brake pedal pressure( new master cylinder) 109 2a mod

[glbft1]

I have installed a new master and believe I have gotten all air out of lines but it still takes 2 pumps to get pressure so my question is do I need to readjust the brake shoes? if so does it matter which one I start on? i am also using a power bleeder but read somewhere that on a 109 it is best to raise the front to help bleed.... when i get pressure it stays and there are no leaks.
thanks
greg

[graniterover]

You can turn the adjusters all the way in and strap the shoes closed, then bleed, but it sounds like you have air in the system.


I have installed a new master and believe I have gotten all air out of lines but it still takes 2 pumps to get pressure so my question is do I need to readjust the brake shoes? if so does it matter which one I start on? i am also using a power bleeder but read somewhere that on a 109 it is best to raise the front to help bleed.... when i get pressure it stays and there are no leaks.
thanks
greg

[jac04]

You can try what graniterover suggested - it is a way of minimizing system volume and places for air to be trapped. However, the 11" brakes are difficult to bleed due to the orientation of the bleed screw on the bottom cylinder of the front brakes.

I was unimpressed with the ability of the Motive power bleeder to move fluid through the system. IMO, the power bleeder is good for a brake fluid change as long as you start with no air in the system. I suggest using the good ole pump the brake pedal method - that's eventually what I used when I did my brakes (11" front brakes). If you keep the power bleeder attached, you can pump the pedal without risking the master cylinder running dry.

If you can't get the air out, there is another bleeding method, but it requires removing the brake backing plates and laying them horizontal with the bleed screw facing up.

[glbft1]

ok have lifted the front of the truck way up bled all lines no air just straight brake fluid, so my question is could it be a brake pad adjustment?

[alaskajosh]

Do you know yet if the air is in the front or rear circuits? Carefully clamp the rubber hoses two at a time.. for example both fronts, a front and the rear (by the diff). If you find a combination that will give you a firm pedal then you've located the air bubble(s) isolated behind the clamp.

I know the fronts are notoriously difficult to bleed but, for me, it's the rear that gives me fits. I've found that air traps in the high point near the rear diff. I have to jack the rear WAY up, unfasten the brake pipes and bend that high loop flat'ish to get the air out.

Leave the un-affected wheels clamped at the hoses while you bleed and you'll get more targeted, efficient bleeding (same effect as strapping the brake shoes, or running them out tight to the drums, but easier).

For clamps I've put some pieces of rubber hose over the jaws of needle nosed vise-grips so as not to damage the brake hoses. But even a folded over shop rag beneath your vise-grips would probably do.

Kind regards, Josh

[rovers2a]

yes you have to adjust the brake shoes. if that dosent work then there may be defective rubber flex lines.... adjust em up first and then start isolating each cornnor with the brake line clamps as mentioned above. there is also an adjustment on the master cylinder push rod and or pedal height adjustment.

[rovers2a]

also with regards to the brake shoes, there is a leading shoe and a trailing shoe. if they are in stalled incorrectly then the whole adjustment will be outa wack. hopfully some one will chime in and post the measurement for the leading and trailing shoes. it is very easy to install the shoes out of order, especially if you dont know what to look for. the shoes look almost identical but there is a difference.

[rovers2a]

http://www.expeditionlandrover.info/landRoverFAQ/FAQ_rearbrakes.htm and or google a lot of info ...:thumb-up:

[glbft1]

ok will try clamping off the lines and adjusting the brake pads, thanks everyone for the input will keep you posted!

[jac04]

Just to clarify about adjusting the brake shoes & bleeding the brake hydraulic system:
When trying to bleed air out of the system, it may help to adjust the shoes all the way IN (away from the drums). This is best accomplished by removing the drums, turning the adjusters all the way in, and strapping the shoes together. This will push the wheel cylinder pistons all the way in, minimizing the area in the cylinders that can trap air.

If you do this, you MUST re-adjust the brake shoes after you have bled the hydraulic system. If not, you may need to pump the pedal two times to get the brakes to work.

If there is no air in the system but the shoes are not adjusted properly, you will need to pump the pedal twice to get the brakes to work, but the pedal will feel firm. If there is air in the system, the pedal will usually still feel a little 'mushy' after the second pump.

[glbft1]

I have put alot of fluid thru the lines, still takes two pumps to get pressure then it is hard and does not feel mushy, so I am wondering if the shoes need adjustment??\
thanks for your help !!

[alaskajosh]

I'm able to get a firm pedal with air in the system by pumping X2. I'd still put my bets on air for now. It can be danged elusive.
Kind regards, Josh

[rovers2a]

bud.... you can add 30 more gallons of brake fluid to the system and keep bleeding them for a month, however the brakes will still need to be pumped. start first with the brake pedal height adjustment! then move onto the the freeplay adjustment on the master cylinder push rod, then check that the shoes and pull off springs are installed correctly, if they are, replace the drums and then set or adjust the brake shoes with the adjusters on the backing plate, once all of the above steps are completed as per the specifications, finally move on to bleeding.... your working backwards... get a shop manual if you all ready do not.:thumb-up:

[rovers2a]

http://forums.lr4x4.com/index.php?showtopic=39618&pid=375713&st=0&#entry375713

[glbft1]

brake pedal adjusted, have about 1/16 inch pedal freeplay. and the brakes worked great until the old master cylinder went......going to clamp off lines and see if it isolates which area is suspect I guess this is a rite of passage in series ownership thanks for all the advice would buy you all a round if i could:thumb-up:

[LaneRover]

Which of the 109's benefit from getting the front end as high as possible when bleeding the brakes? Something about an illusive pocket in the MC if I remember correctly.

Brent

[glbft1]

had the rig front end way up in the air last nite re-bled entire system still the same......

[Terrys]

If you use a Handi-Vac, or Mighty Vac, whatever it's called, you don't need to put the vehicle up down or sideways.

Also, keep in mind, the master cylinder piston is smaller in diameter than the wheel cylinder piston, so if all your brakes are slightly out of adjustment, the amount of fluid the MC pushes, devided by all the wheel cylinders, means that the wheel cylinders only go out a little bit, hence the double pumping.

[glbft1]

thats what i was thinking... going to try to adjust the shoes and then see what happens

[siiirhd88]

When I rebuilt the brakes on the 109 I ended up with the same problem, always a double pump to get a firm pedal. I tried all of the above suggestions, including taking everything apart, fabbing new steel jumper lines and moving the bleeder to the upper wheel cylinder. After a few weeks of careful (sometimes scary....) use, the problem fixed itself and I now have nice, firm, single pump brakes.

Bob
'96 Disco SE7
'80 SIII 109
'75 SIII 88 V8
'68 SIIA 109 V8

[lew_sa]

I couldn't get my brakes firm until I unbolted the brake backing plate that holds the front wheel cylinders so I could rotate the bleeder screw from the bottom to the top. Once I did that, the wheel cylinders "burped" a big air bubble and all was good. I also used this as an opportunity to replace the front seals and repack the bearings. It didn't take all that long.

Lew

[rovers2a]

.... lol... ARE YOU DUTCH?

[rovers2a]

thats what i was thinking... going to try to adjust the shoes and then see what happens

right here. your starting to get a little bit warmer just a tad though, i mean you could always buy another 5 gallons of brake fluid and keep bleeding..." pump, pump it up you, got to pump it up" 'dont you know pump it up' guyzee check it! http://www.youtube.com/watch?v=0HtyF0jux2Q

[glbft1]

We blocked off the rear brakes and the pedal worked , unblocked and went back to 2-3 pumps pulled the rear wheels found the shoes paper thin and the wheel cylinders were sticking and generally bad condition so I will replace I think this is the problem any thoughts

[jac04]

Glad to see you found the problem.