Traveller '68 - Left Hand drive conversion

[Nickol]

Binding Brakes

I will add this final Problem to this thread as before I did the conversion all was working well.

Did some road testing this afternoon and it is quite clear now that all wheel Brakes are binding ( some smoke and all 4 wheels have heated up)- thus for my logic it can only be that something is wrong with the master cylinder.
As it is a bit of a brute to remove I would be pleased for suggestions on what I may be looking for as a culprit? I have replacement rubber seals ready but I would have thought that worn seals would impair the Quality of the Brakes , not lock then on?

As a recap, my System has a remote Reservoir and a brake servo System so it is a bit away from the norm.

Edit : I might be getting to the root of the Problem but it may not be a solution I would like.
There is not the required 20mm free movement of the brake pedal. Probably, because I had to locate and drill my own holes for the clutch/brake pedal assembly it is to close to the Master Cylinder. I have now made an adjustment to the push-rod as far as it will go - I have about 15mm free pedal movement - more in not possible. Will it be enough?

[bmcecosse]

You MUST have the free play - and try without the servo (ie just take the vacuum pipe off) which may be dragging the brakes on.

[Nickol]

Made another small test drive just now and it is better News but not perfect. The rear Brakes are obviously not binding any more, the front less so, Drivers side still warming up.

Will try without the servo connected, next time - thanks Roy for the tip.

As this appears to be the root of the problerm, it seems to me I will probably Need to remove the push rod and shorten it. That way I can get the correct adjustment. It will still be necessary to remove the MC though but at least I know now what to do.

[amgrave]

Did I read somewhere that if you have a servo fitted you have to remove a rubber part from the master cylinder otherwise the brakes don't fully return from on, or am I thinking of something else.

[Nickol]

That sounds interesting - I wonder which part was had in mind? Master, secondary or valve Cup?

[bmcecosse]

No - that's with disc brakes

[amgrave]

Thanks Roy, I wasn’t sure but at least it's ruled that out

[Nickol]

So, Master Cylinder removed, push rod unscrewed ready to be shorternd by 4 -5mm. (measure twice, cut once )

Some advice though please

Is there a possibility, even remote that the innerds of the MC are contibuting to the fault of binding Brakes? Under the golden rule of "if its not broken, then it does not Need Fixing" I am reluctant to open up the MC and renew the seals, even though I do have a set.

[bmcecosse]

Could well be, only one way to find out.... - but it must have some free play. You shouldn't need to shorten anything -it's adjustable.

[Nickol]

Very true, but remember I had to locate and drill and braze etc all the holes locating the bolts for the MC itself as well as the clutch/brake pedal set up - Thus it is quite possible that the critical distance is slightly out of tolerance, enough anyway that I did not have enough adjustment available to get the free Play.
I am going to measure tomorrow with digital calipers (???) the distance from the centre line of the clutch/brake shaft to the first hole drilled for the brake cylinder bolt. and compare with that from the RHS. There should be a difference, otherwise something else is wrong that there is not enough adjustment to get the required amount of free Play.

Will therefore renew the "Cups" anyway - should not be a big Job..........if you get it right first time.

[bmcecosse]

If there is no free-play, I would sort that out first. Your 'cups' are probably ok as they are.

[Nickol]

My measurements have now confirmed that due to my wonderful "made in Germany" Engineering skills, the distance is shorter than it should be, therefore can either drill new holes for the MC bolts furhter back ( not very practical as to do so Need to drop the gearbox to allow working room for the drill) or shorten the push rod assembly. 5mm will be needed, can round the end after cutting with my small lathe.

The only thing though Roy, is that if the existing Cups are not ok, it is a lot of work removing and replacing the MC, so might as well Exchange them now while the MC is out . Judging by other bits on the car, it probably has never been changed before.

[amgrave]

Personally I would change the seals after checking and cleaning the master cylinder as I wouldn’t be in a hurry to remove the cylinder again. If because your error in the measurements the cylinder piston was not being allowed to return to the rest position that would cause the brakes to bind I think, would that be what was happening do you think. The last bit of travel by the piston relieves any pressure in the brakes system I think.

[bmcecosse]

You can surely remove the push rod - shorten it -and refit it without disturbing the master cylinder??

[Nickol]

Hallo Amgrave - that is what I think too and Roy has confirmed that the allowed 20mm free Play MUST be present. Anyway that is what I intend to do, when I get home again.

Roy - to remove the push rod you need first to disconnect the swivel Connection to the brake pedal by first removing the Holding "Splint" (engl : split pin?) I cannot get my Hands to it and even if I did, I cannot imagine being able to get it back again. The Location is just too tight. I gave up trying this way in the first place when installing it and in the end had to remove the entire clutch/pedal assembly and install it to the brake pedal as removed - and then put the assembly back.
In any case teh MC is already out and on the bench!

My master cyliner is at least less complicated as most cars due to the brake servo mechanism. There is only one brake Union Connection at the side and the rear is a hose Clip Connection from the Reservoir. See previous pics.

[Fingolfin]

The brake pipe nut isn't metric, but rather Whitworth/BSF, an ancient measure unique to Britain. A set of Whitworth wrenches and sockets is worth its weight in gold when working on a Minor, or any BMC car of that era.

[bmcecosse]

My brake pipe unions are AF - not Whitworth, although some (actually most) of them have BSF thread - the hex size is still 7/16" AF as far as I can see.

[Nickol]

My 7/16" AF spanner was a loose fit but adequate for all but the tightest unions. The 11mm on the other Hand is a good fit and especially so if the Union is very tight and difficult to turn initially.

It may well be though,along with many unusual things with my car, that a or some non-standard replacement has been made in the past.

[Nickol]

Here we go.

Took off the circlip Holding the innerds of the Mc and after it exploded out, here the Picture of the parts.

It does not match the exploded view in the manual at all.

The valve Cup at the end is different and sems to have used the Master Cup there instead. There is no master Cup where it should have been and no dished washer either.

Bearing in mind that I have this funny brake fluid Reservoir mounted in the engine bay and , for what it is worth the brake servo System, can it really be that the set up in the MC was so modified or have I discovered yet another previous bodge?[frame][/frame]

[Nickol]

Here from the manual[frame][/frame]