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MG Midget and Sprite Technical - Frogeye Disc Brakes

I'm in the middle of a ground up on my MkI Sprite and I've fitted disc brakes on the front and later drums to the rear. I couldn't source a 3/4" master cylinder, so I still have the Frogeye 7/8 piece. In looking through my parts bin, I found a number of 7/8 MCs - one from an MGA 1600. Is there a benefit/need (aside from more fluid capacity) to fitting the larger mga top cover to the Sprite MC now that the car has updated brakes?
Kemper

I don't think there's any real benefit to the larger top cover apart from appearance. The original reservoir has enough capacity for normal use, assuming you check the fluid now and again.

Disc brakes don't retract as far as drum brakes do, so discs require less fluid movement for each use. As disc pads wear, the fluid level in the reservoir drops, so it is possible you might run low on fluid if the pads wear out before you check the level.

I have the the later brakes on my Sprite, with the standard cover on the M/C and have had no problems.

- Bill
Bill Gavin

Many thanks, Bill. What's the pedal effort like? I've heard the 3/4 MC is better for disc cars. I have a 7/8 on my MGA with disc conversion and the pedal is heavy, but manageable. I'm assuming the Sprite will be the same.
Kemper

I use the 7/8 and I am very happy with the disk drum combination. Braking is much more under control, the effort is not like a modern car but stil effortless. I use 1144 pads.

Flip
Flip Brühl 948 frog 59

I have the 3/4" M/C in my car and find the effort is OK.

One of my friends had a 7/8" M/C in his Mk2 midget, and I liked the higher brake effort and the firmer pedal. The down side was the mismatch to the clutch slave cyl; his clutch worked OK, but had a very strange feel, especially around the friction point. My friend was used to the pedal, and didn't have a problem with it.

If your M/C still has a residual pressure valve fitted, it would be a good idea to remove it for use with disc brakes.

- Bill
Bill Gavin

This thread was discussed between 23/02/2011 and 24/02/2011

MG Midget and Sprite Technical index

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