Gearbox Cutch CVs - Clutch slave-cylinder

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Note some of this information is out of date and after market parts are now available from brickwerks including the flexible rear pipe to the clutch slave and 6mm hard pipe and unions

There are at least two different configurations of slave cylinder pipework from master through chassis to slave. When some of the metal parts corrode or break, it can be difficult to work out exactly what you need, source the parts or carry out the work. However, There is now enough information around to short-circuit soem or hopefully all these problems...

Please use the links provided below to the 80-90 Tech Archive topics 

ClartsOnly: The difference between the pre '86 clutch slave cylinder pipes. the pre '86 is a flexipipe, a bracket and a solid "brakes pipe" the later upgrade is the £18 plastic pipe from the clutch pipe on the chassis directly to the clutch slave.

Baxter's Brickwerks sells some clutch operating system parts now difficult to obtain from VW..

Pipework Explanation

Simon Baxter The clutch pipe union is M12x1. The clutch pipe is 6mm, not 1/4" as your local place will try to sell you. 1/4" pipe does not fit 6mm unions.

The copper clutch pipe supplied from brickwerks is the following spec

Saville Brake tubing 90/10 Cupro Nickel

confirms to BS EN 12449

outside diameter 6.00 mm

wall thickness 0.71mm

Length 7.5mm

Max working pressure 160Bar

Cunifer is also available but is harder to bend

Hacksawbob This pipe common to all front to back pipes goes over the fuel tank and tank removal makes removal and refitting easier but not necessary. cut the pipe then remove the front union with a socket and a spanner . Replace in two sections with the Brickwerks repair kit. This will need a flare putting on the pipe. The repair kit only comes with one union and a wade compression fitting for joinng the two ends in the middle and is intended for one section replacement but with some foresight and a request they could put a flare and a union on both ends of the supplied clutch pipe so you have it there just in case you need to do the whole run, the end union is only 88p and could save you a lot of chasing about trying to find one locally. If you think you are only replacing the rear section where it has burst, double check the front section for rust. It is likely to need replacing and the movement of the pipe when changing it over will show up any marginal rusty pipes elsewhere.

Fuel tank in situ If you are not using the original route over the fuel tank you will need to be creative and use some metal with rubber P clips to support the pipe through which ever route you take. If your van has a rear air blower console between the front seats this will allow a self tapping screw to go up through the floor without protruding as a sharp thing on the floor of your van. Alternativley a round headed bolt could be dropped down from above and covered with carpet it shouldn't be too obvious. I suspect there more be more options on a LHD van but check for collisions/wear with gear lever handbrake cable and throttle cable. It really is a twat of a job and requires some 3d puzzle solving which is not to everyones mind set. It really is 'easier' to remove the tank to fit the pipe but fuel tank removal has its own complications which require some forward planning, there may not be that many mechanics who would take it on unless they have done it before. T25 aware mechanics would probably remove the tank and be prepared for the eventualities of snapped breather pipes etc and have the spares and knowledge of how to refit the tank without trapping anything. Once the tank is off it makes a lot of other jobs more accessible like brake pipes and handbrake cable. If you suspect it is a job that needs to be done then try and book it in advance with a good T25 mechanic. Rather than waiting for it to occur on the motorway when your options will be very limited. As a bodge sleeving the pipe with some 6mm internal diameter thick hose and hose clips might get you out of a sticky situation in a foreign country on a national holiday but it really isn't recommended, and permanent repair is needed at the earliest opportunity IF you get away with it! Putting the gearbox in second may allow you to pull off a motorway if your not far from a services/slip road and you need to get out of a dangerous stopping point.

Slave cylinder explanation

These can fail, rust badly, have sheared off bleed nippes, get blocked (so won't bleed out) etc

Often the slave cylinder condition comes into question after the Master Cylinder fails, is replaced, and then th system cannot be bled out, slave investigated, piepwork breaks or comes under scrutiny..

Not a problem to leave with an inexperienced garage (time and money), older experienced well-equipped garages should be able to cope..

Fitting yourself The bolts for the slave cylinder are accessible but awkward from the engine bay especially if rusted solid (spray from road wheels) heat, plusgas and persistence will help greatly stubby 13mm spanner on the under side and socket on the top. When you have rotated the top bolt enough to lock the spanner aginst the bracket maintain the force and you can then get both hands on the socket to apply proper force. Grinder/dremmel is the last ditch solution and great care must be taken not to damage rubber hoses in the area. Some time spent putting tin foil over hoses to protect from heat or gaffer taping some hardboard may prevent further tears, on petrol engines be very aware of fuel lines in the surrounding area. When replacing the rear bolt which is harder to get to, first loosely fit the front bolt and nut from under the van. If you don't have access to a second pair of hands then use a strong magnet placed on top of the slave and bracket in place, as you push the bolt up from below, the magnet will hold the bolt in place while you get to the engine bay , pass your fingers to the underside of the bracket and hold it in place while you remove the magnet then get the nut and washer on the top, 13mm M8 bolts 30mm long are required 8.8 tensile strength recommended.

Useful Forum Posts

Aidan: You have been sent one for a syncro, which has a banjo connection at the slave cylinder to facilitate swap outs because of the worse access.

The rear pipe for the early hydraulic set up, eg. CU and other aircooleds is no longer available from VW

The pipe for the waterboxers chassis number D 0000001 to F 079999 is 251 721 479 C and is £27 plus the vat from VW (asof 2007)

The pipe for the early Diesels upto F 079999 is no longer available.

The pipe for the Diesel F 080000 is 251 721 477 J and is £14 plus vat from VW

This same pipe is used on the later Waterboxers, as well as the Diesels

Both use a connecting hose 251 721 477 D from the fixed line and this is £24 plus vat. (asof 2007)

Hope this helps

Why don't people ask VW first - stuff is still available, a lot of it has come down in price recently too, get it now while you can

sendiw: Well done Clartsonly

251 721 477J is definately the right part replacement for the old metal/rubber clutch hydraulic pipe. I fitted it today.. no problem. Give yourself a big pat-on-the-back.

A tip for separating the flexihose from the front line pipe without damaging the front pipe. File an 11mm spanner to 11.5mm and use that with a little persuasion on the front pipe union, if you use a 12mm it will round off and you will probably have to replace the entire front pipe. Don't turn that union just hold it and unscrew the flexihose from the union.

That done... if the union is seized on the pipe, use a blow lamp on it and allow it to cool. It should free off. It needs to be free to screw into your new replacement part. Well it worked for me!

Topic Links

80-90 thread on slave cylinder plastic pipe connection

Another 80-90 thread on slave cylinder pipe connection