Long Pedal Travel

[dch1950 37 1 Cars]

Hi all,

I have finally got my handbrake fully sorted this morning. I'd also been carrying out a sequence of bleeding to get the system working as well as possible. I finished the full bleed (including a the rear limiter bleed) and the pedal seemed fine.

Took it for a test drive. As soon as the engine was running the pedal travel increased significantly ( the brakes did work though) and was accompanied by what can only be described as a wheezing sound.

I have replaced my original front calipers (Bendix) with the 1.9 Girlings. Would this cause the aforementioned symptoms?

or is it likely to be the master cylinder.

regards

Dave

[Baz 421]

Nope, the 1.9 and 1.6 have the same size MC, so changing from 1.6 to 1.9 calipers won't change the pedal travel needed to displace the fluid in the new calipers any more than the old.

 

Is the pedal still hard or soft when you do find some feel?

[dch1950 37 1 Cars]

Nope, the 1.9 and 1.6 have the same size MC, so changing from 1.6 to 1.9 calipers won't change the pedal travel needed to displace the fluid in the new calipers any more than the old.

 

Is the pedal still hard or soft when you do find some feel?

Hi,

the pedal is "hard" i.e. it seems as normal to me - when the car is stationary - engine switched off.

If I start the engine the pedal travel increases before I get any feel. This seems to be related to the servo charging up.

Dave

PS JUst been out to check again. Pushed the brake pedal 4 or 5 times to discharge servo. Kept my foot on the pedal (which was fairly solid after about an 1" of travel). Then started the engine.The pedal then moved down another 1" before any feel came back. This does seem excessive to me. Could it be the rod connecting to the master cyclinder - if so how do I get at it to check and or adjust it?

DCH

Edited October 19, 2009 by dch1950

[dch1950 37 1 Cars]

Hi,

still being puzzled by this longish pedal travel, I asked a mate to take car out and see what he thought. He says the brakes seemed fine (especially the handbrake) with possibly a little bit too much pedal travel. The thing is I think that since I last played with the brakes (some 5 years ago) I think I've been running with no servo operational. This would explain why I'm used to a high firm pedal. Added to this the fact that I've not heard the "wheezing" sound of the servo operating before.

I have performed a total brake refurb/replace with only the front to back pipe and the M/C being original and wonder if this coupled with a fluid drain and refill has kicked the servo back into life.

Just thinking out loud.

regards

Dave

[welshpug 1,655]

try adjusting the rear brakes manually, might have too much brake shoe to drum clearance which would cause a long pedal.

[dch1950 37 1 Cars]

try adjusting the rear brakes manually, might have too much brake shoe to drum clearance which would cause a long pedal.

Hi WP,

I've done that already and the handbrake is fine - see my posts re this with Tom F about starwheel acces etc.

The only adjustment to pedal movement that I can see is the rod that goes through the servo housing connecting the pedal to the M/C. Presumably this would require me to remove the M/C first - which sort of defeats the object (just to check it) as I'll have re-bleed everything again.

regards

Dave

[welshpug 1,655]

depends which engine you have in there, and how flexible your brake lines are, but you can often pull the MC out enough to check and adjust the rod without disturbing any unions.

[dch1950 37 1 Cars]

depends which engine you have in there, and how flexible your brake lines are, but you can often pull the MC out enough to check and adjust the rod without disturbing any unions.

standard 1.6

Dave

[lagonda 42]

I had a similar problem with mine....pedal travel got longer & eventually I had to pump the pedal before brakes would actually stop the car....also had wheezing noise. Changing the master cylinder solved the problem. Suspect bleeding brakes might have dislodged crap maintaining a seal in your m/c. Would be wary of adjusting rod...my understanding is that that adjustment is only there for the factory to set things up in the first place. There's no reason for that to go out of adjustment, when you think about it.

[GLPoomobile 958]

Is there actually a problem here?

 

With the engine off, you should get a little bit of pedal movement for the first few pokes, then as you've used what vacuum is left in the servo, the pedal will become much harder to push. You said this happens. So that's normal.

 

When you start the engine, you get vacuum back in the servo. If you've left your foot on the brake pedal it will now creep down another inch or so, until such point as the pads/shoes are fully engaged. You've said this happens, so that's normal.

 

You said it makes a bit of a wheezing noise. I can't rule that out as a potential fault, but I will say that every one of the cars I've ever owned has made a little bit of a wheezy noise upon pressing the brake pedal.

[dch1950 37 1 Cars]

Is there actually a problem here?

 

With the engine off, you should get a little bit of pedal movement for the first few pokes, then as you've used what vacuum is left in the servo, the pedal will become much harder to push. You said this happens. So that's normal.

 

When you start the engine, you get vacuum back in the servo. If you've left your foot on the brake pedal it will now creep down another inch or so, until such point as the pads/shoes are fully engaged. You've said this happens, so that's normal.

 

You said it makes a bit of a wheezing noise. I can't rule that out as a potential fault, but I will say that every one of the cars I've ever owned has made a little bit of a wheezy noise upon pressing the brake pedal.

Hi,

It really depends what you call a little movement. This was not a feature of my brakes before this particular set of work I've just completed. The movement is certainly more than I'm used to with this car - I've had it 10 years - so I notice anything out of the ordinary. I can understand servo assist - but once you start hitting that brake pedal you should start slowing down and I'm not getting that so something isn't moving twixt M/C and pads/shoes until the pedal gets more than 1/2 way down. I don't think there's air in the system - I bled it 3 times., so it's looking like the M/C in my view.

Any thoughts ?

regards

Dave

[dch1950 37 1 Cars]

Hi All,

I finally resolved this problem/symptom. First of all I jacked the car up at the front - both wheels up.

Started the engine and ran it in second gear - wheels turning and applied the brakes progressively. They were coming on earlier than I thought (given that I thought the easy first third of the pedal travel was doing nothing.). I then put her in neutral (got my mate in the car to press the pedal) and turned the front wheel by hand to see when the brakes actually started to engage. This again was earlier than I was expecting. It does seem as though my vacuum servo has not been working up to now and for whatever reason has decided to start. This has led to my confusion as I wasn't used to it.

Thanx for your input guys.

Dave.

PS At least while I was looking at all this I made up a handy little tool using 10x1 bleed nipples (3 off) and plastic tubing to bleed the M/C with.

D