kav

DavidRB posted an excellent thread back in February about bumpsteer removal. I had a question for him now that he's run the car for a couple of months but I can't get his e-mail address so I'll throw the question over to all those that have had the mod done as well.

Have you noticed an increase in tyre wear? (not including wear due to the enthusiatic driving style that bumpsteer removal encourages!)

Another thing I'd like to know - I'm not an expert in a Scoob by any means and I don't want to change the car's generally forgiving nature. Now that you've had a chance to drive a modified car for a while, what do you reckon? Is it the sort of set-up likely to bite your a**e if you get it wrong?

Cheers
Kav

Gary Foster

Answers

1) No (I'm on 4 months and 11K miles with it now)
2) Err, don't know. Certainly don't get as much of that 'Slow down your going to fast' understeer but I wouldn't say I really slide it around on the public highway. I personally prefer all 4 Wheels to lose traction rather than just the fronts, so I prefer it.

That said I did spin in the wet at Goodwood but that was driver incompetence.

Gary

Trout

iTrader: (1)

Bumpsteer for nearly a year now - I'm a crap driver, but I ain't spun on track or lost it on the road - even when I try and drive fast!

Tyre wear is less as you need less neg camber and you still get more front-end bite with great turn-in.

R

RobScreene

I recently took a concealed roundabout on an A road too faster than I would have knowing how sharp the corner was.

Bumpstyeer/Proxies T1-S with about 650 miles under them in the dry and the slide was beautifully banaced front and rear and easily controlled.

I too prefer it to the previous "understeer, overcorrect, catch the back after the speed has been scrubbed off" attitude.

Not something I plan to repeat on a public road though, where's a forthcoming track meet near the south? 8-)

regards,
Rob.

DavidRB

Sorry Kav, been a bit busy recently, not to mention paranoid about leaving my E-mail address on display!

Tyre Wear:
Haven't noticed anything unusual yet, although I'm not expecting to. The negative camber on the front tyres was increased (from -0°33'/-0°34' to -1°24'/-1°22'), but only up to the same level as the rears (-1°25'/-1°13').

As my previous set of rear tyres lasted 22,500 miles, I'm not expecting any increase in front wear from motorway journeys (where there would be minimal cornering load). If -1°25' of camber destroyed the inside edges of the tyres, then all standard Scoobies would be chewing up their rears.

Handling:
This is always going to be subjective, but personally, I prefer the handling of the car now that the bumpsteer has been removed.

There is less understeer under all conditions, but the car is not alarmingly tail-happy by any means. The car turns in more eagerly and feels more planted & more neutral through the bends, inspiring more confidence. I have noticed that the car wants to tuck in more tightly than before if you lift off mid-corner, but that's something I try not to do any more! Most of the time, I try to set the car up so that I am on the the throttle (even if it's only slightly) most of the way around the bend.

As far as I am concerned, the car now handles more predictably than before. I always found the onset of understeer a little unpredictable, particularly when entering a downhill bend that changes to an uphill bend (there is one near me). Now, I find that the car holds a consistent attitude all the way around a corner.

I think a lot of the understeer problems do stem from driving style. One way to provoke understeer is to nail the throttle in 2nd gear and then to try to steer. With my Scooby, I find that I have to begin turning before I open the throttle. That way, I get a much more neutral attitude through the corner. It helps to point the car into the corner a little more than "normal" and then try to push the car away from the inside edge using the throttle. The car now maintains a more neutral feel on-throttle and is more likely to follow the line I want.

I haven't had any scary moments since my trip to Powerstation, no unexpected tail-out moments or sudden snap changes from understeer to oversteer. Any car with the performance of an Impreza demands respect from the driver, but I don't think that the car is any more likely to catch me out than before.

In summary, if you have £100 to burn and you want a cheap way of making a big improvement to the cornering ability of your car, then I can thoroughly recommend the bump-steer mod!

kav

Great stuff!

Thanks David and the rest of you guys. It's off to Cheltenham then......

kav

Great stuff!

Thanks David and the rest of you guys. It's off to Cheltenham then......

Trout

iTrader: (1)

David,

interested in your comments.

Before I went to PS I had -1.3deg neg camber at the front and after making the bumpsteer adjustment, PS were insistent on removing much of the negative camber, saying that it was not necessary and that the car would both handle better AND have reduced tyre wear with around -0.5deg. This is the setting that I now have.

Did you insist on having so much negative camber, or was that recommended by PS. I have my car done last May from memory.

Cheers,

R

DavidRB

I was offered the choice of two "standard" setups, a road setup or a more aggressive track setup. I chose the former, as that's where I do all my driving, so no, I didn't ask specifically for that amount of negative camber.

I'm very happy with it so far and I can't see any reason to change it!

What camber were/are you running on the rears? That might have influenced the front camber settings as they can't easily adjust the rear camber.

Mikey Ace

iTrader: (1)

Guys,

this bump steer mod sounds a gift from the Gods....

.. three questions for you out there,
1) I have an STi 3, is this mod still a good thing or is the STi set up sorted enough to not need this mod?
2) is there any one closer than Cheltenham that can do this? (I'm in Horsham in West Sussex)
3) Anyone had it done to an STi and how's it gone so far?

Cheers :-)

IWatkins

Mikey,

1) Powerstation's own car is also an STi3, and it worked well on that
2) I do not know anybody else who is doing it except for Powerstation.
3) There have been a few, and maybe they will post their findings.

Cheers

Ian

firefox

Hi guys...

I had bumpsteer done a while back... but never noticed what Rich was doing.

Can someone detail what PS due to perform this mod.

I know the majority of the results from this mod is due to the 4 wheel suspension alignment they do as a complete package.

J.

Steve vRS

Is the mod. all in the geometry or do they change any components within the suspension?

In either case, do insurance companies need to know?

Steve

Trout

iTrader: (1)

Strangely STis are not well sorted enough - in fact they benefit more than UK cars.

My car had horrendous geometry change on bump/rebound.

The adjustment is made by loosening the steering rack and placing accurately measured shims in to counteract the bump/rebound geometry change.

I watched them do this on my car the the result was a perfect, with no change in bump or rebound.

IMHO - my car was already set up well on a 4 wheel laser set up - I would attribute the mod to the bump steer adjustment

Many Subarus are not set up well when they are delivered so at £100 it well worth a trip to Cheltenham for the majority of Scoobs.

R

---=CeeDee=---

Please guys/gals...for us that have no PS near (first PS is like 4 days of driving from here) can someone take a picture of shims and their position...maybe some of us can make such mod at local workshop...thnx upfront

Markus

Is it for the big boys? nope, I'd say that everyone should get it done. I'm not a great driver or track superstar, but it made the car handle a hell of a lot better than it did before the trip to Powerstation. I would recommend this mod to anyone and everyone.

MorayMackenzie

---=CeeDee=---

Bumpsteer removal just means getting the steering linkage to wishbone angle as parallel as possible through the suspensions travel. Obviously, the steering rack is easier to relocate then the wishbone mounts, so the easiest way to adjust the bumpsteer would be to move the rack by placing some metal spacers (shims) between the rack and the chassis. These spacers would be very simple to make up, they are, after all, just a bit of metal with a bolt hole in it. The tricky bit, which you could, I guess, do with trial and error, is to find the correct distance to space the rack out by.

Moray

PS: Rannoch,

the outer shoulders on my front tyres used to wear out in very short times with the 0.5 to 0.7 degree negative front camber that PS set the car at, I asked to run more negative camber on the front on more than one occasion, but was refused as doing so would destroy the handling.

I now run ~1.5deg neg at the front and, shockingly enough, the handling seems to have improved.

As I understand it, they are now dialing in over 1 degree neg at the front in current bumpsteer jobs. Guess thats progress.

---=CeeDee=---

2 Moray: Do you by any chance have a picture of shims alone or in place...i'm a bit confused here...If i place only shims where bolts are now than i will have space on top of rack...so i can only assume that shims are something like half cuted cylinder with bent ends with holes...in that way i can lower whole rack and clamp bolt shims without leaving space on top of rack (between rubber and rack hole on steering column)...do i see it correctly ?

[Edited by ---=CeeDee=--- - 5/16/2003 2:10:41 PM]

MorayMackenzie

Hi there,

Not sure quite what you are suggesting... As I see it, the shims are basically the same as a stack of washers in that they are a flat surface with a hole for the bolt. They simply space the rack on its existing mountings. They can be cut out of a flat sheet of metal (of the appropriate thickness.

Moray

Dodge

I had this done on Saturday - it's fantastic, and I'm no roadwarrior or trackday monster.

Other than that, the car is completely standard, and it's brilliant. They can set the toe to a level best-suited to you - mine is a road-friendly ~1 degree, rather than the more track-oriented 1 degree 30'.

It makes the car a lot more balanced; less understeer, rather than loads of oversteer. The new STis (7 and 8's) apparently have very
little bumpsteer, so they've obviously cottoned on...
Do it...

---=CeeDee=---

2 dodge: do it where ? as i seid, i have to drive at least 3 days to get to UK...thats why i'm after pictures of shims or rack with shims in place to at least see what are you guys talk about...

ozzy

The only suggestions I can think of are asking PS if they will just send you the bumpsteer shims and you get them fitted locally, together with some appropriate geometery settings.

Other than that, you could see if someone (who already has the mod) is prepared to take pics and measure the shims on their car. Not sure how practical that is.

If I had the mod myself, I'd volunteer. I'm looking at getting this done to my own car, but it maybe a couple of weeks away.

Stefan