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Cornering Optimizing your suspension system.

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  #16  
Old 11-15-2006, 03:17 AM
JuniorMint JuniorMint is offline
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Im not so sure exactly how they work but what I am thinking about is the install, whats that like. I have done all the suspension installs on my car so far so im pretty confident in that area, but I only have basic tools
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  #17  
Old 11-15-2006, 09:46 PM
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Well, I don't wanna go too far without confirming that it is indeed a replacement for the big control arm bushing, but you have to drop the subframe to swap that bushing out, from what I've read. The Bentley manual says you can do it without dropping the subframe if you have a special tool from BMW, but I donno how much that costs or how it works.
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  #18  
Old 11-15-2006, 09:54 PM
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Ive been biting my tongue on this thread, and this product since this summer! I was sworn to secrecy, but now I can discuss this new Alta product freely.
I got the go ahead from Alta today.

I have been running & testing these bad boys on the race car since August, with great success.

Some benefit's I have observed:
1. Much more stable handling.
2. The steering wheel returns to center easier after a turn.
3. Much more stability under hard late braking.

I have only used the P.S.R.S. on the race track, so I'm sure that there are much more benefit to be found on the road I'm not aware of yet.

Heres all the lowdown on the P.S.R.S. from Alta.

What is the PSRS?
Positive Steering Response System, is what it stands for. The PSRS replaces the front control arm, rear bushing. This OEM bushing is designed to be extra compliant to reduce NVH, and make the ride more comfortable. The compliancy of this bushing is not something a performance oriented driver is looking for.

OEM Bushings Installed

Under braking, this OEM bushing has enough flex in it to cause the wheel to move back and forth .500"! This deflection of the wheel causes drastic toe in and toe out changes under braking. These toe changes will cause steering input changes, cause the tires contact patch to change, and even wondering.

When accelerating, this OEM bushing causes unwanted wheel hop, and again toe in and toe out changes. During acceleration, the car will want to follow the ruts in the road, as the bushing flexes back and forth. This is one of the most noticeable changes

PSRS Installed
Under Braking, after the ALTA PSRS is installed, the wheel will not move front to back period! Since there is no way for toe changes to occure, the steering feedback issues, and wondering under braking all goes away!

Under Acceleration, after the ALTA PSRS in installed, wheel hop disappears, the car will have far less tendency to follow the ruts in the road, and in turn the car will have more front end traction.

Adds Caster
Besides removing all the unwanted flex of the OEM bushing, our PSRS has an offset to where the bushing is mounted. This allows the installer to add 0-1.5 degrees of caster to the front suspension. Caster is the angle at which the steering knuckle rotates on. Adding caster makes the car turn in faster by providing a larger contact patch as the wheels turn on the steering axis. Think of it like camber for your steering!

Anti-lift features.

Hope this helps.
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  #19  
Old 11-15-2006, 09:56 PM
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^--called it.

Thanks for the scoop, Bob!

Hey now, what's this "Anti-lift features" section you left out?
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  #20  
Old 11-15-2006, 10:22 PM
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Car lifts the front less under acceleration.
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  #21  
Old 11-15-2006, 10:31 PM
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Hm... I'm not really following how it would accomplish that. More positive caster in the front would actually cause more front-end lift.
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  #22  
Old 11-15-2006, 10:38 PM
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Quote:
Originally Posted by iDiaz
Hm... I'm not really following how it would accomplish that. More positive caster in the front would actually cause more front-end lift.
I think it's because the stock rubber bushing allows the back of the trailing arm too deflect so much & the rigid solid design of the Alta system eliminates this problem.

You ad more or less caster, by where you clock the bushing when you press them into place.
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  #23  
Old 11-15-2006, 10:52 PM
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Quote:
Originally Posted by CANYON MINI
I think it's because the stock rubber bushing allows the back of the trailing arm too deflect so much & the rigid solid design of the Alta system eliminates this problem.
Yeah, that might work.

Quote:
Originally Posted by CANYON MINI
You ad more or less caster, by where you clock the bushing when you press them into place.
Check it:

http://www.realoem.com/bmw/showparts...79&hg=31&fg=05

In order to change caster, wouldn't you also have to relocate where the ball joint (#12) mounts to the subframe? I'll have to really think about how the whole assembly moves under load, but it seems to me like the only way you could change caster would be to either lean the top of the strut further back, or move the mounting points for the lower control arm forward.
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  #24  
Old 11-15-2006, 10:53 PM
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Either way though... whether it does add caster or not, I think it's definitely worthwhile for the benefits you'd reap in more accurate toe control. The steering on your race car must feel rock solid!
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  #25  
Old 11-15-2006, 11:30 PM
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WOW......this sounds great!!!!! Maybe down the line I'll pick one of these up, after all this "anti lift" would work for my benefit out on the auto X course.... (and not to mention all the other features of this product!)
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  #26  
Old 11-16-2006, 12:08 AM
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Canyon Mini, Thanks for Spilling the beans!!!
Just kidding.

Yes, it is a front control arm rear bushing replacement, and yes it does all those things mentioned above. If you go back to our site with the PSRS on it, you will see more info than posted above. I was literally writing more things on the site as this post was happening.

We have been playing with this part for a while now, and we are finally poking the button on them. Thank in large part to Canyon Mini!

This OEM part on the car is a joke! You can literally move the bushing/arm .5" or more. Imagine this while driving and the Toe changes that occur. Its amazing how the car doesn't wonder toward ruts in the road also!

The one question i know is coming is how is the NVH. Well normal driving, you won't know the difference. The only time you will notice anything is when you hit a big pot hole in the road, or large seam. Other than that, its nothing we expect people to complain about.

Expect to see parts in hand at the dealer level in 3 weeks or so.

Yes this is our first post here, it was a long time comin, expect to see many more!
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  #27  
Old 11-16-2006, 12:11 AM
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Quote:
Originally Posted by ALTA2

Yes this is our first post here, it was a long time comin, expect to see many more!
Welcome!!!!!!!.............
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  #28  
Old 11-16-2006, 12:11 AM
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Quote:
Originally Posted by ALTA2
Canyon Mini, Thanks for Spilling the beans!!!
Just kidding.

Yes, it is a front control arm rear bushing replacement, and yes it does all those things mentioned above. If you go back to our site with the PSRS on it, you will see more info than posted above. I was literally writing more things on the site as this post was happening.

We have been playing with this part for a while now, and we are finally poking the button on them. Thank in large part to Canyon Mini!

This OEM part on the car is a joke! You can literally move the bushing/arm .5" or more. Imagine this while driving and the Toe changes that occur. Its amazing how the car doesn't wonder toward ruts in the road also!

The one question i know is coming is how is the NVH. Well normal driving, you won't know the difference. The only time you will notice anything is when you hit a big pot hole in the road, or large seam. Other than that, its nothing we expect people to complain about.

Expect to see parts in hand at the dealer level in 3 weeks or so.

Yes this is our first post here, it was a long time comin, expect to see many more!
Thanks for the info, and welcome to motoring|underground! About damned time!

I know you don't wanna give away any secrets, but how does this go about adding more positive caster?
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  #29  
Old 11-16-2006, 01:11 AM
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Quote:
Originally Posted by ALTA2
The one question i know is coming is how is the NVH. Well normal driving, you won't know the difference. The only time you will notice anything is when you hit a big pot hole in the road, or large seam. Other than that, its nothing we expect people to complain about.
What happens when you hit a pot hole or seam? Does the impact feel larger as compared to the stock setup?

Sounds very cool overall. Awesome product!
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  #30  
Old 11-16-2006, 03:01 AM
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Im loving it, thats all i gots to say
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