Jump to content
Sign in to follow this  
hoobby

Brake pedal travel trouble

Recommended Posts

I still have about 65mm pedal travel with no affect on the brakes not a nice feeling every time you touch the brakes there's nothing there....brakes?...push down further and brakes are fine.

 Brakes needed total overhaul new pistons,seals,boots,sliders,rear drums,shoes, wheel cylinders and a master cylinder.

Blanked off all outputs pedal is firm

Blanked off n/s or o/s output only and brake pedal is firm

Blank off rear circuit output only pedal feels firm

I have even bypassed the brake valve and still have travel 

I have used about 6 liters of fluid chasing this problem

this makes absolutely no sense to me anymore the problem is every where and no where.

One difference tho original master had a stop screw which held the piston for the front brakes in a compressed state the new one does not have this rear brakes are auto adjusters.

IMG_20190824_063418.thumb.jpg.795e428ce95fa566127b1c85c09b2ae4.jpg.9cf7772c6ac49bb5b171aeba210e45ff.jpg

Totally peeeeeeeeed :( off from Braintree.

 

 

Share this post


Link to post
Share on other sites

Had this problem 

Carried out a Audi discs Astra callipers mod with stainless brake hoses.

Brakes where spot on 

Share this post


Link to post
Share on other sites

I think Wayne might be on to something there Graeme.

It sounds like the only part of the system you haven’t changed is the flexi hoses.

The MC stop screw is a strange one too - can anyone else comment on this?

Share this post


Link to post
Share on other sites

When do you notice the long pedal more, static or when it is driving?
When you take rear drums off, or spin the wheels do you get a sense they are adjusted properly? It could be that the rear are not Adjusting properly. They should very close to drum. 
there are also 2sizes of rear shoes, if the smaller is fitted into a larger drum this will cause a long pedal.

finally, What is the new master cylinder bore Diameter?

whilst flex hoses do go bad, and can balloon, what you describe is too much travel taking up clearance between material and disc/shoe

  • Like 2

Share this post


Link to post
Share on other sites

hi mr hooby. sad to see you are still having this brake issue.a quick check as i may have mentioned before but its been a while and my memorys not that good!

if you are stationary and handbrake is applied.press brake pedal a couple of times to settle the shoes .if your travel is still excessive then its a fluid issue,air in system ,swelling hoses .but nothing in the rear brakes.(as they are fully applied by the handbrake)or an issue with the front calipers.but if its now non excessive movement then its something in the rear brakes.first guess air.

next  or   

 

clamping the 3 flexis should result in a solid pedal.if it does then master cylinder is good.unclamp a line each to find the problem leg.

which sounds like exactly what you have been trying except no leg shows up as faulty. 

so as jess asked,is it when stationary or when moving. if only when moving it suggests a piston being pushed back due to some radial movement .warped disc, drum or even a wheel bearing .

Edited by cam.in.head
  • Like 1

Share this post


Link to post
Share on other sites
50 minutes ago, cam.in.head said:

hi mr hooby. sad to see you are still having this brake issue.a quick check as i may have mentioned before but its been a while and my memorys not that good!

if you are stationary and handbrake is applied.press brake pedal a couple of times to settle the shoes .if your travel is still excessive then its a fluid issue,air in system ,swelling hoses .but nothing in the rear brakes.(as they are fully applied by the handbrake)or an issue with the front calipers.but if its now non excessive movement then its something in the rear brakes.first guess air.

next  or   

 

clamping the 3 flexis should result in a solid pedal.if it does then master cylinder is good.unclamp a line each to find the problem leg.

which sounds like exactly what you have been trying except no leg shows up as faulty. 

so as jess asked,is it when stationary or when moving. if only when moving it suggests a piston being pushed back due to some radial movement .warped disc, drum or even a wheel bearing .

Sorry forgot to mention Flexi hose have all been changed with the overhaul.same moving or stationary.

Master cylinder 20.63mm 130mm drums and shoes.system has been bled and bled and bled.....

With the handbrake on and pump pedal still the same I have even clicked the adjusters out until the drums are  binding.

With master all blanked up pedal is firm.

Sorry but this bit sounds like something from quantum physics  if I remove any one leg then the pedal goes firm so all are faulty but only when working together.

Things I have noticed  put a length of wood between the steering wheel and pedal keep adding blocks and fronts go on hard rears are just starting to bind thought this was supposed to be the other way round to stop diving.

Left the drum on n/s removed o/s drum and pressed pedal down slowly nothing moved for a good portion of the 65mm play. 

Well there it is my nemesis.

 

 

 

 

 

 

 

 

 

Share this post


Link to post
Share on other sites

like you say none of this makes any sense .

so if im reading you correctly.

if you clamp all 3 hoses pedal is hard and virtually no travel.

if you release ANY 1 and keep the others clamped pedal is hard and virtually no travel ?

so all circuits are ok on there own but not when all 3 released at once ? 

is that definately correct ?

definately ?

wel get there mate 

  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, cam.in.head said:

like you say none of this makes any sense .

so if im reading you correctly.

if you clamp all 3 hoses pedal is hard and virtually no travel.

if you release ANY 1 and keep the others clamped pedal is hard and virtually no travel ?

so all circuits are ok on there own but not when all 3 released at once ? 

is that definately correct ?

definately ?

wel get there mate 

yes its only when all circuits are connected the play appears but i will double check this in case i've got it wrong some where i was very busy and rushed with life stuff when i went through this last time may have made a mistake.will let you know the result.

Share this post


Link to post
Share on other sites

Front should lock way before rears. Due to load shifting, rears will hardly do any effort and a locked rear axle is dangerous. Remember, that manual should be changing down during breaking, so you already gave engine brake effect. This is why Autos use larger rear drums.

Rear pressure regulator - check pipework, or bypass it completely and see how it is.

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.

Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...