Hello,GD owner needs info

[malcy.t]

Hi, just finished a GD427 mk4, (SVA passed Fri 13th! March), at present running around on donor Jag wheels, (they came with 4 new tyres). I have seen Lee Tophams car,and would like to change to something similar, possibly over the winter. I hear you can get peg drive knock ons and hubs to replace the Jag hubs from Gerry Hawkridge, does anyone have any experience of these? Also, are there any members in the north of Scotland?

GD427 Jag.(Ken Coleman Chevy 350)

[ldtopham]

Well done on the SVA pass

I think that you may be limited on rim choice as the GD in both euro chassis or Jag chassis has a wide track. If you fancy knock ons using adapters then the rim centre will have so much positive offset that it would look daft.

My Jag axle is 1.5" narrower than standard on each side. I opted for Team 3 rims from the USA (when the dollar was poor) made to my own offsets. They have covers for the wheel nuts and threaded spinners. I was very particular about getting the rims well inside the arch with a decent offset (actually worked out at zero which is good as the centre of the rim falls over the centre of the hub and bearing). Even with my narrowed axle Vintage wheels couldn't make a traditional style rim with my offset requirements as the rim centre would be outside of their safe manufacturing limits. So without major re-work of the rear I don't think knock ons are an option. The front would be even more difficult as you would need to move the wishbone mounting points further to the chassis centre line, major chassis modifications

Sorry to be the bearer of bad news Unless you have an S type rear axle fitted then it might not be so bad!

[malcy.t]

Looks like knock ons are not an option, unless someone else knows a way....
I would still like to run 15 inch wheels though, is tyre choice limited these days? How wide can you go at the rear and does handling suffer if you don't go for larger diameter and lower profile? I work in the motor trade, (self employed mechanic), but these cars and tyre sizes are so different to ordinary (boring) stuff that I have no experience concerning them. GD use a lot of Image wheels I believe, has anyone any comments on size, quality, etc. etc. I am currently running Pirelli P600s (I think) in 235 by 15 all round, as the donor XJS came with 4 brand new tyres. I think it handles pretty good so far, but I have only done 1800 miles since SVA in March and am by no means pushing any limits as its a lot faster than anything I've had before. Any comments appreciated!

[ldtopham]

If you push the rim a little further out at the rear then a 275 section may just fit but it would be close to the inner tub when hard cornering if the side walls are not of stiff construction. I would get the tyre true cross section which includes the side wall buldge and measure , measure and measure. Yes tyres are limited. There is only one matched set road legal performance tyre and that is the CR6ZZ Avon. It is pricey. There are all sorts of 4x4 or misatched tyres available but I personally wouldn't fit them.

The handling of the Avons is very good despite the larger profile that come with using a 15" tyre. They have an increased side wall strength for hard cornering in competition use. I have absolutely no complaints apart from the price.

I don't personally like the UK 15" Halibrand replicas on a GD, they won't suit the lack of offset that make the 15" so choice in the first place. The 16" rim is better suited for all round tyre choice, cost and looks. Speak to Image and ask about the JC5 (I think that is what it is called) That was my number 2 choice.

HTH