psfracer

Ok, I get the instant center idea, and the parts below will enable me to adjust pinion angle and instant center. Trouble is, how do you do that? There are different mounting holes on the LCA brackets, two different mounting locations on the UCA bracket, and the UCA itself seems to have infinite possible adjustments. Where to start? Is it just trial and error at the track, or is there an accepted pinion angle that is a good starting point?

dustindu4

-2 degrees i thought

psfracer

<div class='quotetop'>QUOTE(dustindu4 @ February 14, 2006, 7:31 AM) Quoted post</div><div class='quotemain'>
-2 degrees i thought
[/b][/quote]

Yes, most people are saying -1 to -2 degrees. Now next question: How do you measure it so you know its -1 or -2 degrees? Is there a tool for that? Since the rearend wants to rotate towards the bottom of the car when torque is applied, I am assuming the (-) in the -2 degrees is the rearend tilted down?

psfracer

Well, if anyone is intereseted, a friend of mine on another forum found this......it explains how to measure pinion angle and what amount is best depending on your suspension set up.

http://www.baselinesuspensions.com/info/pinionangle.htm

thump_rrr

<div class='quotetop'>QUOTE(psfracer @ February 14, 2006, 8:50 PM) Quoted post</div><div class='quotemain'>
Since the rearend wants to rotate towards the bottom of the car when torque is applied,[/b][/quote]
The nose of the diff actually wants to come up.Remember the saying every action has an equal and opposite reaction? If your wheels are trying to rotate clockwise when standing on the passenger side of the vehicle the differential is trying to rotate counterclockwise or nose up.

Use method 1 since we have a 2 piece driveshaft.

This must be measured with the weight of the car on the rear axle to get an accurate reading.

islandmustang

i put the non adjustable BMR LCA's on my car and it was a inch or so shorter than the stock lcas. Is shorter better than adjusting to make it lenthier. Which way would get a better pinion angle. I am driving my car with it, and it is not vibrating or anything. Just looking out for the future..

JLH

<div class='quotetop'>QUOTE(islandmustang @ February 19, 2006, 1:32 PM) Quoted post</div><div class='quotemain'>
i put the non adjustable BMR LCA's on my car and it was a inch or so shorter than the stock lcas. Is shorter better than adjusting to make it lenthier. Which way would get a better pinion angle. I am driving my car with it, and it is not vibrating or anything. Just looking out for the future..
[/b][/quote]

Are you saying that the BMR lower control arms are 1" shorter from mounting hole to hole? If so, this would probably take your pinion angle from - to +. I would find it hard to beleive that the non-adjustable arm would be any different in mounting length from stock.

JLH

islandmustang

yeah...thats what i'm saying.....

But just debating now if i should get the adjustable LCAs...There is no problem with the vibration or anything..But is it bad to have positive pinion angle.....

thump_rrr

<div class='quotetop'>QUOTE(islandmustang @ February 19, 2006, 1:46 PM) Quoted post</div><div class='quotemain'>
yeah...thats what i'm saying.....

But just debating now if i should get the adjustable LCAs...There is no problem with the vibration or anything..But is it bad to have positive pinion angle.....
[/b][/quote]
That's weird. If your pinion angle is 0 when you launch it may go as high as +2 or +3(just a guess as to how many degrees) By starting at -1.5 when you launch it may go +0.5 or +1.5.

If you get an adjustable Upper Control Arm it should help. Why not call BMR and ask as to why they're shorter?

JLH

You don't want to start with a + angle as the angle will only get more + under acceleration. What you want is for the pinion angle to get no greater than 0 under acc.

I would talk to BMR about the length of your LCA's. It just does not seem right.

I have not put an aftermarket arm on my car yet, waiting for the $ to come down on them, or will just fab myself. Or a mfg. to offer poly bushings for stockers.

Already have made my own mounting brackets with multiple adjustment points and installed on rear end housing.

JLH

islandmustang

i emailed them to ask why...just waiting for feedback...

well..i guess if there is no crazy vibration at high speeds, it is safe to drive in the meantime??

JLH

Should be ok to drive, I would just stay away from hard launches.

Get yourself an angle finder and check the pinion angle. An angle finder is less than $10.00 at any home improvement store.

traffic142

Ok,

I added steeda ultra springs, if I add BMR non Adj. LCA's do I need to worry about my pinion angle?

I am guessing but it should have changed when I dropped my car in the rear by about 1 1/2 inches, correct?

They say it should be loaded to measure it. How do you do this with out a lift? Is there some way you an do this with your car backed up on a ramp?

Thanks

BTW why was this not mentioned in all the posts about replacing the springs? or did I just have a blonde moment and miss it.