Suspension Geometry

[Shaun_E]

I have just replaced my steering rack so took the car to have the toe in set. This has now been corrected to 20' toe in (parallel is too twitchy on the road).

I also have the measurements for camber and castor and they are somewhat outside the Caterham recommended settings.

Camber is -1^o42' left and -2^o00' right (Caterham recommend -1^o20' )

Castor is 6^o45' left and 6^o01' right (Caterham recommend 4^o.

Car is used road/track/sprint and runs on 13" CR500s.

Question - are these settings way out and likely to have an adverse effect on handling (bearing in mind they haven't been changed since I bought the car)?

The steering is a bit heavy so mabe reducing the castor would be a good thing. Which way do I move the washers on the lower wishbone to reduce castor? How much will one washer alter the castor by?

The camber is mismatched (assuming car had settled properly on suspension) - should I adjust to match and what settings are recommended for sprinting?

As camber can only be adjusted by complete turns of the ball joint, roughly what camber change is achieved with one turn?

The rear camber settings are 1^o09' left and 1^o39' right - left rear is out of spec - is there anything that I can do and should I be worried?

Rear has a slight toe in (40') - is this normal?

Hope you can help?

Shaun

 

Yellow SL #32

[Adrian Williams]

Hi Shaun

 

As a road/track compromise -1.75 degrees of camber would be about right. If I remember correctly one turn of the ball joint is 1/4 of a degree so one turn in on the right and one turn out on the left. If the taper isn't keen on coming out of the hub it might be easier to take off the arb and remove the top wishbone pivot bolts, then the whole wishbone can be turned around the ball joint.

 

I'd leave the castor where it is if you can live with the steering weight on the road, I don't think reducing it will inprove performance on track. If you do want to reduce it you need to move the lower wishbone towards the rear of the car, sorry no idea how much per washer.

 

Toe in at the rear is normal on older cars like ours, I think later ones changed to straight or thereabouts. Camber at the rear can't be changed without shimming which I'd avoid, I don't think it's worth worrying about in performance terms. If you've had the rear apart I'd ask yourself the question was everything nice and clean when you put it together just in case there's some muck causing the camber problem and carefull re-assembly might cure it.

 

If you want to borrow a camber gauge I have one, just let me know.

 

 

 

Adrian

[Simon.Rogers1]

Just to agree with Adrian. But also clarify that if you get the Rose Joint wishbone ends you can adjust by finer amounts.

 

The last time I ran radials I ran with 2 3/4 neg camber. I was ok on the road also.

 

Remember tracking alters with camber and vice versa.

 

 

 

Giving it some Welly. As Always!

[6speedmanual]

Castor

Each washer worth about 0.6 degrees.

 

 

 

6SpeedManual

*tongue*There's no such thing as too much BHP per Ton 😬

[Shaun_E]

Thanks for the info. I should probably sort the front camber but will leave it for now as I don't have time between now and Llandow. Will leave the castor as well as it looks like I'd need to move several washers to get the recommended setting - might give it a go when I take the lower wishbone off to change the spherical bearing. Adrian thanks for the offer - I'll give you a call if I go that route.

 

Yellow SL #32