Faulty Master Cylinder?????

Post by **Bullmansboy** » Mon May 01, 2006 4:23 pm

Problem I have is hard brake pedal.

Front wheel O/S wheel cylinders both operate (changed recently). However, both wheel cylinders will not return to rest position this also occurs to lesser extent with N/S wheel cylinders.

Release front o/s bleed valve, fluid come out both cyliners return to rest position.

Could this be a faulty master cylinder?????

If so any tips on how to get to fixing bolts without removing T/bar?

Post by **bmcecosse** » Mon May 01, 2006 8:54 pm

The master cylinder on the Minor is designed to retain a slight pressure in the system during use - the idea is to keep the shoes close to the drum and ready for action! Overnight this can leak away - and so the first stroke in the morning can be long - then ok after that. If this is so - then it's an indication that the brakes could do with a bit of adjustment. The cylinders that don't return are getting sticky - the new cylinders are nice and fresh and so they retract when you ease the pressure. Ideally - they should all do it! Do the brakes 'drag' in use - in other words is the car easily pushed along a flat road ? I suspect this is your real problem - sticky wheel cylinders.
If you are determined to change the m/c - the bars can be levered away enough to slide the bolts past - and then put them back in the other way round! But make sure if you do that - that the nut and/or end of bolt is not rubbing on the T bar

Post by **chrisd87** » Mon May 01, 2006 9:07 pm

Like this:
<img src="http://i31.photobucket.com/albums/c390/ ... C00793.jpg" height=240 width=320>

Post by **Willie** » Mon May 01, 2006 9:31 pm

Ihave just experienced this 'front wheel cylinders not retracting properly' for
the second time but the difference for you is that if I opened the bleed valve
the fluid came out but the cylinders still did not free off i.e. the fault was in
the cylinders themselves, whereas you released the pressure and they did
retract. This could be a fault in the Master Cylinder which means that a small
hole in the unit which allows the fluid to flow back into the reservoir is either
partially gunged up or partially blocked by the piston rubber. BUT, if this is
the fault then the rear wheel cylinders would also tend to drag too.

Post by **bmcecosse** » Tue May 02, 2006 9:15 pm

If your cylinders were not already fully retracted - then they are getting sticky. Time for a wee clean up. Pull them out - wipe clean with old brake fluid - wipe inside the bore of the cylinder - but don't move the seal - then a spot of brake grease - and pop them back in.

Post by **rayofleamington** » Tue May 02, 2006 9:39 pm

and then put them back in the other way round!

Just for reference - nobody should ever do that if they value their life.
Just because they look clear when you fit them is not good enough. I did mean to show this effect on the green car when we were in Bristol (but never got round to it) - they had been fitted the WRONG way round and had worn a scary pair of grooves deep into the torsion bar, despite looking like there was clearance.
I've seen this grooving on many cars, and presumably the ones where a torsion bar snapped were never seen again (if it failed on a bumpy road or on a high speed corner)

Post by **bmcecosse** » Tue May 02, 2006 11:19 pm

I did say you need to be sure there is clearance! They must NOT rub against the T bar. On my Traveller they have been put in reversed (was like that when i got it 6 years ago) there is bags of clearance and no sign of rubbing - so it can be done.

Post by **Willie** » Wed May 03, 2006 7:36 pm

I have reversed mine and found it necessary to trial assemble to find that the
ends of the bolts was too close to the Torsion bar, easy enough to either add
a washer under the bolt head end or remove the end of the bolt thread.

Post by **bmcecosse** » Wed May 03, 2006 8:58 pm

Exactly - as Willie says - they need a bit of shortening so the bolt 'just' makes it through the nut.

Post by **Bullmansboy** » Sat May 06, 2006 11:44 pm

Thanks everyone, for your help.

Was a faulty master cylinder, changed it today and bingo.javascript:emoticon('

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Post by **rayofleamington** » Sat May 06, 2006 11:57 pm

Exactly - as Willie says - they need a bit of shortening

So not just a case of putting them round the other way

Cheers Willie for the tip on how to do it 'safer'.
As for making sure they don't rub, the static clearance isn't enough as the bar moves in service. Personally I prefer to have them the right way round, but as long as they are checked regularly to ensure the torsion bar isn't getting damaged then reversing them and reducing the thread sticking out should be fine. Bear in mind that as the eye bolt rubbers wear, the torsion bar will move closer to the nuts (hence the bolt head is thin - to make sure there is clearance)

Morris Minor Owners Club

Faulty Master Cylinder?????

Faulty Master Cylinder?????

sticky brakes

MC bolts