axle sit under normal driving conditions, that plane would be entered and exited under harsh cornering when the angle between the subframe and the axle changed.

So, what is the goal as far as that angle? Is it ideal to have the lca go straight back to the axle from the subframe? Does that generate the best handling conditions? Is that not the purpose of LCA relocation brackets in the first place?
What are your thoughts Brad?

Ironhead

My LCAs point down towards the front.

The car is very, very nice to drive hard. It would likely take a Watts link to improve it any further.

The car still leaves reasonably hard with no wheel hop at all.

I've pulled 2.0 60's on pebbly, unprepped, 60 year old concrete with no more than a 3000 rpm launch. This was on low profile Hoosiers and with decidedly non-drag racing shock settings, springs and bars. Stock(ish) power.


YMMV

z28bryan

iTrader: (7)

I like having my LCA's pointing down from the axle to the chassis personally. I race in spectator drag events where I need to launch and then turn around a short oval track. I get wheel hop on only about 3% of all my launches. My car also is hard enough to keep from oversteering as it is around the corners. Haven't tested out other LCA angles, but my current setup works well for me and I can take the turns better than most competitive cars at my local track.