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Bleeping - I mean bleeding clutch

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JPSmit

JPSmit

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well, First I took the MC apart and checked - all looked good. Then I used the Duncan method - left the MC loose and filled filled filled. Reinstalled MC, reinstalled SC, everything flops around. It feels to me like the piston in the MC is not returning when you push the pedal. So,

1. Is this possible? and

2. If it is, can I assume I reassembled it wrong. Here's what it went together like.

Starting at the Clutch hose (to the slave cylinder) end.

First the spring - wide end first
then the plastic cap on the narrow end of the spring
then the rubber cup with the lip pointing to the clutch hose
then a spacer
then the piston
the rubber cup on the piston has its lip pointing in the opposite direction - facing the engine (this is where I am anxious)
the bar to the pedal
the circlip
the rubber cap

any thoughts?

thanks all
JP

PS I did rebuild it. so everything is new

PPS Trivia for the day - did you know that if you use air to extract the piston, not only does it fly ten feet through the air and leave a divot on the wall BUT you get to hunt for parts for 1/2 an hour also - don't ask me how I know.
 
I usually find the part 6 months later when I sweep up and move equipment. I had a clutch fork retainer clip (1991 BRG Miata) fly away at light speed and disappear... looked all over for it. Had ot go to a Mazda specialty salvage place 20 miles away to get a 2 dollar clip! Finished clutch job, and forgot all about the flying clip... found it 6 months later under my brake lathe!
 
JP, I think you have the order correct and the cups faceing the correct direction.
 
Sherman said:
I usually find the part 6 months later when I sweep up and move equipment.
Click to expand...

which brings me to a different observation - how many have installed black holes like mine under their workbenches? Not wanting to hijack my own thread but mine is Harbor Freight so it only works intermittently sometimes I actually find the part back.
 
jlaird said:
JP, I think you have the order correct and the cups faceing the correct direction.
Click to expand...

thanks Jack - any theories as to why it won't return?
 
My guess is you still have a lot air in there. Do you have the see-through style clutch hose. If so, get someone to pump the clutch while you look at the hose. You will be able to see the big air bubble moving back and forth.

The BL designers really gave it their all when they set out to design the most difficult to bleed clutch system in the world.
 
the problem is that when I move the clutch it doesn't seem to be moving anything at all. It's more like it's just flopping back and forth.
 
I vote for air in the line and slave cylinder. A lot of bleeding is in order. Best get a speed bleeder put some vacume on the bleed valve and suck it through.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]the problem is that when I move the clutch it doesn't seem to be moving anything at all. It's more like it's just flopping back and forth.[/QUOTE]

That's what it feels like when there's a big ol' air bubble in there. Get Mrs. Smit to pump the clutch for you while you watch everything. Then you'll know for sure if it's an air bubble or a mechanical issue.
 
tonights update. First off had my friend come and help set timing - hurray! 1976 Midgets are supposed to be 2 deg ATDC but we ended up at about 5 deg BTDC - sounded much better.

then the clutch. here's where we are at. took the master cylinder apart - cleaned it all again - turned the rubber around on the piston - Reiner helped me reason that the piston only pushes one way and then slides back therefore both cups should point the same way. Bench tested and everything worked fine. reinstalled it and started to bleed and suddenly the piston doesn't return any more. took it apart again. cleaned the resevoir even more, cleaned out the three tiny holes at the end of the piston and reinstalled. once again the piston doesn't return. even tried stretching the spring. it does seem to return when the bleed nipple is open but then stops. Reiner took it home to compare to his Lotus - but, any thoughts?

BTW went to a very nice all make show at the local Ford dealer - a goodly number of MGB's, Minis and a few Triumphs - no spridgets.
 
today's update.

yesterday spent about 4 hours on this #$%&^* thing. Reiner took the MC home, checked again - the inner cup broke - his Lotus kit is exactly the same - saved! even turned 40 thou off the plunger to make it move more easily. got it here and reinstalled etc. got a vacuum pump and away we went. currently, we left thinking it is bled. I won't be able to check till after today or tomorrow but the more I think, the less I think it is right. so, here is today's question.

what does your clutch feel like when you press it? Mine has nothing till about the last 3-4 inches when there is pressure. Is this normal or should there be pressure through the whole play of the clutch?
 
John-Peter:

It took me two months to get my rebuilt MC bled on my 1960 BE.

The culprit for me was DOT 5 synthetic brake fluid - it caused the rubber pieces to swell (causing the pistons to not return properly).

We had tried EVERYTHING, but after we completely drained the system, replaced the rubber part, and then went with DOT 3/4 the MC bled in a few minutes (and has been working ever since).

Mike Pennell
 
well that might be the problem then as I'm using DOT5 - but, now the piston seems to work - can you describe what your clutch feels like when you push it?
 
You should feel back pressure through out the travel of the clutch.
 
Yes, I do feel back pressure throughout the entire travel of the clutch. It does shift very well.

John-Peter: I reiterate - we tried EVERYTHING from Mitivac on down and was only able to get pressure on the brakes. I took it to a local expert (Ross' Restorations in Tennessee) who ultimately determined that the rubber parts were occassionally sticking. He said they never use DOT5 on his restorations, despite the fact it does not eat paint.

We fixed ours in April and have been driving it ever since.

Mike Pennell
 
JPSmit said:
today's update. (...) What does your clutch feel like when you press it? Mine has nothing till about the last 3-4 inches when there is pressure. Is this normal or should there be pressure through the whole play of the clutch?
Click to expand...

Once you've got it bled right, you should have constant resistance, and a nice smooth pickup in the bottom half of travel, pretty much like a modern clutch (but with a slightly heavier feel.)
 
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