bleeding again

After the trial with my new clutch slave cylinder, I have decided to bleed fresh fluid into the brake system. More problems. After reading several authorities which suggested the normal procedures, I discovered that on the 1979 Spider with the dual mastercylinder, you have to bleed the right front and right rear, TOGETHER. They suggest two bottles and hoses with fluid in bottles and the hose submerged so that air will not be sucked back into the system.
After gathering half a basketball team I tried it and found that pressing the petal pushs fluid out but sucks it right back in when you let it up. I have made a home made pressure bleeder, but reading had suggested that you cannot use this with a plastic resavoir as it will break it. The vacum system won't work as I only have one of them. Seemingly my only method that might work is pressure bleeding from the bottom, which incidently was the only thing that worked on the clutch slave cylinder. If I do this, will the fluid go all the way to the master cylinder if the petal is in the upright position? Will it work on one caliper, or will I need two pressure bleeders? It sure isn't like bleeding my old 50 Merc coupe. Things get more complicated as I get older and less able to understand them. Thank the Lord for this site and all you help. Any opinions would be appreciated. Catch

Why would pressure bleeding break the reservoir?. If you use a traditional eezibleed system powered from a tyre the pressure is not a problem to a plastic reservoir.
Mind you i'm not saying it will work, single systems on these cars are hard enough, but the dual circuit must be a real nightmare.

I am not sure that it would break the plastic res. You may be correct, but some of the authorities I read cautioned against it. I suppose it might be that if there was some constriction in the lines it would build pressure in the master cyl. plastic res and crack or break it. The question I guess is still can you go from the bottom and inject the brake fluid from below and alleviate the possible problem, (as I did with the slave clutch system), and also do each wheel by itself? You would also not have to have the special cap to fit each master cyl that you were servicing.

Question,
is your spider left hand drive with master cylinder on servo under bonnet or right hand drive with master cylinder under floor?
I used to bleed underfloor units with two helpers but when pedal was down we used to close the bleed screws again before lifting pedal. It always seemed to work.

It is a right hand drive with the master cyl under the hood. Some printed authorites led me to believe that you could just keep pumping if you had a hose on the bleeder screw and it led into a container with the hose submerged in brake fluid. It just didn't work out that way. You are right about closing the bleeders before you let the petal up. I was hoping to use pressure from the bottom so I could 1. eliminate one helper. 2. not have to continually open and shut the bleeder valve. Thanks guys for the help, Catch

Originally Posted by Catch

It is a right hand drive with the master cyl under the hood.

Is it?
That's unusual!
Do your brake and clutch pedals hang down from the bulkhead or come up from the floor?

Most RHDs have the master cylinder under the floor with floor mounted pedals and only the reservoir and servo(es) under the bonnet.

If you have twin servoes I also think you need to bleed the system with the engine running - I'm not 100% sure of that as thankfully I don't have them but it's worth checking. Good luck!

I am sorry Rick, I told you wrong it is a LEFT hand drive, with a two stage master cylinder. I finished bleeding and replacing all the old fluid yesterday. I used a vaccum bleeder attached to a small vac pump.
It worked very well, and I didn't have to touch the brake petal. I started on the right rear and worked my way to the others and had new fluid and plenty of brakes when I got done. Thanks again.