15" wheels; an alternative?

[Splat]

You'll remember that when I offered-up the 15" wheels to my car, I thought that the hubs (Whubs!!) were too long (or the Shubs too short). No thread protruded through the wheel. In fairness to myself, this is the only car that I've ever owned with wires. And when the 13" MG Midget wheels are seated on the Midget hubs, about 5mm of thread protrudes. This allows the spinners to engage by some four and a-half full turns.

But as Jan correctly pointed out, much of the thread engagement happens INSIDE the whub. So I went back out to the garage and tried again. And sure enough, although almost none of the Shub protruded through the Whub (maybe one millimetre DOES protrude!), the spinners DO engage, with about two and a-half full turns until tight. This is about a turn LESS than MWS would advise, but the consensus is that all will be well as long as I predominantly drive FORWARD!!

These two photos show the rear axle with both a 13" Midget wheel (with it's short Whub) and a 15" MGA wheel, both fully seated on the Shub. Note how much thread protrudes through the 13" wheel.

[Splat]

That was at the rear. At the front, the Whub was still fouling the brake calliper before the wheel was fully seated on the Shub. But, knowing that I no longer needed four or five millimetres of thread protruding, it now became feasible to machine a relief into the callipers. Four millimetres of material needed to be removed, rather than the "about nine" that I originally thought. And there's PLENTY of spare material cast into my MGB callipers!!!

So; off to my local hotrod shop to have them mill my callipers.....

[Splat]

With the relief machined into the calliper, the 15" MGA wheel will now push fully home onto the Shub.

[Splat]

Three photos. Before and after. But firstly, a shot showing a 60-spoke 13" wheel alongside a 48-spoke 15" wheel. Quite a dramatic size increase, isn't it?

[Splat]

I've only driven about five miles so far! Acceleration is still plenty enough (I was a little worried!). I've initially set the pressures at 25psi all round, which may be a little low? Myself and a mate spent an hour or so pushing the chassis up and down the church car park on Thursday afternoon to gather the info required to recalibrate the speedo (which I'm changing from the 100mph Midget offering to an identical 120mph MGB unit). And the ride height is too tall both front and rear. I've backed the springs off to their slackest, but to little avail. Unless anyone has a better idea, then I think that it'll require the (Protech) shocks to be rebuilt with shorter damper rods! But I'll drive it for the summer and think about that next winter. It certainly LOOKS quite purposeful, with it's raised haunches.

Here's a triptych of snaps to finish for now..... as ever, tap/click the photo to see it full size.

[Splat]

Actually......

Not quite all; I forgot to show the pictures of the bodywork mods. They were minor; a slice out of the alloy sheet behind (and a little inboard of) the front wheels and likewise a reprofiling of the inner wings behind the rears.

[Westfield 129]

If you are looking for better handling, remember that your car is half the weight of other cars that use those tires.

Try 20 psi and see if it is a bit more stable when you flick it sideways. It should be more progressive as it breaks traction. At 25 psi, it probably skitters around a bit, will lock up under braking and transition to over steer without much warning.

I run 18~20 psi on my 13" 185/70s and on the Dunlop 4.50X15 and 5..00X15. I used only 16 psi on the 145/155X15 Michelins that I had on my Lotus 7 Series 1, which weighed a whole 907 lbs with fuel and road equipment.

The W11 a very light car, and you will likely need much lower pressures to keep the over steer and skitterig around under control.

Your ride height should be roughly half the difference in tire diameter. Not really much. You shoulld not have to make any adjustment at all. Ride height must be measured with the driver in the car. Witout the driver, the car will be roughly 1/2~3/4" higher on the driver's side. If you set the car up like this initially, it is likely you will be within 2% of equal weights between LF/RR RF/LR diagonal weights.

I would not be in a hurry to install shorter dampers, as you will lose suspension travel, which is not what you want. If you have the current dampers from the late chassis, they are already too short. The front end is almost on the bump stops and there is very little travel in the rear. You really want MORE suspension, rather than less travel with shorter dampers.

I run the longer Protechs with the 15" Dunlop race tires, and live with the 1/4" increase in ride height. Your road radials are a bit taller, but not that much taller. I get much better handling, and a far better ride.

Remember, when you are sitting in the car, it is nearly an inch lower.

My suggestion is to check your tire diameter, and then see what your origianl ride height increase is. if it is half the increase in tire diameter, I would probably not make any changes other than to set the corner weights and check the front toe and camber. All with the driver or driver's weight in the seat.

Your rear tires are a bit too tall. You might want to run the shorter front size to get the car to sit properly. The diameter difference between a 4.50 and a 5.00X15 is only about half an inch... You pobably have a 2" difference in front to rear diameter. Too much. Try a 155X15 rather than the too tall 165. That should fix the problem.

[jonclancy]

Seems the change to 15” wires and tyres is going to be the thick end of two grand. I think I might hold off for a while and run my 13” Minilites with 165 tyres for a little longer.

I’ll have a good gander at your set up when I next see your car again Splat. I’d really like a set!