Project EXI

The building of a Marlin 5EXi kit car, using a Seat Leon 1.8T 20v Donor
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< 10:08:16 >

Mon May 14 10:08:16 BST 2012

Ooopss. Wheel Arch problem


I managed to take the car out again over the weekend. Its longest single trip to date. About 30miles all in all. There are some problems that need addressing!!!
Perhaps the biggest problem is the rear tyres fouling the rear wheel arches. Under load (e.g a roundabout) the shocks compress and the tyre fouls the arch. Allow this to happen long enough and smoke comes of the tyres, and cuts the wheel. This is seriously bad.!! So on sunday I set about lookig into what can be done to fix this.
I started by jacking the car up and putting it on axle stands. I removed both rear springs, and used a trolley jack so I can raise and lower the rear wheels to simulate compression. One the bumb stop it is apprent that rear wheel arches are way too low, sanding away from the inside of the wheel arch, to cater for full travel on the wheel, the wheel needs alot more travel.
I have had to cut a hole in the top side of the rear wheel arch, to accomodate the wheel. As I am having to re-do the rear wheel arches, it makes sense this time to allow a larger diameter wheel to fit in the space. I will use the orignal 17" seat leon rims and tyres, as a template. I may decide to fit 16" rims at a later date, but using my current 15" rims in the space of a 17" rim will give a good inch or so clearence in all directions.
Its a shame that I didnt think of this before, but a simple oversight, I should of removed the springs from the rear, put the rears into full compression, and then formed the wheel arches.
See the photos in the build diary for some of the photos, of the problem and the solution.

I have also seen that the 300lb rear spring is fully compressed. The shock is fully wound up, this is indicating to me that the rear spring rate is too low. the current spring is 2.25" ID, 7.5" long and 300lbs rate. I have bought some 2.25"ID 8" long 450lbs springs to try as a replacement. The maximum length spring that can be fitted is 9", so 8" would be about right. 7.5" long springs are kind of an odd size.
The big difference in spring rate is probably down, the heavy rear end. I have a 6 speed gearbox, which would add alot more weight. I am guessing that previous Marlins, say 1.6 Rover engine and 5 speed box, may be fine with 300lb spring. for £50 delivered, I can experiment with spring rates to find the optimum setting for my particular car. The 300lb springs on the front seem firm, but doing a good job.

Posted by Steve | Permanent link | File under: bodywork