Dodgy Brakes

[Red_MAv]

After my dramas last week with only 3 wheels on the Maverick, and we jammed a rock in the caliper once we had removed so that the other 3 brakes would work, we cant get the system to work now. It has a new CV, stub axle, bearings, Disc rotor and caliper and new pads, but cant get it to stay firm. Could the master cylinder be damaged by using the brakes with only 3 actually working? Also as only the one rotor was damaged we only replaced one, if the LHS one is thinner than the new one could that effect the braking in any way?

[GOT MUD]

ok this might sound silly after all the work you have done but did you bleed the system of air

[eighty8]

when u say new calipers etc, is it new /new or new s/hand?. may make a difference using odd calipers. maybe new/s/hand needs o/haul. if so do both to make even. does it bleed evenly? did u loose pedal with only 3 wheels? when bleeding brakes never push pedal to floor, only 1/2 way, will damage m/cylinder seals otherwise.

[Red_MAv]

Caliper from wrecker but rotor is new. and new pads. Bleed whole system but when wheel was still on last weekend (just) each time I tried to use brakes it would go to floor once then seemed nearly normal, but obviously was gripping the wheel that had no bearing and was f$%#ing up the rotor and caliper with major rubbing. THis is possibly what has stuffed the master cylinder. YES it has been bled of air, several times now.

[muzza_fattire]

each time I tried to use brakes it would go to floor once then seemed nearly normal

Are you loosing fluid in the reservoir? Is there any dripping into the cabin along the brake pedal linkage?
Usually when you push the pedal to the floor, the piston seal hits rust and gunk at the end of the cylinder that never usually gets touched and the seal gets ripped to shit. Fluid then leaks back past the piston and can come into the cabin.
You will either need a new seal kit or a new master cylinder.

[Daisy]

each time I tried to use brakes it would go to floor once then seemed nearly normal

Are you loosing fluid in the reservoir? Is there any dripping into the cabin along the brake pedal linkage?
Usually when you push the pedal to the floor, the piston seal hits rust and gunk at the end of the cylinder that never usually gets touched and the seal gets ripped to shit. Fluid then leaks back past the piston and can come into the cabin.
You will either need a new seal kit or a new master cylinder.

sounds like the right one to me... i had a simliar problem and had to have my master cylinder exchanged for a reco'd at 300 bux

[Red_MAv]

Looking in my gregory's manual the master cylinder is just the little bit under the reservoir with 4 lines coming off it from memory. The big 10" round gadget its attached to is the servo unit or something, does it really cost $300 for the pissy little master cylinder?? I will see what I can get on Monday in the way of either a new one or a reco kit. Cant check inside at the moment because its at a workshop in Croydon.
Does anyone have any idea as to the 2nd part of my original question, regarding whether one new and one old Rotor would make any difference to the braking. The mechanic says to get another rotor so they are both brand new but the old one is only 20,000km old. Its not the cost of the Rotor thats only $30 its the labour to pull the whole assembly apart to fit it I am concerned about if its not going to make any difference.

[AndrewPatrol]

I would have thought that It wouldn't make too much difference but they always say to replace wearing parts in pairs (brakes, bearings etc). Brake caliper pistons have a self adjusting capability where the more a rotor wears the more the piston pokes out of the caliper. Having different rotors may create a slight unevenness of pull-upability but once bedded in I would have thought it may become more even. Your old rotor is only 20k - how worn is that, does it have a good surface. Maybe get both surface skimmed to the same thickness if possible. The other thing is that - what price safety?????

[Rainbow Warrior]

I would have thought that It wouldn't make too much difference but they always say to replace wearing parts in pairs (brakes, bearings etc). Brake caliper pistons have a self adjusting capability where the more a rotor wears the more the piston pokes out of the caliper. Having different rotors may create a slight unevenness of pull-upability but once bedded in I would have thought it may become more even. Your old rotor is only 20k - how worn is that, does it have a good surface. Maybe get both surface skimmed to the same thickness if possible. The other thing is that - what price safety?????

I'll second this, a barely noticeble pull to the right becomes no fun at 100kph when you hit the anchors suddenly.

[Red_MAv]

I'll get him to put on another rotor then, I wasnt so concerned about the price but whether we may just be chasing something that wasnt part of the problem. At least that should get it pulling up evenly, just have to sort out the fading pedal now which as most people seem to think its when the pedal went to the floor its stuffed the seal in the master cylinder. This one stuffed wheel bearing has led to a big repair bill, will be very interesting to see how I go when I rock up to the workshop that did the bearings last time.

[eighty8]

I'll get him to put on another rotor then, I wasnt so concerned about the price but whether we may just be chasing something that wasnt part of the problem. At least that should get it pulling up evenly, just have to sort out the fading pedal now which as most people seem to think its when the pedal went to the floor its stuffed the seal in the master cylinder. This one stuffed wheel bearing has led to a big repair bill, will be very interesting to see how I go when I rock up to the workshop that did the bearings last time.

If its pulling up unevenly,( ie: pulling left or right), having different disc surfaces with new pads will cause that. machining 1 disc will cost at least $20 so its a better option to replace with a new one if u already have one on the other side.
as I said earlier its worth o/hauling calipers when purchased from a wrecker, simply because u dont know how its been kept. doesnt take long for moisture to get in and cause damage to pistons & seals etc. a seal kit is easy to install. plenty of rubber grease & fine sandpaper to clean parts.
an easy check for m/cyl is clamp off all lines & and apply pedal pressure, if pedal sinks its f%@^ed....cheers

[Red_MAv]

Thanks 88 that sounds like an easy test. I'll get him to do that before I launch into buying it. Hopefully can get a rebuild kit as it sounds like its just seals that go. Cant believe a new one is 300+ but nothing surprises me any more since I own a 4x4.

[J Top]

You won't get brake fluid in the cab from the M/C because there is a booster between the M/C and the pedal.
Locking off all the lines is a good test but not entirely conclusive as you have also factored in a load sensing valve above the rear diff, which has it's own bleed nipple and is often overlooked giving similar symptoms to your problem. Also as discussed elsewhere on this forum, check all caliper sliders are free as they affect the pedal feel and efficency.
J Top

[AndrewPatrol]

given the age of your car Pete it'd be worth having the other wheels looked at as well if not done already.

[Red_MAv]

Yeah, thats been done, the good side (the one that didnt fall off) was 1 and a half turns loose on the locking nuts and the seals were rooted naturally. Both sides are now replaced. Just waiting for my master cylinder to go in now.