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MG MGB Technical - are slotted discs (rotors) worth it?

Hello all

I'm going to replace my old worn standard bgt discs and wanted your opinion on replacements.

I can get some mintex discs for about £50 or 12 slotted discs for about £120 so quite a difference.

Anyone experience of the slotted discs on a bgt? what are your views - are they worth the money, what performance gain have you noticed? are 12 slot much of an improvement over 6 slot?

please leave your messages here. Let the debate begin!

ps (i run it for road use only)
Mal

I bought new drilled rotors but have not found the time to install them (and they only recently became legal in SCCA SP class for auto-x). The theory is good but may break down in practise. Understand the slotted design is even better.
Sorry I can't be better help BUT Brembo makes drilled, slotted and drilled and slotted rotors for the MGB for much less cash.

Mike!
mike!

IMO, Slotted or drilled discs are really only necessary if you are going to "track " the car. The slots or holes in the discs are there to allow the built-up gasses to release and also cool the brakes. They also dissapate water quicker.

To improve brake efficiency I would suggest the money would be better spent on stainless brake lines that won't expand. They also give a nice hard pedal. And change out the pads to Kevlar pads to reduce fade and resist higher temperatures. They also have a nice side effect of not creating much brake dust (for those of us w/ wire wheels).

Luigi
Luigi

Mal,

4-6 Slots only and to delay fade and refreash pad which means more wear.

Paul
Paul

To add to the above.

I also had a set of drilled discs from a major parts supplier known to us all. After a year, used only for street, mind you, a few stress cracks started appearing around some of the holes. They now reside on my garage wall.

Cheers,

Luigi
Luigi

My experience of slotted rotors (discs) are that they warp. Racers seem to use good quality solid ones with no probs, so i think i shall go back to them next...

~PHIL
Phil

A waste of money better spent on better pads.

Modern brake pads gas very little and even when driven fairly hard there is still no need for slotted and especially cross drilled rotors. You'd be better off buying better pads rated for the type of driving you do.

Luigi is far from being alone in having problems w/crossed drill rotors. Unless they are made to OEM specs such as Porsche, Ferrari etc they are usually not made all that well, and the prices are far higher too.
Mike MaGee

Mal, If the car is for rosd use (legal)only then I can't see why you need to go further than the standard set up. B Hive supply Lockheed disks at £10.95 each and you could also fit V8 pads which fit the standard caliper and would increase the surface area by just over 10% giving a useful upgrade
Iain MacKintosh

If your driving style places enough heat stress on your brakes that you are noticing fade then slotted or drilled discs are probably going to help. The purpose of the slots or holes is to both vent gas from the pad surface and to aid in cooling. If you aren't having problems with fade then they're probably a waste of money for you. Invest in a good quality pad and stainless hoses if you have a soft pedal feel. I think you'll like the results.
Bill Young

That's a good point Bill, the stainless hoses certainly eliminate the sometimes rubbery feel from the pedal and reduce the travel a bit too. Well worth the effort.
Iain MacKintosh

As an update to my post above...
I have run the stock rotors on my modified "B" for three seasons at the local SCCA autocross with no issues whatsoever. I was going to upgrade to the x-drilled because I thought it would be better... Since then I have heard the same horror stories about them.
The stainless braided lines helped A LOT.

"Warping" of rotors is usually due to improper pad bedding proceedure and is not actually warping at all but rather material build-up and metal alteration at the crystalline level due to excess localized heat.

Mike!
mike!

I run V8 discs and green stuff pads , my early car has no servo , and I am very happy with the brakes .Fade has never been an issue on the road. I have a set of DS11s which I can put in for track days, on the road the car seems to speed up when you apply the DS11s and they are cold.
S Best

Mike,

I agree with your last comment although EBC did have a Mft problem not so long ago.

The advice from EBC re V8 is to use ceramic red which are also being used on track instead of yellow.

Paul
Paul

thanks for your comments so far.

seems like general consensus that standard non slotted rotors are absolutely fine for road use.

Are there any makes out there recommended makes of rotors out there?
Any ideas where i can get brembo ones from? cheapest i've seen is £45 pair


MAL

What's wrong with the Lockheeds. At the end of the day it's the coeff of friction that affects the braking and with plain carbon steel it will be the same with all makes. If they warp they will be replaced within the 12m warranty.
Iain MacKintosh

I have the drilled and slotted rotors on my BGT. I have track run the car with both the solid originals and these rotors. No difference. Then again, the shiny paint does not make a difference either, but I will continue to wax the car ;)

I have yet to find a pad with good "bite" when hitting the binders. With "R" compound tires I can mot lock all four wheels at high speeds.

Pete
Pete

This thread was discussed between 25/08/2004 and 28/08/2004

MG MGB Technical index

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