Brake bleeding experience

[Ceejay 72]

Having made and fitted the PDWA immobilising tool, we bled the brakes yesterday.
My wife noted that when bleeding the rear circuit, the brake pedal only travelled half way to the floor, whereas when bleeding the front, it went all the way to the floor. Is there any reason for this?
Also, I noted that the rear circuit was being fed fluid from the front part of the reservoir and the front circuit was fed from the rear section, so it looks as if someone connected the circuits back to front at the master cylinder compared with what the manual says. Is this likely to be a problem? The brakes perform perfectly well as it is.
Thanks,
Chris

[Lingen]

C.J.
The pipes are connected correctly. The front part of the cylinder supplies the rear brakes, and vice versa. The pedal travel is also normal. Once both parts of the master cylinder have been bled of air, the pressure at the rear will operate the front one. That is why the front brakes should be bled first. If that hasn't been done,then the pedal has to travel much further.
Mike.

[Ceejay 72]

Thanks Mike. My misunderstanding about the pipe connections came from the Brooklands manual, which is clearly wrong, now I have looked at the ROM!
Your comment about the order of bleeding is interesting - why in that case does the ROM say to bleed the rear brakes first?
Chris

[Phil S]

always start with the shortest pipe then work to the longest when bleeding brakes.
was taught that way ## years ago, it stops air bubbles being created by pumping fluid back and forth in the long pipes if you try them first. many manufacturers use a vacuum or pressure bleed that dose not need the pedal to be pumped, so they can bleed the longest first

[Rod1883]

That's the exact opposite to what I always thought Phil - I always start with the longest run....

[DJT]

I was taught to always start with the longest pipe too. I was watching a classic car programme on TV the other day and a well-respected mechanic said the same. I guess with the Stag front/rear split, it doesn’t make much difference as the master cylinder is sectioned too.

[MandM]

I was taught to always start with the longest pipe too. I was watching a classic car programme on TV the other day and a well-respected mechanic said the same. I guess with the Stag front/rear split, it doesn’t make much difference as the master cylinder is sectioned too.

+2

[Lingen]

CJ. I tend to agree that with a split braking system it isn't going to make much difference which end you bleed first. However, if you are starting with a dry master cylinder I would start with the front brakes first,
(rear cylinder) because as I wrote earlier, it will allow that cylinder to properly operate the front cylinder (rear brakes) when you come to bleed them.
If anyone happens to have a Haynes manual for the Stag., have a look at page 111 re the master cylinder. Its operation is well described but they have got the front/rear cylinders reversed as well.!
It's probably a bit late to tell them now!
Mike.