Thank Sanzo,
Yep, I'm getting mine from Mike S, LHD and good price for a new unit.

I posted some pics a long time ago - there is a section on the input shaft that is flat on the metro one but splined on the TF one. It is where the pinch bolt goes through. A couple of splines need grinding flat over a 6mm section or so IIRC otherwise when you try to get the pinch bolt through you'll find you can't and as that'll be with your arm through the access hole down by the pedals you'll curse. Compare the two before you install the new one and you'll see.

Did the "track" pressures produce the best times? They are surprisingly low.

Yep, those are what I found gave the best times (trial and error) although on UK track days you aren't allowed to time your laps so obviously only discovered later when analysing the video. No phone apps where ever used

So I will be tracking (1 lap autocross) with semi-slicks 205/45/16 all round. From your numbers (16-F 20-R) I am thinking to start at 16-F 22-R

If you only have one lap you may need to start a bit higher. I usually take the first lap a bit steady to warm the tyres (which increases the pressure a bit). If you don't have a warm up lap the cold pressures would need to be higher as they'll still be cold for most of that lap. I'd go 18F 22R in that situation

Hi Sanzomat. Do you have GAZ dampers? I ran another autocross day with the new tyres. Tyre grip was improved but not to the level I expected. Tyres were definitely not getting up to temperature (50 - 60 seconds per run).

I am still running what I think are fairly soft settings on the dampers, about 10 clicks (of 28?) on the rear and 8 on the front. It wasn't until after the event that I realised I should have tried firming them up - maybe next time. Can you offer any guidance on street vs track settings?

Yes, Gaz dampers on the GTM. I thought they only go up to 20 clicks but could be wrong. I use 8 clicks front, 10 rear on the road and add two clicks all round for track days. Any more than that and they start to jack down!

I'm not surprised your tyres aren't getting to temperature on 1 minute runs. Mine (either slicks or semi's) take at least a whole lap of Combe to start to grip well (around 90 seconds) for the first half a lap it feels very nervous and you have to corner and brake quite gently and then build up. The left handers (only 2 at Combe) on the second lap can be scary as the right side tyres take longer to warm up. When I do Llandow circuit, only 45 seconds laps, it doesn't grip properly until well into the second lap and that has a very abrasive surface.

So I am going back to the 450 lb springs on the rear. Too much body roll on the track. Photos are with setup: 300lb rear and ARB 8/8 hard, 250lb front and ARB 3/7 hard.
The 300lb springs are going on the front so the balance should be better than the original 450 1/8 : 250 5/7. Hoping the bars can be closer to midrange now. Starting point will be 450 4/8 : 300 4/7 - it will certainly roll less.

300 lb is about as stiff as you can go at the front without the springs unloading at full droop. 300 lb springs only compress about 40mm at static ride height.



You can also see the camber loss on the outside rear in these photos. (Top photo is mid-corner and under brakes bottom photo.)

Looks like you are pushing on well there! Hope you enjoyed it.
Re your ARB settings, I'm interested that you've gone full hard on the rear but less so on the front. The suspension Guru in my local club (a former race engineer) advised me to make the front ARB do most of the roll control and tune the handling with the rear until it became neutral and could be steered on the throttle. For me that was full hard on the front and only about 1/3 on the rear.

Very enjoyable - thanks!
The rear is too soft with 300lb springs (250 front) - even full hard didn't feel like enough ARB. I might end up close to your ARB settings - are your springs still 425:250? I have just changed the springs to 450:300 but haven't driven it yet.

Yes, still on 250/425.
I've tried to find some photos at similar corners/views for comparison with yours. it might be that I'm not pushing as hard but there definitely seems to be less body roll on mine and less camber loss on the outside rear. I think I might have my ride height set a bit lower to start with too.

in very simplistic terms.

On a rear wheel drive car you want the front bar to do the majority of the roll control and the rear bar just used to balance up the car. A roll bar on the rear is an enemy for traction.


Lots of factors to take into account but this is a very simplistic answer.

My Coupe has no roll bars and I plan to fit one to the front eventually when I get to it. Only adding a small rear bar if I need to balance things but the maths suggests I should not need it.

Great to see those comparison pics sanzomat - very helpful. I suspect the excess body roll is causing a lot of the rear camber loss. In the rear shot of my car (under brakes) you can see the wheel still has some neg camber relative to the car but it has gone positive relative to the ground. I am pretty confident the spring change will cut the body roll significantly and improve grip.

Is your spring setup in the photos 425 lb : 250 lb and (approximately) 3/8 rear and 7/7 front on the ARBs?

Sanzo has more body lean in the drivers seat, which must help