Vibrations, tyre pressures and suspension tweaking

[jackh707]

Following on from my thread a fortnight ago, my dad and I recently acquired a 1992 super sprint with dedion, with a raceline 1800 zetec on 40 webers, on 14 wheels.

We've had a bit of weekend hoonage in it, and it is an awesome introduction into the world of caterhams... but we have discovered a few things....

Vibrations,
In 5th gear and only in 5th gear at 3200rpm + there are some vibrations under throttle, like the whole car is thrumming. All other gears are smooth. Not a massive issue as 5th is only really needed on the motorway. What could this be? prop shaft out of balance, engine mounts? we don't have a clue...

Tyre pressures,
The ride on the car was very crashy and skittish over bump mid corner, not what we had expected, turns out the tyre pressures were at 35psi! we know they should be a lot less, we dropped them to 22 and the whole car was massively better, we usually run the car 2 up, what tyre pressures do you all reccomend?

Suspension,
We want to take the car on track in the future, Anglesey being our first stop hopefully, but we would like the suspension well sorted before that. The shock absorbers may well be the originals, and We don't trust them on track on a 20 year old car.
What reasonably priced upgrades can we do, and what maintenance should we be doing.

Any other things to check, we are planning a proper engine service, with a cam belt change, anything to look out for?

[Some Gump]

Jack,

IMO get standard caterham bilsteins - widetrack if you can, but the bits don't come up that often. The race spec ones are too hard for the road, spoils your fun. Make sure you have adjustable platforms, then set up the car as described in numerous threads on here.

[Shropcat]

Most people have their tyre pressures around the 17-20 psi depending on the type of tyre.

[jackh707]

cheers for the advice, found 3 bolts out of 6 missing from the bell housing, and they were loose, and various other bolts loose including engine mounts and, some attached to the diff,(not sure what to call them). Whole car feels much more confident now they've been tightened and/or replaced.