Ideal angle of LCA's?
 

With the BMR relocation brackets on a mini-tubbed Firebird that sits low with a 28" tire, we are seeing the mount on the car is sitting closer to the ground than the one on the rearend, even with it in the bottom hole.

I was under the impression that these brackets (regardless of brand) were intended to put the LCA's at a favorable angle to help the instant center. Obviously it would be much worse without the brackets, but will the LCA sitting parallel to the ground or close to it on the other side as described above get it done? Or will we have to add-on and create more locations to the brackets?

im gonna bump this cause i hear alot of people talk about having the the lower control arm being higher at the front of the car and being lower on the rear attachment point.

i always thought that you would want it about 1-2* higher on the rear than the body so when you launch it brings it down to about 0* when the rear of the car starts trying to roll under the car and pushes against the LCA's...

I thought it was the other way, as the rear rotates up (pinion side) under power.

it is up under power
and the lower the rear mounting piont the more leverage the LCA has on the car and pushes the rearend down with the weight from the car. but i could be wrong and you need to find out what works best for you
just my 2 cents any pros out there

You are opening a can of worms with this one. I will say that it depends on the weight and where the weight is. Play with instant center and see where you end up.

I would mount a different bracket or add to the bracket you have now to lower the LCA on the rear a bit.

you can get into tire clearence problems...or ground clearence with this though...idealy you could move up the body mounting point

looks like i'll be making some brackets or something... i should be mapping out my IC this next week and hopefulle at the track next saturday.

I would build your own bracket and make it low enough that the rear-end attach point is about 1/4 to 1/2 lower than the front chassis attach point.
Bob

I always thought you want the LCA to be lower at the rear than at the body?

I though that was the point of the relocation braket, to bring the LCA at the rear down. Not up...

Mine is fine at this length. I can see if you made them too long and not offset the LCA's it may have tire clearance issues...

http://pic18.picturetrail.com/VOL915.../353272349.jpg

http://pic18.picturetrail.com/VOL915.../353272322.jpg

wow that looks very nice

You definately want the rear lower than the front. The theory is when the rearend is trying to drive the car forward, you want to also push the body up. The opposite reaction is the rearend will go down and plant the tires. I don't have the tires on the car right now or I would take a pic of the angle when it is sitting. But I run 28" tall tires with factory springs and have the rears mounted 2 inches lower than stock. I did test at the track and tried them at 3 inches down and hurt the 1/8 mile by about a tenth...I was wasting too much energy driving the car up.

Jon

i have no doubt yours look fine...but lower your car more...and see what happens...and my cars not even that low...

This might help
 

Who built your brackets they look good and can i ask why you did not turn your shock half around. Just wondering ??

What is going to happen, just curious? BTW, how much lower do I need to go before I see what happens? Here's a hint, my car has less than 2 inches of shock travel, I have to cut off the bump stop on the shock even or I would have no travel, I can't go much lower ;).

Thanks! Why would the shock need to be turned in this setup?

I think the concept is to eliminate binding.

when you go low enough the body mounting point is so low that you cant make the lca angle up anymore...at least not in a street car because the rear lca point with hit the ground

I see that you have the best shocks in my opinion you can buy and they have bearings which helps a issue i see with the shocks on these cars. As you change the angle of the rear it will bind the shock body to a certain degree. It is really not an issue but with under the rear anti roll bars make it almost imposible with 2 way adjustable because you cant turn the knob, but you dont have that so i was just wondering why not take care of the bind issue. Dont get me wrong not bashing. (Mine are mounted the same way but my BMR bar makes it hard to adjust it you turn the shock) as i ask who made the LCA brakets my car is so low now i need to get some more may make my own but those look really good thanks Phil