hillbillyracer
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| posted on 3/2/14 at 10:05 PM |
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Trackday suspension & tyres advice mk3 Astra.
Not been on here in a while, life is busy! A couple of mates & myself have a mk3 Astra as a trackday car, some of you may have met us at Blyton at
the trackday organised by Frank Hall. That day showed up more than ever that we need to sort the handling out. The car currently is essentially a SAAB
9-3 built into the Astra shell, easy enough as they share floor pans. So we have the struts, arms, hubs, brakes etc from the 9-3 & the tyres are
195-50-15 as we already had these from a previous car.
We're thinking of a coil-over conversion to let us play about with springs & ride height. Maybe a change of wheels & tyres will be
needed anyway if a possible brake up-grade we're thinking of go ahead.
We have a good workshop, I'm decent enough at welding & fabrication & we'll be looking to do this without much money. We
don't mind spending a bit on stuff that'll really benefit the job but if we can make it or get it from scrappy for no real loss other than
the effort & bling then that's our way.
Any advice or links to sites etc that will help us would be great.
Thanks, Kev.
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daniel mason
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| posted on 3/2/14 at 10:17 PM |
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id seriously consider selling it and opting for a 172 clio. £2k will get you a decent ish example and it would cost as much to make the astra as
fast!
if your going to stick with the astra,you desperately need decent brakes allround. they were nearly on fire at blyton
stiff settings,grippy slicks and brakes will make a huge difference but will cost!
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hillbillyracer
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| posted on 3/2/14 at 10:51 PM |
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Yeah, the Clios were much faster through the corners, but we did have the edge on the straights. They'd catch us & then get left behind when
we got out the corner then all over us by the exit of the next one so we'd back off at a place good for them to pass & a couple of more
corners on they'd be way ahead despite us having more acceleration. However, neither Will or myself are keen on Renaults, ask anyone in the
motor trade! We also like to have something other than a Clio/MX5/106 that are so common (though I know they're popular for a reason! )
We're hoping the brakes will be fine with a minor upgrade if we have the handling sorted so we don't have to slow down so much for the
corners!
I suppose we're looking for ways to workout an idea of suitable spring rates, tyre sizes, things to beware of etc.
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Nickp
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| posted on 3/2/14 at 10:57 PM |
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Kev,
Get some cheap coilovers off ebay, swap the springs for something stiffer for the track. Get some negative camber on the front, 2-2.5deg should do it
(so you stop torturing those poor outer tyre walls!!  ) Then get some proper track tyres / slicks off ebay too, the stiffer sidewalls will make a
big difference. Then as Dan says, sort the brakes for ones with less smoke in them 
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daniel mason
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| posted on 3/2/14 at 11:11 PM |
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totally agree with nicks comments if budget allows. if not sell and buy a track prepared car. they are very cheap now.
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Nickp
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| posted on 3/2/14 at 11:17 PM |
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quote:
Originally posted by daniel mason
if not sell and buy a track prepared car. .
It wouldn't be Will & Kev if it wasn't a ratty old Astra (that goes like stink)
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hillbillyracer
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| posted on 3/2/14 at 11:30 PM |
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Stiffer springs yes, but how stiff? Like your car weighs X, try spring rates around this etc. Obviously the rate of spring will vary massively
dependant on suspension type, the leverage of the wheel on the spring etc but things won't vary so much between two cars of a similar weight
both running Mac struts as we have. At the rear we're cosidering replacing the Astra seperate spring/shocker with coil-overs which will put the
spring right at the wheel. Then is it better to use a softer spring with more pre-load or harder but almost loose at full droop?
We do have slightly more negative camber on the fronts due to the SAAB suspension being slightly wider track than the Astra, we can work with the top
mounts for more.
An easy upgrade for the brakes is to go from the 285mm discs that fit under the 15" wheels ( cheap tyres! ) to the 308mm discs that will need
16" wheels. The brakes currently have EBC yellow stuff pads which some folk love but others slate terribly, we wore stock pads right out at
Mallory over 6 15min sessions but the yellows at Blyton where we worked them much harder over a longer distance still have plenty material left &
are only starting to break up at the edges. We do have some ducting to the centre of the discs but ain't sure how much good it's doing!
Power is not a problem, despite the lack of grip from the 195 section tyres it does 1/4 mile in 13.5 secs @ 109 mph.
A pre prepped car is not for us, doing it ourselves, learning along the way etc for little money is our way, as is this very forum surely?
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Nickp
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| posted on 4/2/14 at 06:38 AM |
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As a guide I raced a Golf (back in the day ) and used to use 300lb front springs and 400lb rears. In the Golf the springs acting pretty much
directly on the wheel so this could only be used as a starting point if you have coilovers all round doing the same. At these sort of poundages
you'll have very little preload.
285mm isn't a bad size disc tbh and about the same as out MR2 runs. That's good for about 10-15 laps on Yellows before they start to
struggle. The MR2's advantage though is that it has the same size discs all round and uses them all better due to the weight distribution. Your
braking is virtually all on the front. So, if you can't get any more cooling to them then you'll either have to go bigger or go to
'proper' race pads ie Carbotechs(££) or suchlike.
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jossey
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| posted on 4/2/14 at 07:24 AM |
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If it twaz me.....
I would buy cheap coil overs and bushes off e bay then for them. Have a play with them on the track and see how you get it handling with your current
wheels and tyres
then save up for someone to set it up for you n buy some track tyres.
You may get it running well on your own but as a lot on here have found your car will run like a totally different car (for the better) when it done
properly.
I have my car going in for setting up this week along with a load other work doing at mac#1
Thanks
David Johnson
Building my tiger avon slowly but surely.
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Nickp
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| posted on 4/2/14 at 07:36 AM |
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quote:
Originally posted by jossey
If it twaz me.....
I would buy cheap coil overs and bushes off e bay then for them. Have a play with them on the track and see how you get it handling with your current
wheels and tyres
then save up for someone to set it up for you n buy some track tyres.
You may get it running well on your own but as a lot on here have found your car will run like a totally different car (for the better) when it done
properly.
I have my car going in for setting up this week along with a load other work doing at mac#1
Tbh jossey, setting up an old Astra is a lot simpler than a '7' where everything is adjustable. If it has coilovers then you're only
looking at ride height, front camber and tracking. I personally wouldn't be paying anyone to set any of those.
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jossey
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| posted on 4/2/14 at 08:10 AM |
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Hi nick,
I didn't think setting up camber n tracking was easy without a machine?
I should have bought an Astra lol. I know when I had my 911 it handled like a bag of pooo until I got her set up.
Needless to say I did crash it after that cos I thought a 1980's porchse could out break a 48k evo. Turns out it can't lol
[Edited on 4/2/14 by jossey]
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hillbillyracer
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| posted on 4/2/14 at 08:15 AM |
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If it was a mk2 golf then if we move to coil-over setup on the rear then the suspension on the Astra will be much the same so that's a good
start point, if we can use the standard 2.25 springs then we can easily swap about if we want. Time to start messing about in the workshop, but not
till we get a cambelt done on Will's road car, then my girlfriend wants the roof redone on one of her sheds, & the end of another tinned in,
and there's a Clio I've got to put through an MOT for a mate ( did I mention I don't like Renaults? ), finding time may be the
biggest problem!
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hillbillyracer
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| posted on 4/2/14 at 08:44 AM |
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Yes, this will be no state of the art operation, a level smooth floor, spirit level, straight edge & string will feature! It's just Mac
struts at the front & plain trailing beam at the rear.
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Nickp
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| posted on 4/2/14 at 09:22 AM |
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quote:
Originally posted by hillbillyracer
Yes, this will be no state of the art operation, a level smooth floor, spirit level, straight edge & string will feature!
I hear you brother!!
Mine was a Mk1, which is a bit lighter, but the suspension set-up is the same TBH. It was a very stiff set-up but I did drive it on the road and it
was just about bearable, although I was much younger (and dafter!!). If you do go rear coilovers just make sure the top shock mount area is up to
taking all the load at the rear.
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