Jump to content

Master cylinder replacement (90)

Recommended Posts

The same thing on later series motors - this vehicle is a 2.5 N/A 90.


Unscrew the steel pipe that goes to the slave cylinder (13mm or 1/2" spanner)


Then the pipe adaptor (15mm or 5/8") .Make sure you retrieve the copper sealing washer as the adaptor has to be fitted to the new master cylinder.


Undo and remove the 6 x screws that hold the top cover on the pedal box - there should be a thin rubber gasket between the two.


You can now see the operating rod/pedal top connection.


From inside the vehicle on the drivers side - remove the pedal trim and then unhook the pedal return spring and the 6 x 13mm/ 1/2" bolts that secure the pedal box to the top of the footwell.




From under the bonnet - lift the pedal box up and turn it 90-deg and withdraw it from the vehicle.



The master cylinder is held to the pedal box by the operating rod and two 13mm/ 1/2" nuts/bolts.

Socket on the outside and spanner on the inside for the bottom bolt and the reverse for the top.




Remove the operating rod end nut with a 13mm/ 1/2" spanner - you may have to grip the rod with a pair of pliers/long-nosed mole grips if it turns instead of the nut.



The new master cylinder comes with just one nut on the rod - screw the nut approximately 1/2 way along the threaded part of it. Leave the blanking plug in place until the pedal box is fitted back on the vehicle.


Fit the new master - making sure that the rod passed through the hole in the pivot point on the top of the pedal. With the pedal in the up position - the inner nut needs to be a small amount away from the pivot point. Put the second nut on the outside of the pivot and tighten it - not so much as to clamp hard or the pivot will jam.


Put the pedal box back in the vehicle and bolt it in place - not forgetting the return spring. Screw the pipe adaptor in - along with it's sealing washer, then attach the clutch pipe but do not tighten it. The thread is quite fine, so be careful not to strip it.

Fill the master with fresh clutch fluid, place a wad of cloth under the pipe connection and get someone to press the pedal a few times until fluid comes out of the connection. With the pedal down - tighten the pipe. Keep an eye on the fluid level and top it up as necessary. As a rule of thumb - the reservoir needs to be refilled after every 4th press of the pedal.


The system needs to bled from underneath - on the bleed nipple on the clutch slave.

The nipple is usually 11mm/ 7/16", so crack the thread on the bleed nipple, attach a bleed pipe to it.


Open the nipple, get an assistant to press the clutch pedal, and while it's still down, tighten the nipple. Release the pedal, open the nipple, press the pedal, close the nipple, release the pedal - and so-on until clear fluid comes down the pipe. Don't forget to top up the reservoir every 4th press of the pedal or air will get in again and the system will have to bled again.

Once there seems to no air in the system, press the pedal and if the clutch is working - you will be able to tell. It's quite common for there to be a small amount of air left in, but it will self bleed out as you use the clutch, so it may well improve slightly over a couple of days.

Clutch fluid will strip paint off, so be careful about spillage and wipe any off straight away.


Link to comment
Share on other sites


  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy