Bump steer
28 December 2009, 02:17 AM
#2
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.
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.
28 December 2009, 10:20 AM
#4
Scooby Regular
iTrader: (67)
Join Date: Oct 2007
Location: w,yorkshire
Posts: 4,061
Likes: 0
Received 0 Likes
on
0 Posts
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.
28 December 2009, 01:26 PM
#6
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.
Only really needs bump steer correction if car is lowered.
Trending Topics
28 December 2009, 11:07 PM
#14
Scooby Regular
iTrader: (67)
Join Date: Oct 2007
Location: w,yorkshire
Posts: 4,061
Likes: 0
Received 0 Likes
on
0 Posts
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.
28 December 2009, 11:17 PM
#15
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...
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...
29 December 2009, 09:30 AM
#16
Are there any aspects of the cars handling you are unhappy with?
You might find some of this thread useful
Last edited by bonesetter; 29 December 2009 at 09:35 AM. Reason: link addition
29 December 2009, 12:28 PM
#17
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.
I have rear camber bolts to be fitted aswell. Thanks for the the link
Cheers,
James.
Last edited by JdcTypeR; 29 December 2009 at 12:30 PM. Reason: RE link
29 December 2009, 01:59 PM
#18
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!!
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!!
29 December 2009, 03:40 PM
#19
It is essentially a thread on reducing oversteer but there's also alot on reducing understeer too.
29 December 2009, 04:05 PM
#20
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
29 December 2009, 04:12 PM
#21
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
29 December 2009, 04:18 PM
#22
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.
It is essentially a thread on reducing oversteer but there's also alot on reducing understeer too.
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.
30 December 2009, 04:31 AM
#24
Scooby Regular
Join Date: May 2008
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
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.
Of course all this has to be supported by a good geometry set-up as well as decent tyres.
30 December 2009, 10:15 AM
#25
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.
Of course all this has to be supported by a good geometry set-up as well as decent tyres.
Cheers,
James.
30 December 2009, 11:16 AM
#28
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
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
30 December 2009, 11:23 AM
#29
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.
Just need some opinions please
Cheers,
James.
30 December 2009, 11:34 AM
#30
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