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Suspension set up

Posted: Mon Mar 16, 2009 5:59 pm
by phils
Hi, I know there is a lot of info on the forum regarding suspension set up but I could do with some advice.
I read on the forum that the springs supplied with the kit are not up to the job and that 250 front and 200 rear were required. I bought and fitted these springs.
I took the car out yesterday for the first time since passing its SVA last November and it was rubbish! It was like riding a bucking bronco bouncing all over the place!
I have both front and rear AVO shocks set at about 1/3rd clicks soft but it is as if the car has no damping at all.
With the car stationary you can grab the roll over bar and shake the car from side to side and it just bounces away.
The shocks I have are the ones that came with the kit, 12” open, 8” closed and are brand new and have not been used however they have been on the car for several years during the build.
I could dial in more damping but am reluctant to do so as I thought, and have read, that for road use fully soft or just 3 clicks from soft is enough, I am already over the 3 clicks and have no damping.

Any advice would be appreciated.

Regards

Phil.

Re: Suspension set up

Posted: Mon Mar 16, 2009 6:40 pm
by mikeb
Phil, just start clicking the dampers up in hardness.

Re: Suspension set up

Posted: Mon Mar 16, 2009 7:55 pm
by stylussprinter
phils wrote:Hi, I know there is a lot of info on the forum regarding suspension set up but I could do with some advice.
I read on the forum that the springs supplied with the kit are not up to the job and that 250 front and 200 rear were required. I bought and fitted these springs.
I took the car out yesterday for the first time since passing its SVA last November and it was rubbish! It was like riding a bucking bronco bouncing all over the place!
I have both front and rear AVO shocks set at about 1/3rd clicks soft but it is as if the car has no damping at all.
With the car stationary you can grab the roll over bar and shake the car from side to side and it just bounces away.
The shocks I have are the ones that came with the kit, 12” open, 8” closed and are brand new and have not been used however they have been on the car for several years during the build.
I could dial in more damping but am reluctant to do so as I thought, and have read, that for road use fully soft or just 3 clicks from soft is enough, I am already over the 3 clicks and have no damping.

Any advice would be appreciated.

Regards

Phil.
OK -- the first thing you need to establish is -- have you got travel in the piston of the shocks ie. can you see any shiny half inch stem through the springs :?: Then how much can you see before the bump stop :?: The amount that's a minimum varies depending on how hard your springs are . If you run 250's up front then 15mm will suffice . If the bump stops are hard not the soft type that you can push with your finger THEN cut them in half to increase the travel available. The rear will need more travel so would be safer with a minimum of 25mm's and cut the bump stop if hard. Secondly what tyre pressures are you running :?: If using Yoko's or Toyo's 16 to 18 psi is sufficient . Horrible road tyres like dunlop , michelin , goodyear etc need 18 minimum because they are primarily designed for tin tops that weigh 1.4 tonnes :roll:
Finally you need to establish whether your shocks are actually working properly ie. can you push them up and down when off the car :?: have you very carefully undone the shock adjusters all the way anti-clockwise to establish the base setting :?: Sometimes the grub screw that holds the adjuster onto the shock becomes loose , messing up your clicks judgement :wink:
Having checked all the above , have you got a wedge setting that's sufficient ie. start the rear measurement at 20mm higher- (under the 25mm tube running across under your seat pan front) - than under the front lower chassis 50 x 25mm rail . Hence my term --- wedge :wink: You can lessen this measurement difference to suit your driving preference. High rear -- low front = oversteer tendancy . The lower the rear is in relation to the front the less oversteer you'll have and a tendancy to understeer will be apparent . Personal preference :roll:

If I had to guess what was wrong with your set-up without seeing it and knowing the spring rates you have , I'd say there's probably not enough travel --- pistons :wink: Have you been trying to lower the car to get it to look good but not checked the ' above ' :?:

Are you quite sure you are winding the clicks the right way ie. clockwise :?: