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MG TD TF 1500 - TC Brake Drums Needed

A customer can't afford to buy new Alfins, but his drums are already +.060, so the adjuster runs out of play and snaps back to zero.

Does anyone have any good, used TC drums? I DO need to know their diameter (9" was stock).

Thanks. Tom Lange
MGT Repair
Bar Harbor, Maine
t lange

Tom I've often wondered whether thicker linings, if indeed they are available, would render oversize drums serviceable? Cheers
Peter TD 5801
P Hehir

I would ordinarily do that on a TD or TF with cast iron drum, but the TC drums are steel pressings, and I don't trust their integrity when they get this thin.

Tom Lange
MGT Repair
t lange

Thanks Tom. Good to know. Cheers
Peter TD 5801
P Hehir

Hi Tom,
This solution might not suit your customer and probably you know about it already ..... but perhaps it might be useful at some stage. I use Datsun 240Z or 260Z (rear) brake drums on my road and race TCs. They are alloy with cast iron liners and although the fins go across the drum, I think they really look the part. As you would know, cast iron has a better coefficient of friction than steel. To fit them to a TC the centre hole has to be machined out and six new holes need to be drilled to mount them to the hubs. Best not to weld up the old holes because they are out of site behind the wheel centre and it could cause distortion. The edge of the liner has to be machined back too. To clear the backing plate the edge of the fins can be machined back OR the backing plate can be trimmed.

I use good second-hand drums but I think new ones are available. The Datsun Z (Nissan) guys in Australia often fit discs to the rear and so have drums to sell.

I have a diagram of the modification which I could scan and send if it is of any interest.

Bob Schapel
R L Schapel

Couldn't find a photo of my own so found this on the net. The flat machined face is nearly all covered when the wheel is fitted.

Cheers,
Bob

R L Schapel

Hello Bob,

Could the Datsun drums be modified to fit a wire wheel TF? I understand the ID is 9 inches for both.

Kind regards,
Michael
M R Calvert

“They are alloy with cast iron liners and although the fins go across the drum, I think they really look the part.”

See attached picture of the rear drums on a 250 F Maserati in a dealer’s showroom in Melbourne. The epitome of style for a racing car of the era.

I think you are in good company Bob.

Michael


M R Calvert

The 250F.

Michael

M R Calvert

Hi Michael,

Yes, Maserati and some other 50s cars had a similar fin set-up.

Are TF drums 9 inch? I should know and probably did know once but have forgotten! I know MGA drums ars 10 inch. If TF are 9 inch, the Datsun drums might be able to be adapted but you would have to investigate that yourself. TF drums are efficient cast iron units so there is not such a need to fit something different.

Tom, Y-type drums could probably be re-drilled to fit TC. I think they are identical except for their five smaller stud holes ... if that is any help.

Cheers,
Bob
R L Schapel

Thanks to all who replied - I have a set on the way.

Yes, TD/TF drums are also 9", but the Datsun drum has no central axle-shaft splines, as needed with TD/TF drums. TC drums just have a large hole in the center to fit over the wire-wheel hub, so they work just fine on a TC.

Tom Lange
MGT Repair
t lange

TD/TF drums are 9".

I was loading up some TD/TF wire wheel drums today and took the chance to measure them.

The inner circle is very close to 3.25" at 3 15/64.

It looks like the stud holes are on a 4" PCD and the depth (width of shoe) of the drum is 1.75".

Datsun 240/26Z Aluminum drums are costly, but steel are about 60% of he price of MG drums and are finned.

It would be interesting to see how much machining needs to be done to make them usable.

Peter
P G Gilvarry

I modified a pair in the 70's, with relatively little machining, as I remember. The inner hole was enlarged a bit, the outer diameter was cut down along the edge (may not always be necessary), and the holes were re-drilled for the TC retaining screws and nuts.

Tom Lange
MGT Repair
t lange

Bob,

I have found a set of technical drawings of the 240Z drum online and comparing it with a TF drum (wire wheel drum Tom) I think it could be machined to fit. That said I cannot do it myself and would have to check with someone who does that kind of work.

At a weight saving of over 1kg per drum the idea has considerable appeal on that count alone. Heat dissipation is obviously the other advantage.

I hope to find one locally and investigate further.

Thanks for the information provided.

Michael

PS will you be taking the TC to Winton in May?
M R Calvert

Hi Michael,
I don't know how much is in common between TC and wire-wheeled TF brake drum fitment. However, I have included an image of what I do, in case it is of some interest.

Remember that instead of trimming down the back plates the ends of the fins can be trimmed. In fact I think that is the better option on an original car because it avoids chopping original bits.

There is one other thing I should point out. I have cracked the cast liners in a few (front) drums on my race TC. I doubt that it is an issue on a road car driven sensibly, but racing is much harsher on components. I now warm up the brakes on the "warm-up-lap" because it has been suggested that sudden heating of cold drums at turn 1 has been the culprit.

I will be going to Winton in May but possibly as a spectator. I have been ultra busy lately and also have two pregnant daughters due in mid May. I enjoyed spectating at Phillip Island in March so I'll probably do that again.

Cheers,
Bob Schapel


R L Schapel

Thank you for the drawings Bob. I have some drums on order so shall see how it goes when they become available. The plan is certainly to avoid ‘chopping original bits’ so that the original drums may be easily swapped back.

A big month for your family with two new arrivals being scheduled. Race car preparation clearly comes a distant third place. Speaking of daughters I have one living north of Melbourne not too far from Winton and so can do cars and family in the one trip. I booked flights earlier today so may see you there.

Regards,
Michael
M R Calvert

The Datsun drums work well on the TC once you drill the correct hole pattern and trim the lip back a bit to clear the backing plate. Several of our local TCs run them without issue. Also, if you know someone who can get you undrilled drums, that's even better. I know such a person but I'm not allowed to share his info unfortunately.
Steve Simmons

This thread was discussed between 05/04/2018 and 10/04/2018

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