the RV8 clutch master and slave cylinders
Peter Garton (Woodcote Green 1238) from Germany provides a useful
guide to maintaining the clutch master and slave cylinders. (Aug
When the clutch pedal suddenly goes partially to the floor, two
culprits are the usual cause, namely: the master cylinder or the
slave cylinder. Repair kits and new units for both master and slave
cylinders are readily available from sources such as Brown &
Gammons, Clive Wheatley or Past Parts so the job is one of diligent
Step one is to go for the slave cylinder under the car
When one takes the slave cylinder apart there is little to discern,
but when one looks carefully into the cylinder itself, there is
often a slight uneven ridge felt by one's finger about 1 inch down
- see photo! In my case it was caused by rust which had formed whilst
the car was standing unused for many months in Japan. Looking very
carefully at the plunger/piston assembly one can see that the seal
is not perfectly round and has been deformed by friction with the
rust line. These defects will allow fluid to leak past the seals
when under pressure during the operation of the brakes so that the
clutch pedal will go down floorwards without proper function. The
repair kit completes the repair!
two is to check the master cylinder
The master cylinder, visible from under the bonnet just above the
steering column, is a second cause for concern because of disintegrating
seals. A telltale sign that something is not right, is a black residue
on the surface of the brake fluid when one unscrews the top cap.
As can be seen from the photo, the small end seal has clearly deteriorated.
The piston also needs to be cleaned and polished to remove the microscopic
layer of stain covering 80% of the surface. Here again the repair
kit completes the repair!
problem occurs, it is wise to go for the two above items and overhaul
both at the same time.
Master cylinder plunger/piston mechanism piston discolouration
which can be polished. (Photo: Peter Garton)
Master cylinder plunger/piston end seal disintegration. (Photo:
Slave cylinder - the rust is visible one inch inside but can be
polished out (Photo: Peter Garton)
Slave cylinder innards (top) and master cylinder innards (bottom).
(Photo: Peter Garton)
Master cylinder repair kit, Past Parts 17-0139. (Photo: Peter Garton)
Slave cylinder repair kit, Past Parts 17-5229. (Photo: Peter Garton)
my repair kits from Past Parts at Bury St Edmunds. They supply them
at £17.39 plus P&P and VAT. Their contacts are in the V8LIFELINE,
the listing of recommended specialists providing V8 spares and services.
A copy of the V8LIFELINE is available online - just click the grey
"Spares/Service" button on the V8 website homepage. They
also offer a brake cylinder stainless steel sleeving service - see
their website at www.pastparts.co.uk
for more details.
reserved by the
V8 Register, PO Box 888, London SW14 7YT