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MG Midget and Sprite Technical - brake info needed

So now i've found a good(cheap) brake parts suplyer( compbrake.co.uk )
And have got a spare pedal box (combined MC) I can finaly start my conversion to twin brake cylinder's

But it now has the combined 3/4" mc to keep all pressures in the same ballpark i need to know the diameters of the caliper cups and the rear cylinders.

Then i can calculate the relation of the mc bore to brake bore and try to keep it the same when i seperate front and back.

so who knows the diameters for a std "66 midget?

Onno Könemann

Onno, don't know the diameter of the rear cylinders, but I believe that the master cylinder should still be 3/4" bore. That's what all I've seen converted to dual cylinders use such as the setup in the photo. Also uses a 3/4" cylinder for the clutch master as well.


Bill Young

i did hear something like that

But i just do not think that using the same bore for front and back (witch have verry different bores)is the best solution.
Certainly not if you want to keep the hydrolic and pedal pressure in the same ballpark as they where.

for the clutch i will indeed be using a 3/4"bore MC

The planned setup will indeed look like the pic you posted.
But than with the early pedal box so i dont have to cut my midget up
Onno Könemann

M*ss list the same rear wheel cylinder for disk-braked 1098 and 1275 as GWC1102, which is 19mm diameter IIRC.
Dave O'Neill 2

indeed all discbraked models are the same (apart from the mc)

so that is 19 mm for the rears thanks
Onno Könemann

Not quite 'all' disk-braked models. The 1500 had smaller rear wheel cylinders.
Dave O'Neill 2

And then 19mm equals "drie streepje vier", right Onno?
Alex G Matla

Onno - do you intend to run adjustable front/rear bias on your pedal box (as the pictured set up)? If so I would be inclined to use the same bore master cylinders and use the adjustment for bias... In fact I did exactly that on my previous race car and it worked nicely.

J
James Bilsland

James i indeed intend to fit a bias bar to adjust the front to rear balance.

so i might have to follow my own advice (kiss) and keep it simple and go for 3 3/4" mc's

makes life easyer in maintenance as well

What brake setup did you run on the racer?
and how was the pedal pressure?
Onno Könemann

I had a Wilwood pedal box with 3 3/4" master cylinders with a driver adjustable bias knob - the brakes were Wilwood 4 pot dynalite calipers onto 2.8i Ford Capri vented discs with standard Midget brakes on the rear. I wound the bias knob so as to give about 60/40 bias to the front IIRC.

I can't really comment on pedal pressure as I always hit the pedal as hard as I bl**dy well can when racing... ;). It all worked well however!

I still have the pedal box and intend to fit it to my current racer in the fullness of time...

Cheers

James
James Bilsland

I run 0.625 front and 0.7 rear master cyls on my racer with a wilwood type box. It gives a little bit of movement as I found that a 0.75 and 0.7 was too firm. Use 0.75 on the clutch.

If you wanted to keep it simple go for 0.625s on both front and rear.

Cheers

Mark
Mark Turner

ha great i knew there was more to it!
are you running std front calipers?
Onno Könemann

This thread was discussed between 30/12/2009 and 02/01/2010

MG Midget and Sprite Technical index

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