Subject: [Healeys] Fwd: bugeye brake problem

From: mark henderson <[email-masked]>
Date: Thu, 31 Oct 2013 13:52:46 -0400

I have a rear brake issue with my '58 Sprite.   The Bugeye has the stock
.875" rear wheel cylinders and we have installed a 1967 Sprite/Midget
tandem master brake cylinder and front disc brakes. The problem is; we can
turn the rear brake drums by hand when the front brakes lock up. We have
sealed all leaks and bled the system thoroughly, no air remains in system.
We have adjusted rear brakes shoes as tight as possible. We backed off
pedal stop to try to increase piston travel in master cylinder. When we
bleed front brakes first then check rear brakes, drums are locked.

My summation is that the new master cylinder is not pushing enough fluid to
the rear brakes before the fronts lock up. When the front brakes lock, the
piston cannot go any further into the cylinder to push any more fluid to
the rear brakes. Bleeding the fronts first and then checking the rears are
locked seems to prove this. I have gone thru the math to see if the
original .875" cylinders require a lot more fluid than the .75" cylinders
of the 1967 Midget and they will require more volume of fluid to travel
equal distances but not a lot.

Short of replacing the rear brakes with later Midget/Sprite  backing plates
and wheel cylinders, does anyone know of another fix for this? Has anyone
done this swap before with only the tandem master cylinder and front disc
brakes swapped over. My old Lucas/Girling books show no wheel cylinder with
smaller bore that will fit the Bugeye backing plates. Thank you for any
thoughts.  Regards,  Mark
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From: Michael Salter <[email-masked]>
Date: Thu, 31 Oct 2013 14:32:57 -0400

Hi Mark,
I presume that you are using one of the in line master cylinders with the
plastic tank.
Based upon what you have said in your message I don't think you understand
the theory of operation of that master cylinder.
In short, if either the front or the rear system develops a leak those
master cylinders isolate the leaking system and allow the other to continue
operating.
If you are sure that air has been eliminated from both systems you need to
centralize the "shuttle" in order for both systems to operate.
To do this open one bleed screw and press down hard on the pedal, this will
push the shuttle to one end. Close the bleed screw.
Press down on the pedal then have an assistant slightly open a bleed screw
of the other system. Do this very slowly. You should feel a "bump" in the
pedal as fluid seeps out of the bleed screw and the "shuttle" centralizes,
release the pedal and close the bleed screw as soon as this occurs.
The idea is that you are moving the "floating" shuttle" to the mid
position. On the original systems there was a brake fail indicator light
which went out when the "shuttle" was centralized making this process a
little easier.

Hope that helps,

Michael S

On Thu, Oct 31, 2013 at 1:52 PM, mark henderson <[email-masked]
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From: Richard Ewald <[email-masked]>
Date: Thu, 31 Oct 2013 12:26:49 -0700

You have two choices.
Find smaller wheel cylinders that fit on the existing backing plates
or
Put the later backing plates on.
The master only moves so much fluid, and yours isn't moving enough.

On Thu, Oct 31, 2013 at 10:52 AM, mark henderson <
[email-masked]> wrote:

>  I have gone thru the math to see if the

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From: Chris Dimmock <[email-masked]>
Date: Fri, 1 Nov 2013 11:45:41 +1100

If you want to upgrade to disc brakes on a bugeye, you need to fit the rear
cylinders as well. And that means you need the rear brake backing plates. And
handbrake rods, as the cylinders are in a different location on a later
sprite.
How do I know? Been there, tried that.
You will also be in trouble with your clutch - the earlier cast one piece dual
master cylinder has different diameters to the later cast dual master
cylinder,for the clutch, as well as brake.
There is a guy who now machines the master cylinders with different diameters
for brake and clutch.
The only 'easy' way to upgrade the front brakes on a bugeye without changing
the rear cylinders/ backing plates, clutch etc is to use Austin A40 Farina 8
inch front drums. And add a brake Booster.
Try any Sprite email list for more info.
Best
Chris
Owned and raced a bugeye 1981 - 1995. With a40 farina drums on the front...

Sent from my iPhone

On 01/11/2013, at 4:52 AM, mark henderson <[email-masked]>
wrote:

> I have a rear brake issue with my '58 Sprite.
>
> _____________________________

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From: Charlie Baldwin <[email-masked]>
Date: Thu, 31 Oct 2013 21:22:43 -0400

Mark,
This website may help you:
http://www.gerardsgarage.com/Garage/Tech/DbrakeUg.htm
I don't have any Spridgets, but saw this as I do have an MGA with a dual 
cylinder.
Charlie

On 10/31/2013 1:52 PM, mark henderson wrote:
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