Master Cylinder "plunger". How Long?

[gncgray]

Morning

 

What length bolt have you all used for the "plunger" from your pedal to the brake master cylinder?

 

 

 

Ta

Graham

[sj-bradley]

Not sure I remember. As the pedal travel on the brake is much less than either clutch or throttle, make it comfortable for yourself

and adjust the others to match it.

 

What you DO need though is a back stop so that the pedal does not move so far back that the plunger comes out of the cylinder and jams giving you no brakes. I think IVA will check for this.

 

Simon.

[gncgray]

Cheers mate, I have put a back stop on. I'm just sorting out the plunger bolt. I have bought a long M10 which I will cut down bit by bit and find the correct length. I have been told that the Sierra master cylinder olny has about 30mm travel. Dont know how true that is.

 

 

I'm bricking myself over Monday...the test and the drive up!!! My Neice and her boyfriend are following me up there with a boot full of tools ect and some more petrol. I'll let you know how I get on.

 

Graham

[Guest iank]

Not sure how long mine actually is but its somewhere around 4 inches. The approach you are taking is the best to cut it down bit by bit, I ended up cutting mine down twice to get it comfortable and line up the pedals.

 

Ian

[gncgray]

Hi Ian

 

Ta for the reply. I have been having real issues with my brakes. The pedal is really spongy and I have bled them so many times now. I have put bleed nipples in the cylinder and the pedal is rock hard so I know thats fine. When you put your foot on the brakes its fairly hard to start with then it slowly drops down. I cant see it being air in the calipers as I have wound the pistons in and G clamped them in possition to get as much air out as pos.

 

Any help would be appreciated as my IVA is Monday!!!

 

Graham

[Dave R]

remember when cutting the actuator rod, you want a little slack at top position so you know the piston is fully returning

 

silly question, but you have the calipers on the right way round ? ie bleed nipples at the top ?

[gncgray]

Yeah they are at the top. I have removed the rears and placed them on top of the disc so the nipple was pointing up too.

 

I have also wound the pistons right in and clamped them then used the Eezibleed system but stil spongy pedal.

 

I really don't know what to do now

 

Graham

[Guest iank]

Check the brake light switch. I had to use a hydraulic sealant to stop it leaking. Although I don't think it had a major effect on the brakes, but something to check.

[IanS]

Slowly drops down has to be a leak.

If fitting blead nipples to master cylinder has it rock solid and not creaping down then it has to be some where else in the system.

From nipples in the master cylinder I would fit one pipe at a time.

In my case first one front (my master cylinder has 2 ports for the fronts) and then the second and finally the backs to check which circuit is the problem.

The solution should now be easier to determine.

-Ian

[Guest Jthorne]

Hi, I have this exact same problem with my car, the pedal is still soft ish and the brakes seem to do nothing until the pedal gets almost to the floor and then bang they come on. I have done all the above and still have the issue, its like you cant softly apply the brakes, you have them almost all or nothing. (this is hitting a max of 5mph testing though..

[sj-bradley]

The pedal travel is only around 1 inch travel I think maximum and should feel hard from the start. If you have that much travel then you have air in the system somewhere or possibly the master cylinder washers have become inverted and not working properly.

 

(I'm told that this can happen when new pads are inserted and the caliper pistons are pushed back to fit them forcing the master cylinder back)

 

I used an easi-bleed system with air from one of the tyres to force the fluid through for a one man operation. Works very well if you keep an eye on tyre pressure and reservoir fluid levels.

 

Simon.