Rear Wheel Brake Cylinders on ERA

Any Technical Queries? This is the place to ask/give advice.
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kayball
Posts: 51
Joined: Sat Feb 03, 2007 7:11 pm

Rear Wheel Brake Cylinders on ERA

Post by kayball » Fri Jun 08, 2007 7:44 pm

Just discovered interesting things about the brakes on the ERA :o Whilst carrying out a pre-MOT on our ERA (R1031). I was annoyed to find that the nearside rear brake drum was binding. With the hanbrake fully on, however, it would still not lock the wheel. Backed off the adjuster, but still binding so, with difficulty, removed the drum, . Found that the wheel cylinder had seized solid in a slightly expanded position - don't understand how this occured :? Even using a long bar as a lever in either piston groove I was unable to turn a piston, or fully retract either with G-Clamp. Hence the binding.

Now to the main point of this posting. I checked the Microfiche, under 'Technical', for the correct rear cylinder and noted that the Rover part number for the very last ERA's was GWC 1131, but the earlier cars show an ERA part number, which we cannot cross reference. However, the stated Rover number was also given by a MiniSpares brake data sheet in an old parts list. In fact, it transpires that this cylinder was also used on one other Mini, the 1977/1978 Mini 850/998 with diagonal split brake system. The bore is given as 0.5625 in, which is much smaller than the usual cylinder size of 0.75 in, and will therefore require more pedal pressure to lock the back wheels.
I was still a bit sceptical that this was the correct cylinder, but ordered two equivalents from the local factor. On receipt, I immediately thought they were wrong, as they are fitted with large, 10mm, bleed nipple (Like the front calipers.) but the fitted rear cylinders had the small nipple, like all Minis I have ever worked on.
On reflection, I remembered that there was a works drawing of the ERA Rear Back Plate, showing modifications to the standard 'City' item. On checking, this drawing shows the original bleed nipple hole enlarged to 10.3mm and elongated downwards and the cylinder locating pin hole was also elongated downwards. To cut a long story short, when I removed the defective cylinder I found that the back plates had been modified as per the drawing and the new cylinder fitted perfectly :D . New shoes completed the refurb and the brakes are now fine.
For your information, the equivalent cylinders are made by at least two manufacturers, since the demise of Lockeed AP. and these are Brake Engineering, with the part number WC4415 (made in Italy) or Quinton Hazel under part number BWC 3099. I see that Moss and Mini Spares list them under the Rover part number, but without disclosing the make. (You pays your money and makes your choice!)
Since these cylinders are not normaly associated with a Mini I would advise that you all take a quick look behind the rear wheels, to see if a large bleed nipple is fitted. I doubt if many ERA's are still fitted with the original cylinders, so the odds are that they may have been fitted with incorrect items. Please check, as the brake balance will be upset by using the larger bore items. Please give feedback on this forum as to what you find fitted.
Best regards.
Pete K

kayball
Posts: 51
Joined: Sat Feb 03, 2007 7:11 pm

Re: Rear Wheel Brake Cylinders on ERA

Post by kayball » Mon May 28, 2012 5:43 pm

Further to my earlier posting on this subject, I have just stumblesd across an article on the MiniSpares website concerning rear brake balancing.
http://www.minispares.com/Articles.aspx?ty=ad&aid=127

This article by Keith Calver is very informative, reccommends the original ERA rear brake cylinders (GWC 1131) and gives a work around alternative to the Brake Pressure Reducing valve if yours is not working
or un-obtainable.
Well worth a read in my humble opinion.
Pete K

loe 2
Posts: 14
Joined: Sun Jan 24, 2010 1:19 pm

Re: Rear Wheel Brake Cylinders on ERA

Post by loe 2 » Sat Jun 02, 2012 9:27 pm

very interesting thanks for pointing this out.

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