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MG MGA - New Brake Rotors?????

I think I already know the answer, but please humor me.

The left rotor measures 1/4" thickness (0.25")the right measures 5/16" thickness (0.31").

The workshop manual suggests a minimum thickness of 0.33".

So in the past 40 years has experience to taught that we can live with less thickness.........or am I buying new rotors?

In addition is there a suggested means of removing the rotor from the hub? On one a blow straight down on the side of the hub while the disk was in a vise separated them with no problem, the other hub is not coming apart no matter what I do????

Thanks as always
Tysen

Tysen,
If you're counting votes, I vote for new rotors.
I use an arbor press to separate rotors and hubs, but not everone has a press. As usual, heat is your friend in separating old, rusted parts.

GTF
G T Foster

Hi Tysen. MGA Brake rotors are of barely adequate thickness even when new. If they are worn below the minimum thickness, then they need to be replaced. brakes are something that you cannot afford to cut corners on! Your life depends on good brakes! My advice is to buy new rotors and take good care of them, and change the brake pads before metal on metal destroys them. Cheers! GLenn
Glenn

Couldn't agree more in fact I would say that they are dangerously thin with a risk of mechanical failure i.e the rotor shearing off the centre. I personally wouldn'r drive a mole further in the car. Heat from a large butane torch applied round and round the flange will cause differential expansion which will part the joint.
Iain MacKintosh

The vote for new is unanimous.
R J Brown

You could have soldiered on with the .310 for a while, but as the other one is so thin, might as well replace both.

Easily obtainable and not expensive.

Check the calipers while you are at it - you may want to replace the pistons with MGB parts if they are at all corroded.
Bill Spohn

I figured as much....

thanks as always
Tysen

As Bill inferred the .330 is not really a minimum number for in service rotors. The minimum refers to the minimum that you can resurface a rotor to and still reuse it. After being resurfaced to .33 the rotor will wear and that has already been accounted for in the spec. If once turned to the minimum the rotor should be replaced the next time pads are installed. .330 is .020 thinner than minimum and more than I would expect from wear. It was most likely less than min at the last pad replacement. The .250 rotor is way to thin to use. Some of the more aggressive pads like the metallics tend to wear the rotors faster and if used rotor thickness becomes more critical. Bills other comment can be a real $$$ and time saver, the pistons and caliper kits of a MGB fit the MGA calipers.
R J Brown

I don't think for one moment that you have any intention of doing it but it is always new rotors/new pads. I addition always replace both brake sets on the one axle in order to preserve braking balance.
Iain MacKintosh

Iain,

Its funny you should mention that.

I was wondering what to do regarding the pads. The existing pads have quite a bit of life in them. I was figureing that they'd just wear in.

What's the downside to this? Will it damage the new rotors?
Tysen

Yes, unfortunately they will cause uneven wear but initially poor breaking due to reduced contact area on the new rotors. Throw them away and fit new.
Iain MacKintosh

This thread was discussed between 28/11/2005 and 30/11/2005

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This thread is from the archive. The Live MG MGA BBS is active now.