The DC2 Castor Thread

[tinkerbell]

just found this:

http://www.spcperformance.com/PROD_D...txt&cmd2=72160

seems to indicate that even small changes to the position of the top ball joint can affect castor a large amount...

since i estimate we moved the top ball joint about 0.75 - 1 inch rearwards... maybe we got ~3 degrees gain?

roughly?

now that is a fair bit to add... isn't it naysayers?

[milkman]

The reason why castor is at times more desirable than camber is because of its dynamic nature.

If you were just to add, for example, -4.5degrees of camber, your tyre contact patch will be significantly affected, thus reducing your acceleration and braking capacities.

That being said, a certain amount of camber is healthy but too much or too little can also be detrimental.

yes, very similar results indeed...

however, static camber increases tyre wear - that is why castor increase is seen as "free" camber increase.

see...

the negatives of bump steer changes are felt most on a bumpy straight road or while braking/booting suddenly during a corner... i thought? in rapid comp/rebound

however, the positives of increased castor is the increased dynamic camber that increases as steering input increases... isn't it? like szy says...

yes, *marginal* performance increase at most on the dc2, but the principle is sound. it improves the immediacy of the chassis, so why not?

Exactly why I started this topic.. I was interested in its dynamic natures.

I was hoping to run some castor to provide me the benefits of increased chamber without the straightline traction, wear and tramlining issues (also increased steering feedback )..

I suppose the biggest problem is trying to find a happy medium for a mainly road driven car/occasional tracker.

I'm afriad trial and error is probably the only way to discover if/what will work for me. As our suspension setups do vary.

In my case I have Ground Control Sleeves 8kg/6.2kg/mm springs with KONI yellow dampers.

[freakygeek]

I completely agree that a couple of degrees of castor equates to sfa camber during your average corner on the track (DC2 and DC5), however every little bit helps. Also, Tinkerbells comment "it improves the immediacy of the chassis" strikes a chime with me and also adds to why camber is desirable.

There are better ways of doing this than by screwing up your bump steer.

just found this:

http://www.spcperformance.com/PROD_D...txt&cmd2=72160

seems to indicate that even small changes to the position of the top ball joint can affect castor a large amount...

since i estimate we moved the top ball joint about 0.75 - 1 inch rearwards... maybe we got ~3 degrees gain?

roughly?

now that is a fair bit to add... isn't it naysayers?

Are you telling me that you haven't even had your car aligned since doing this swap??? If I aligned your car on our machine at work here, I would be able to tell you exactly how much caster you have, to the minute.

BTW if it's only 3 degrees it's bugger all. I remember a particular Mercedes is something like 11 degrees, most current BMW's run 6-8 degrees. Then again they are almost exclusively McPherson front ends, perhaps they use caster to compensate more for the lack of camber change under suspension compression. Not entirely sure, but that reason makes some sense in my head.

[tinkerbell]

In my case I have Ground Control Sleeves 8kg/6.2kg/mm springs with KONI yellow dampers.

with your 8/6 springs,

there may be more bumpsteer effects compared to the discussed situations with 12/8 springs and 14/10 springs...

i dunno what springs benjammin is running? i assume the N+ which are 10/6...

[tinkerbell]

There are better ways of doing this than by screwing up your bump steer.



Are you telling me that you haven't even had your car aligned since doing this swap??? If I aligned your car on our machine at work here, I would be able to tell you exactly how much caster you have, to the minute.

i have aligned my car 3 times since the UCA swap...

sorry i didnt memorise numbers

IIRC it was about 4.5 degrees +ve...

BTW if it's only 3 degrees it's bugger all. I remember a particular Mercedes is something like 11 degrees, most current BMW's run 6-8 degrees. Then again they are almost exclusively McPherson front ends, perhaps they use caster to compensate more for the lack of camber change under suspension compression. Not entirely sure, but that reason makes some sense in my head.

fyi - this thread is about increasing castor on Honda Integra's, not BMW's

[freakygeek]

i have aligned my car 3 times since the UCA swap...

sorry i didnt memorise numbers

IIRC it was about 4.5 degrees +ve...

fyi - this thread is about increasing castor on Honda Integra's, not BMW's

I realise that, I'm just saying that +3 degrees isn't exactly a big deal compared to what other manufacturers run standard.

Anyway, I've said all I think I need to say on this topic.

If you want more caster without the negative side-effects, why not input the suspension data into Susprog and figure out where you need to relocate your steering rack to to compensate for the change in the UCA?

[tinkerbell]

wouldnt you relocate the tie-rod ends, rather than the steering rack?

[e240]

http://www.teammfactory.com/products...er%20Adjusters

[milkman]

http://www.teammfactory.com/products...er%20Adjusters

hmm that deserves its own thread. lol

[e240]

Sorry - In response to Tink's comments about adjusting the tie rod ends to address the roll centre. Thats what I use anyway.

I have swapped my UCA left to right though...Dunno, don't feel any more bump steer, the car's just as skaty anyway...but I am Ham fisted around how my car handles...My theory is, if you feel the car's going out of control, just accelerate...sometimes, I don't even know why my car's doing what its doing (i.e. spinning out of control)

[ChargeR]

Sorry - In response to Tink's comments about adjusting the tie rod ends to address the roll centre. Thats what I use anyway.

Tie rod ends have nothing to do with the location of roll centres, and roll centre adjusters don't add castor, or address the bump steer issues with the UCA swap so they do not really pertain to this thread .

[e240]

taaaatttt..fail...

Its all related

http://www.longacreracing.com/articles/art.asp?ARTID=13

Another one
http://forums.hybridz.org/showthread.php?t=103886

Tie rod ends have nothing to do with the location of roll centres, and roll centre adjusters don't add castor, or address the bump steer issues with the UCA swap so they do not really pertain to this thread .

[tinkerbell]

thanks for that, but keep it on topic e240...

what was your last castor reading Leo? do you knowthe pre-swap castor?

[e240]

I don't know... :-( Never did pay attention to these settings, and even then, I tell Peter how it feels, he makes adjustments and off I go... :-p
and considering we've only done 2 alignments since the start of the year...


Anywayz, the point above is that, you dial in more castor for stability but you adjust other components to address other issues as bump steer, roll etc....

[szymonsta]

yes, my comment was an elaborate and less blokey way of saying "oversteer"

which is a slightly quicker way around a race track than via an understeering car...

mm i dunno tinks..from my basic understandings of tuning cars for a circuit the quickest setups are neutral-to very slight understeer. boring but fast.
if u look at any race car setup- original runduce lancer evo around tsukuba, superGT cars, etc they are all setup with slight understeer at the limit.
of course excessive understeer will be just as slow and detremental as excessive oversteer, but most professional setups find that a slight-under is quicker than a slight-over.
i can however see the merits of an oversteer-biased dc2r for stuff like gymkhana. but im not into that kind of activity..