TR4 Aluminium rear drums mith/fact?

[tr4u2]

I have been told by an american friend that Datsun 240Z aluminium drums fit TR4's with no problem.

 

before i shell out is this true? anyone know for sure

 

regards adrian

[marvmul]

Two small adaptations have to be done (on a lathe) : the central hole must be widened a little and the drum is touching the back plate, so the rim should be cut back a couple of mm.

[tr4u2]

Two small adaptations have to be done (on a lathe) : the central hole must be widened a little and the drum is touching the back plate, so the rim should be cut back a couple of mm.

 

Thanks just bought a pair off US ebay brand new for less than half the price of Al drums advertised in UK

[robgeev]

Forgive my ignorance, but are these drums steel lined, or are they just alloy?

 

I assume the benefit is one of weight saving?

 

Rob.

[Ade-TR4]

You're right Rob.

 

The lining is steel and seems to be much "gripper" than the standard cast drums. Definately noticed a difference when I fitted the Bastuck Finned drums.

 

They save weight, and dissapated heat too (not that that's a huge issue on the rears unless driving very hard).

 

I think they're a better alternative to doing a disc conversion.

 

cheers

Ade

[Dale Moore]

Hi Adrian,

Keep us posted on how you get on with these, looks an interesting modification!

Also a link to the ebayer in the states would be useful, assuming he has more than one pair

regards

dale

[jellison]

Two types of TR drums Alfin radial - (on our 4), one or the concentric ribbed one (better I think - but doubt really much in it) - (on our 6).

[Tr4Tony]

Hi chaps - quite a bit to add here as its all not quite as simple as that ....

 

Firstly the Datsun 240 / 260 drums have approimately the same dims as those for the TR3a to TR6 and also the axles have some common parts etc. So the answer to the original question is yes ....... my first pair of these drums were off a scrap Datsun 240 and they are still on my TR4a and doing fine.

 

The Brembo drums that you can buy on ebay are effectively the Datsun replacements. Originally the Datsum parts were manufactured by the firm that became Brembo etc. etc.

 

These drums do need to be modified to fit the TR backplates and axles ..... and beware that although they look close, drums to fit the 3a to 6 are all ever so slightly different ....... so when they say they fit ll its not quite a fact.

 

Mods required to do the job properly on these are;

 

1. Wheel bolt holes are slightly too big when you need them to fit the later IRS cars ..... so they move about unless securely attached by the two countersunk screw holes; holes need to be champfered slightly to allow the drum to sit further into the axle;

2. Countersunk bolt holes to fix to the hub are sometimes missing .....need to be positioed and drilled .....see above;

3. Centre hole through which the hub nut protrudes is too tight ....needs milling out and champfering as above to allow drum to seat properly;

4. Inspection hole ..... slightly out of line and needs widening;

5. Radial fins protrude into the line of the outside edge of the backplate ....need to be carefully milled off and hand finished to remove contact zone;

6. Inside the drum the internal lining wall is also too big .... so needs trimmed to suit the backplate, shoe edge etc.

 

So its not all a cakewalk ......

 

The Bastuck drums are a lot further on from this and a lot of the machining is done, however the quality is variable and as noted above what fits a live axle TR4 will not fit an IRS TR4a etc. etc. ....... and here im talking properly ..... for example;

 

I bought a pair of the Bastuck drums and did a lot of work modifying them, finishing up the machining, hand finishing little bits as above and noted the following;

 

1. With the front brakes disconnected on my TR4 rally car (!!!!!!!!!) ........ the braking distance HALVED at 30 mph using my modified drums over the standard cast drums. Using the off the shelf set I reckon I still stopped about 20 ft earlier;

2. With the rear footbrake and front brakes shut off (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) and just the manual handbrake left, the braking distance was HALVED between my modded pair of Bastuck's and the standard pair (most of this due to the seating of the shoes on the drum inner)

 

So; my take is buy a pair of the BASTUCK drums and have them hand finished properly ....... I had about a dozen pairs done like this a year or so ago and the feedback ive had from those that bought them was that first they fitted well, second the had no cooling problems or broken fins etc. after using them for a bit and thirdly they definately stopped the car better. So well worth the effort and extra £35 it costs to get the work done.

 

Lastly RACESTORATIONS are doing a centrifically finned cast drum which costs a bot more and looks like the early 10 inch drums ......... dont know anything about how good they are but they certainly look the goods.

 

Hope this helps you out. No doubt other will have more to say also.

 

Regards

 

Tony

[tr4u2]

I have been told by an american friend that Datsun 240Z aluminium drums fit TR4's with no problem.

 

before i shell out is this true? anyone know for sure

 

regards adrian

 

 

Thanks for all your replies ,the drums i bought are Brembos and are in transit(i hope!) somewere

 

when i get them i will take all your comments in mind, thanks tony for the detailed script

 

will advise how i went on

 

cost was £125 inc shipping which made me take a chance

 

regards adrian

[stuart]

Thanks for all your replies ,the drums i bought are Brembos and are in transit(i hope!) somewere

 

when i get them i will take all your comments in mind, thanks tony for the detailed script

 

will advise how i went on

 

cost was £125 inc shipping which made me take a chance

 

regards adrian

Bloody h**l an amphibious Transit they dont show that one in the adverts!!!(sorry Adrian hope they turn up ok.)

Stuart.