Jump to content
mackev

TR4 Brake bleeding Issues

Recommended Posts

Hello to all the members, A sorry situation considering the weather, I cannot take a chance and use the car

No matter how many times we bleed the brakes we still have a soft pedal. After the second application in succession of the brake pedal it's perfect.

Do you think the new Master cylinder could be faulty ?. Before the overhaul of the system they were fine. Even paying a garage, could not improve them

Any help would be appreciated Thanks in advance

Share this post


Link to post
Share on other sites

Hi Mack,

 welcome to the forum.

Did you do other work to the brake system before attempting to bleed.

Did you replace the front calipers?

Did you replace the caliper piston seals?

New front calipers have a problem that the piston seals are too grippy. After application they pull the piston back to where it started.

This means you have a long pedal travel on first press. Second press good. After a few moments the seals pull the piston back.

Options for above.

Replace the piston seals with new old stock.

Press the pedal down and keep it there for 24 hours.

or

Remove the pad and replace with something thinner (don;t let the pistons pop out). Press the brake pedal to move the piston further than needed.

Replace the pads.

Roger

 

Share this post


Link to post
Share on other sites

In addition to Rogers list.

Are the rear brake shoes correctly adjusted. Too much free movement there will send the pedal a long way down, but a quick pump will bring it up again.

Bob.

Share this post


Link to post
Share on other sites

There are various ways of bleeding brakes, bleed front and rear together with bottles on each, always lock off the bleed screws with the pedal held down, also is there a non return valve on the tee to the front circuit it could be faulty..

             Phil..

Share this post


Link to post
Share on other sites

Check if your long pedal problem goes away when the handbrake is on... If it does it confirms that pullback of the rear shoes is giving the long pedal.

Share this post


Link to post
Share on other sites

First thing to try is pump the brakes up until they are as hard as you can get them then jam the pedal down with a bit of wood between the pedal and the seat and then leave overnight.

Stuart.

Share this post


Link to post
Share on other sites

I'm guessing that can work because under compression any air bubbles which might be trapped somewhere in the system will be squeezed to be much smaller, & then can find their way up through the fluid in the pipes till they get to the master cylinder. After which, when the pedal is released they will pass up to the reservoir ?

Bob.

Share this post


Link to post
Share on other sites
8 minutes ago, Lebro said:

I'm guessing that can work because under compression any air bubbles which might be trapped somewhere in the system will be squeezed to be much smaller, & then can find their way up through the fluid in the pipes till they get to the master cylinder. After which, when the pedal is released they will pass up to the reservoir ?

Bob.

Pretty much yes. Its a very old car dealers trick from all drum brake days as some cylinders used to have a spring in them so it was very difficult to bleed without taking the drum off and wrapping a very long hose clip round the shoes then winding them in tight until the cylinders were fully compressed. Jaguar drum brakes from early MK1 and early XK especially needed this trick.

Stuart.

Stuart.

Share this post


Link to post
Share on other sites

 I have just replaced the fluid in my 3A and used a self bleeder I made out of a 2lt milk bottle which worked fine with just a small amount of air in the brakes so I did the bit of wood trick and the next day, firm pedal first time every time.

 

Graham

Share this post


Link to post
Share on other sites
On 6/5/2019 at 10:14 AM, mackev said:

Hello to all the members, A sorry situation considering the weather, I cannot take a chance and use the car

No matter how many times we bleed the brakes we still have a soft pedal. After the second application in succession of the brake pedal it's perfect.

Do you think the new Master cylinder could be faulty ?. Before the overhaul of the system they were fine. Even paying a garage, could not improve them

Any help would be appreciated Thanks in advance

It Depends what you mean by soft pedal, if you mean spongy then you have either a faulty master cyl, or air in the system, or the hoses are ballooning, if you mean long travel then either the pads are moving away from the disc and/or the rear shoes are too far away from the drums. if as you the pedal pumps up I would go for the latter. Cheers Bill.

Share this post


Link to post
Share on other sites

Welcome Mac - You will get it sorted now on here....

 

Further the post above from Bill, I was going to throw ‘hoses’ into the mix this morning.. Definately worth x-checking and ruling out, they can still look good from the outside but cause all sorts of grief if even one is collapsed inside.. I learnt that the hard way!

 

Final note to Bill, not to hijack thread, don’t suppose that was you in the 3 around noon Sunday around Woodmansterne? - Only caught a glimpse but looked like really well sorted original..

Share this post


Link to post
Share on other sites

Good Morning every one. Thank you all so much. I've been away and got back yesterday. I'm so pleased with the responce. At least I have a selection of idea. The first will be the 24 hours of push to the solid pedal.  I will keep evryone posted. I think that the rear drums would be the second activity, although that sounds a bit pessimistic, them what do you think about re installing the old master cylinder ? 

 

Once again thanks, I will keep you posted on the progress I make.

 

Mackev 

Share this post


Link to post
Share on other sites

We are all assuming your setup is standard and that
you do NOT have twin brake master cylinders and
separate brake lines to front and rear.

That setup requires a different technique.

AlanR

Share this post


Link to post
Share on other sites

Yes, just the standard set up, but new master cylinder and new pads and calipers to the front and aeroquipe hoses to the calipers all round

I will be grateful for any further information that may be useful Thanks again, Mac

Share this post


Link to post
Share on other sites

Hello Mac

If it helps I posted some of this this on TR6 forum a while back.

Try bleeding the brake system again starting at wheel furthest from master cylinder. I use an eezibleed which makes job easier. If you have replaced the braking system then it is easy to get air trapped somewhere. On the rear wheel cylinders push the piston in and clamp it in this position so there is little space in the cylinder itself for air to get trapped and do one wheel at a time. Take the clamps off the cylinders, refit hubs and press brake pedal to get the pistons back to "operating" position. On the front push the pistons in and clamp them and bleed them one at a time. Then release clamps and operate foot pedal. You will need to keep master cylinder topped up during all this. At the servo if you have one, ensure that all the air is removed from the system. You can't always tell if there is air simply by pumping up the pedal. Also check brake fluid is ok using a brake fluid tester to make sure that the water level is less than 1%. Dot 4 fluid is fine but should be renewed every 3 years.

Secondly ensure all the bits that should move do actually move. Rear pistons should slide on the backplates, rear shoes slide on the 3 raised dimples on the backplate and should slide in the adjuster at the bottom. On the front the disc pad holders slide on flat faces on the callipers. Use copper grease and white brake grease for lubrication on moving parts. Obvious but don't get it on the discs, pads, shoes or inside of rear hubs. Only a thin smear of grease on moving parts.

Also make sure the rear adjustment is correct. Turn adjuster clockwise, press brake pedal to centralise brake shoes and then spin the rear wheels by hand. If shoes rub then back off 1/4 turn. If no rubbing sound then tighten 1/4 turn until you hear the shoes rubbing on the inside of the hub then back off 1/4 turn. Pull up the handbrake one notch and try to spin both wheels. Pull up another notch and repeat until both wheels are locked. Both rear wheels should lock up evenly. If one locks before the other then handbrake cable may not be pulling evenly or you haven't adjusted the rear adjusters properly.

Hope you get it sorted.

Keith

 

Share this post


Link to post
Share on other sites

Hi Mack,

have you got the restrictor fitted

Item #43  Here

These can play up and are not really necessary.  Keep the body but remove the innards

 

Roger

Share this post


Link to post
Share on other sites

Good advice (s) guys, I hate bleeding brakes! And, I'm choosing a seriously hot day to attempt it again after giving up yesterday.

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.   Restore formatting

  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.

Loading...

×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.