S outer CV and drive Flange to fit drum Brakes

[rpb203]

Hopefully someone has tried this before and has an easy answer?!
I have a plastic fantastic car with an engine in the back, the drive shafts have the small outer CV joint and drive flange, as per drum braked cars.
I want to upgrade the outer CV and the drive flange to the larger S/GT type, but retain the drum brakes on the car, for hand brake issues more than anything else.

Anyone done this before and how easy was it?
I assume that its mainly a case of getting the drive flanges machined to suite the inside of the drum?
Cheers
Gary

[rich@minispares.com]

you can do this as it has been done on gtm's, but its quite a fiddle to do

they do it on the high powered stuff as the drum cvs break so easy

[rpb203]

Thanks Rich,
Thought that it must have been done before, car originally had a 998 engine and box, but if I go down the S route didn't fancy possibly putting it all through the small CV's and drive flanges.

Fancy the idea of discs all round but the hand brake could be a bit of an obstacle.

[Matt_Tupman]

If I had ever finished my GTM I was going to use these on the rear along with a set of standard discs.

http://www.rallydesign.co.uk/product_in ... ts_id=8312

May be an easier option to the machining? Plus better rear brakes.

[rich@minispares.com]

Thanks Rich,
Thought that it must have been done before, car originally had a 998 engine and box, but if I go down the S route didn't fancy possibly putting it all through the small CV's and drive flanges.

Fancy the idea of discs all round but the hand brake could be a bit of an obstacle.

gtm did a rear caliper that had a handbrake attachment so you could go the disc route

I wish I had gone this route with mine as the std drums and small cvs are right on the limit

[rich@minispares.com]

http://www.gtmdrivers.com/forum/disc-cv ... -t970.html

[rpb203]

Thanks for the feedback from all.
Really appreciated and will have a good read through, trying to keep to 10" wheels where possible, although the width of the wheels not a huge issue within reason, so that may be a bit of a stumbling block.

[mk1]

It would make far more sense to me fitting S Disks with a handbrake mod than faffing about converting drums to work with big CVs.

[rpb203]

Hello Mark, wouldn't disagree with that, just want to see what the options are.
Cheers
Gary

[mk1]

Always good to look at all options before starting to do the work.

[rich@minispares.com]

the problem with fitting s discs to a lot of 1960's kit cars is that they where not designed for it, so the wheels then stick out the arches.

this is why you have to mess around with other options, plus the big cv in the drum conversion is quite neat as its fairly cheap when compared to buying the gtm hand brake calipers (which only fit on 8.4" brakes) - plus, ive never seen a conversion that will take a 7.5 inch disc and a proper handbrake .

its an interesting conundrum

the biggest issue I have found on my gtm is that as you have to 'push' the rear shoes off with the stiff handbrake cables, so if you dont make sure that the handbrake is all the way off the shoes rub and then when you press the brake pedal it goes to the floor..

I have learnt that you have to leave every thing far slacker than you would on a mini to make sure that there is plenty off free play when the brakes are off

[rpb203]

Thanks Rich,
It's actually for a Unipower, the rear drums and handbrake are already as existing, (well sort of as the car is in a hell of a state!), but the thoughts are to possibly change the engine from 998cc to S, and not sure if I would trust the smaller CV's.

Noted about making sure that the handbrake is fully off, although the Unipower has separate master cylinders for the front and back so I suppose there must be some way to have a hand lever of some form to operate the rear master cylinder if discs were to be used instead of drums.
Again thanks for the input.

[ianh1968]

There must be some way to have a hand lever of some form to operate the rear master cylinder if discs were to be used instead of drums.

Is there any reason why you could not have two master cylinders pressurising the rear system?

Some kind of small additional one off a motorcycle, perhaps? The pull motion from the original handbrake lever would need
putting through a pivot to make it "push"... I'm thinking like the kind of mechanism that you might have on an "up-and-over"
garage door. You could even experiment with the "gearing" of it by having unequal length arms either side of the pivot point...

You can buy hydraulic handbrake assemblies, but the ones I have seen have been the "fly-off" type.
Using the above concept would retain the ability to leave the brake on for parking, as per normal
road usage.

Ian

[smithyrc30]

There must be some way to have a hand lever of some form to operate the rear master cylinder if discs were to be used instead of drums.

Is there any reason why you could not have two master cylinders pressurising the rear system?
Ian

How would you pressurise it?
When the foot brake is released the master cylinder fluid reservoir is connected to the piston (so additional fluid can get into the brake circuits as the pads/shoes wear).
If you added an additional cylinder that applied a pressure for parking, all the fluid from that system would go back to the foot brake reservoir.
Also when you applied the foot brake the same thing would happen to the 'park brake' reservoir.
You cannot add one way valves into the pressure circuits because the brakes would never release.
Adding them between the reservoir and the master cylinder would work but would be fiendishly difficult and make changing pads and shoes a nightmare.

There are calipers available with a mechanical link that pushes onto the caliper mechanism but whether they would fit under a 10" wheel is debatable.
An alternative is to mount a separate caliper onto the disc and use that for parking if a disc is used.

Some Australian S drums have solid spacers rather than voided ones.
It might be possible to machine these to fit over the standard S flange so the drum sat in the correct place on the shoes.
I'm not sure of the diameter of an S flange so cannot check.

[Spider]

I'd suggest fitting Discs (I wouldn't even look at Drums), have a look at Rear Calipers from the likes of Honda and Toyota, though you need to be mindful of Brake Balance, but that's not at all insurmountable.

I've done a number of Rear Disc Conversions, mainly to get lower maintenance Brakes and a decent Handbrake, though, those I have done have been for bigger than 10" wheels, but I'm sure you could get one of those calipers I've mentioned in there. These have both Hydraulic for the foot pedal bit and mechanical for the handbrake bit and they auto adjust, as Discs normally would. Note that with any floating caliper, you'll need to use sheathed handbrake cables. Open ones will only make the caliper jam on the slides and likely damage them in time.

[rich@minispares.com]

don't forget that hydraulic handbrakes are not legal for road use in the UK, so you would have to use a cable (or one of those new fangled electric things?)

the other thing to consider about the strength of the small c.vs is that they are not turning, so are not getting the hammer that they would on the front, the gtm boys who have the problems with them are the guys who are drag racing etc, so its the shock loads with sticky tyres that breaks the cages

[ianh1968]

<SNIP>secondary hand-brake master....<SNIP>

How would you pressurise it?
When the foot brake is released the master cylinder fluid reservoir is connected to the piston
(so additional fluid can get into the brake circuits as the pads/shoes wear).
If you added an additional cylinder that applied a pressure for parking, all the fluid from that
system would go back to the foot brake reservoir.
Also when you applied the foot brake the same thing would happen to the 'park brake' reservoir.

Having looked closely at cutaway diagrams of a couple of master cylinders, I can now
see the problem with my theory...


What confuses me now is how the "hydraulic handbrake" systems that are available
do actually work - You've got to assume they do, or such things would not be sold.
Perhaps they are used on multi-piston/multi-feed calipers, thus achieving the necessary
isolation between hand/foot actuation?

Ian

[smithyrc30]

What confuses me now is how the "hydraulic handbrake" systems that are available
do actually work - You've got to assume they do, or such things would not be sold.
Perhaps they are used on multi-piston/multi-feed calipers, thus achieving the necessary
isolation between hand/foot actuation?

Ian

The ones I have seen either have a two piston floating caliper design, where one piston is used for the foot brake and one for the park brake.The mechanism is complicated and is susceptible to jamming.
However the majority are separate circuit (fixed caliper with 4 pistons) and one circuit for foot and the other for park.

There is also the completely separate caliper.

In order to get around the no hydraulic park brake rule (which I don't understand really, we have hydraulic foot brakes so not sure why a park brake would be any more likely to fail than the foot brake which gets used much more often) these are generally cable operated.

Cars I can think of with separate cable calipers though are fairly rare. Metro 6R4, Ford RS200, Lancia Delta S4. Less exotic but still relatively rare is the Jaguar Type R cars with the Brembo brakes. There are others though....

The 6R4 and RS200 had the same AP racing caliper (when sold as a road car) which is now no longer made. The last pair I saw for sale on evil bay were at UKP1000.

My old Lancia Delta turbo had a integrated caliper on the rear with a cable operated park brake. I don't think this would fit under a mini 10" wheel though.

[minimans]

I dont see the need for an integrated caliper, there are plenty of mechanical brake calipers out there from Go Karts, aircraft, ride on lawn mowers it would be far easier to mount a small caliper opposite the hydraulic caliper and cable operate that.........Just my personal opinion though. Me I would just keep the drums unless I was going to race it, I can't see you breaking the CV as has been said there's no turning movement for them to cope with.

[Spider]

This is the Honda Calliper I mentioned earlier



One Calliper, two bolts to fit up, has Hydraulic for the foot brake and Mechanical for the hand brake. Done a few with these.