Jump to content
mpp

Soggy Brakes

Recommended Posts

Mk3 Cortina-based kit-car, just finished a nut-and-bolt rebuild. (I know, I know, I'm sorry too that it used to be a Cortina. But back in 1975 no-one was collecting write-offs for rebuilding, so it ended up as a Spartan.)

 

Almost all original specification brake fittings:

Professionally recon front calipers. Girling Type 16.

New rear cylinders.

New Mk4/5 master on a Bendix servo.

New disks newly mounted on clean hubs with no measurable run-out.

New(ish) "Greenstuff" pads.

New rear shoes.

Original, scored, but un-cracked rear drums.

Goodrich hoses.

Bled. Lots. I mean really bled. Over 2 litres of glycol have been through that system using an Eezi-Bleed. I've tilted the car up to get the rears to bleed properly, too. If there's air in it, I don't know where it's hiding.

And no leaks, either.

And checked the ratchet adjusters on the shoes. They're free and I heard them working after resetting them.

 

So why is the pedal so soggy? Properly soggy. Like the pedal goes to the floor with moderate brake pressure and only just locks the wheels on a dry road. Yes, it passed the MOT, but it feels horrible.

 

I'm going to change the master to a Landy NRC8690, which will firm it up a bit and shorten the stroke. But it's not the whole solution.

 

Does anyone know where all the give in the system could be coming from? Old pads on new disks and new shoes on old drums? Would that account for it? All help would be much appreciated.

post-1153-086889900 1311083125_thumb.jpg

Edited by mpp

Share this post


Link to post
Share on other sites

I guess new doesn't always mean working :unsure: Have you tried clamping the hoses and seeing if you can narrow it down to a corner thats at fault? :headscratch:

Share this post


Link to post
Share on other sites

I had a similar problem on my MK2.

 

Have you checked the flexible hoses ??

 

That is what the problem I had. They were acting like a one way valve allowing air in but no fluid out.

 

Once I changed the flexi hoses the brakes were perfect

Share this post


Link to post
Share on other sites

Thanks both.

 

I doubt it's the hoses. I changed from NOS rubber hoses to brand new Goodrich, and that made no change at all.

 

Clamping each hose seems a good idea. Can I clamp braided Goodrich hoses without damaging them, though?

Share this post


Link to post
Share on other sites

:unsure: oooo I doubt it. I never knew you have braided ones :headscratch:

Share this post


Link to post
Share on other sites

:unsure: oooo I doubt it. I never knew you have braided ones :headscratch:

No you can't clamp them if they're the plastic ones with stainless outers.

 

Also have you made totally sure:

1. You have the right bore rear cylinders

2. self adjusters are working (you might have to back off the handbrake to sort this

Share this post


Link to post
Share on other sites

Thanks again to recent repliers.

 

Rear cylinders were replaced by a local garage. The old boy there has since retired, but he was on the ball at the time he did the work. And he would have worked on Cortinas in his prime, unlike the kids who have taken over from him. So I'll put "wrong bore size" at the bottom of the list for now.

 

I took apart the self-adjusters and ran the ratchet-nut up and down the thread until it was properly free. Then reassembled. I could hear them working for the first few dozen pulls of the handbrake as they took up the slack.

 

BUT they didn't do anything when I worked the footbrake. Not a single click from them. Are they supposed to? Haynes does say to work the footbrake to ratchet the adjusters... but they only seem to work on the handbrake. Is this the issue, maybe? I don't really know how to tell if they're working.

Edited by mpp

Share this post


Link to post
Share on other sites

Is the Master Cyl, New or NOS? If the latter could the seals be perished? :headscratch:

Share this post


Link to post
Share on other sites

They do not click when at the optimum. As the shoes wear they will click again to take up the slack. As the initial slack is taken up either the pedal or the handbrake lever should trigger the uptake.

If one, or both, click all the time then the lever is jumping over the ratchet wheel and not turning it.

I had this on my 1600E which resulted in the purchase of new adjusters. Theyre now fine with a decent pedal.

Is there an improvement when you pump the brakes? If so, this will normally be air in the system.

Share this post


Link to post
Share on other sites

Had all this last month ,it was a knackered new master cylinder, another master on and good brakes

Share this post


Link to post
Share on other sites

Phew... a lot of suggestions there with much focus on the master cylinder. Thanks again everyone.

 

Self-adjusters: After reassembling the drums, the adjusters definitely clicked on the handbrake (but never the footbrake). They ceased to click after a couple of dozen pulls. So they're not slipping. But why not working on the footbrake? Getting the drums off to recheck them again was hard work, which means the shoes did expand properly to inside the wear lip. So the adjusters are probably doing their stuff OK.

 

Master: Is brand new new, not NOS. It replaced a leaky one but I can't remember how firm/soggy the pedal was with the old one. Sometimes the pedal went to the floor with the old one as fluid just went right past the seals and onto the road. And sometimes the brakes worked properly. (Which made for an exciting trip back from the MoT test.) The new master is a non-genuine part from ebay. Guess it could be a dud but the seller (popy760) is a vehicle parts specialist and has 37,000 feedback at 99.9% positive so it's improbable. I'll message to ask if they've ever had problems with these.

Share this post


Link to post
Share on other sites

Sorry everyone. I'm an idiot.

 

Got my new Landy master and went to fit it. And spotted that the shiny new front brake pipe goes to the... (I bet you're already ahead of me by now) ...rearmost port on the master. And the rear copper pipe goes to one of the front ports. (The other front port is blanked by a bleed screw.)

 

Swapped the pipes around and bled it, and things are better already. Pedal is still a bit soft compared to - say - my T4 Transporter but I guess that's probably normal for a '71 car. I may take it down to the MOT man and get him to retest the brakes, just to be sure. Dunno now whether to use the Landy master or not.

 

You might be interested to hear that ebayer popy760 already offered to swap the master, no hassle. But I told them to hold off until I had tried a different master first. So +++ve feedback to them for great customer service.

 

Many thanks to everyone for all the replies. And I'm sorry I wasted your time.

 

Cheers,

Ian.

Edited by mpp

Share this post


Link to post
Share on other sites

soft and low for the first 2 inches is about right for a cortina with a good system, they never did have a very firm pedal, glad you sorted the problem anyway :thumbup:

Share this post


Link to post
Share on other sites

make sure u have loosen the hand brake adjuster off before adjusting the rear brakes or your be running on the handbrake easy way to tell is pull up the handbrake then see if the petal feels better,alot of people forget to do that.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...