rockoosi1

I have an 89 RS that had been lowered by the previous owner. I'm currently running a turbo LQ4 combo and it is exposing all of my suspension weaknesses.

This weekend I put on a set of LCA relocation brackets. With it set in the bottom hole the LCAs are almost perfectly even. My guess is the car must have been lowered quite a bit and I didn't realize it.

My questions is how much lower do the rear of the LCAs need to be in order for them work correctly? I mean the anti-squat that I’m looking for.

86firebird350

Are you still experiencing wheel hop and/or traction loss? The stock LCA angle is supposed to be about 0* or angled down slightly from front to back so that when you accelerate the back end of the LCA will be below the front end because of weight transfer. This will apply more force to the differential in a downward direction thus increasing traction. The relocation bracket will help make up for LCA angle loss due to lowering the ride height but will only do so much. In order to increase traction further you have to address other areas of the suspension/chassis and the tires.

rockoosi1

I haven't taken it back to the track yet to see if my traction has improved. I expected to see more angle when I added the LCARBs but I guess my car was lower than expected. I spoke with the tech support at UMI and he told me that a general rule of thumb woulb be 2" lower in the rear of the LCA to get some real body lift.

I was just wondering of the guys that use them when they started to see a real benifit. 0* is about where I am now so it should be slighty better than before. My next moved to try and raise the car up an inch or so in the rear to get more angle. Any thoughts?

UMI Sales

Nice talking with you. Your car looks pretty sweet!

ramey

86firebird350

Well if it was angled up before you will definitely see an improvement. Your LCA angle will now be working FOR you rather than against you. I would try doing a spring change to either a stock spring or a mild lowering spring (something like the eibach pro-kit) to get the rear a little higher as it sounds like you've got dropzone springs or something really low on it now.

rockoosi1

Same here and I'm definitely going to try some of the things you recommended and let you know how it works.

rockoosi1

Yeah it apparently is pretty low. I like the way it sits but the turbo is waaaay too much for the current setup.

AM91Camaro_RS

I think the lca being 2" lower in the rear is way too much. I'd go try it with the lcas level.

sofakingdom

iTrader: (1)

2" of LCA lowering is WAY low for anything other than single-purpose drag racing. That'll make it hook up like you won't believe; but it isn't all that pleasant on the street. For street use, they need to be slightly lower at the rear end, than at the frame; maybe ¾" at the max.

Lowering these cars (or for that matter, rasing them) causes all sorts of FUNCTIONAL problems. It always amuses me to see people talk about how lowering "looks" "good"; I have yet to figure out how, when even somebody as DUMB as me can take ONE LOOK at it from HALF A MILE AWAY and see that it's SLOW, how all the sudden SLOW "looks" "good". I guess I'll just never understand .... humans. A totally irrational illogical species.

SlickTrackGod

This is scary- Good ol UMI giving wonder tech advice still I see. You came in here and did npt give any dispute to him listing that (and I will quote) "I spoke with the tech support at UMI and he told me that a general rule of thumb woulb be 2" lower in the rear of the LCA to get some real body lift."

Ramey- Care to elaborate about his dangerous effects of Roll oversteer you are advising?

UMI Sales

Certainly. The customer is building a street/strip car. I did explain roll oversteer, as I do with all my relocation bracket customers. Outside trailing arm gets longer in bump while inside trailing arm gets shorter in droop (arc-wise of course, the arm stays the same length, you know, just to clarify). This causes roll oversteer due to the difference in wheelbase. Sometimes we even use relocation brackets on a car which doesn't need them for forward traction to achieve roll oversteer on purpose if the car tends to understeer.

So, relocation brackets prompting roll oversteer on a customer's car desiring forward traction are no more dangerous than running a 1500lb/in anti-roll bar which as you know screws up the roll couple distribution enough to make a 4-cyl seem like a drift car.

UMI Sales

And the customer, after relocating to the lowest hole, had the lower control arms slightly past level. Our actual discussion was that it was probably close to the angle GM intended for street use and that we couldn't get the desired angle for forward traction.

2" is popular for drag oriented cars, of which we have many. The first hole is popular for general correction or moderate street/auto-x use.

ramey

rockoosi1

I hope I didn't cause any confusion. I'm just learning some of these suspension trick.

SlickTrackGod

You gave a motion discription, but still no explination of danger to the layman consumer.

When the trailing arms change horizantal length from side to side they push and pull the axle per side creating rear wheel steer. When someone droops the LCA angle 2" lower in the rear they now create a VERY DANGEROUS rear wheel steer outward from the corner (roll understeer) when the car leans and will make the car very unstable and *** around.

THis is a bandaid fix for a novice suspension setup to try and achieve traction on drag launch while disrupting other charateristics of the car. Often at the evpense also of shock loading the tire sidewalls and causing the entire car to bounce rather than just wheel hop bounce.

The correct fix- Keeping the LCA angle mostly parallel at stagnant height (I say mostly because you want to favor the rear just a tad downward if parallel is not acheived with driver in the seat (Always include drivers weight). If you are still experiencing wheelhop? then your shock damper/and-or spring rates are not high enough to control the torque motion of the chassis. If this car is driven on the street at all? these angles should be what I recommend about....period! Otherwise you are recommending a bandaid fix to one driving charateristic and causing danger in others. Roll oversteer is about as dangerous as it gets in a freeway panic situation. This is like the thrid UMI tech I have had to educate over the years- this company has nice fabrication skills, but absolutely no chassis dynamics backgroud. Scary, but most companies don't and should not be giving tech advice.

Dean
(And since you probably don't know Ramey- I'm a former NASCAR supertruck crew chief with one hell of a winning resume)

UMI Sales

Hi Dean. It's awesome to e-meet you. I'm sure your accomplishments are fantastic and I'm looking forward to learning more from you.

ramey

UMI Sales

And actually, the LCA's create roll oversteer, not roll understeer as you mention.

Flip 2

iTrader: (1)

That RS is sweet, and seriously lowered. I have Eibachs and skinny spring isolators (on the rear- front is coil overs, and set to the rear's height- minus a bit)... plus Thin Spokes... my car is way higher. (sig pic is before)
Perhaps those are Drop Zone springs- or cut stockers??-, and maybe a tad weak for the turbo HP.
Having the trailing arms going the wrong way is NO fun. Drove my car with a 383 that way... just spun tires. The LCA brackets will do wonders. If it is still flaky under power, you might want to look at diff springs.

SlickTrackGod

I notice you don;t boither quoting me when I write the correct thing lower in the same response----" Roll oversteer is about as dangerous as it gets in a freeway panic situation."

an obvious mistake in a hurried reply- the correct message was delivered so no harm.

Base91

iTrader: (1)

Welcome back.

rockoosi1

First let me start by saying I really appreciate ALL of the input. I'm smart enough to extract the useful information and ignore the rest. All of you seem to have more knowledge on this particular subject so I'm in no position to judge anybody.

So here is the plan. I'm going to the track Friday night and I will share my results. We can compare notes then. I currently have about .5-1.0 inch drop in the LCAs. The last time I took the car out my slip went something like this.

1.6x 60', 11.17 @ 131 mph in 1/4 mile. My race weight with me in the car is around 3800 lbs. Since the car only seems loose traction under boost I don't expect my short times to improve much. I'm hoping for my ET to improve more than anything. I will keep you good folks posted.

rockoosi1

Thank for the kind words. I'm really not sure what springs are in the car. All I know is that they are purple. I will let you know how the LCARB work.

JamesC

iTrader: (5)

Please keep to topic for the forum's benefit.

JamesC

rockoosi1

Well, I finally made to the track. I was a little rusty and quite frankly didn't expect to see much improvement. After only 3 passes I managed to get my ETs down from 11.1x to 10.6x!!!!

This car as already met or exceeded my expectaions so I'm real happy right now. I may go chasing a little more oooorrrr I just might just let the turbo do the work. Thanks for all of the input guys!

UMI Sales

Wow, sounds awesome. Half second is an eternity.

rockoosi1

Yeah, for less than $100.00 I would say it has proven to be my best investment to date. Thanks for for the help.

AM91Camaro_RS

how about the 60' times? and, what angle do you have the lcas at? about level?

GreggymacZ28

How does the angle help you besides off the line? That's a very impressive increase for nothing changing in the 60 foot!

rockoosi1

It's only because my car is a turbo. I was having problems once I went into boost. I might change the converter at some point to improve my 60' but for now I like the way it drives on the street. A mid 10 sec car that cruises around 2k @ 65mph is a pretty good combo IMO.

rockoosi1

My 60' is soft because of my overall setup. The lcas are about 3/4 lower in the back now and that seems to keep the tires planted once I go into boost.

GreggymacZ28

Ah ok i see now, thanks!