88' Brake issues

[stonefox]

Having trouble bleeding the brake system on my 88'. Simple procedure just can't get any real pedal. It seems to be air in the lines and not the MC malfunctioning because I clamped the front and rear and got a rock solid pedal. If I clamp the rear lines I get about half pedal and about 3/4 on a second pump. With them all unclamped I have little to no pedal on the first and about 1/2 on the second pump. Now I've done the procedure by the Bible and at this point getting no more air from the bleeders. I've pushed all most three 12 oz bottles threw it thinking there is still some lingering air ...no luck .Three bottles should have done it right? Oh Yes , all brake parts are new shoes, drums, lines, wheel cylinders, but not the MC .
Thanks for any thoughts

[bkreutz]

Check your brake shoe adjustment, when the pedal pumps up it usually means it's taking more than a full stroke of the master cylinder to get the shoes to contact the drums.

[stonefox]

Thanks for the reply Gale.I thought of that but the manual states "Completely slacken off each brake shoe adjuster on all four wheels , to minimise the wheel cylider volume" then on to say commence bleeding.Are you saying the adjusters should be set before you bleed them? Sean

[NickDawson]

your clamping idea seems like an interesting troubleshooting technique...
could you start moving the clamp(s) along the system and see where you lose pressure? I wonder if it is not the flex hoses or a minor leak somewhere?

[bkreutz]

Thanks for the reply Gale.I thought of that but the manual states "Completely slacken off each brake shoe adjuster on all four wheels , to minimise the wheel cylider volume" then on to say commence bleeding.Are you saying the adjusters should be set before you bleed them? Sean

Never heard of that method, seems counter intuitive, slackening the adjusters would increase the volume (if it changed it at all) but it wouldn't affect the bleeding procedure, but you have to readjust them before determining if you have a good pedal, otherwise the pistons in the wheel cylinders have too far to move. The hard pedal occurs when the pistons stop moving (shoes contacting the drum) Blocking off the hoses are a good way to isolate brake pressure problems, I usually use it to determine which end (or wheel) the problem area is. I'm thinking that your pedal will be normal after adjusting the brakes back to normal.

[LaneRover]

Never heard of that method, seems counter intuitive, slackening the adjusters would increase the volume (if it changed it at all) but it wouldn't affect the bleeding procedure, but you have to readjust them before determining if you have a good pedal, otherwise the pistons in the wheel cylinders have too far to move. The hard pedal occurs when the pistons stop moving (shoes contacting the drum) Blocking off the hoses are a good way to isolate brake pressure problems, I usually use it to determine which end (or wheel) the problem area is. I'm thinking that your pedal will be normal after adjusting the brakes back to normal.

I second the readjusting after you have bled the brakes to get a good pedal. If you don't then the brakes are quite 'far' from the drum and that distance needs to be made up before the brakes start working.

[jac04]

Never heard of that method, seems counter intuitive, slackening the adjusters would increase the volume...

As Sean stated, it is the method per the factory manual. Slackening the adjusters will definitely decrease the system volume, since the shoes will move away from the drums, pushing in the wheel cylinder pistons = less fluid volume = easier to get all the air removed from the system.

So, slacken the adjusters, bleed the brakes, then go back and use the adjusters to properly adjust the shoes. Then press the pedal and see how it feels.

By the way, are these 10" or 11" front brakes? The 11" brakes can be a real PITA to bleed and there are a few 'tricks' to bleed them.

[bkreutz]

As Sean stated, it is the method per the factory manual. Slackening the adjusters will definitely decrease the system volume, since the shoes will move away from the drums, pushing in the wheel cylinder pistons = less fluid volume = easier to get all the air removed from the system.

So, slacken the adjusters, bleed the brakes, then go back and use the adjusters to properly adjust the shoes. Then press the pedal and see how it feels.

By the way, are these 10" or 11" front brakes? The 11" brakes can be a real PITA to bleed and there are a few 'tricks' to bleed them.

Ooops, my mind must be getting dyslexic, Got that one backwards. But then I've never changed the adjustment for bleeding purposes. (but I've been using a power bleeder for over 20 years)

[stonefox]

Mission Complete

Thanks fella's . "Nigel" is up and running with good brakes.
God I love driving these machines.I can't help but get a huge smile every time I'm behind the wheel.

[jac04]

... with good brakes.

Good news. So, what solved your brake problem? It's always nice to have a follow-up so when others have a similar issue they know a potential solution.

[stonefox]

Once they were bleed I just adjusted then up,and walla.Kind of feel like a idiot ,once bkreutz mentioned the adjuster a light when off and I went to the shop and had them up in a jiffy.Thanks everyone for your input