MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Healey thin discs

Our Frog has what we believe to be the Healey thin disc conversion - small discs that fit onto the original drum kingpins and smaller calipers than later types. After 50 or so years the discs are somewhat worn ;-).
Does anyone know of a supplier for these discs?
David @work

that's the sort of thing that Brian Archer at Archer's Garage, or Paul Woolmer might know. Also John Hopwood who has an FIA frog and is an FIA scrute so contact details for him should be in the Blue Book, or Tom may appear soon with more ideas...
David Smith

The person who really knows about the Lockheed thin discs is Jonathan Whitehouse-Bird, as he has 9256 WD, which is thought to have had them fitted from new by the Healeys ...

However, I don't think we have a positive ID here. The discs may be thin (and look it), but they aren't 'small' - at 8.75" they're larger than both the Sebrings' Girlings or the standard Spridget Lockheeds. Also IIRC the Lockheed PL calliper isn't small, either - it does have 'sunburst'-like radial ribs which are quite distinctive.

Might these not be the 7" discs from the 997 Mini-Cooper? I haven't heard of these being fitted to Spridgets, but it seems feasible that people would have tried it in 1961/62.

Tom
Tom Coulthard

Yes Tom the 7 inch disc was fitted to coopers and Ss with 10 inch wheels. I remember at least 2 cases of being told that these were fitted to frogeyes and were a great modification at the time. That said I have never seen one.
Bob (robert) Midget Turbo

Thanks for al the information, I'll have a measure up and photo session at the weekend and post details.
David@work

O.K.,
The discs are approx 8 5/8inch by 1/4 inch.
No visible markings on anything.


David Brenchley

and another


David Brenchley

another


David Brenchley

bump


David Brenchley

No one got any ideas then?
David Brenchley

David,

They remind me of Triumph discs, maybe spitfire?. My GT6, Vitesse book shows 1600 Vitesse as having a 9" disc.
David Billington

David, Yes very much like spitfire discs, found a pair and machined one down to diameter and it fits, total "height" is about 3mm more pushing the wheel out a little and the caliper needed a spacer to centre it over the disc. They are a fair bit thicker but I think that is a good thing rather than bad.
Run out of time for now but will fit the other at the w/end.

I hate machining cast iron......
David Brenchley

David,

I know what you mean, messy stuff. I have machined it on many occasions in small quanities but can only imagine the mess in a place that machines it all the time. A mate used to work at such a place and he said lots of surfaces that didn't get cleaned were covered in the fine black dust. One company I used to work for supplied some PCs to an iron foundry for use on the shop floor, the company had bought cabinets and filters but didn't use them so one day one of the monitors arrived back at the office after about a month having died, iterior covered in the same black dust.

Good to here you got some discs sorted.
David Billington

David,

Tom C. just alerted me to your post.

Glad to hear you've manged to sort out some replacement discs.

Up until recently, Triumph Spitfire discs were the only option for Girling equipped Sebring Sprite owners too. Machining the disc to size and fitting a spacer to centre the caliper also had to be done in the same way.

However, J.E.M. in Leicester now produce a brake disc to the correct specifcation for the Sebring Sprite, doing away with the hassle. Sadly, these would be of no use for the set up you have on your Frogeye, so you'll be pleased to hear that you've not wasted your time and effort!

I can confirm that your car is indeed fitted with the Lockheed 'Thin-Disc' brake conversion, although you appear to be missing the original (and I think unique) dust shields that sit behind both brake discs.

I've attached a photo of the 'Thin-Disc' set up that was fitted by the Healey Motor Co. to my works modified Mk.II Sprite - 9256 WD.

I'm aware of only 4 Sprites in the UK (your Frogeye included), that have the Lockheed 'Thin-Disc' conversion (3 MkI Sprites and my MkII), alhough I'm sure there are others still out there to be discovered.

Pretty rare nevertheless! Great news!

Jonathan.


J Whitehouse-Bird

David,

The original press release for the Locheed 'Thin-Disc' conversion, as offered by the Donald Healey Motor Company.

January 1961.

Jonathan.


J Whitehouse-Bird

David,

The "extension added to the fluid tank" mentioned in the press release, is nothing more than the standard MGA tandem master cylinder lid.

Just in case you're unaware, the Lockheed part number for brake pads is: LDB 8 (I presume 'LDB' stands for Lockheed Disc Brake)?

Jonathan.
J Whitehouse-Bird

Jonathan,
Thank you very much for that information. Both discs now machined and fitted but not tested as we are waiting for the bonnet to come back from the paint shop.
Using the spitfire discs has pushed the front wheels out a little - the front track has always seemed a little more than the back, may put a spacer on the back end to even it up.
Our master cylinder has not got the extension and as it was renewed some years ago I don't think it has been modded at all - we have had no problems previously but that maybe because the old discs were warped and tended to push the pads off a little, will see what happens now.
We have never changed the pads but I assume they are readily available?
Never had the dust shields but I don't think this matters - our rally midget doesn't have any either due to the KAP calipers.

Regards

David
David @ work

Jonathan,

I fitted discs to my frogeye years ago and carried on using the drum master cylinder without modification for a couple of years, as I didn't realise there was a difference. When the master cylinder needed replacing I went for the disc one as in those days it was available and the drum one not. The only time I had occasional front brake binding was with the disc master cylinder and that may have been down to the discs being too thin, even in the late 1980s the MOT man didn't seem to have info on permissible spridget brake disc thickness to hand.
David Billington

This thread was discussed between 28/07/2008 and 11/08/2008

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.