JPSC Forum

As some of you will know I went up to Birmingham last weekend to visit Procomp to get the car set up. Procomp, for those that don't know, have a reputation for setting up kits (and race cars) and also supply a Locost chassis called an LA Gold. They also supply 'specially' valved Protech shocks which are built to order by Protech. They (it is a Father and Son team) have a reputation of calling it how they see it regardless of the 'collective' internet knowledge says....so interesting times ahead.

Arrived just after 10am on Saturday and after the normal greetings got the car into the workshop (which is behind their residential house). Mug of coffee later and we are ready. Car is quick lifted and the bonnet comes off closely followed by the front shocks. The settings and which side they came from are noted and then they are cleaned up and the spring removed. The shocks then go on the shock dyno to be measured at each click setting. Interesting aside here that the shock dyno (made by Intercomp) is designed to work with heavy, US, shocks on big cars and it had issues with noise or interference on the graphs so Procomp removed the motor and isolated that for vibration and the set the dyno on vibration mounts.

So the graphs for my front 'matched' pair of shocks showed there was a 340lb difference in rebound valving and that the shocks had never been put into their operation range in the factory. So not a pair and never been set up The rears are taken off and the same process is gone through, slightly better news is they are pretty much a pair and are in the correct working range. Next all the springs are tested (regardless of what is written on them) and they are 225lb front and 200lb rear and match across the axle. They then adjust the shocks so they match as close as possible across the axle although the fronts need replacing really they don't carry stock as each car needs different valving. The operating range for the rear shocks (out of 13 position on the knob) is 8-9 clicks and the fronts are 3-6 clicks....think about that then you are clicking your adjusters.

Shock/Springs are put back on the car and the setup can commence. They first check all the bearings and trackrod ends (one of the front bearings is loose so that is fixed and both bottom tapers are also loose !) then camber is set based on the look of the tyres...2.4 deg neg left and 2.6 deg neg right, this is checked with the Mk1 human (Ivan the dad) standing on the chassis to ensure it isn't changing under compression

And so it continues through caster, thrust angles, toe (front and back)....all of them with me in the car. They adjusted the steering rack to make it central, the rear axle so it was giving the best thrust angle and so on. They then corner weighted the car (623Kg) and adjusted it to give 7Kg more on the passenger side front so that both tyres would lock together rather than the one tyre.

All of this is done with lots of questions being asked of me as to how the car handles currently and lots of banter. There was lots of things going on with the car I don't even remember but it wasn't till 8pm that I left Birmingham....So I need two new front shocks (£100 each which will be valved and dynoed for the car) and £226 for the setup (two skilled engineers for 10hrs !) Didn't think that was half bad.

Final settings are

Camber left 2.4 deg neg, right 2.6 deg neg
Castor left 4.687, right 4.593
Tracking 2mm toe out (at rims)

Rear
Camber left 0.3 deg neg, right 0.2 deg neg
Tracking 1.2 mm toe out at rims

Thrust alignment at chassis front 6mm to the left

Corner weights
Left 346.5Kg 47.4%
Right 384.5Kg 52.6%
Rear 376.5Kg 51.5%
Cross 346.0Kg 47.3%

Front Left 179, right 175
Rear Left 169, right 207.5
Total with driver 731.5Kg

Damper Settings
Front 3,4,5,6 (Set 4)
Rear 9,10 (Set 9)

Front Springs 225lb
Rear Springs 200lb

Rake is set to 25mm

I went sprinting on the Sunday at Debden and it is a very different car to drive.....took me 4 runs to work it out. The datalogging shows I can use 0.2 G extra force on the brakes before locking (which is a massive improvement) and 0.15G in the corners. The car feels planted now which much more front end and this is before the correct shocks. I'm off up to Llandow for a trackday Saturday and will be able to try it with the ARB disconnected (Procomp want me to test with and without my very stiff ARB).

So highly recommended.....just remember that those shocks on your car which have never been measured will not be even close to each other unless you get them dynoed.

Good to see a review of the company. I keep looking at the shocks they supply and trying to find a reason I shouldn't replace my 18 year old spax units

On one of my shocks I can't even move the adjuster any more

Your review just means I need to weigh up the options of new wheels or new shocks I had settled on new wheels this year and new shocks later in the year/ early next year....now I am not so sure

How does it feel on the road with toe out? Does it make it twitchy?

I thought rear toe-out wasn't desirable but I guess is in the axle.

ProComp are very highly regarded by several members of another kit-car club I know.

Interesting to see what it's like on the track, Jeff.

adithorp wrote:How does it feel on the road with toe out? Does it make it twitchy?

I thought rear toe-out wasn't desirable but I guess is in the axle.

Seems fine just driving, the rear toe out is due to welding/cooling on the axle tube and is so small I'm not worried.

Very interesting Jeff. Do they give advice on spring rates or just stick with what you have? Also excuse my ignorance but what is "Thrust alignment at chassis front 6mm to the left"?

They will advise on what springs and dampers to use and what settings on those dampers (once they have been valved and dynoed). Thrust angle is the angle which the axle will push on compared with the chassis. Effectively my axle is offset by 6mm.

corner weight was set when you sat in the car i guess?

Doesn't take a genius to work it out.

"....all of them with me in the car"

and certainly not a German Genius apparently....but the 623Kg was without me in the car.