[Mgs] MGB rear brake questions

Max Heim mvheim at sonic.net
Sat Oct 23 11:23:50 MDT 2021


I don't really have any answers, I can just confirm that wheel cylinders are a part which has been “down-qualitied” to the point that they are scarcely serviceable. The offshore manufacturers seem to have settled on the tiniest possible bleeders, often with 7mm hexes — a size so small that it is not included in most wrench sets, and which offers almost zero resistance to rounding.

Next time I am going to try rebuilding the cylinders instead. If they have been driven at all they usually don’t need honing — just new seals.

As for the vacuum bleeder, I don’t know what the bleeder fittings in your kit look like, but maybe you could just substitute a different size hose? It has to seal well or it won’t work. In the past I have cobbled up adapters using metal tubes, different sizes of hose and hose clamps.

Good luck.

--
Max Heim
'66 MGB

> On Oct 23, 2021, at 10:04 AM, wkilleffer at epbfi.com wrote:
> 
> Hello everyone,
> 
> The car I'm working on is a 1974 MGB roadster. I decided that I wanted to replace everything relating to the brakes and their hydraulics except for the metal lines. I ordered the parts from Moss but had to sit on them for a couple of years before actually starting the project.
> 
> So, I got the new master cylinder installed, which is probably one of the more challenging things I've ever done on the car. Next step was working on the rear brakes. The rubber hose in the back was pretty simple, but the issue is with the wheel cylinders. I replaced them maybe twenty years ago and didn't have any trouble. But these new ones have a roller pin on them that doesn't line up with the holes on the brake's backing plate. It's been too long to try and swap them with Moss, and I'm not sure that would do any good anyway because I don't recall that there were too many choices for that part. You could get a cheaper aftermarket or a more expensive part that may be made in England. I went with the cheaper one.
> 
> Has this been an issue for anyone else? I could probably drill another hole in the back plate to match the roll pin, but that seems like one of those DPO solutions. Also, I don't feel like I should have to entertain such a notion anyway. The part should fit and function correctly. The current wheel cylinders are probably ok to re-use, but I liked the idea of all new parts. The front brakes are also on the agenda, but we're not there yet.
> 
> The next question has to do with bleeding the rear brakes. I started to bleed the brake furthest from the MC using a vacuum tool I got at a well-known less expensive (think shipping at a port) tool store. It's been a letdown for several reasons, among them that the bleeders on the wheel cylinders seem too small for the bleeder fittings that came with the tool, which causes the tool to draw a great deal of air through its system. I seemed to barely be able to get any fluid through the system. The trouble I have is that I am single and live alone, so I don't have any readily available sources of help. If the brakes are going to be bled, I have to do them by myself. Does anyone have any advice on this topic?
> 
> Thank you,
> -William
> 1974 MGB
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