LCA brackets, car slows down?

[slagburn]

Not quite sure what's going on here. I thought LCA brackets were nearly a guaranteed improvement to 60' times. Not in my case.

Car: stalled, Whippled auto, 28" slicks, stock front suspension minus swaybar, rear suspension is Boss springs, stock LCA's with BMR relo brackets welded in. Stock rear swaybar and shocks, Roush upper arm/ bracket.

Took it out last night with the arms in the middle hole, spun bad. Back to the pits and raised it to the upper hole, better but it seems to hit the tires really hard and then unload. I was unable to match the best 60' of the stock brackets, a 1.46. 60's fell to the 1.51-55 range, prep was decent but not great.

I don't really want to buy a bunch more parts trying to get it back to how it worked before.. fortunately with these brackets I can still put the arms back in the stock location if needed. But I'd rather not.

Ideas?

 

[BMR Tech]

Well, unfortunately....and many people do not know this....but.....the Roush UCA System actually increases the AS% and shortens the IC, already...

You have too much AS%.

You will want to swap back to stock UCA Mount, grab aftermarket....or grab a set of Double Adjustable Rear shocks.

 

[BMR Tech]

I should probably clarify this, so people reading are well informed.

Typically, I do NOT recommend lowering the front of the UCA mounting point, AND lowering the rear of the LCA. I like to go one way, or the other, especially on a car that is not lowered substantially.

Thanks to a great member on this board, Tob, I have some excellent pictures to share. I have always known this about these parts, and was very excited when Tob decided to share his pictures of the stock UCA system VS the Roush UCA system:

As you can see, which is awesome actually, Roush goes ahead and does this great duty for the end user. They lower the UCA mounting point down, which increases AS% and shortens the IC.

IF you have a Roush UCA system, and use LCA Relocation brackets....the back of the car will raise up drastically when launching, sometimes being too excessive, causing traction issues either on the "hit" or right afterwards.

To fix this, you need to install a mount with a higher position on the UCA, or you can likely address the issue with a set of Double Adjustable Shocks, which can work well.....if it works, because you will be pounding the crap out of the tires!

If you use shocks to do this, you want the compression to be full stiff....and the rebound to be about 1/2 stiff. This will still allow the car to raise up, but will not allow it to fall as freely....keeping the tires planted.

Pfffeww.,....hope I covered everything. lol

 

[slagburn]

Thanks, I was wondering about that. I haven't crunched the numbers, do you think the car would be happier with stock upper/ bracket and BMR relo, or the Roush upper and stock LCA location?

 

[sean04]

Well, unfortunately....and many people do not know this....but.....the Roush UCA System actually increases the AS% and shortens the IC, already...

You have too much AS%.

You will want to swap back to stock UCA Mount, grab aftermarket....or grab a set of Double Adjustable Rear shocks.

What would be the difference between stock uca and relocation brackets vs roush upper with no brackets?

Thanks

 

[BMR Tech]

Thanks, I was wondering about that. I haven't crunched the numbers, do you think the car would be happier with stock upper/ bracket and BMR relo, or the Roush upper and stock LCA location?

It is hard to say, because of all the variables, but, I usually have better luck with stock UCA Position and Lowered Rear LCA Position. That being said, stock ride-height cars will, can and do perform great with just the UCA dropped down. You would honestly have to just test it out sir.

What would be the difference between stock uca and relocation brackets vs roush upper with no brackets?

Thanks

On OEM height tires....and OEM-ish ride height, using the stock UCA position with the LCA's dropped down to the "TOP" of the BMR Brackets....

The AS% is in the 105% range - which works very well.

If you run the stock LCA position, and use the Roush UCA system...

The AS% is in the 90% range -which can also work very well.

The factory set-up is in the 50% range.

100% means basically, the car will not squat or raise.....below 100% means the car squats.....above 100% means the car raises.

Raising slightly is a good thing, typically, as it applies more force/pressure to the rear tires.

*The numbers I posted above are from notes, experience, and overall numbers over the years I have gathered....and can be slightly different depending on MANY variables. Please do not use that information to expect optimum results, or to base your suspension from. I recommend using this calculator provided by Baseline Suspension:

Instant Center Calculator for your drag car suspension

 

[BMR Tech]

I hope this thread gains some attention.

I would love for people to see this stuff, and understand.

Too many times I get calls where people are dissatisfied with results, and it is often hard to tell them everything possible over the phone. They have a hard time accepting what I have to tell them, and often just remove parts simply because they did not perform magically on their first try at the track.

THIS IS EXACTLY why you will see me constantly tell people to avoid products on the market that force you to use a single positions. One size does NOT fit all.

 

[sean04]

I also have the roush upper, but I'm running k springs in the rear with the stock shocks set to 4 out of 5 and my car squats dramatically and then pogos all over the place

What do I need to change? I'd love to see some
1.4x 60's

Here is a video of a launch
2013 Boss 302 Sacramento Raceway July 6 2013 SBRacing 11.2 seconds N/A - YouTube

 

[slagburn]

Thanks for the info. I'll try putting the stock upper back on first and see how it goes.

Just so people see the difference- here is the Roush upper only, go to :23
[youtube_browser]RwsyjumU18k[/youtube_browser]

and here is the same upper arm, with LCA brackets on the upper hole, go to :30
[youtube_browser]HL2C1r0LeRg[/youtube_browser]

edit: got some youtube weirdness going on lately, the video doesn't actually play sideways

 

[BMR Tech]

Sean04, You can cut a decent sixty on those springs.

You are well under 100%....as evident by the car squatting like that.

You are bouncing, so that is telling me that you need to definitely increase your IC....and you should probably look into a better rear shock.

A manual transmission car, really needs a nice Double Adjustable rear shock, in order to give it everything it has and cut the best sixty-foots possible.

In your case, I recommend a set of multiple mounting point LCA Relocation Brackets, and an UCA mount with a factory mounting point.

If that doesn't work perfectly, add more AS% and get double adjustable rear shocks.

In an auto, the double adjustable rears are not quite as important, assuming the car is not running an excessive amount of AS%.

Here is our car, with 107% AS:

Notice the flat black tape above the tire, on the fender. That is what we use when we Go-Pro our launches, to monitor fender-tire separation.

This (current) AS% / IC setting is money for us. We have not cut worse than a 1.47 sixty foot time with this setting, while bracket racing (deep staging)....regardless of track prep, temps, etc. Our best is a 1.45....which equates to a 1.3X if we were shallow staging (shooting for ET, instead of shooting for a "light")

 

[BMR Tech]

slag, your call sir. I was dead-on....your car sitting that high, should not be raising an additional "few" inches on the launch, like the second video.

You need to aim for a little more AS% than the first vid, and a little less than the 2nd vid.

Throw the stock Upper Mount on, or grab an aftermarket piece. The BMR version for your car has a stock mounting point, and a 1" lower mounting point....in case you have better luck with the initial setup.

I am very certain that raising the UCA back up, will give you the results you are looking for sir.

 

[BMR Tech]

Oh and....lower that thing...

 

[slagburn]

Can't, I have a steep driveway and the mufflers will drag.

 

[BMR Tech]

I'd rather move and lower the car.

IJS..

 

[sean04]

Thank you BMR! I will be calling you guys soon

 

[Dave_6]

Great info in here!

 

[JUIC3D]

Kelly, how "extensive" are the modifications to the CAB005 LCA relo brackets when used in conjunction with the sway bar relocation?

 

[BMR Tech]

Kelly, how "extensive" are the modifications to the CAB005 LCA relo brackets when used in conjunction with the sway bar relocation?

Non-existent, usually.

Thats a "save my ass" note, that I figured would be smart to add to the web-site.

Here ya go, it's even the same color!

 

[DD2013 5.0]

I'm lowered 1.5 in the rear. It was of my understanding I need an adjustable upper to correct the pinion angle. I was going to do this plus lower relocation brackets w/ the multiple ca mounting points.
Sould I keep the stock upper ca mount in place? Or does the BMR upper and mount retain the stock mounting point? I have UPR lowers but the angle down towards the front which I'm sure is "unloading" the tires.?.
What would the ideal set up be lowered 1.5in? The front of my car is almost 2in lower than stock

 

[1930ford]

Great info, Thanks BMR , I run the Strange dbl adj rear shocks with great results. I have also found when running above 100as the tires usually need a little more air pressure to control "bounce". My view is that when the tire is driven that hard into the ground it tends to distort more(store energy) and shortly after it tends to be released causing the bounce.