Trying to re engineer the Brake pedal

[Bubblemechanic]

Hi guy's and gal's I am trying to re engineer the Brake pedal and install a Mini Brake Master cylinder which is a stand up one
the problem is that the brake pedal works the other way by pushing the plunger in
I was wondering if anyone has changed the system round so it get's rid of the master cylinder in the tunnel
I have fitted a Remote servo from Ame353 and all went well till I tried braking and the pedal just went to the floor before any type of resistance was felt (Sh++ myself ) frightening
Me and my wife have spent hours and hours bleeding the system but cannot get the pedal to come up and stay pressured it keeps going back to just off the floor and you have to pump to get any decent braking pressure?
So am thinking of trying to re configure the brake pedal or the lever system so everything is under the bonnet in the engine bay
Cheers Bubblemechanic

[Bill_qaz]

Was it OK before you fitted the servo?

[kevin s]

Have you got the outlet of the servo pointing up, they are a pig to bleed if not.
A remote reservoir with a level sensor in the lid is a good safety measure.

[jaekl]

A pull rod from the pedal can be directed up and forward through the upright for the cross member behind the engine. Then you will need a rotating lever to change the motion to push the master cylinder.

[Bubblemechanic]

Thank you for the replies and I have the remote servo with it's outlet tilted at approx 30 degrees as near as dammit and the rear bracket in place and I presume that it is made to fit around the rear of the uni and made to length as long as that is holding the servo's rear end up then it is in approx right orientation.

When you say that a push rod can be used how does that work I am interested in the concept because at the moment all the movement of the pedal and master cylinder is focused on pushing towards the rear of the car.
So to say a pull rod can go up through the bulk head then I am a little lost ?

Thank's to Bill-qaz No not really because I had tried to stay old school and keep the system as original as poss with the 7inch drums all round I thought they would be fine I remember driving my dads first Moggie Traveller and it used to stop as they did. Anyway I took the car over to where I worked and at 5.30 in the morning it was not too bad but a different story coming home at 15.00hrs change of pants needed when got home, I was leaving enough braking room and other drivers thought it was their space to cut into. That is when I decided to fit a remote servo and reservoir well al the alterations needed changes to the master cylinder, changes to the pipework configuration It is finally all done when I ran into this bleeding problem.

[Bill_qaz]

Just some thoughts.
When you are bleeding the system are you doing this manually? Can you reach the point when no more air is visible in the bleed pipe? Are you brakes adjusted correctly, is it definitely air in system not excessive travel at the wheels. Is the mastercylinder pushrod correctly adjusted.

[Bubblemechanic]

Thank you 1 I am doing this manually with the wife operating the pedal, 2 I have put over 2 Li'ter of fluid through the system and we get to th point that you are just going round and pushing fluid into the container. The brakes are adjusted to the point where you have that noise of just catching the brake drum but not locked the drum can still be turned by hand. The master cylinder push rod is a set length from the brake pedal fulcrum and the master cylinder is locked in position by the bolts through the Channel.

[Bill_qaz]

The master cylinder pushrod is adjustable, just wondering are you getting full stroke.
When bled is the pedal hard or spongy? If you get a brake pedal keep it pressed and start the engine, the pedal should drop slightly showing your new servo is working.
If you're not getting a firm pedal after all that bleeding it's possible your master cylinder has failed. During bleeding the cylinder goes to part of the bore that hasn't been used in normal braking so corrosion can damage seals. If you watch in the resevoir while pushing the pedal does fluid push into resevoir.
For pushrod adjustment
See topic viewtopic.php?p=635920&hilit=Master+cyl ... od#p635920

[geoberni]

I suspect the seals have gone in the Master Cylinder.
I had to change mine due to a similar problem of spongy pedal. But I opened the floor up and found a thin film of fluid laying in the box section, where it was leaking out of the front of the MC.

It won't make that much difference, but is the Servo mounted with the Air Valve towards the bottom?
If the air valve is uppermost, you'll never get all the air out of the Servo.

servo.JPG (90.54 KiB) Viewed 988 times

Servo 2.JPG (71.81 KiB) Viewed 989 times

[jaekl]

The concept involves making a new rod to connect to the end of the brake pedal. Instead of point to the rear, have it point forward and slightly uphill. It would emerge above the tie plate in the engine bay. Now the direction of travel needs to change. That can be done with a bell crank. This is simply a rotating member (straight or angled) with holes on either side of the pivot point. Alternately, simply add a new attachment point to the brake pedal above the rotation axis the same distance of the original one. Now you would have a push rod going forward towards a master cylinder mounted to a bracket mounted to the floor of the engine bay.

[geoberni]

The concept involves making a new rod to connect to the end of the brake pedal. Instead of point to the rear, have it point forward and slightly uphill. It would emerge above the tie plate in the engine bay. Now the direction of travel needs to change. That can be done with a bell crank. This is simply a rotating member (straight or angled) with holes on either side of the pivot point. Alternately, simply add a new attachment point to the brake pedal above the rotation axis the same distance of the original one. Now you would have a push rod going forward towards a master cylinder mounted to a bracket mounted to the floor of the engine bay.

Just because it can be done, doesn't mean it needs to be. There is clearly a problem with the existing brake system, modifying it when it needs fixing isn't the way to go.

Fix it and then decide if it needs modifying.....

[Bubblemechanic]

Thank you all again for all your inputs and advice am still having probs but working through all the suggestions and am absolutely peed off of keep having to keep jacking the car up getting wheels off just so I can crawl under the car.

[Bubblemechanic]

Hi Jaerkl thanks for your input could you not use the original hole in the brake pedal, As you sat we are trying to change the direction and have the rod facing forward I was thinking using the original hole in the pedal and have the rod face forward then like you say it would need to come out into the engine bay then have a bracket fixed to the floor and then with the rod attached to the bottom of the bell crank I have made at work you would be pulling and the rod to the piston of a classic Mini Master cylinder you would be pushing the rod and hopefully get the brakes to work and take away all the faffing about in the channel in the floor if I can find enough room in the drivers side engine bay space.