The Importance of Proper Control Arm Angles: VIDEO

[BMR Tech]

This video is of Greg's KB Powered Coyote Car. Greg contacted me a while back, and I have been working with him on getting the car to hook ever since he added a little more power, and made some suspension changes.

The car has been hitting the tires WAY too hard, causing severe unloading and tire shake. He is using BMR Suspension parts, so naturally; he contacted me to get things straightened up.

The first pass shows the car hitting the tires super-hard, then unloading, shaking the tires, then spinning his way out for another 100 feet.

The second pass shows the affect of simply changing the rear mounting height of the LCA 1"......

I cannot stress enough to everyone, DO NOT settle for a set of Relocation Brackets that only feature (1) mounting position.....AND do not settle for an Upper Control Arm Mount that only has (1) position. If you do, you will NOT be able to dial the car in to it's potential, then simply rely on shock adjustment. You will be relying on the sidewall of the rear tire, and the shocks, primarily - OR pulling a ton of power from the tune.....and if those don't work you had better hope the track is prepped the best it can possibly be prepped - then cross your fingers!

 

[JEWC_Motorsports]

What springs is he on?

 

[BMR Tech]

He is on the stock springs. He has gone through Roush, Steeda, FRPP, and Cobre Jets.

His BMR Springs are on track to arrive Monday, as well as his Strange Struts, Viking Shocks and a full BMR Front Suspension System.

 

[Sharad]

Kelly, I heard from someone with a similar position to you and I (but at one of our competitor's companies) say that their two position UCA mounts were just a gimmick. Personally, I wouldn't mind having the option to RAISE the chassis side UCA mounting point on my car... but I know there are some interference issues with the body.

What say you?

 

[BMR Tech]

Kelly, I heard from someone with a similar position to you and I (but at one of our competitor's companies) say that their two position UCA mounts were just a gimmick. Personally, I wouldn't mind having the option to RAISE the chassis side UCA mounting point on my car... but I know there are some interference issues with the body.

What say you?

What I say?

I say, that is disappointing - to say the least.

Unfortunately, companies out there make product, that they don't know anything about. Or maybe I should say, the people selling them do not know. When BMR released the UCA Mount for these cars, many companies followed suit, and likely had no earthly idea why we designed the parts, as we did.

Let's not forget - BMR Suspension built and drove an S197 Chassis into the 8's in October of 2005 - before most other companies even owned it. It went mid 8's in October.....and by March of 2006, it was in the 8.0 range.

That said, let's take a look into a few things. First - we will look at the Roush UCA System....known as the "anti-wheel hop package".

Preventing wheel hop is done by axle stabilization AND improved traction. I will show a few examples below. When it comes to "engineering" these components, not many companies surpass the level of engineering that Roush performs. Their engineering department is comprised of more employees than ALL of the employees combined at BMR, UPR and Steeda...

Roush's kit, does a damn good job. They use a higher durometer material to stabilize the axle, and they increase AS% by dropping the front UCA Mounting point down.

As you will notice, they drop the UCA Down about 3/4".

Ironically, BMR's measurements were similar, years before Roush released their piece. Did they copy us, not necessarily. Did they figure out what "works" like we did, probably so.

Below is a before and after. This is a Brembo GT, 3.73 Manual trans car on stock tires. The only mods are a tune and a BMR Rear control arm package. The first pass resulted in more tire spin, and wheel-hop.....than the second pass. The change? You guessed it - watch the video and note the UCA Position.

THESE ARE IMPORTANT TO WATCH - THE VIDEO IS OF THE ACTUAL UCA IN ACTION!

2013 GT - BMR UPPER CONTROL ARM / UPPER POSITION

After having a 20 minute conversation with the customer, I suggested to place the UCA in the lower position - before spending any more money to resolve the issue. He did:

2013 GT - BMR UPPER CONTROL ARM / LOWER POSITION


What you just saw was not bogus, it was not staged, it was simply a change in UCA position resulting in better sixty-foots, more traction, and elimination of wheel-hop.

Here is what he (customer / driver in video) had to say about it:

IT'S FIXED!!!! I moved the upper control arm to the bottom position on the mount and reset my pinion angle again. Took it to the track again today and ran it about a dozen times. Wheel hop is completely gone. I was skeptical that it was going to make a difference, but it worked!

So, again - I am disappointed that this person who sells components, told you it was a gimmick. I am not surprised however, it just shows the difference between the leaders in the S197 Suspension industry, and the followers. If you would like to invite him into this thread, that would be excellent. Maybe he can share with the members why changing control arm geometry, is a gimmick.

 

[Wicked97]

Kelly, I heard from someone with a similar position to you and I (but at one of our competitor's companies) say that their two position UCA mounts were just a gimmick. Personally, I wouldn't mind having the option to RAISE the chassis side UCA mounting point on my car... but I know there are some interference issues with the body.

What say you?

If the car is low enough having it higher will work better for sure

If the car is slammed on the ground your basically doing the same thing as dropping the mounting point so the lower the car goes the higher the arm should go....

Just sayin

 

[BMR Tech]

What do you know about suspension Eric? The JPC car only went a 1.19 sixty foot.

 

[Wicked97]

What do you know about suspension Eric? The JPC car only went a 1.19 sixty foot.

dont you forget that was on drag radials...


i know nothing

 

[Sharad]

If the car is low enough having it higher will work better for sure

If the car is slammed on the ground your basically doing the same thing as dropping the mounting point so the lower the car goes the higher the arm should go....

Just sayin

This is what I was getting at. As low as my car is, leveling the LCAs with relo brackets would give it some AS, but it would have a super short IC. Crazy pinion angle changes and issues with wheel hop under braking. I don't want that.

But the person in the video has a stock height drag car. It's just a different application.

 

[BMR Tech]

But the person in the video has a stock height drag car. It's just a different application.

And lowering the UCA down on a stock ride height car, is optimal.

That said - his car has stock springs, but sits about 28.45".....which is almost an inch lower than stock. The car is 4K lbs. You can tell just by looking at the video, it is definitely lower than a bone stock GT.

So anyways, the primary reason that I set him up with the UCA/LCA positions that he was running, is because he was supposed to be running our springs at the track, but they didn't make it in time.

I am simply showing people the changes that happen when moving the control angles around.

 

[Wicked97]

This is what I was getting at. As low as my car is, leveling the LCAs with relo brackets would give it some AS, but it would have a super short IC. Crazy pinion angle changes and issues with wheel hop under braking. I don't want that.

But the person in the video has a stock height drag car. It's just a different application.

you can move the upper "up" just add grinder welder and labor lol

 

[Sharad]

And lowering the UCA down on a stock ride height car, is optimal.

I am simply showing people the changes that happen when moving the control angles around.

Yessir. And it's solid tech, as usual, from you!

you can move the upper "up" just add grinder welder and labor lol

I'm not opposed to doing that. Seriously. You know what gave me the idea of that? I actually saw a 3-link setup with the body side UCA mount above the floor on an SN95 Mustang! It was tripping me out, but the car handled awesome. I don't know that I need THAT much adjustment, but higher than stock would be nice.

The recent fad, is, customers (handling specific) are calling me and ordering the 2011+ UCA Mount and our relocation brackets. They are using the 1" longer UCA (they grab a stocker form ebay), and our Upper Mount actually has a position that is 1/4" higher than the factory - so this alleviates some of the erratic axle movement due to the aggressive AS%. They pair that position with the Middle position of our brackets, and it is working extremely well.

The 1" longer UCA, paired with a higher UCA mount.....can do wonders. You can go more aggressive on AS% - specifically adjusted by LCA, and not suffer as much from an erratic rear axle.

^^Kelly mentioned this in the other thread, and it pretty well described what I want to do.

 

[onebadgsx]

And lowering the UCA down on a stock ride height car, is optimal.

That said - his car has stock springs, but sits about 28.45".....which is almost an inch lower than stock. The car is 4K lbs. You can tell just by looking at the video, it is definitely lower than a bone stock GT.

So anyways, the primary reason that I set him up with the UCA/LCA positions that he was running, is because he was supposed to be running our springs at the track, but they didn't make it in time.

I am simply showing people the changes that happen when moving the control angles around.

sent you a pm. looking for the next step in my suspension setup. prolly going this route. need some more info please

 

[CCS86]

Roush's kit, does a damn good job. They use a higher durometer material to stabilize the axle, and they increase AS% by dropping the front UCA Mounting point down.

Did you mean to write, "decrease AS"?

 

[BMR Tech]

Did you mean to write, "decrease AS"?

I did not.

I guess in certain instances, it could reduce/decrease AS%.....but 9 times out of 10, just dropping the UCA mounting point down will raise the AS%.

10 times out of 10, it will shorten the Instant Center.

Check this out:

http://www.baselinesuspensions.com/instant-center.php

Drop the UCA measurements down, and see the result on the measured AS%

 

[stepqhen]

I am not an engineer, nor do I fully understand everything that goes into suspension design (who am I kidding, I am a moron). What would be the effect on cornering from increasing the anti-squat and change to instant center?

I currently have gt500 LCAs, no lower relocation brackets (SCCA rules and all), and Steeda ultralight springs with Tokico D-specs. I just got the BMR adjustable UCA and mount for my 2011 GT and I was wondering if you would go for the lower position or the upper position to start with and what would be the possible unintended consequences of those choices.

 

[BMR Tech]

I am not an engineer, nor do I fully understand everything that goes into suspension design (who am I kidding, I am a moron). What would be the effect on cornering from increasing the anti-squat and change to instant center?

I currently have gt500 LCAs, no lower relocation brackets (SCCA rules and all), and Steeda ultralight springs with Tokico D-specs. I just got the BMR adjustable UCA and mount for my 2011 GT and I was wondering if you would go for the lower position or the upper position to start with and what would be the possible unintended consequences of those choices.

Our 2011+ Upper Mount is a unique piece.

The upper-most position, closest to the body, is specifically designed for a lowered car that will utilize the LCA mounts to adjust IC/AS accordingly.

The lower-most position is designed for stockish ride-height cars, that do not use the LCA position for the IC/AS adjustments. Stockish height cars will perform better in every situation, with the UCA mounting point lowered down a little. This is why Roush's UCA System works so well on a drag strip, or a road course, on a lot of cars.

As for what someone should do with our Upper Mount, on a lowered car, without LCA Relocation brackets - your guess is as good as mine. If you use the Upper position, it will reduce your AS slightly. If you use the lower position, it will increase your AS.

Due to your case; inability to use relos - I recommend just trying both positions and seeing which one works best. I rarely ever try, or recommend the lower position on a lowered car, as I always recommend the LCA Brackets to perform the task.

I could play around with a calculator to see where your AS will be - but it really doesn't matter a lot, as results are what matters. Both spots will lead to a poor IC location, in my opinion, so testing will be the best route to take.

 

[CCS86]

I did not.

I guess in certain instances, it could reduce/decrease AS%.....but 9 times out of 10, just dropping the UCA mounting point down will raise the AS%.

10 times out of 10, it will shorten the Instant Center.

Check this out:

http://www.baselinesuspensions.com/instant-center.php

Drop the UCA measurements down, and see the result on the measured AS%

Yup, my morning brain was neglecting reaction torque on the axle housing.

 

[C.Love]

So I'm in the market for relocation brackets and I am relatively new to the straight axle suspension game. Lets compare yours (multi holes) vs whiteline. I assume in the yours vs theirs comparison you would say use yours simply because you have the ability to tune via the different hole locations.

What is the end goal here? to have a completely flat LCA for maximum traction?

 

[BMR Tech]

^ The goal is to find a position that works best.

The best thing about our brackets is, they are proven more than any other set - and they do allow for multiple mounting positions. I run into customers needing to change positions alllll the time, so I would NEVER recommend someone using a one hole bracket.

I have a friend here locally, who has excellent results with his BMR Brackets....and he ends up using various holes, based on track conditions. He thought I was crazy when I told him to raise the LCA up a position because he was bogging to bad. The next pass, ran his PB sixty/ET/MPH. And he races a lot...

I would also say "ours" based on the fact they took ours, and duplicated them, and deducted 2 holes. IMO, it's a no brainer.