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Re: premature hydraulic failure (clutch)

To: Allen Nugent <A.Nugent@unsw.edu.au>, triumphs@Autox.Team.Net
Subject: Re: premature hydraulic failure (clutch)
From: Atwell Haines <carbuff@scooter.net>
Date: Thu, 19 Mar 1998 09:32:41 -0500
At 01:20 PM 3/19/98 +1100, Allen Nugent wrote:

>
>My TR7 clutch hydraulics have failed, only 2 years since I rebuilt them.
>Naturally, I want to know why. I have the following suspects:
>
>1. The fluid was contaminated, and had changed from dark green to dark grey.
>Does this sound like engine oil?

No way is it engine oil.  Most likely contaminants from the hydraulic
cylinders or seals.
>
>2. I previously replaced the slave cylinder with a recon'd unit. This had
>been honed, and I objected (Haynes and factory manuals warn against honing
>them); I was told that they (TR Spares) trusted the judgement of the guy who
>rebuilds the things for them. Has anyone else had trouble with a honed slave
>(or master) cyclinder?

I have honed mine, no problems for 2 years.   The reason honing is not
recommended is that anything that enlarges the bores results in a less
positive seal by the rubber inside the cylinders.   Residual "roughness"
can shorten the life of the new rubber inside.  Early failure can
result...as you may have learned.
>
>3. The rubber boot on the back of the slave cylinder had a small tear at the
>hole that the rod exits through. There is oil leaking at the back of the
>engine, and some gets onto the exterior of the slave cylinder. Could the oil
>get onto the shaft (either from the mounting hole on the transmission plate,
>or elsewhere from within the bell housing) run up the shaft, past the piston
>and onto the internal rubber seal?

IMHO not very likely, practically speaking.
>
>I'm going to assume 3. is correct, and try to modify the rubber boot by
>building-up the seal around the hole with silastic. (I have to figure out
>what to coat the rod with so the silastic doesn't stick to it.) I'm also
>going to put brake grease on the rod, and maybe silastic on the joint
>between the cylinder and the transmission plate.

If you rebuild/replace the slave again, a new seal should come with it.
>
>I'm not sure if I should assume 2. is a problem, and get the thing sleeved.
>(If I do, I guess I'll sleeve the master at the same time.)

Good idea.

My hone job was just to smooth the bores of the master & slave cylinders
after re-doing my clutch system (in other words, shipwright's disease).
Getting the insides of the bores very smooth is critical...without taking
any more metal thickness off than is neccessary.
>
>I'll be grateful for your comments & advice. Thanks.


You're welcome!


Atwell Haines
'79 Spitfire  FM96062 UO (On the road soon!)

Succasunna, NJ USA
"Now that cars are better, why do they keep lowering the speed limits?"

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