dela

In preparation for starting my trackday career next year I am considering getting the bump steer mod done to my STI 3 Wagon.

Being a responsible BBS'er, I've searched my way around this subject and am still left with one questoin.

Everyone says that bump steer is built in to protect people who don't know how to drive.
From this I assume bump steer invokes understeer when the front of the car is loaded up due to braking or natural reaction "ease off the gas".

So for all the advantages.
- sharper turn in
- more stability under heavy braking

have people who had the mod done noticed any disadvantages? (ie savage Lift off oversteer)

cheers,
Dave

AndyMc

Dela

good question

After all it must be there for a reason.I don't understand how a car with more grip and greater turning in power at the pointy end will not be more nervous at the blunt end.

Maybe its just there are no average drivers who need protecting from themselves on this board

Andy

Hoppy

Yes, a very good question. If it makes such a big difference, you should expect a similarly large counter effect.

I'm also pondering various mods for a glorious season of track days next year, and I'm increasingly annoyed with understeer when pressing on (already got Prodrive geometry). But I think the standard OEM tyres I'm running have got a lot to answer for, so, one thing at a time, I'm gonna get some decent rubber first.

Hoppy

Robb

I had the bump steer mod done this morning by Powerstation. I then drove about 140 miles around damp (and muddy) Welsh B-roads to see how the handling had changed. The most noticeable difference is the feeling that the front end has much more grip and the turn in is more positive. There is no loss of stability under breaking (I tried several break tests at high speed to zero without any problems)or while driving in a straight line (including on uneven roads). I have not experienced any lift-off oversteer/instability. The only thing I haven't tried is driving in heavy rain.

The reason I went for the mod was that I didn't like the way my MY99 scooby understeered, particularly in the wet. I had only owned rear drive cars before and found the understeering characteristics a bit disconcerting. The handling is now completely neutral and the car is much more satisfying to drive. I would strongly recommend having the modification done.

As Powerstation pointed out, there is no magic to the modification, and much of the benefit is attained by ensuring that the toe-in, camber etc is correctly set - Subarus are notorious for having widely varying geometry settings and respond very well to the optimisation of these.

I hope that helps

Cheers

Rob

dela

Hoppy, like you I think I suffer duff tyre syndrome, so that will have to be the first thing to change.

Robb, thanks for the insight. I think I will get the bump steer mod done, then sign myself up for Don Palmers "Wetter the Better" to get a feel for how the car behaves in on-limit situations.

Whatever happens, I can't wait to get the car on a track and really open it up.

cheers,
Dave

NOZZER

I to had the bump steer done at powerstation at the same time i had a unichip fitted. Firstly,top marks to powerstation for their service and work. Secondly, when i drove the car hard, i found more diference with the bumpsteer & geometry done than the extra power with the unichip. I also have only ever had rear wheeldrive cars and did not like the understeer. Now it is a different car to drive and nearly all of the understeer gone. Definatetly the best pound for pound mod i have done to my MY97

JAMES.M.

Sorry to stray off subject.
NOZZER,
What are your thoughts on the Unichip? How much did all the work cost?
Cheers.....JAMES

Hoppy

Back on topic, well sort of, the question of tyres. On a previous post above I suspected that my standard OEM Bridgestone Wassnames were not helping the understeer problem.

Well, since then, case proven. Over the weekend I did a deal to swap my OEM wheels and tyres for a set of Prodrive ST2 17in wheels shod with part worn 205/45-17 Pirelli PZeros. The difference in the rubber, turn-in, feel and feedback etc is in a different league.

My conclusion is, and this surely ain't rocket science, is that the most important contributor to handling performance is tyres. So, before I do anything else, I'm going to play with pressures etc, and then, in a couple of months or so, try a set of Bridgestone SO2s.

Hoppy

Triggaaar

Dave,
I was asking myself the same question before I had the mod done - I hadn't been to any track days, and didn't know what sort of driver the mod would suit.

A few track days later, and having just driven Brands in the wet, getting the car sideways constantly (turning under braking) it still understeers too much when on the power (I find bump steer has most affect when braking), and is still easy to get back in a straight line when the back goes (on track that is). I would have thought that all keen drivers would prefer the handling after the mod.

rsquire

Hoppy

Might be worth having a look at the Toyo T1-S.. They have a slightly lower limit than the SO-2 but provide nice feedback on break away at the limit.. The SO-2 have a slightly higher limit but are not so forgiving IMHO


Oh I also have the Powerstation setup.. is all I can say for it.

Richard

NOZZER

I also have Toyo T1,s and like them. i had Pirelli pzero,s before and did not like them at all. I guess it is personel preference with tyres but so2,s, Toyo and pirelli,s seem to be the most popular. I get a lot less understeer now with Toyo,s.
James,
The unichip is now working well. When i first had it fitted the intercooler was mullered and restricting. All in with the boost controller, it cost £650 ish at powerstation. Mail me if you need any more details
Ian

SDB

Hi All

As mentioned above, the powerstation set-up is going to be far more rewarding to drive for the enthusiastic driver.

The increase in front end bit is really only the most obvious part of the set-up, the benefits go deeper and deeper, the more you test and analyse the car's handling on the limit. These guys really know what they are doing.

Out of ALL of the scoobies I have driven on the limit (which is over 150) the ones setup by powerstation are head and shoulders (genuinely) better (IMHO) than the others, and they are isntantly recognisable. I have driven at least 5 or 6 Imprezas at MIRA with the owners in the car and after the first lap have said "You've taken this to Powerstation haven't you!".

It's like there are two makes of Impreza, SUBARU and PowerStation.

It is really difficult to appreciate what a difference it has made until you have had it done. But I don't think there has been a SINGLE case where anyone is dissatisfied??

Cheers

Simon

DavidG

Simon - I'd appreciate your views on this one question. Do you think the bump steer mod might result in nasty surprises for the "ordinary" driver? By "ordinary" I don't mean "less good" (I have no illusions about my skills) but someone who expects the car to drive like a normal car.

Like many on this BBS, I am not the only driver of our Scooby (UK car, MY98 no suspension mods). My wife drives mine. I drive more ... ahem .. enthusiastically than her. I'm sold on the bump steer mod for myself, but I don't want to do it if it will make the car unpredictable for her. She likes to drive relatively fast on motorway type roads but not over the twisties.

What do you think?



[This message has been edited by DavidG (edited 30 October 2000).]

Sith

David,

I have been reading all these Bump Steer posts as I was considering it.

But I have decided against it. For these reasons - I don't drive the car enough, nor do I drive it hard enough (WUSS that I am. ).

I feel it would remove to much of my safety margin should I ***** it all up.

I'm still getting my mind round keeping the power on in a corner when it's going south to let the diffs work.

My opinion from what I have read and understand. Ready to be corrected if I have got is **** about face.

P.

NOZZER

I do not necessarily think it is harder to drive with, certainly not if driven with a normal right foot. My missus drives mine and has not mentioned any difference, but then again!!!!!!

Stef

David.
If your wife doesn't drive fast on the twisty bits, I doubt she'd be at a greater risk with the bumpsteer mod. It only becomes an issue when you start to push the car to it's limits. On the motorway and driving steadily on twisty bits, tthe only noticeable difference is that the car responds quicker to inputs on the steering wheel. Hell, she may even like it and start to drive a bit quicker! Get it done NOW!

Stef.