Hello, just wondering what is involved in carrying out the bump steer mod.
Is it something i could do myself as i have access to laser alignment/geometry equipment? Is it a worth while mod?
Cheers,
James.

 

I imagine if you are confident enough to remove a steering rack (not a big job) then the bump steer mod could certainly be a DIY thing.

All i know is the mod involves shimming the rack where the rack bushes go to reduce/eliminate understeer. Exactly what and how they do i have no idea. It's not something i've ever had done. I think Powerstation were very hot on doing that mod.

Also after the mod i know Geo has to be done but what settings they recommend or use again i have no idea. There will be Scoobynetters about though that know exactly what the score is with that.

 

What year car ?

 

i dont know whether its different for classics but all it is for the newage is track rod ends and ball joints.i did it on mine doesnt take long at all then go get the geo set up.i think the new ball joints supplied in the kit are longer or something,dont ask me how it works i just fitted it along with my alk so that i could get them all set up at the same time.

 

Thanks for the replies, it's a 98 sti
Cheers.

 

Don't think you need to remove the rack. Quite an easy job. Depends what's in your kit, if its just the track rod ends then i wouldn't have thought you need geo. If it's ball joints too, then yes

Only really needs bump steer correction if car is lowered.

 

Mines still standard suspension so should i leave alone for now?

 

yes the bump stear kit is mainly for lowered cars,start with things like springs or coilovers,anti roll bars and drop links first.

 

Ok mate, I'm looking around for a/r/bs etc at the moment

 

If your suspension is standard at the moment, the first and most definitely biggest bang for buck upgrade is a rear ARB

It will transform your cars handling

 

Thats what i've been thinking but what size though 22mm or 24mm?
How will it effect a type r?

 

Christ, you obviously love a mobile rear end if you're considering a 22 or 24mm rear ARB... on a DCCD Type R!!! Good luck lol...

 

So what do you recommend then? A thicker front A/R/B?

 

i carnt speak for how the classic would be as mine is the 04 sti and the newage cars are a lot heavier.the first suspension mod i did was some tein coilovers and the geo setup.back then i was just getting the hang of the car and it made a world of difference.it wasn't until last year really that i wanted to go further with the handling side.so i got a 24 rear arb and a 22mm front with alloy drop links,but as always when i start something i get carried away.so on went the stiffer steering rack bushes,alk and the bump steer kit a geo set up and some 18in 8.5in rota g force wheels with toyo r888.now it sticks to the road like glue.it all depends on what your going to use the car for and how much you want to spend.

 

It's entirely up to you - it totally depends on how you like your car to handle. I personally don't like oversteer on the road, so would never have a Type R... and then add a thicker, stiffer rear ARB, thus magnifying it's inherent rear-end mobility! But that's just me.

What do you like: over- or under-steer? Or as near-neutral as possible? Answer this as honestly as possible first, then we can advise what ARB/s and what size/s would best suit your preference...

 

It makes a little difference being a Type R, but the principles are the same.

Are there any aspects of the cars handling you are unhappy with?

You might find some of this thread useful

 

It does understeer going into roundabouts but i would like as near neutral as possible.
I have rear camber bolts to be fitted aswell. Thanks for the the link
Cheers,
James.

 

A tiny bit of oversteer is a good thing. It's much easier to correct oversteer than it is understeer. All the quickest cars tend to have a bit of oversteer but it's very controllable.

You can get the back end of a scoob out no probs, even with 50/50 diff lock like the WRXs, but the great thing is it tends to correct a lot of the oversteer by itself with just a little bit of steering wheel input. They are never so lairy like a RWD car that needs a decent amount of opposite lock to get it back on line.

A neutral car is better on the high speed bends and long twisties but a slightly oversteering car is much better on the very tight stuff like roundabouts or streets. Understeer just kills cornering bigtime and is good for nothing. Very undesirable trait!!

 

How are you getting on, did the oversteer reduction thread help? There is alot of comment in there from lookout who is spot on when it comes to scooby suspension set-up and was a big help for me dialing in my two scoobies' suspension.

It is essentially a thread on reducing oversteer but there's also alot on reducing understeer too.

 

Bump steer is exactly what it says, it’s caused when your suspension goes into compression or droop, as the track rod arm follows an arch, to reduce this problem you move the car up an down on it’s suspension and measure how much the tracking deviates, you can then shim the rack to reduce this effect, it will be more noticeable on lowered cars as they have changed the angle on the track rod arm. Hope this helps

 

Cheers mate for the info, i'll probably leave that mod for the moment as mine isn't lowered.

 

Yes mate it was very interesting. I'm going to print it off so i can keep referring to it when needed.
I'm still thinking about the set up as mine being a type r and already has the reputation of being tail happy. Today i fitted some 17s with nearly new parada 2s and already it felt better. Maybe i should get the rear camber bolts fitted and a geometry set up first? What ideal settings for a type r?
Cheers,
James.

 

Erm?

 

I have never found front bumpsteer to be a huge problem with the Impreza. To reduce and change the bumpsteer curve you could shim the steering rack by a few mm, but this has a negative effect that the rack won't be as solid under load. To increase front end grip a bit there are quite a few options. An increase in caster with a Whiteline ALK, Whiteline caster bush or caster adjustable top mounts are the easy options. Replacing the rear ARB with a 22mm adjustable one is an easy way to increase grip, both at the back as well as the front. Without a bigger front ARB, a 24mm rear ARB would make your car a bit tail happy.
Of course all this has to be supported by a good geometry set-up as well as decent tyres.

 

Thanks lookout for the advice, so fitting a rear 22mm ARB would be ok to fit to a type r considering it can be a bit tail happy due to the dccd distribution? Also what geometry values would you advise for a nice fast road set up?
Cheers,
James.

 

You need to decide what you want to dial out. Is your car understeering or rear biased?

 

Hello mate, I want to dial out the understeer but don't want it too tail happy. Am i asking to much

 

I think if it isn't rear biased at the moment it would stand a rear arb, which would improve things overall, including your understeer.

It seems a very popular upgrade and one which makes sense, both financially and for how much difference it makes.

The one to go for is the Whiteline adjustable, which means you can then tweak the car's handling by hardening or softening the arb, which will also help you to see directly what the differences make

 

I think i'll do that mate and go from there but i'm definately getting a geometry check/adjustment done in the new year but would like to know some settings. -1 degree camber all round? 0 toe front and rear?
Just need some opinions please
Cheers,
James.

 

As you have the rear camber brackets you can go for a little more negative on the rear. I would say a good 'fast road' setting would be fine - something along the lines of what I went for in post number 39