Back brakes locking up

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MarcosLandy

Member
Posts
17
Location
Essex
I have just completed restoration of late series 3 hardtop . 84 model SWB which had been part restored by someone else. it has twin cylinders on front and servo . It's had new cylinders on the front all shoes recently replaced as the new cylinders had seized up where it has sat so long, all drums adjusted well and the pedal is really good minimum travel. If I brake hard rears just lock. Could this be due to a problem with the master cylinder as it had sat for a long period before I obtained or possibly wrong master cylinder. If the previous owner have fitted different size rear cylinders and could this be the cause? It's a dual circuit system which I understand has a flow switch not as I initially thought may have balanced flow, previously brakes pipes were in wrong position to this but made no difference to brakes balance when swapped so makes me think master cylinder is working correctly. If this unit is sticking could that also be cause? Any suggestions appreciated. Thanks
 
Backs were adjusted by locking up then backing off until I get slight resistance when spinning drum. I will double check master cylinder rod adjustment to see if its ok.
 
Was forgetting it seems to have later master cylinder with servo so would need to remove master cylinder to check adjustment of rod unlike early series. Will try and identify master cylinder used as seems different to the ones advertised. The tyres pressures are standard, resistance on shoes is minimal so don't think backing off more will work but will try again .
 
The back brakes are not dragging just lock up to easy when braking. I had concerns about the master cylinder in case this had been piped in correctly. This checked out okay but it appears that past owner has upgraded master to a later 90 / 110 type with what appears to be a series servo . I am sure this is the problem possibly causing to much pressure. Researched on web and found very informative site on dual circuit brake conversions that was really useful and seems to confirm that a master cylinder for a 109 should be used as has same dual wheel cylinders on front drums as my late series 3. Apparently the defender master cylinder is the one to use if converting to disc brakes. I will order one and change it next weekend and hopefully this will sort it but I will report back once changed. Cheers for comments
 
Finally sorted the problem. The landrover is the last of the series 3 and has used some of the parts namely master cylinder used on the 90's /110. I changed the master cylinder and same problem occurred. As previously mentioned the pipes leaving the master cylinder and going to the top of the brake circuit valve were swapped but again made no difference. The pipework is as per the Haynes manual . The brake circuit valve worked as intended cutting off the supply if one circuit fails and illuminating the dash light. I know on later vehicles they use a pressure regulating valve but was unable to identify this in any manual to confirm if mine included the regulating valve . It has two pipes entering the top and one from the bottom and one from the side. I swapped the two bottom pipes and they now work perfectly. We're also a bit tricky to bleed initially and sequence could be as later 110 or series which is the diagonally opposite one but tried both and have now sorted it. Thought I should advise in case anyone else has had this problem .
 
MarcosLandy said:
Finally sorted the problem. The landrover is the last of the series 3 and has used some of the parts namely master cylinder used on the 90's /110. I changed the master cylinder and same problem occurred. As previously mentioned the pipes leaving the master cylinder and going to the top of the brake circuit valve were swapped but again made no difference. The pipework is as per the Haynes manual . The brake circuit valve worked as intended cutting off the supply if one circuit fails and illuminating the dash light. I know on later vehicles they use a pressure regulating valve but was unable to identify this in any manual to confirm if mine included the regulating valve . It has two pipes entering the top and one from the bottom and one from the side. I swapped the two bottom pipes and they now work perfectly. We're also a bit tricky to bleed initially and sequence could be as later 110 or series which is the diagonally opposite one but tried both and have now sorted it. Thought I should advise in case anyone else has had this problem .
Click to expand...

Thanks, it's always good to hear the outcome / resolve.
 
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