suspension set-up

[_SBD16v]

right guys i have coilovers on the front, coilovers on the rear (in the standard position)
adjustible top mounts althou i all looking into some new bottom arms to give more adjustability

its going to be used on the track and on the road for driving to track's and sometimes used for just going for a drive,

at the moment i have no springs and dont ahve a clue what to set the caster and camber to also tracking on the front ?? any toe in or out needed on the astra.

and also the rear worth making a shim to give some more rear canmber ??


cheers rob

[Austinspace75]

Re: suspension set-up

I've just done the set up on my racer, some of which may be a help. I don't have turreted rears, so had to multiply the desired spring rate by the 'levering' effect of the spring position.... which is about 1.5 I reckon. Anyway, I wanted the rear end very stiff, so went for 1100Ibs springs resulting in a rate of about 700Ibs, on GAZ adjustable shocks wound right up to near maximum. On the fronts, I have 375Ib coilovers again on GAZ shocks - but these were custom made using the existing strut - top adjustable. I ran the car like this at Combe the other day and on the whole was happy with the balance. I thought the rear might be a bit over-stiff, but it felt fine and after carefully watching some video footage it looks about right too...
Given that you'll probably running your car mainly on the road, I wouldn't have thought you'd want to go quite so stiff, but the ratio front to rear might be a useful starting point. If you can, try a few different set-ups to see what you like.
Haven't made any changes to mine yet regarding camber/caster. I'm probably not going to change the rear at all as I reckon, if anything, I'd rather lose some grip at the back than gain any.

[teej]

Re: suspension set-up

Bloody hell, Tom - that's really stiff!

Mine was 450lb front, 550lb rear, (all standard-position damping) and was fine on the road as long as you didn't try and hammer it down any bumpy country lanes! No idea what that converts to in coilover language, I'm afraid.

Tom - O/T - is your engine standard? Have you still got original windows? Thinking of going back to a boggo 16v engine and coming to play in pre-93 to give you some company, but have lost all of my glass! Out at Lydden in the little toy next weekend but one with the DMN and Tintops.

[Austinspace75]

Re: suspension set-up

ello Tim! I looked for you in the DMN entry at Combe when I was spectating last weekend but figured you'd not made the journey... ah well, next time.

Yeah, it sounds pretty extreme doesn't it! I had quite a long chat with GAZ though, and they'd recently done an MG ZR at the same sort of rates (ok, its not an Astra, but the basic configuration is the same). To be honest, I don't know that its right for sure. BUT, on the basis that Combe is probably one of the bumpiest circuits in Britain, has a good mix of fast and slower bends, and the car felt absolutely fine, I really think this is the way to go for now. The key point regarding my set-up, is that everything else is absolutely standard i.e. The ARB is still there, the top mounts are standard (and knackered!), the bushes are old rubber (and knackered!), rack in its original position etc... So, the car has a vast amount of natural understeer... so I figured the cheapest and easiest way to get a better balance front to rear was to stiffen the rear right up and get it moving around. On cars with a more extensively developed front end, my rear spring rate may not be at all appropriate.
The way it is now, I found it was quite chuckable and good fun... and I got a 1m 25 out of it at Combe despite braking about 75 yards earlier than I should have been due to the complete lack of pedal feel. Considering that the engine is standard, the gearbox is off an 8v and it was the first time I'd driven it on the new suspension, I was quite impressed with the car's lap time.

In answer to your questions about my car, as I said the engine is standard I think... Compared to the grunt of other cars around me it seems to perform about right for that. Yes its still all glass.... as per Pre93 regs. I like the sound of your plans!.... it'd be great to have you out with us!

[HUNTER]

Re: suspension set-up

Ι have in my kadett 320 lbs in front and 390 lbs in the rear,with adjustable top-mounts in thw front (-2,1 camber)
It's a pleasure to drive it in the track or in the road (i've got a quaiffe differential too) as the tail of the car is in his own path now,and it doesn't just follow the front.
It hasn't too much roll,and it's a little on the soft side of the set-ups
With this set-up I have a very good lap-time in the track-days that we do