Caster mod??
- Thread starter johnsy
- Start date
bob the builder
New Member
i would say you would do.
just a quick question, whats the benefit of doing this mod as i was thinking of doing it too?
sorry to jump in on your post.
just a quick question, whats the benefit of doing this mod as i was thinking of doing it too?
sorry to jump in on your post.
Trip
New Member
Why were you thinking of doing it if you don't know what it does. : )
It increases the caster angle to help give more dynamic camber in turns.
bob the builder
New Member
i had an idea what it did, but was just wondering what the actual benefits were as i am not that technical.
plus if it makes my track toy go round corners faster i am all for it.lol
plus if it makes my track toy go round corners faster i am all for it.lol
johnsy
Active Member
ok so if i take the the nuts off drop the coilovers drill a 10mm hole approx i nut away from the existing hole, then rotate both coilovers clockwise and refit nuts thats it?
apart from doing the same to the strut brace obviously, that seems simple enough.
what camber did you achieve doing this?
i was going to modify the strut mounts anyway as i can only get -5deg at the mo, i want -1.5deg for zee track,will this solve both camber and caster
apart from doing the same to the strut brace obviously, that seems simple enough.
what camber did you achieve doing this?
i was going to modify the strut mounts anyway as i can only get -5deg at the mo, i want -1.5deg for zee track,will this solve both camber and caster
Sunny-D
Member
The guy you need to speak to is Jim (campellju).
The drivers side needs to be turned clockwise and the passenger side anti-clockwise (looking from the front of the car).
I made a template for the topmount using the rear topmount gasket iirc, two holes will line up perfectly leaving the hole that needs to be drilled.
After this mod you may need to do the camber mod (elongating the top hole in the shock) to dial in a bit more camber.
The drivers side needs to be turned clockwise and the passenger side anti-clockwise (looking from the front of the car).
I made a template for the topmount using the rear topmount gasket iirc, two holes will line up perfectly leaving the hole that needs to be drilled.
After this mod you may need to do the camber mod (elongating the top hole in the shock) to dial in a bit more camber.
johnsy
Active Member
http://www.gtiroc.com/forums/showthread.php?59689-Johnsy-s-r/page6
Im just looking into something joey said, as i cant find the caster thread on here, iv looked all over. but i get the gist of it now.
I moved this thread to Tuning and upgrades.
I can't seem to get the search function to work for me either. What others have posted has saved me typing though
The castor mod increases the caster on the front wheels from around zero to around 3 to 4 degrees. This level of caster is pretty standard on most modern fwd and 4wd cars that have PAS.
Caster makes the car more stable and increases dynamic camber on tight corners. The level of increase given by this mod gives few downsides. It does jack up the wheel on the outside corner when you turn. I found this effect gives a little turn in oversteer on our cars and helps to get the power down on the exit.
The basic mod is quite subtle but enough people have noticed a real difference now to make it worthwhile. It works best on 2nd/3rd gear corners, above that and the amount you turn your wheel means the ffect becomes more marginal. It still helps with straigh line stability a little.
If it's purely a track car then -2degs front camber might be a better starting point. If it's a road car then -1.5degs to -1.8degs is well proven. Above -2degs on the road and I found it introduced other problems.
I can't seem to get the search function to work for me either. What others have posted has saved me typing though
The castor mod increases the caster on the front wheels from around zero to around 3 to 4 degrees. This level of caster is pretty standard on most modern fwd and 4wd cars that have PAS.
Caster makes the car more stable and increases dynamic camber on tight corners. The level of increase given by this mod gives few downsides. It does jack up the wheel on the outside corner when you turn. I found this effect gives a little turn in oversteer on our cars and helps to get the power down on the exit.
The basic mod is quite subtle but enough people have noticed a real difference now to make it worthwhile. It works best on 2nd/3rd gear corners, above that and the amount you turn your wheel means the ffect becomes more marginal. It still helps with straigh line stability a little.
If it's purely a track car then -2degs front camber might be a better starting point. If it's a road car then -1.5degs to -1.8degs is well proven. Above -2degs on the road and I found it introduced other problems.
olliecast
Active Member
http://www.gtiroc.com/forums/showthread.php?55220-Olliecast-GTIR/page4
halfway down shows the rough mods mate
halfway down shows the rough mods mate
BabyGodzillaGTi-R
Member
Get more castor by fitting a castor kit bush from whiteline.
Fabricate adjustable top mount to dail in more castor.
For extreme cases, fabricate lower suspension arm for more castor.
Sorry for sidetracking abit.
Does anyone know off hand how many deg of castor does the car come stock?
And after fitting the Whiteline castor kit how much does more castor does it adds?
Reason i ask coz i'm a tad surprise when i did my alignment recently the car only has a miserable 2.5deg of castor considering it has a Whiteline castor kit.
I'm contemplating of swapping my top mounts from camber to castor adjustable (my top mount plates was fabricated to do this without having to drill holls into the chassis like what you guys do hehehehe ).
Any idea likely how much more gain in castor by doing this?
Right now i've set my top mounts at maximum inboard which works out to be 15deg king pin inclination (steering axis inclination). Honnestly i still dunno how does this help but the steering feel seems to improve by being more direct but the car still feels understeerish.
I'm running neg 2 deg of camber adjusted via camber bolts.
The other day someone posted some subaru forum talk about camber, castor, kpi/sai, and i'm all so confused now.
I still don't know what's the benefits of KPI more or less is better. On this forum i interpret more kpi is good because its like having more negative offset rims and "camber gains when the car rolls". However on the STi forum it's the otherway. They suggest minimal KPI as possible without the rims hitting the coilovers.
What say u handling oracales?
I'm lost.
Fabricate adjustable top mount to dail in more castor.
For extreme cases, fabricate lower suspension arm for more castor.
Sorry for sidetracking abit.
Does anyone know off hand how many deg of castor does the car come stock?
And after fitting the Whiteline castor kit how much does more castor does it adds?
Reason i ask coz i'm a tad surprise when i did my alignment recently the car only has a miserable 2.5deg of castor considering it has a Whiteline castor kit.
I'm contemplating of swapping my top mounts from camber to castor adjustable (my top mount plates was fabricated to do this without having to drill holls into the chassis like what you guys do hehehehe ).
Any idea likely how much more gain in castor by doing this?
Right now i've set my top mounts at maximum inboard which works out to be 15deg king pin inclination (steering axis inclination). Honnestly i still dunno how does this help but the steering feel seems to improve by being more direct but the car still feels understeerish.
I'm running neg 2 deg of camber adjusted via camber bolts.
The other day someone posted some subaru forum talk about camber, castor, kpi/sai, and i'm all so confused now.
I still don't know what's the benefits of KPI more or less is better. On this forum i interpret more kpi is good because its like having more negative offset rims and "camber gains when the car rolls". However on the STi forum it's the otherway. They suggest minimal KPI as possible without the rims hitting the coilovers.
What say u handling oracales?
I'm lost.
Trip
New Member
I don't think i ever read here that having lots of KPI is good.. Adjusting camber from top plates will alsi increase the KPI.. Thats a by product unfortunately.
Whats best is to adjust Camber from camber bolt loacation not to upset the KPI. Caster is whats lacking in our cars (apart from other factors). Turning round or fabricating new top mounts plate will give you added caster but not too much either.
Wheel Offset.. Do a google search on pros and cons about negative or positive scrub radius.
From AutoData
Whats best is to adjust Camber from camber bolt loacation not to upset the KPI. Caster is whats lacking in our cars (apart from other factors). Turning round or fabricating new top mounts plate will give you added caster but not too much either.
Wheel Offset.. Do a google search on pros and cons about negative or positive scrub radius.
From AutoData
Last edited:
BabyGodzillaGTi-R
Member
Hey Trip,I don't think i ever read here that having lots of KPI is good.. Adjusting camber from top plates will alsi increase the KPI.. Thats a by product unfortunately.
Whats best is to adjust Camber from camber bolt loacation not to upset the KPI. Caster is whats lacking in our cars (apart from other factors). Turning round or fabricating new top mounts plate will give you added caster but not too much either.
Wheel Offset.. Do a google search on pros and cons about negative or positive scrub radius.
From AutoData
With reference to KPI, i'm actually still confused with what it does in theory and i must have misinterpreted when trying to digest everything that has been said across the boards.
As for Castor i'm well aware of the benefits.
So i thought the best way is to actually try it out and perform back to back testing. My views is pretty subjective simply because there's no imperical data to back it up and testing is not done on track. All down to backside feeling.
With KPI set up to the max the steering feels more responsive, seems to give better feedback.
However the front does feels kinda softer (i don't know how is this possible). But i do know as an offroader sometimes we set up the dampers more an an angle (less upright) to get softer damping. Probably because of this and correct me if i'm wrong as per what i digested on the forums. More KPI increases the roll centre slightly. So i don't know if that could have contributed to the "softer" front feeling.
But what i don't like is that in the initial phase, entry into a corner it feels "precise", then mid phase it just washes, ploughs understeer.
End of the day i'm still curious how much roll does KPI plays in geometry/ alignment setup before i swap the top mounts around and dial in maximum castor. What was initially holding me back from the idea of dialing in more castor was the fear of fouling up the fenders as i'm runing 215/45 R17s (by right it should be 205/40 R17 by rule of thumb).
Trip, would appreciate if you could share more of your experiences when messing around with KPIs again. Thanks.