Brake query - fronts or rears?

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guys.

Had servo failure in the 90 so replaced it with a TRW part, at the same time I also replaced the master cylinder with a Lucas item, and the flexi pipes. Pads/discs/shoes and drums not changed as all have plenty of meat left and are not contaminated.

Have re-bled the system 4 times now, pedal has gotten better but still a bit spongey/lacking feeling in the first 2cm of travel so will bleed again in a couple of days.

Brakes are working much better but when I emergency stop the back left wheel would lock up first. I investigated the rears and had a partially seized wheel cylinder which I have sorted out. Now both rears lock up. Possible I have a smidge more fiddling with adjustment to get a better pedal though.

But I cannot get the fronts to lock up before the rears, this is doing an emergency stop from 30mph.

I have been reading about the 'G' valve, do these fail?

Or is a defender 90 with drums on the rear prone to locking up the backs first due to weight transference when stomping the brakes?

It pulls up fine, the brakes are good in normal use, but an emergency stop is a bit alarming as it tries to spin me one or other way (predominantly the back wants to come round to the left).

Any clues what to look at next? Or is this 'normal' tratter behaviour lol
 
Last edited:
guys.

Had servo failure in the 90 so replaced it with a TRW part, at the same time I also replaced the master cylinder with a Lucas item, and the flexi pipes. Pads/discs/shoes and drums not changed as all have plenty of meat left and are not contaminated.

Have re-bled the system 4 times now, pedal has gotten better but still a bit spongey/lacking feeling in the first 2cm of travel so will bleed again in a couple of days.

Brakes are working much better but when I emergency stop the back left wheel would lock up first. I investigated the rears and had a partially seized wheel cylinder which I have sorted out. Now both rears lock up. Possible I have a smidge more fiddling with adjustment to get a better pedal though.

But I cannot get the fronts to lock up before the rears, this is doing an emergency stop from 30mph.

I have been reading about the 'G' valve, do these fail?

Or is a defender 90 with drums on the rear prone to locking up the backs first due to weight transference when stomping the brakes?

It pulls up fine, the brakes are good in normal use, but an emergency stop is a bit alarming as it tries to spin me one or other way (predominantly the back wants to come round to the left).

Any clues what to look at next? Or is this 'normal' tratter behaviour lol

Have you got a pressure relief valve on your vehicle? If you have, it sound to me like it's failed. The front should lock up, not the rears. The rear wheels skidding is dangerous and can spin the vehicle round, hense the need for a pressure relief valve (bias valve) to limit the pressure to the rears during heavy braking... stopping rear wheels locking up.

Hope this helps.
 
Okay will check that. I haven't had it off but that doesn't mean it hasn't always been like that from before I had it tbh - will check cheers
 
Early and later cars have different valves, I dont know what the difference is but do know they are different shaped.
 
Okay drivers side caliper is ****ed, can only get 3 of 4 Pistons moving so will replace.
Didn't look at the passenger side as it looks in similar condition so will replace to.

Will leave the defenders G spot alone lol
 
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