MK 3 Cortina brake help

[fredsajs]

Needs recommendations of help.
Due to recent brake rebuild have a problem. New Master Brake Cylinder MK3 Cortina replaced with new unit. Replaced brake fluid with DOT4also. Due to corrosion at Master Cylinder, both exit brake pipes cut out and replaced with in line joint 6" from Mast/Cylinder together with non return air valve on Servo.
Problem is now all bakes working but feel like its a drum brake system stopping, missing suddern stop or nose dip. Peddle is hard and servo does work to usual phyiscal tests ( peddle drop on starting, hiss on exusting pressure). I am wondering if (A) Have mixed front and rear pipe connections at Master Cylinder ( they are front brake pipe at front of cylinder and rear brake pipe at end next to Servo). Or (b) Have put non-return valve on Servo vacume pipe in reverse ( arrow on valve facing manifold).
Any help would be appreciated.

[chris]

Re: MK 3 Cortina brake help

Not sure if this will help, but if you master cylinder was corroded could you still have contaminated brake fluid in the pipes? also was the replacement a "new old stock", when I changed mine I had to rebuild the new unit as the seals had perished with age in the packet

[fredsajs]

Re: MK 3 Cortina brake help

Thanks Chris.
However the master cylinder was a new unit from Pettersonsonoffroad ltd, manufactored for them using MK3 Cortina design for there MK3 Land rover and for Kit Car use..
All brake fluid was replenished with new DOT 4 type.
Do you have any sugestions on correct pipe connection to master cylinder or non return vale correct way round as you didnot say?
Regards
Fred.

[chris]

Re: MK 3 Cortina brake help

I swapped mine for a mk4 master so had to add the third pipe (splitting the front circuit), not wishing to "teach my grandmother to suck eggs" the rear most pipe from the master cylinder goes to the rear brakes and the frot to the front which then should slit into two pipes one to each front caliper. As to the non return valve, mine seems to be part of the servo and I can see no arrows I am afraid

[Dane_Rescueman]

Re: MK 3 Cortina brake help

As above but did you shorten the master cylinder push rod as in the Berli build manual (page 11). It is shortened to make the measurement from the rear flange of ther master cylinder to the pedal pin centre 144mm. If this is not done then the master cylinder is partially compressed with the brakes off thus giving little movement when applying the brakes.
I swapped to a Mk IV, as above which gets rid of the splitter housing needed for the Mk III. i would not have gone for an in line join but made up new pipes to reach the master cylinder - it's just one more thing to go wrong !

Wishing you the best of luck sorting the brakes out.

[fredsajs]

Re: MK 3 Cortina brake help

Hi Chris,
Thanks again.
I have checked pipe configeration and by luck have connected as you state, so good news.
Pity about non return valve, perhaps someone else may know in line non return configeration in direction flow ?.
In mean time will attemp to re, bleed system again now I kno pipes are in correct order.
Many thanks
Fred.

[greyV8pete]

Re: MK 3 Cortina brake help

I think your vac pipe valve is correct as the arrow will show the "direction of flow" of the air, which is from the servo to the inlet manifold so that a partial vacuum builds up in the servo to make it work. Peter.

[fredsajs]

Re: MK 3 Cortina brake help

Hi GreyV8pete,
Thanks for that !.
Regards
Fred.

[fredsajs]

Re: MK 3 Cortina brake help

Hi Rescuman.
Thanks for info, but did not build car but have been forced to rebuild 70% of it in two yrs of ownership.
Two years of proving its not a MK4 as build manual states but 60% mk3, 30% mk4 and 10% Escort. I have replaced like for like to make some sence of parts,so I hope your recommendation has been done back in 1989 ?.
Regards
Fred.

[danny_nelson]

Re: MK 3 Cortina brake help

Hi Fred,
Rescueman is spot on with 144mm, I am sure yours would have been done at build stage , unless it was altered in between ownerships by someone who did not have any information on this. Everything you have described that you have carried out sounds correct , hope all is okay when you bleed again.
Regards
Danny.

[cameronfurnival]

Re: MK 3 Cortina brake help

Hi Fred, it sounds like the front brakes arent working, or are very inneffectual. If the pedal is hard, its unlikely there's air in them. Maybe one/both of the calipers is stuck? I know that sounds unlikely, but I would start by going through the whole thing methodically. Start at the front, push pistons back in and check they come out again when pedal pressed. iirc the cortina ones have a piston on each side - check em both first... Dont assume that work you have done is the cause of the fault - it might be, but then again don't rule it out.

[chris]

Re: MK 3 Cortina brake help

Hi Fred, I also struggled with bleeding the brakes as I could not seem to get rid of all of the air, but this gadget worked like a charm (Gunson G4062 Eezibleed Kit) it uses air pressure from a Tyre to force the fluid

from the reservoir along the system - best gadget I ever bought!

[fredsajs]

Re: MK 3 Cortina brake help

Hi Cameron.
Know the feeling well !However on ramps they work fine !.On road seam to not work. Cant understand it. They pull up o/k but the feel not there. Feels like a 1950 drum brake car?.
I think its chill out time .
Regards
Fred.

[fredsajs]

Re: MK 3 Cortina brake help

Hi again Chris,
I used to have one of these, but now its just me the wife and a bottle with a tube with non rtn valve in it.
Thanks again.
Fred

[Mike]

Re: MK 3 Cortina brake help

Hi Cameron.
Know the feeling well !However on ramps they work fine !.On road seam to not work. Cant understand it. They pull up o/k but the feel not there. Feels like a 1950 drum brake car?.
I think its chill out time .
Regards
Fred.

Fred

If you are not happy with your brakes, have a read through this thread on the Madabout Kitcars site;

http://www.madabout-kitcars.com/forum/showthread.php?t=3149&page=16

There are 16 pages, but there are some good points well made, and you may decide one of these could improve your brakes too.

The group who adopted these all had small 7" Metro servos, which are just not adequate in a Sportster or Cabrio. I believe the old Cortina servo is only 7" too? So, one of these Dual 7" servos could well offer you much improved brakes. Worth a look.

Regards
Mik