How "stable" is your car on the open road???

[stephen low]

Bobby et al

Haven't had a chance to drive mine at serious speed but just too had alignment prior to my engineering visit on Friday with the following outcomes:

Before After
Castor: L +1.33 R 2.34 L +2.41 R 2.30

Camber: L -0.07 R -0.24 L -0.31 R-0.49

Toe In L 4.0 R 3.7 Tot 7.7mm L 1.5 R 1.6 Tot 3.1mm

Had requested Castor 3.0 degrees and Toe 3mm and would live with whatever camber for the moment, as front is so far up in the air for clearance with 50 series tyres it looks like a 4WD at the front.

My guy's been at this 25 years so I had some confidence. Definitely felt more sensitive on the road but still stable. Would agree toe out is for race cars, makes direction changes much faster with the loss of stability. Do you want this for a road car Bobby? Is your guy a race car tuner?

Its the same issue for castor, heaps of caster helps in turning stability but without power steering you have to be superman from 6 or so degrees onwards, at park speeds anyway - don't you Mike!!

I'd like to get to about 4 degrees castor and - 1 degree camber and lowering the front will all help after engineering. However I do have S1 uppers and have run out of adjustment.

It took my fellow some time and jiggling to tweek what I've got in terms of camber 10 minutes extra left and only 3 extra right ie bugger all.

Knowing of the G Force / RMC rear axle alignment issue he was able to indicate my car has rear toe as L -1.5mm R +2.3mm but one or two turns on the left rose joint will give about equal toe in.

He said this helps compensate camber in cornering and improve stability and grip somewhat in corner ie achieve more tyre face to road in corner (all marginal stuff of course).

I too would like to hear about the changes to handling if you hit 4 degrees castor.

Cheers

[David Hodgson]

Get rid of the toe out. Toe out can help 'turn in' on the track, but on a rear wheel drive car on the average Aussie road is not good

1 -1.5 mm Toe in with around 3 degrees caster should be a good starting point for street.

I experimented with alignment setting a bit for the track and toe out seemed to help a bit on turn in, but was very nervous under brakes. On the road it was wandering all over.

[400TT]

My RMC was running around with these figures for years:

Front
Camber: -0.5(L) -0.5(R)
Caster: 4.0(L) 3.6(R)
Toe in: 1.0(L) 1.0(R)

I'm not sure yet what I will run with.

[Rebel1]

Yep..pretty close to my start point for the front Craig.

If I remember the previous owner told me the car was great on a smooth highway by a bit nervous on an undulating road.

One of the problems with the RMC is the variation of the placement upper arm mounting.

My car has the two bolts holding the upper arm above the bottom of the front chassis cross member. If you look at the picture in Ross Smiths gallery at his chassis pic you'll notice the same holes are below the cross member.

Whilst not an issue at rest Ross's car will invoke negative camber with less body roll which is exactly what you want.

Sadly the RMC chassis varies quite a bit.

[400TT]

As you know my car has already got some and is getting the rest of Scott(Ozvenom) RMC Enhancement package.

In his words, it will be a pleasure to drive on the road. I'll look to Scott for guidance on the wheel alignment settings.

[Rebel1]

Originally Posted by 400TT

As you know my car has already got some and is getting the rest of Scott(Ozvenom) RMC Enhancement package.

In his words, it will be a pleasure to drive on the road. I'll look to Scott for guidance on the wheel alignment settings.

And the same fella will be doing mine Craig. He has already done a little bit.

But that's exactly my point....Scotty is a wizard because he:
1. Knows the cars
2. Attends to the detail.
3. Makes the required changes.

He was the one who drew my attention to flattening the upper arm. Since then I have noticed the variation between RMC's.

Both the RMC and G-force ( being closely related) can be made to be an absolute pleasure to drive. Dare I say, ( and I just know I'm gonna cop $hit for saying this) that the RMC, ( and G-force by implication) properly set up are close to the best street cobras you will find.

There, I said it.

[PCC]

All sounds good guys, but....

I went from complete nerves on undulated roads to complete confidence by simply replacing the Falkens with Toyos T1R's.

I have absolutely no wandering at all now.

Grips as good as the WRX! (Well at least 2 wheels at a time).

[Rebel1]

Here is my take on the RMC...and to a certain extent the G-force for a start point for a stable road car.

Front toe...total 1/16 to 1/8" in.
Front Caster...as much as your muscles will allow at parking lot speeds. 6 degree common but achievable only with series 1 uppers.
Front camber 1/4 to 3/4 positive.

Rear toe total 1/8 in.
Rear Camber 0- 1/4 to 3/4 positive.

Rear camber doesn't change much with suspension travel but try to set the rear with the drive shafts near horizontal. The lower arms will still incline slightly upwards to the diff and will cause negative camber with body roll.

Dial in both the rear toe and camber by making your own shims. Because of the shortened rear shafts the standard Jag shims may not be quite right. Purchase some Champion 316 stainless shims sheet and make your own shims. ( comes in a pack with a 100x100mm sheet of .002,003,005,012.).

The standard jag camber shims are .020 so the .12 stainless shim will give you a half thickness shim approx.

The thinner champion shims are great for dialling in the toe.

I think it is unwise to "pull" toe by loading the drag arms.

Cheers