I'm thinking about converting my Longbridge model from a single to a dual circuit brake system.

Does anyone have any advice?

Is there an alternative master cylinder to the expensive Healey one?

Would it also be necessary to instal a brake servo?

Any help/advice would be useful

That's a very good idea; if I was to embark on such a project, I'd start with an MGB master cylinder circa 1968-1974 US-spec (w/out servo).

Similarly, the one for a US-spec MGC, but I'll bet it costs an arm & a leg (maybe both arms...).

Naturally, there'd be Asian units available, but it might be harder to determine individual bore sizes, plus the need for Metric pipe connections.

Hello higgins, I did it to a BN1 back in the early 1980's. I used 2 3000 type master cylinders with BN1 type reservoirs. Obviously a 6 cylinder car is different from a 4 cylinder car but it is possible. DWR has a dual circuit system available.
Best regards,
bundyrum.

Higgins -

I replaced the stock Girling system on my '57 Longbridge 100-6 MM
racer with this Wilwood dual-circuit system. It was a direct replacement, no cutting or fabrication needed, just run an addition brake line. I have 4-wheel disc with a bias valve and this system works well under race conditions.

http://www.hrpworld.com/client_images/ecommerce/client_39/products/pdf_5232_1.pdf

Dougie

Dougie, would you set it up any differently if you were still running rear drums (and 3000 MKI fr discs); would you still want to plumb in an adjustable bias valve?

I'm going to hope that master cylinder in your link will fit my car, as I narrowed the LH scuttle brace right up to the edge of the original m/c, so I could fit a 1-3/4" air filter on the 3rd 45DCOE.

Higgins, thanks for getting the ball rolling, as this is a very practical upgrade.

Hello Randy Forbes, if you're fitting the dual circuit system having the adjustable bias valve would be good. Discs generally need a greater line pressure and because of this you would overcome the pressure needed for the rear drums and end up with the drums working (ie locking) and yet the discs would not. For a street car the other way of doing it is to reduce the rear lining area but this is done with a lot of testing. Basically you start by having your brake shoes relined with material all the way along the shoe. Then you reduce the length by removing say 1/2 inch of lining material from each end on all 4 shoes till you get a happy balance (meaning the rear wheels don't lock up anymore). This is a lot of work but if you like doing this kind of thing it can be interesting.
Best regards,
bundyrum.

Randy - I would still run a bias for the same reason stated by Bundyrum above. It was an easy install the small dial on the valve enters just behind the front passengers seat.

Dougie

Thanks guys, I am going to move this to the top of my "to do" list.

I've driven cars where the brakes have failed before, but I was much younger, and I suspect my reflexes were a tad faster then too...