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Old 23rd May 2015, 10:23
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bigrich bigrich is offline
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Hi Martin,

Welcome to exi ownership....where are you in the country - 'up north?'.

You've found the first challenge! (really like your rims by the way!). This post will be a bit lengthy, but worth reading - trust me (point 6 esp).

I built mine back in 2006 and instantly found some serious handling issues - particularly at the rear. I've since solved these (well solved enough to stop me worrying when I drive!)....but there are other basics you need to check too.

You're running a K series engine setup on the original Mk1 chassis (same as mine) ....I'm assuming tyres are 185/55 R15 or 195/50 R15. Below are some basics in order of simplicity to check /adjust!

(1) Tyre pressures - cold pressures need to be somewhere between 15psi - 18psi all round. I run mine at 15psi front, 17psi rear. If you inflate tyres to the usual car pressures of 28 - 32psi then it will skip around like a mountain goat.

(2) Damper settings - the Gaz adjustable dampers have the setting knob on the damper body. Fully clockwise is maximum, fully anticlockwise is minimum...the difference between the 2 is about 40 'clicks' on mine. I run at between 8 and 13 clicks from zero....i.e. soft. Again, if you set them at the upper range the handling can get skittish.

(3) Ride height / corner weights - try to get the ride heights as even as possible around the car by adjusting the spring platform. I run 130 - 140mm ride height measured from floor to chassis rail. If you can then get the car on scales so you can corner weight it to get the balance spot on.

(4) Spring settings - Marlin seemed to supply all manner of spring heights and stiffness for these cars. Search this forum for spring setup and you will be able to see the different setup's people have tried. In my experience this is one is a bit trial and error....but my car definitely improved for stiffer, longer front springs

(5) Geometry settings....I could never get any baseline settings from marlin (be interested if you have) when I asked, so ended up using Lotus Elise / 340R geometry guidelines (see SELOC for the data). Each wheel needs some negative camber. The toe setting front and rear can also make it handle like a bag of spuds if wrong. I generally set my rear toe in at approx2-3mm overall & my front wheels to parallel.

Beware using standard garage laser alignment.....the chassis and suspension on your car is hand made and probably won't be the same on each side once assembled. This is known as 'setback' in geometry terms. I once had a good local garage set my tracking with gauges and it was worse than when they started because of this setback issue. Either use the DIY fishing line and poles set up (also a link on this forum somewhere for it) or a decent 50+ 4 wheel alignment that measures setback and compensates for it. I use the string method and get reasonable results

(6) This is a critical one - the rear hub assembly on the Mk1 chassis have an inherent design weakness. The toe control link pivots on the top of the hub using a different size ball joint to the wishbone pivot. This means that as the suspension travels up and down the toe control arm actually induces passive steering on the rear hub - and it does this a lot. This is probably the cause of the feeling you had when the car skips around on uneven roads. At speed this can be a real problem and I had a couple of really hairy moments before I fixed this. Marlin have redesigned the rear suspension to eliminate this but this involves new upper wishbones, hub etc.....I created a less intrusive fix by using rose joint type rod ends to get the pivot points at the same height. Again, there is a thread on this forum detailing what I did to solve the issue on mine (usual caveats apply - It worked for me but I cannot take responsibility for your own setup if you choose to adopt this)

(7) Tyres - almost forgot these - dependant on use for the car some 'sticky' tyres can also greatly improve things once you have addressed these other points. I opted for Kumho V70a trackday tyres (road legal) - they are fantastic on my car....R888 etc would probably be great too.

So...if you made it to here you are probably thinking 'OMG!' - but the benefit from sorting these things is really good!

Also - there is a company called Track Developments based at Castle Coombe race circuit. Dave Gallop is the main man there and he has done lots of work on redesigning wishbones and geometry setup for at least 2 5exi's that I know of. He is good and I'm sure would put your car right for a fee. (Depends how much you enjoy tinkering with it yourself )


Cheers

Rich
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