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MG Midget and Sprite Technical - Wire wheel limitations

I've got a standard 948cc engine and am quite happy bimbling around for now but have a history of sticking different engines into cars. That whole, 'if it ain't broke, fix it until it is' mentality

At the moment I'm on standard wire wheels. I've read that they are not very practical with power gains. Just as a thought exercise, as you increased power, at what point would wire wheels start to fail? Ie splines wearing prematurely, spokes going out of true or something else that meant it was necessary to change to a solid wheel?

Also, with motorcycles, you can fit a wider rim on an existing hub. I did this with an MZ once since it was a factory variation anyway. Is this possible with MG wire wheels? Eg to fit a rim with a deeper inset onto existing spokes to widen the wheel without going outwards and touching the (non RWA) arches? Or are the spindles marginal in terms of stresses already.



P Peters

I’ve had 5.1/2”x13 wire wheels on my Sprite for over 50 years and over the years I have increased the 1098 engine power by over boring it, better cam bigger carb (HIF44), LCB manifold etc.
It’s only lately that I have had to change to alloy wheels due to the splines on the wire wheels being worn. (50 years is not bad though). To replace them like for like was going to cost me in excess of £2000, (5.1/2 inch wires seem to have a premium price tag attached) so I’ve reluctantly changed to alloys. This involved buying a steel wheel axle and front hubs but I was lucky to find a refurbed axle. All of this including wheels and tyres cost me just over half the cost of new wires.

But to answer your initial question, wire wheels are definitely strong enough to handle most power increases on a midget.

Bernie.
b higginson

Thanks Bernie,

Out of interest, does boring out make the same bore and stroke as the standard 1098cc? Also, what power increase did you end up with with your mods?
P Peters

My engine is a 10CC type 1098cc over bored 40Thou, giving 1133cc. With all the other mods it is putting out approximately 50bhp at the wheels, about the same as a standard 1275 engine. All done on Peter Burgess’s rolling road.
The 1098 engine has a long stroke so gives good torque. It has a Kent 266 cam advanced 4 degrees, which gives a bit more torque.
I recently changed the carb needle to a BDL, which is the one recommended for a 1275 when using a HIF44 and although my engine is smaller it has given a noticeable power increase across the range.
I guess I could squeeze a bit more out of it by gas flowing the head and fitting bigger valves and better pistons, but as I use the car for long distance touring in the summer, I wouldn’t want to compromise reliability.
Bernie.
b higginson

Thanks Bernie.

I'm going to ask a slightly different question about wire wheels so will start a new thread
P Peters

This thread was discussed between 10/01/2023 and 14/01/2023

MG Midget and Sprite Technical index

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