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Locked up wheels

Borderterrier

Offroader
Driving back from a days shooting and the lanny was lacking power. Very hilly here and I though tshe was just struggling a little more than normal. Drove about 5 miles and I was literally in 1st gear to get up pretty minor hills. 4th gear on the flat and I am going no where. Got home and felt the rims which werre quite warm, when to try and drive here again and the peddle is rock solid and th ewheels are locked (well most) 1st gear low ratio and I can go forward. Has the master cylinder failed?
 
The master cylinder or servo (if fitted), if all four wheels are locked up - they're the only parts common to all four.
 
Hello there. It certainly does sound like the brake master cylinder is suspect if ALL drums are locking up. Symptoms can be caused by a bit of sh-t blocking the "bye-pass" port. Try bleeding the brakes to flush the system out, failing that You could try to slacken off the actuation rod. I would recommend replacing a high mileage master cylinder rather than resealing it. Regards Billy
 
Obviously before you start changing parts, remove brake drums and ensure that the brake actuation " wheel " cylinder pistons are free. regards Billy
 
Has the brake fluid gotten anything in it lately? Have you topped it up recently? If so, I suspect you (someone) has put a petroleum based product in it. Although they are "Hydraulic" brakes, they don't use "Hydraulic fluid". They use "Brake Fluid" which is non-petroleum vs "hydraulic fluid" aka "hydraulic oil" which is a petroleum based fluid. Any petroleum product that gets on any of the brake rubbers will make them swell to about twice their original size and will seize the lot.
 
left it overnight and it's fine again. In one of Sandy's posts some time ago he experinced a problem with the rubber hoses collapsing internally, mine are brand new so I hope this is not the case. I might give bleeding the brakes a go the flush any sheite through the system. I was raelly careful with the rebuild though with keeping stuff clean. Oh and Greg, it is definately brake fluid only in the system, DOT 4, Unipart.
 
Could be not enough clearance on the actuation rod...
Did you replace the master cylinder during the rebuild???
If you did, there is something about fitting the wrong one. It will fit, but you need a spacer between "it" and the bulkhead, without the spacer it does not allow the rod far enough back to release all the fluid. Over a few miles this builds up and applies the brakes....
Sorry to be a little vague, to be honest I can remember the fault, as I had it on a lwb I had, I didn't find out the cure till after I had sold the landy:eek:
Hopefully someone will come along and explain it better:D
Cya
Mungo:)
 
Morning Mick. The MC is the correct one, I treble checked this having read some of the nightmare stories peolple posted regarding the fitting of the wrong type.:confused: I have probably done 600 miles since the rebuild, so why now?
 
Morning BT
:scratchCh ...As it is affecting all 4 wheels it has to be something that is common to them all...as Snagger has already said.
The symptoms are identical to what happened to my lwb though...I would look at the master cyl first...Have you still got your old one?...might be worth swapping back...At least it would prove your new one:confused:
Cya
Mungo
 
Definitely check the master cylinder pushrod for free play, another possibility is that the one way valve seal is stopping the return flow by either the rubber being swollen and contacting the end face of the cylinder or the innards have popped apart so the one way valve is again sealing off the return flow path.:)
 
Is it a single or dual line system, with servo or not? Different cylinders have different ways of recouping the fluid, so have different problems.

As CC says above, if it is the single line system, the master cylinder has a valve in the end to seal the reservoir off when you initially press the brake pedal. If the rod has no free play, it can hold the valve to the end and seal the return flow. When you let the brake off, you can draw a little bit more fluid in as the line pressure drops, so after a couple of presses, the brakes start to bind. But it cannot return quickly enough, that is why it is OK in the morning.( Seepage past the seal)

First thing is check the rod for free play.

Chris
 
BT,

Did you ever resolve the problem with your brakes locking up? My lightweight seems to have developed the same problem. Any advice would be appreciated.

Can anyone tell me how you can tell if you've got the wrong master cylinder? The previous owner has stuck a new one in so I don't know what was in there before. I'm not sure it is the wrong one though as the problem has only just surfaced.

Cheers

Chimp
 
I have not no mate. The master cylinder has been removed and there was fluid fresent at the rear of it. I reckon the seal shave failed which is bloody annoying as I replaced them when I rebuilt it.
 
Alright mate, I'm gonna try and have a look at mine this weekend if I get chance. If I have any joy I'll let you know.

Cheers

Chimpy
 
This sounds totally different - but did you replace footwells as part of the rebuild? I did, using pattern parts and after using the brakes for a while they started locking on. This was because on the pattern part footwells, the hole for the pedal box wasn't correctly cut out so when the pedal was released it never came up fully. Sounds simple but it took me ages to work it out as I carefully replaced all drums, servo, cylinders, bled the system 50 times.......
It passed the MOT first time because I didn't need to use the breaks on the way there so they hadn't locked on..
It may not be remotely relevant, but it may help someone else!
Adrian
 
This sounds interesting, I did notice this during the rebuild and I thought I had cut enough away to allow for the pedal to return correctly. I think you are onto something here. How did you cure it though out of interest?
 
This sounds interesting, I did notice this during the rebuild and I thought I had cut enough away to allow for the pedal to return correctly. I think you are onto something here. How did you cure it though out of interest?

I had to cut the hole for the pedal at the top, to allow the pedal full travel. I thought it was half an inch, but having just looked I think it was a lot more. You can see it still looks tight, but worked ok after that. I cut it far enough back to match the pedal box. On mine, the bolt holes in the footwell were in the right place but the cut out was wrong. Does this make sense? Sounds simple but we wasted a lot of time effort and money replacing other things when this was the actual problem. If you look at the clutch on the left hand side that has far more travel.

Also pic of Santana attached for comparison. Hope you get there. If this doesn't help, can't suggest anything else! Adrian:)
 

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The fluid in the servo and rear of the MC indicate a seal failure. I wouldn't risk a seal replacement - there is likely to be a machining fault that caused the seal failure in the first place. This suspicion would be almost guaranteed if the MC is not OEM, especially if it was in a blue box.

Replace the MC and get as much of the fluid out of the servo as you can. Depending on the severity of the leak and how much fluid has been lost through the servo, I'd consider an engine oil change - I don't think brake fluid would do the engine's seals any favours and that's where it ends up (on 12J/19J/Tdis, anyway, though I know the 10J has a different system - where is the vacuum tank drawn from?).
 
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