Thread: 101 Front brakes retaining pressure

Check the pushrod from the brake pedal to the piston on the master cylinder.
That pushrod should have a adjustment nut.
It must have some free play or your brakes will build up.
With the brake pedal at rest the push rod should rattle around abit if you try a move it with your fingers.
The back brakes will not get as hot because of the load proporsioning valve near the back axle.

Brake hoses develop a restriction. As was explained to me, it's like cholesterol in your arteries. It allows the brakes to be applied but restricts them from releasing.
This happened to the hybrid and the fintail.
You may wish to change the brake hoses for new ones.

As Mick said - I would replace the rubber hoses if you have not already done so - can cause symptoms as you suggest - rubber de laminates inside and acts like a one way valve.

If it is not that then I cannot help - except that my booster and master cylinder were rebuilt by my local brake place - so I think the position that there are no parts for them is a bit of a furfy.

Garry

If both front rims were equally warm, then it's probably not going to be a brake hose issue. Check the master cylinder freeplay first as suggested by 101Ron.


I'm not familiar with the set up of these brakes but I know on some old English cars the master cylinder cap has a breather hole. If this is blocked, it can cause a similar problem.

Originally Posted by Scouse

If both front rims were equally worn, then it's probably not going to be a brake hose issue. Check the master cylinder freeplay first as suggested by 101Ron.


I'm not familiar with the set up of these brakes but I know on some old English cars the master cylinder cap has a breather hole. If this is blocked, it can cause a similar problem.

Your right on that one too.

Originally Posted by Scouse

If both front rims were equally worn, then it's probably not going to be a brake hose issue.

While each of the front brakes has their own rubber pipe, there is one central rubber hose that brings the brake fluid down from the chassis to the front axle where it then branches to go to each brake. If there were problems with this pipe both front brakes could stay on.

This pipe was an issue on my 101 and as result I replaced the lot.

Garry

Originally Posted by garrycol

While each of the front brakes has their own rubber pipe, there is one central rubber hose that brings the brake fluid down from the chassis to the front axle where it then branches to go to each brake. If there were problems with this pipe both front brakes could stay on. This pipe was an issue on my 101 and as result I replaced the lot.

I think you may be on the money here. I have heard of this problem by thought CanDo was not old enough for blocked arteries but probably is. I'll put three new hoses and a kit in the master cylinder and let you know what I find.
Thanks everyone.
Peter

When you do the master cylinder be aware that it is basically two master cylinders in one (one for each brake circuit) - there is a small seal (o ring?) on the main shaft that separates the two circuits and this can be easily damaged when the master cylinder is being rebuilt or sometimes it just fails. The result is not a safety issue but if there is higher pressure on one side compared to the other, fluid can leak across to the other brake circuit - this slowly drains one circuit of fluid and puts it in the other with each application of the brakes - maybe less than 1 ml at a time. This shows up as one fluid reservoir going down and the other filling up - as I said not a safety issue as the pressure equalises on both sides when the brakes are on and transfer stops.

It is quite common with 101s and most people just transfer fluid back to the low reservoir when required. Ron fixed his by using silicon fluid in his system and I have a small pipe joining the two reservoirs so the high one just drains back to the low one.

My master cylinder was built OK but started fluid transfer about 10 months later.

Oh - and another thing that could be causing the issue is the brake shuttle valve - has the slide inside moved to close the front brakes off - would stop the fluid releasing the brakes but then you would have no front barkes either and if operational the brake light on the dash should light up.

Garry