Before we started doing any setting up it is important to first check the tyre pressures are all consistent. We set this to 30psi all round. We also placed the 4 wheels on to grease plates which are essentially just two circles of aluminium sheet metal with grease painted between them. This was important so we could remove any friction between tyre and ground and allow the wheels to move freely. This would then let suspension to sit without tension on it and would then give us a true measurements from the wheels.
We decided the obvious place to start would be to set the ride height. Initially we contacted Stuart Clarke to ask him the ride height measurements on his 289 build to give us a rough idea what to aim for. He confirmed measurement from centre of the wheel to top of the wheel arch were rear: 375mm front: 365mm. We had the jaguar XJS rear axle as opposed to the MG back axle set up on Stuarts build and we had been told previously that the Jaguar rear axle can often ride slightly higher than the MG equivalent.
We firstly used a Plum line (string with a weight on the end) and used a sharp to mark the centre point of the wheel and wheel arch which gave us a consistent position to measure from.
We could visually see the rear was riding way higher than the front and the first measurement confirmed this; O/S/F: 349mm, N/S/F: 355mm, O/S/R: 410mm, N/S/R: 410mm.
Rear Ride Height
We started by adjusting the rear. Firstly we marked a position on the platform adjusters to count the number of turns we made when adjusting the height. We knew the thread on the shock absorber had a 3mm pitch so each turn would reduce the ride height by 3mm.
We set the platform adjusters to one thread from the bottom of the shock absorber which we worked out would give us a rear height of approximately 375mm. We soon realised that when the shocker was at maximum extension the strings moved slightly so we discussed whether we might need to add additional helper springs to keep spring location when at full droop. This is something we will add later. This is assuming that we ever drive so fast that we get air!
Front Ride Height
We wanted to achieve a ride height set up with an approximate 10mm rake. Knowing that we had a ride height of 375mm at the rear this would set the ride height at the front of 365mm. The front shocker absorbers also had a 3mm thread pitch so we adjusted them accordingly to achieve the 365mm measurement at the front. This meant adding height to both front nearside and offside.
Once adjusted we lowered off the jack to confirm the measurements. We bounced the car on the turn plates and also rolled the car backwards and forwards several times to allow the suspension, tyre and chassis to settle before re-measuring.
We went through this process a few times before we got the ride height set up correctly, eventually getting a 10mm rake with Rear: 375mm Front 365mm,