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MG Midget and Sprite General - Alloy Rear Brake Drums?

Recently I found a posting that included an image of an alloy brake drum for the Spridget. Are these still available. and if they are, from where? See the image below-

Stephen Strange

Are you really sure you want a pair


http://www.minimania.com/web/Item/SUPERFINS/InvDetail.cfm
Prop

Why shouldn't he want them?

Go for it - pretty ............. :)
rachmacb

Rachael

I think prop may be pointing out the price,($330!)

If price is no obstacle then, why not!!..


John.
j b biggs

LOL - after all he's spent on his engine ......!!!
rachmacb

I'm aware of the Minimania items. Although the advertisement on their website states that "they will also fit the rear of any Mini or Sprite/Midget", there is a problem with them: They have a 1" spacer designed into them. That not only would increase stress on the rear axle and its bearings, but would create an interference problem between the sidewall of the tire and the outer edge of the wheelwell. Machining out the spacer would be a real problem. Are there any out there that are specifically meant for use on a Spridget?
Stephen Strange

Sorry stepen,

Beyound knowing minimania carries them I dont know anything about them, what are the advantages? if your wanting a closer gap look into the mini cooper front drum shoes there supposed to be a thicker pad, I cant remember the details, ... call minimania and ask there tech department they might know, theres also info in the archives and david lieb has some insight on this mod...certianly less expensive then $330... and considering the brake baies is around 10 to 15 percent for the rear, i cant imagine there being a noticeable differance in braking ...unless your doing one of those reverse sliding skip rolls from reverse to to 1st with out stopping at high speed, it does look cool in the movies

you might try "peter may enginering" in the UK, I think he deals in them

http://www.petermayengineering.co.uk/

Prop

I think the mini shoes would be a big plus and better value then the aluminum fins at a fraction of the cost ... sorry for the mis-understanding
Prop

Wow rach,

you seem to know about ever ones egine build, I wasnt aware stephan had done one...LOl

Im pretty sure you confused me with stephan

But your correct I am getting a rear brake up grade, to disk brakes this winter, it comes with the rear end axle/suspension upgrade using an RX7 rearend with disk brakes and LSD.

Prop
Prop

Maybe you need a double bearing hub kit as well? Tyre clearance will be wholly dependant on what wheels and tyres you are using.
Daniel Thirteen-Twelve

There are (were) two types of minifins,

the picture is of a standard (original). The 'superminifin' included a 1" cast in 'spacer'.

they do come up on eBay occasionally

Rob
robnrrugby

Machine off the spacer and you will be fine

they have been made without the spacer but i have not seen those for a long time.

go shopping in the UK even with shipping and taxes they can not be that expensive!!

http://www.minispares.com/Product.aspx?ty=pb&pid=37940&title=
Onno Könemann

Onno-
The spacer really can't be turned in a lathe because the only practical way to mount it in the chuck would be by means of a jig that would project studs through the mounting holes. The studs would interfere with the cutting tool. The only other method for removing the spacer that I can think of would be to clamp it on a turntable by means of its flange and use an end mill, which isn't practical in terms of the rate of feed into the cutter. Do you have any suggestions for removing the spacer?
Stephen Strange

The big advantage with that red car (mine) was the weight saving. It never developed enough heat to need alloy drums but perhaps if I had driven it a bit more like an idiot then I might have got enough heat in.
Wolseley/Sebring brakes would make a better and more cost-effective option?

http://www.spritespot.com/gallery/view_photo.php?set_albumName=toomanyspridgets&id=seb_brakes
rob thomas

Stephen,

IIRC the drums are 7" ID so just put them over the likes of a 6.25" chuck, a common size, and wind the jaws out possibly with some protective material in between the jaws and iron drum lining. If your looking for real accurate then soft jaws could have the OD machined to suit the 7" ID. Pretty straightforward bit of machining.
David Billington

As David said
It does not seem that difficult to me?

You could measure the complete height and if that is even all round you could also mount it in a clamp and mill the 1" off
Onno Könemann

Don't know if they keep the brakes any cooler but they definitely look cooler. However, I'm confused about the spacer you're talking about machining off. Is it the top tier of the wedding cake? If that is machined off, will there enough of a mounting face left? I haven't seen one of these in person, so I don't know if the mounting flange is the entire thickness of that tier, if that makes sense.

Jack Orkin

Jack, the fins on the image that you've posted stand way higher than the ones in the first image.
Gary lazarus

Please excuse my ignorance. Do these have a steel friction band inside that is replaceable?
Trevor Jessie

Trevor has the magc question of the day

If the inside diameter, isnt smaller then the inside diameter of the midget drum, it will be $330 of cool factor bling...

Oh Great Now I have to get a pair to continue to be cool...hahaha
Prop

yes, of course, they have a steel braking surface inside!

Never heard of replacing the steel before though.
(how long do drums last, nearly forever if the shoes are replaced at proper intervals).


Norm
Norm Kerr

Trevor they do have an iron band inside, but it's cast in so that it won't slip or turn and is not replacable.
Jack, that "top tier" is indeed what the spacer is. For a Spridget rear that needs to be removed so that the drum would slide over the lug studs as shown in the photo Stephen posted. Seems like a lot of work for such a small reward if any other than appearance. The rear brakes do so little of the braking and very seldom does anyone have fade problems with them. If you're racing and a rear disc conversion is illegial in your class then the aluminum drums might be worth the investment.
Bill Young

The key advantage to alloy brake drums is the weight saving, which is an unsprung weight saving which is also on the driven wheels.

Originally they were called Minifin drums
Daniel Thirteen-Twelve

Thanks. I knew they had to have some sort of friction band, but I did not know if it were replaceable.
Trevor Jessie

Gary, yes, I thought the higher fins on the picture I posted (from the Minispares link that Onno gave) were due to the 1" spacer that is now part of the drums. Is that the part being discussed that can be machined off?
Jack Orkin

The benifit is not in the braking but in the weight!
Remember you are reducing unsprung weight (the kind you realy want to save)

As for the price sorry for you in the US you realy get the bad deal every time with spridget parts

Onno Könemann

Daniel-
Yes, the real payoff is in the saving of unsprung weight. That would give better roadholding, plus a somewhat smoother ride. Disc brakes would add unsprung weight to the rear axle. From a standpoint of heat disipation, that could be justified on a racer, but not on a street machine, which is what my car is.

Rob-
Wolseley brakes are not available here in the USA as Wolseleys were never sold here.

David-
The problem with mounting the drum in a chuck would be getting the drum to run on a parallel plane.

Onno-
I suppose that the drum could be placed flat on the table and clamped down, and then milled. Of course, this presumes that the inner face of the drum is parallel to that of the flange. Considering what the thing is, it probably is.
Stephen Strange

Stephen,

If I couldn't get the drum running accurately enough when mounted on a 3 or 4 jaw, with the jaws expanded to hold the internal surface then I'd use soft jaws machined to suit to hold the internal surface. The soft jaws would be loaded to replicate having the drum over them to take up play in the chuck and the OD and face machined.

For doing 2 I think the 4 jaw route would be fine and the time taken in clocking the drum for lateral runout of the face and runout of the drum axis. I've done that sort of thing before with some hubs for bearing pocket machining and gotten down to < 0.01mm TIR runout on both easily.

For a run then the soft jaw route would be ideal as that method gives repeatable holding. Soft jaws while not expensive do cost some money, luckily I got a number with my last lathe as they're quite useful.

I don't see holding the drums for machining in a lathe as being an issue.
David Billington

This thread was discussed between 15/08/2010 and 18/08/2010

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