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MG Midget and Sprite Technical - Wheel stud woe

I've just replaced the disc brake pads of my '70 midget. The job seemed to have gone fine until the very end, when a wheel stud broke as I tightened it. I was only using hands and an ordinary wrench, so I'm a bit worried whether other studs are about to fail under similarly moderate tension.

But the immediate problem is how to replace the broken stud. It seems like they have to be whacked out from the front, coming out the back. But the brake disc is in the way of the stud's head.

Do I really have to take the hub off and then the brake disc, too?

I'm concerned about removing the hub, because I only just replaced the front wheel bearings with rare-as-hens'-teeth originals. I didn't pay the silly money recently asked on eBay, but they weren't cheap, so I really don't want to wreck them.

Assuming hub removal is necessary, any hints to minimise chance of bearing damage?

Once the hub is off, any hints on successful replacement of the studs? I don't have any sort of workshop, just a rented garage, so perhaps I should be looking to a professional to do it??

Thanks in advance,

Pete AC

Hub and disc off, I'm afraid.

As you have only just replaced the bearings, I would expect the hub to pull off cleanly with a sharp tug.

I had one break when I was just about to go out onto the grid for a race.

It was replaced in under 15 minutes with just hand tools.

A vice or press would be useful, but you can tap them out and in with a hammer.
Dave O'Neill 2

There are, or were, 2 styles of brake disc hub one round which the studs won't pass and one squarer which they will, sounds like you have the round type. Both types can be seen on ebay.

I suspect your car may have had Rostyles fitted in the past as years ago I had a stud broken when a wheel was being fitted and when I looked I noticed all the front studs were bent inwards, the disc hub set had come off a Rostyle car. When I looked at other cars fitted with Rostyles almost all had visibly bent studs. On checking the other 7 bent studs on the front of my car most were visibly cracked on the outside of the bend so all got replaced.
David Billington

You can drill oversize and fit 5/16" studs as an upgrade.
Guy W


That must be a typo as the standard studs are 3/8", 5/16" is smaller, so I suspect you mean 7/16".
David Billington

Indeed, David. Thanks for the correction. That's what I meant. Not a typo though, but a brain fart.
Guy W

Can the hub and disk be pulled togather a unit and not seperated... just loosened a bit ???

The problem with a 3/8 stud is there so rare, so you have to order them from a specialist provider like moss

The reason for the studs bent inward is because the minimum wage retards at the tire and wheel shop like to the power up air powered ratchet gun with 500psi and bet each other how tight they can get the lugs on the studs without out breaking the studs...its a popular game among the looser class

So as you might imagine putting 300psi onto the wheel studs on roy wheels, does alot of damage to the hub and the wheel its self

Last note... you cant just drill the hub to 7/16 and insert a 7/16 stud, the hub has to be drilled, THEN SPLINED so that the groves on the stud will lock into the hob, if you dont do this the nuts will wind off the studs as you drive down the road And then your wheel falls off at 70mph

Prop and the Blackhole Midget

Prop, on that last point - yes a simple hole in the hub does work. As the new stud is pulled through into the hub flange the splines cut ito the hub steel, forming the matched set of splines.
Guy W


Hmmmm, I did not know that.

Prop and the Blackhole Midget

Thanks for all the comments.

The hub did indeed come off easily, bearings undamaged. The studs, broken and unbroken, came out nicely too. I couldn't approach the claim of 15 minutes, but it didn't take too long.

Just have to wait for new studs to arrive in post, now. I'll replace the lot, as the one that broke probably wasn't the only one that's been weakened in the past.

Pete AC

Similarly to Dave I had a stud break just before going out on to the track for a a race, probably due to over zealous tightening from all the adrenaline ! the result is I have always used a torque wrench since .
Mike Fairclough

I replaced all mine, after one broke, ever since no one but me touches them, and I always use a torque wrench.

Dave Barrow

Are 7/16" studs still ok with standard wheels and are nuts of the correct profile easily available?

Rob aka MG Moneypit

Good ???? Rob,

On the roy wheels you still need the acorn you will need to search those out

For aftermarkets like mini lights im assuming you probably will need mag or step down nuts... those are easy to fjnd in 7/16.. in the states for 3/8 mag I had to order mine from a guy in Australia...they where available in the usa but at 3-4X the price

Prop and the Blackhole Midget

This thread was discussed between 28/03/2015 and 30/03/2015

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