This is an old post I made in the Vendor Announcements but I think it'll work good here. Please post your questions and comments about the ALTA PSRS in this thread.

Its a good thing, but all day long we get questions about the PSRS...
What is it?
What does it do?
Is it a race only part?

Positive Steering Response System
The MINI has very minimal adjustments to the front suspension, toe in or out only. ALTA has seen tremendous benefits from changing the levels of caster in the front. This increase in caster allows sharper more precise response from steering input, decreases understeer and improves overall feel.

Also, the OEM lower control arm bushings supplied from MINI are a very gooey like rubber compound. While great to reduce road noise, they are miserable at improving handling. As a result even the most minor of imperfections in the road surface can cause the car to dart around. The ALTA PSRS uses a firm bearing material that prevents this. This inspires confidence in all driving conditions, and again adds positive steering response.



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 occur, 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 feature
One of the byproducts with how we add caster is the ability to add some Anti-lift to the front end. Depending on how much caster is being added, some Anti-lift can be added to the car. This reduces the amount of front end lift during acceleration. The benefit to Anti-Lift is it keeps the balance of the car in check. During hard acceleration, Soft springs, and shocks makes the cars weight shift to the back. This in turn removes weight from the front that keeps the tires planted to the ground. Which is a very important thing when you have all that power going to the front wheels!



Now that you have read ALTA's view on this part...............
Here is a link to one reason you MIGHT consider the PSRS as one of your mods.

Lastly here are a few quotes from active NAM members that have experienced the ALTA PSRS first hand. (You can find more posts and quotes on the ALTA PSRS by simply typing "PSRS" into the search function.

Vader – “In terms of performance, they really stabilized the front end as advertised. I have no regrets with this purchase.”

Bean – “i love it. i have a pretty aggressive alignment and the car was "twitchy". with the alta PSRS, the car is much better in a straight line or high speed sweepers. i've had it on my car for almost a year (5 track weekends). if you want to go fast, you need this!”

Bean – “Beckett's Bend, at Sebring is a long, fast left-hander that can be run flat in a MINI. one steering input at the beginning of the turn, then hang on. i usually exit that turn at about 113 mph. i was able to do 102 mph with slicks on a wet track. the PSRS makes this a much more comfortable event. this wouldn't be the first suspension mod that i made, but it becomes almost necessary after other work is done and speeds are higher. my front end doesn't roll side to side!”

Dr_Obnxs – “The front end is much more planted and "connected" for sure. Accelerating and braking are both more controlled.”

Vader – “I wasn't on your list but I now have 1000 miles and a three day DE with the PSRS installed. I was hoping they would stop the back and fourth movement I was getting under hard braking. I'm talking seriously hard 120mph to 30mph threshold braking. Problem solved. Turn-in is better. Front end is solid. I can't find anything bad about these. I'm very happy that I put these on my track car.”

Blumini – “PSRS removes the big rubber bushing and replaces it with a precision spherical bearing. If your car is "slammed" then you're already riding extremely harsh. The PSRS won't make things any worse, just more precise.”



For those of you that took the time read my ramblings above you have a limited time to take advantage of a SUPER Schweet Cool Guy Deal on the ALTA MINI Performance web site!

 

Your description of Anti-lift is wrong and has been for ages. This part removes anti-lift, as in it adds lift. It softens the front suspension under acceleration. This is a good thing for improving grip coming out of corners.

http://www.whiteline.com.au/articles...WL%20ALK_b.pdf


- Andrew

 

I found wheel hop to almost disappear by changing to Bilstein HD shocks. Nothing against this part. It is that the OEM shocks are that bad.

INHO, street cars should be mounted in rubber. Solid are for track. Not as much rubber as OEM, so I am with John on that point. I think I would be more inclined to a higher durometer mount, maybe with the increased caster ALTA has identified.

I disagree with your description of what adding caster does. Caster by itself would reduce turn response. Your contact patch area is defined solely by the inflation of the tire. ( 33 Lbs per square inch, work it out. 2600Lb car...... High School physics) The SHAPE of the contact patch is defined by the geometry and that does greatly affect the grip. A quirk of the suspension causes an increase in caster to also increase negative camber, so the benefit is as claimed, better turn in response. Just not as described. Might I suggest everyone here go back to the old stand by " How To make Your Car Handle" by Fred Punn, or the series: xxx To Win by Carroll Smith to get a grip ( sorry) on suspension geometry basics?

By changing the relative plane of the lower control arm to add "anti-lift", is this not by definition increasing dive? Not so good for breaking. Most cars have considerable anti-dive. ( well not the 66 Ford Galixiee 500. It would stand on it's nose while it plowed on and on)

Please don't get me wrong, I am not at all criticizing the product. Just the explanation. If install was not such a pain, I would have tried them myself already. Sorry to have to rag in on this, but I hate to see a reasonable product that may work well, be described in terms that do not seem to wash with what I understand about suspension geometry. Please clarify where the errors in explanation, ALTA's or mine may be.

 

FWIW, I have installed the PSRS, and what I noticed is better high speed turn confidence, better mid-corner bump absorption, and heavier, more feelsome steering. Also NVH is up. The bushing is definitely not too stiff for road use, but it is definitely harsher. Don't bother installing them unless you weld them in.

My only concern is longevity, because as far as everything else goes, the car feels like the way it should feel from the factory. For most people however, I'd probably recommend a polyurethane bushing like powerflex

 

etalj,
What do you mean about welding them in. They are Aluminum, and aren't the lower arms are iron? Does not longevity and welding seem a tad contradictory?

BTW, what do you notice different with the stainless lines? I have the carbotech pads on my bench waiting for a cooler weekend. I am looking for better modulation.

 

The ends of the control arm are welded on to the sleeves of the control arm bushing (which holds the control arm). I don't know if they are aluminum, but several people on NAM have done the same, because they experienced what I did (set screws coming loose very soon after installing).

To be honest, I installed the ss lines, fluid and pads all at the same time, so I can't comment on individual differences other than increased modulation in the brake pedal, I'm sure due the pads alone. Carbotech do go on about the amazing modulation in their pads. I love the carbotechs so far, just make sure you re-use the stock shims. Which ones did you go for?

 

I would have to look. It would have been their street recommendation over the Hawk HPC. If it cools off, Maybe I'll put them in Monday.

 

Bobcats? I think that's their street pad.

I've never used Carbotech but most people I know that have like them.

I did not like Hawk HPS at all.

- Andrew

 

They're not. They're stainless. I spoke to an Alta tech about this before I finally had mine welded. I thought they were aluminum, too. The typical response when I contacted some shops to do it was "Impossible. Can't weld aluminum to steel." The shop was much more interested once I realized and informed them it was SS to steel.

 

Ah, ss. That makes sense. I was guessing by looking at the picture it looked like anodized aluminum. They must be heavy buggers!

How are they welded? Just a couple little blobs on the edge that could be ground off later? A rose welded where the setscrew would go?

 

3 tiny welds on the end of the arm, then ground off. Works very well. I'm very happy. Let me know how your pads go....

 

Do these affect comfort drastically?

 

Thanks for asking. There is a minor increase in NVH on rough pavement, but nothing drastic. Certainly worth the increased handling and lack of wandering benefits!

Let us know how we can help in anyway!

 

It´s definitely noticeable, but I have a big tolerance for a lack of ride comfort, so Im probably not the best person to ask. Bumps are definitely louder inside the cabin.

 

The effects are cumulative of all your suspension mods. PSRSs by themselves will probably only be a minor increase in NVH on rough roads. Add stiffer springs or coilovers and the net effect will be very noticeable. And if, by some nasty quirk of the universe, you're still on runflats... well...

The PSRSs do the job as any other mono-ball bushing would. I would not recommend them to those with comfort in mind.

 

Hello! Can anybody comment on the longevity of PSRS? I have made 6000 miles on them and they still don’t have free play, just not that tight as from the beginning. At the same 6000 miles Alta rear control arms have got considerable free play and that is not acceptable mileage. Probably this is because of no dust boots on pillow *****. Currently I have to choose which way to go for my new dual-purpose track/DD MINI – PSRS or Powerflex. I want PSRS only because of caster benefit. The roads at my location are generally not bad but dirty.