10 replies to this topic

[Minigman]

Looking to change from single shoe drum to 7” 997/998 discs.

Are any of the parts common to both?

Are any of the parts common to the Cooper S 7.5” discs?

I suspect the answer will be no to both questions but here’s hoping!

Thanks.

[timmy850]

CV joints are the same as the drums

 

The hub carrier is the same as the 7.5 discs

 

The wheel bearings and ball joints are all interchangeable.

 

I don't think it's a cost effective "upgrade" though

[Minigman]

I want to keep the same wheel alignment as it’s an early 1960 car. Otherwise I’d just go 7.5”.

[timmy850]

You could also consider the twin cylinder front drums. My 850 has them now and once they’re adjusted properly they work really well

They’re strong enough to lock up the front wheels during hard emergency braking and I’ve never had a problem with fade.

[Minigman]

That’s a thought Timmy850.

I have a pair of non spaced minifins so fade would be minimised too.

I hear mixed reports about 7” discs. Some are pro (Cooperman) for example whilst many others including Vizard didn’t rate them.

I doubt there are too many people on here who’ve actually used them and most opinions are just repeating what they’ve heard.

Looking at the cost of a set of 7” brakes I may well give the twin shoes a go first and see what I think. Never had an issue with them on my last 850 mk1 but I have a more pokey 1132 in my current MK1.

Edited by Minigman, 31 May 2018 - 10:37 PM.

[minimans]

I'm old enough to have used 'em all! don't waste your money on converting to 997 brake disc's there's just no benefit over a well sorted twin leading shoe. If disc's are a must then just go with the 7.5's as parts are easily obtainable and work. The repro 7in disc's are a mixed bag some need machining to fit and they will still fade like crazy...........................

[DeadSquare]

The 997 discs were a promotional introduction.

 

Girling / Lockheed wanted to sell them, Cooper wanted added glamour, BMC wanted to save fitting time on the assembly line and the fact that the pads had a better all-round friction material than the shoes is not relevant today, as the non asbestos friction materials are different.

[Spider]

The 7" Discs will give you about one good stop, before they are simply too hot. The disc is too small in mass and it takes very little to get them really hot, after which,,,,,,,

 

Once they cool back down, they should be good for that one stop again,,,,

 

Personally, I wouldn't waste time or effort on them.

 

I think you'd be happy with twin leading shoe brakes on Iron Drums, but as you have Mini Fins, I'd suggest, that would be the way forward.

[Cooperman]

I used to competitively rally my 998 Cooper in 1964 - 5 and it had the 7" discs with DS11 pads.

I also used Girling 'Amber' brake fluid and I never had any serious fade issues. Of course, the 998 did not accelerate as fast as a 1275 'S' so I was not trying to slow the car as much at each corner.

On an 850 restoration the big advantage of the 7" disc set-up is more that it removes the need for frequent brake adjustment, you don't get seized up adjusters and the car stops OK. If you want to drive the 850 very aggressively (do you?) a better quality pad material will help like a Mintex 1144 or a carbon-metallic. The other advantage is that it enables the original 3.5" wheels to be fitted and the 'period modification' can't be seen easily.

Pads in that size may not be available, but it would be relatively easy to machine down an 'S' pad to the right size.

In fact I may well do this on the 1964 850 I am slowly restoring.

[Minigman]

I’m running a 1098+0.040” 1132 engine in my 1960 Deluxe. Enjoy the torque but still drive sensibly and rarely over 60mph. I think I’ll give the twin shoe drums a go first and see how they go. I live in a very hilly part of the world. I’ve run twin shoe drums on an 850 before without issues but just considered discs as an alternative seeing the engine puts out about 20 additional horses. The amount of miles I do isn’t really a problem for adjustment as it’s no more than 1000 per year.

[absx2]

I have a 1972 on twin leading shoes and do not have a problem with them as I have been using them daily for 13 years and know their limitations in regards to heat build up.

I also have a 1967 cooper on the 7 inch discs and although you need to press them harder even with the correct 5/8 master cylinder they are quite impressive for the one emergency stop at speed you will get from them.

Drums have more low speed bite without a doubt but the discs pull up nice and straight every time but without the correct 5/8 master cylinder they are terrible.