Brake question

[Andrew S]

My brakes have always been good and I know there are many posts about making brakes better but I agree that if they are set up correctly, they are great. I have a new master cylinder, new rear cylinders, braided flexi pipes all round and front exchange calipers. I run on silicone. The breake pedal pressure is excellent and near the top. It just feels like I cant lock the wheels up.

I decided with an ezi bleed to bleed the system and all fluid was nice and clean. Took the car for a spin around town and on a dry road got one of teh front wheels to lock up with a quick jap of teh pedal and the over all the brakes felt so much sharper. Put the car away feeling very smug.

Took the car out a week later and they were back to how they were.

I read the other post about the adjusters possibly being fitted round teh wrong way and then the adjusters slackening off afterwards, but checked them today and they are as shown in the manual. Shame.


So, my question is, does this point to air still in the system or could it be something else? Its so strange that they worked superbly the week before

Cheers
Andrew

[Andy Rundell]

Hi Andrew, could still be some air in there, the cheap old-school method to fix this is to keep the brake-pedal pressed hard down overnight (use a broom jammed between the seat-back and the pedal. In the morning you should find things much better.

........ Andy

[73stagman]

It would be interesting to know if this gets better if you drive it more or worse. I have a theory but thats all it is and it is to do with water and silicon fluid not mixing in the system. Although this is in most cases a positive condition because the fluid doesn't degrade it is a negative condition if enough water gets into the system.

What I mean is that if the water separates out of the silicon fluid readily, it sits in the pipe work or in the calipers or wheel cylinders. When you stomp on the brake pedal some of the water could be changing to water vapour wherever the heat is highest (behind the caliper pistons which is where I suspect it settles to when the system is at rest) water to all intents and purposes in liquid form is non compressible but it readily forms vapour under heat and pressure which is extremely compressible.

Do you run a dehumidifier in your garage? At present with huge swings in humidity I suspect your system will be drawing "wetter" air than normal into the master cylinder. So a dehumidifer might help.

As a thought .... you know what the little crystals are in the damp collecting packages on the top of your aspirins? Yes silicone beads also in larger dehumidiers sold by the likes of Kleeneze and Betterware to name a couple! The same stuff is used in liquid form in your brake system!

[73stagman]

I dont believe its air exactly because the ezi bleed system will fix that without a doubt. And the air would still be there after your initial bleeding session so you would not have got the initial excellent result.

[wilf]

What are the inner faces of your brake discs like?

[Andrew S]

My discs are great and the brake pull up evenly.

Myabe I didnt bleed the brakes long enbough for air to come out. I started off bleeding the rear offside, then, nearside. On the front, I bled the offside, then the nearside. Although the offide appears to be closer to the master cylinder, the pipe is longer as it goes to the switch then doubles back to the offside. May have got this all wrong.


On the back, the fluid didnt exactly blast out when I undid the bleed nipples but put this down to them being thinner than the front ones. I waited until the fluid came through as a purple.

Maybe I didnt have the tyre pressure high enough and it wasnt able to chase air out, but instead, let the fluid roll over any air trapped.

Alan, this broom method. I presume, I open one of the bleed nipples to allow the pedal to drop, then hold it down with a broom or simialar, do the nipple up, then top up if need be?

Thanks for all the responses.

[Andy Rundell]

Hi Andrew, nope, no need to open any bleed nipple when using the broom...... If you have already given them a good old 'bleeding' .......... Just do as I said earlier, jam the pedal hard down and leave it that way overnight..... If it is only a bit of air kicking around in the system you'll be sorted in the morning ...... It's not like it's gonna cost you anything to try

......... Andy

[Andrew S]

Cheers Andy. Not using the car today so will give it a try

[MandM]

Cheers Andy. Not using the car today so will give it a try

Hi Andrew, this thread and the other one "Excessive Travel on Brake pedal" are of interest to me too as i feel my pedal travel is not as it should be, this may need correcting by the "guru's" on the forum, but when i was a 17yr old apprentice ("A COUPLE OF YRS AGO" ) in the mid seventy,s. i remember watching the machanic adjusting the pedal travel on a car ,triumph or ford capri, by adjusting the threaded rod on the servo that pushes the master cyclinder. I was going to have a go at mine as just have changed the master cyclinder, will mark it then count the number of turn,s out, so it can be returned back to the standard setup, but this adjustment must be of some use when changing master cyclinders or servo. I know that too much will lead to the brakes binding ,

"SO LET'S HAVE A DISCUSSION" . might be talking out of turn if so sorry in advance

[MandM]

Hi Andrew, this thread and the other one "Excessive Travel on Brake pedal" are of interest to me too as i feel my pedal travel is not as it should be, this may need correcting by the "guru's" on the forum, but when i was a 17yr old apprentice ("A COUPLE OF YRS AGO" ) in the mid seventy,s. i remember watching the machanic adjusting the pedal travel on a car ,triumph or ford capri, by adjusting the threaded rod on the servo that pushes the master cyclinder. I was going to have a go at mine as just have changed the master cyclinder, will mark it then count the number of turn,s out, so it can be returned back to the standard setup, but this adjustment must be of some use when changing master cyclinders or servo. I know that too much will lead to the brakes binding ,

"SO LET'S HAVE A DISCUSSION" . might be talking out of turn if so sorry in advance

Does anyone know how to adjust the servo push rod?

[Andrew S]

From memory, its not adjustable, however, that could be changed I am sure with the threaded rod and extension or even a nut on the end.

[MandM]

From memory, its not adjustable, however, that could be changed I am sure with the threaded rod and extension or even a nut on the end.

Mine has a thread rod already fitted must standard issue?

[flying farmer]

I had the same on my PI saloon years ago, my problem was the brakes locking on when hot. The adjuster refused to move so I ended up fitting thin washers between the servo and the master cylinder to cure the problem
Neil