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The monster MGB eating slave cylinders

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The monster MGB eating slave cylinders
#1
straat Avatar
straat Bill Waterstraat
Oak Lawn, IL, USA   USA
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1979 MG MGB
So I've been through two slave cylinders in the past three years. Replaced the first from Victoria B and realized that I should have replaced the whole system. Replaced the whole system and the first slave wore out with alot of wear from the piston on the inside of the cylinder. Then replaced the slave with one from Moss only to have it start shifting hard (but no grinding) after bout one year (700 miles). Went to bleed it and pulled the boot and stuck my finger inside only to find scraps of aluminum ( see photo).
Anybody experience a slave eating monster like I have??


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Re: The monster MGB eating slave cylinders
#2
mac townsend
Fairfield, CA, USA   USA
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1973 MG MGB MkIII
My uneducated guess would be that if you could stick your finger in there under the boot (which is outside the hydraulics), it wasn't into the hydraulic section (which should be sealed) and you are looking at a mechanical not hydraulic condition.

How that might play out, I dunno.

But I'd not think/worry about yanking the engine until I did know.

Of course a slave doesn't require that effort. …


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Re: The monster MGB eating slave cylinders
#3
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straat Bill Waterstraat
Oak Lawn, IL, USA   USA
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1979 MG MGB
You are correct Mac. The fluid coming out as I bled the system was clean. But as you can see, the small amount seeping past the seal shows lots of seal residue and aluminum.
I'm contemplating a sleeved cylinder but would first like to know why this is happening. I've had ten years of flawless clutch operation since the last major engine/transmission rebuild.

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Re: The monster MGB eating slave cylinders
#4
13401h Greg Mouritz
Mentone, Victoria, Australia   AUS
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Hi Bill,

Suggest you strip and clean the master cylinder and assemble with new rubbers. No point sending the accumulated gunk and grime from the M/cyl down to the next new slave cylinder.

Hope this helps.

Greg

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Re: The monster MGB eating slave cylinders
#5
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Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
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1972 MG MGB MkIII
Somehow you have to put more force on the pedal to get the clutch free as indicated in your post. This suggests something mechanical OUTSIDE the SC. Twice a SC going wrong on its wrong is statistically hardly likely eye rolling smiley

At least check the pushrod and clevis pin for excessive wear and feel the sideways play of the clutch fork. Anything beyond this will require hoisting the engine out sad smiley
If the carbon TO bearing is broken or the fork not completely straight, the clutch will also require more force, but one feels it in an uneven clutch function.

How many miles are there on the clock for your clutch assembly?

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Re: The monster MGB eating slave cylinders
#6
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riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
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1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
We are discussing a clutch slave cylinder I assume. winking smiley Some of these, (read: cheapo new ones) have aluminium pistons and do not seem to last long. The OE cylinders have a steel piston. I do not know if this the case but you may consider finding a good condition OE one and rebuilding it.

B


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about 1 week and 3 days later...
Re: The monster MGB eating slave cylinders
#7
straat Avatar
straat Bill Waterstraat
Oak Lawn, IL, USA   USA
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1979 MG MGB
Sorry Don,
Been out of touch for awhile. About 12K on the clutch assembly. Also, as the clutch slave moves through its range, I can hear a scrapping sound. I assumed it was the slave but now I'm wondering if its something in the fork assembly causing the noise.
Will look further into it.
Thanks for your help guys.

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Re: The monster MGB eating slave cylinders
#8
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Mustangsix Gold Member Jack Collins
Oviedo, FL, USA   USA
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1969 MG MGC GT
1973 MG MGB GT
A severely worn fork and pin can cause noise, extra friction and effort, and also alter the geometry slightly, placing more side forces on the piston.


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Re: The monster MGB eating slave cylinders
#9
ACE2 Robert Kinzey
Palm Bay, FL, USA   USA
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1970 MG MGB
I'd try coating the piston and rubber dust seal with a brake silicon lube to reduce moisture intrusion and friction. Also the pushrod/clevis pin may be worn and need attention to reduce side loading. A lot of the replacement rubber seals/boots for tie rod ends and rack bellows are garbage and probably for brake and clutch parts as well.

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