From: Barry Lovelock
Date: 21 Jul 2002
Time: 11:39:05
Remote Name: 62.6.92.90
Bill,
I should probably qualify the 17" wheels comment. I reckon the 16" ones are probably just fine, even with wider tyres, but the 4.50 section 17" ones are very commonly used and they spoil both the steering and the top speed; they also touch the handbrake cables on lock. This latter problem is causing cars to fail the MOT test now and it happens (touching, anyway) with the 4.00 section ones too. This mainly seems due to both the steering stops and the axle having worn, but the bias to one side of the brake mechanism makes it worse.
My Ulster Special, recently sold, was very safe (and dull) with the 450/17 rears, but even with the tuned engine it blunted the top speed in the way an unblown "Ulster" is reckoned to be slower with a 4.9 diff than a 5.66. Once the 400/17s were put on it revved and pulled better. The same thing happened with my '36 tourer, it actually tending to over-rev in top, but in both cases they became quite dangerous until I increased the rear pressures to 28-30 psi.
The S/c Ulster (bought from Grant Cowie, ex Keith Tyrrell), runs on standard 3.50/19" tyres and is a real handful. I was collecting a set of 18" rims, which are used a lot in VSCC racing here, but I am going to try the spare set of 400/17 ones I have with the Vintage Tyre Supplies 400/425/17" "Commander" tyres. This will improve the acceleration too, as it has the very high ratio drop-gear gear mod which makes about 50 mph in 1st possible.
It's Sunday (now) and I may try it out,
Barry.