What's your camber?

[gcarm]

Hi,

Just about to setup my suspension + steering. Just wondering what settings I should use for:

Front:
- camber
- caster
- toe

Rear:
- camber

Front is Toyota Crown suspension. I've added some shims to get some negative camber. Just how much I need I'm not sure. Also, I should have some toe-in, but again not sure how much? Does it depend on track width?

Rear suspension is a Nissan Z32 IRS. At the moment I have a lot of negative camber, but I think its too much. What would be appropriate?

Advise would be appreciated.

Cheers,
Greg

[stephen low]

Greg

Had my car set up by Rob Tuckett, a respected Historic Mustang racer and it behaves nicely.

I do have Jag gear set up all round on Koni shocks but I'm not sure if the different suspension bits coming into play in terms of the settings, I'm guessing not.

I don't have power steering.

Anyway, reading from the printout as follows:

Front

Camber - Left - 1 degree 25 seconds Right - 1 degree 20 seconds

Caster - Left 2 degrees 30 seconds Right 2 degrees 10 seconds

Toe - Left 0.2mm Right 0.3mm


Rear

Camber - Left - 1 degree even Right _ 1 degree even

Toe - Left 0.4mm Right 0.3mm

Cheers

Steve

[gcarm]

Thanks Steve. Just a couple of questions:
- how is the toe measured ?
- is it toe in for front and rear ?

I also have a G-Force Mk I. Do you also have a Toyota Crown chassis? Just not sure how to adjust the caster??? Any tips?

Greg

[stephen low]

Greg

My GF is post the Crown chassis variants though still called a Mk1 version, that was more just to delineate the chassis as torsionally capable to handle up to a 351. The Mk2 chassis were built stiffer and beefier to deal with BB torque loads.

I'm no rubber grub but think the toe measurement is literally the inwards movement of the front face of tyre from parallel ie 0.3mm inwards for a zero (parallel) setting.

Caster is the angle of the steering axis, generally negative, I think, for general road car use to provide predictable handling. Race cars go positive I think to make them more darty and responsive into corners. I could be wrong on that.

As well, I think the more castor you have, the quicker the car will re-centre the steering, but the larger the castor the more force needed to turn the steering wheel, and why power steering is used.

Happy for anyone out there though to correct my take on suspension geometry.

[1985 CCX]

Mine changes as the wheels articulate......

[jknich]

Stephen, castor is positive, Camber should be negative.

[Gaz64]

Originally Posted by jknich

Stephen, castor is positive, Camber should be negative.

Yes, that's correct.

CASTER is the "lean back" of the imaginary top to bottom steering axis, similar to a motorcycle.

Positive Caster gives self centering steering. No steering rake would give no trail, and although the steering would be quick, it would awful to drive.

SAI also needs to be taken into account.

Street cars can run 3 - 7 positive caster. I like 4, and up to 1 degree negative camber front and rear.

High positive caster is good for stability at high speed with less effort from the driver. To much caster will lower grip on high G cornering, so about 2 degrees on a race setup.

[gcarm]

I'm just not sure I can adjust the caster. It seems to be set by the geometry of the chassis/suspension components.

Also, any recommendations for someone who can setup my car based in Sydney (preferably in the Hills area)?

[stephen low]

Gary

Good to see the right commentary came through for you, I was on the right track just arse about on some of the ideas.

Anyway not so sure about the Crown set up but yes the GF chassis have preset suspension attachment points, and I'm guessing the same for the Crown front sub-assembly, I'm presuming.

But I've learnt there are still means of adjustment. My car runs the std Jag stuff, but the front alignment can be modified if you run different jag arms, one of the series has an offset arm plus shims so even this set up can be varied.

I started with the S2 bits that were on my car but went and sourced adjustable top arms, these enabling quite some variation through screw thread adjusters. Photo of an arm and the adjusters shown below.



The alignment numbers I gave you are from this front end set up, albeit with the newer Koni shock set up I now have over the crappy old Monroes showing in this picture. Mine was a part built kit when I started.

Finding a local suspension business that can help with these mods might be the best bet.

Good luck!

[David Hodgson]

Hi Greg, I haven't been on for a while so I missed this chat. I went through my stash of paper work and dug up the original alignment specs mine was set to, by a performance suspension shop here, when I first got it on the road. I have a strengthened '72 Crown chassis with Jag rear.
The caster should be adjusted by the large nuts at the front of the radius rods - like a early Falcon. This will pull the bottom arm forward for pos. caster. Like a HQ etc Holden you can also use uneven shims in the upper arm. this will shift the wheel rearward for pos. caster. You will need to adjust the Camber after the caster if using this method. Using a mix of these two methods can help centre your wheel in the arch if it is also an issue.

Front: Crown
- camber neg 1.25 deg
- caster neg 0.5 deg
- toe -in 2mm each side - 4mm total

Rear: Jag
- camber neg 0.5 deg
- toe -in 1mm each side

Seemed strange to have negative caster however i checked on some old Relim's charts and it is not uncommon. It behaved quite good on the road until i started experimenting with up to 3 deg camber and almost zero toe for track work, but was not happy on second rate roads.

Cheers Dave

[gcarm]

Hi Dave,

Thanks for your response. Actually its quite timely as I have been working on some other issues and I'm just getting back now to look at the camber/caster settings.

It's good to know there's another G-Force/Crown chassis Cobra driving around. I have an MS-85 chassis (circa '85) which I have also strengthened to meet the Beam and Torsional testing.

Regarding the caster adjustment, it had occurred to me several days ago that the radius rods could be used to adjust the caster. Thanks for confirming this.

Wrt your caster adjustment yes it does seem strange to have a negative caster as I understood positive caster would help with auto centering of the steering as you drive.

Regarding the uneven shims, I never thought of this. Let me investigate this further to see if it would be useful for me.

Also regarding the toe-in, trying to accurately measure 2mm may be a challenge. I may need to get a professional workshop setup the toe-in. In any case, I'll probably get a wheel alignment shop to do the final setup once I get it on the road.

How do you find the handling of your Cobra overall? I've read some negative comments about these crown chassised cobras handling. However, I have installed new springs, shocks, ball joints, rubbers, etc as well as thicker discs off a later model crown. I'm hoping with correct adjustments it will handle fine.

Cheers,
Greg

[David Hodgson]

Hi Greg, it handles ok and basically behaves, however at speed the rear end gets really skittish and want to oversteer, particularly through the kink at the bottom of the straight at Wakefield. It currently has no front stabilizer bar (or rear) so when I get around to that it should help.
It doesn't fit in its original position as I have the radiator extending forward of the front member.