Brake pedal notchy on 91 hdj80

[ledgend80]

Ok when i put my foot on the brake pedal either driving around or stationary the pedal does not always go all the way in it will stop but if i press it hard the pedal will go further, but there is a notch in the pedal. the brakes have been upgrade to the 16 inch brakes all round with new brake hoses. so my question is what could it be. i have not looked at anything as yet. wondering if it could be one of the following
- brake pedal linkage
- master cylinder
- sticking caliper

does not seem to pull either left or right when braking

any other ideas would be great

[RAY185]

Sounds like a sticky caliper piston to me.

[ledgend80]

so this could happen even if it doesn't pull left or right.

[RAY185]

Absolutely.

Where they second hand units?

Do you have access to a brake hose clamp and a quiet street that you can use for testing? Go for a drive blocking a different wheel off each time untill you stop feeling the notching. When it stops notching, you have your caliper. If it doesn't stop notching then I am wrong. I reckon it will be a front one.

[ledgend80]

yeah mate i have got access to the clamps they are in my toolbox at work. yes they were second hand units but i did re kit them before fitting them. but that doesn't mean much.

cheers for that will get onto that.

[mutilated]

More likely a faulty master cylinder. If with pressure applied the pedal is still sinking and bottoms out then the seals are gone and fluid is leaking past them.

[glenndini]

I also have a '91 HDJ80. The brakes work OK but if I keep pressing the pedal it does keep sinking. The obvious cause for would be a faulty master cylinder.
However the master cylinder has been replaced and it made no difference to it at all.
I've just had new stainless steel braided hoses all around. No difference.
I've read about many others with the same problem but have never heard of anyone coming up with a definite answer.

[BadMav]

LSPV (Load Sensing Proportioning Valve)?

[ledgend80]

driving around today no problems more driving untill it plays up again

[glenndini]

I have considered the LSPV and it might be the next thing I change as I've run out of alternatives to fix this. Although it is often cited as a possible cause it is difficult to see how it could be unless it's leaking fluid. Mine is not.

[ledgend80]

did you bleed your lsvp at all. i did mine when i changed over to the bigger brakes and from emory the fluid was pretty dirty there too.

[glenndini]

I've bled the entire system to the point of completely replacing all of the fluid on more than one accasion.

[RAY185]

If you're not losing fluid there's not much else that can cause the sinking pedal problem. Would have to be the master, perhaps your replacement was faulty? You bench bled the new master prior to fitting and bleeding the rest of the system right?

If you're prepared to pull the master off again, you can take it down to BHSS at capalaba and get it tested so you know for sure. FYI they rebuild and test masters, slaves, boosters and a whole lot of other things. Very handy.

http://www.bhss.com.au/contact.htm" onclick="window.open(this.href);return false;

[glenndini]

Yeah, it might be worth getting the new master cylinder checked. I have proved it by blocking the outlets right at the cylinder and the peddle was hard as a rock. I guess there could still be some bypass further down the piston's travel.
I have read of people changing theirs two or three times and still having the same problem.