Variable brake pedal feel

[ONE LIFE LIVE IT. D90]

Thanks Brown and trax.

I've been out fault finding today-

There is definitely no bearing play in the front or rear wheels. I'm certain of this. I had it jacked up on stands and used a pry bar under the wheels. No issues or play at all. Even rocked the wheels on the ground.

I also checked lock to to lock and all brake pipes and flexis on the front end. No issues at all, looked perfect.
With the wheels off, I have noticed that the front pads are rocking in the calipers, quite considerably. I'm wondering if this could be knocking the pistons back in some way?

After checking everything over I then took it out on the road and found an empty car park to try and find the fault while looking like a right nutter.....

Here goes...

I drove in a constant circle on full lock either way.

when driving forward in said circle, the first press of the pedal increases (soft). The second press while continuing forward is better!
Then when reversing in the same circle the first press the travel increases, and the second press is better. It seems to be the transition between forward and reversing that's causing the problem which only occurs when turning.

Any ideas fellas? Could it be those pads rocking?

 

[trax]

Thanks Brown and trax.

I've been out fault finding today-

There is definitely no bearing play in the front or rear wheels. I'm certain of this. I had it jacked up on stands and used a pry bar under the wheels. No issues or play at all. Even rocked the wheels on the ground.

I also checked lock to to lock and all brake pipes and flexis on the front end. No issues at all, looked perfect.
With the wheels off, I have noticed that the front pads are rocking in the calipers, quite considerably. I'm wondering if this could be knocking the pistons back in some way?

After checking everything over I then took it out on the road and found an empty car park to try and find the fault while looking like a right nutter.....

Here goes...

I drove in a constant circle on full lock either way.

when driving forward in said circle, the first press of the pedal increases (soft). The second press while continuing forward is better!
Then when reversing in the same circle the first press the travel increases, and the second press is better. It seems to be the transition between forward and reversing that's causing the problem which only occurs when turning.

Any ideas fellas? Could it be those pads rocking?

i'd generally wouldn't have thought so as they'd need some force to push the pistons in... but you seemed to have ruled the obvious out. how many mm do they rock?

as above, i'd swap the rubber hoses back on, then clamp each side until the issue goes away, then either refurb or buy a new caliper.

can you make this happen at slow speeds as well?

you could try taking that caliper off, sticking a block of wood in to wedge the pistons right back and tie the caliper up somewhere. see if it still happens.

obv drive slowly and not on public roads

 

[ONE LIFE LIVE IT. D90]

i'd generally wouldn't have thought so as they'd need some force to push the pistons in... but you seemed to have ruled the obvious out. how many mm do they rock?

as above, i'd swap the rubber hoses back on, then clamp each side until the issue goes away, then either refurb or buy a new caliper.

can you make this happen at slow speeds as well?

you could try taking that caliper off, sticking a block of wood in to wedge the pistons right back and tie the caliper up somewhere. see if it still happens.

obv drive slowly and not on public roads

Thanks Trax.

They rock a fair bit in the caliper, possibly 3 to 4mm. This is with new Ap calipers and pads fitted at the same time.

I've thrown away my old flexis, and don't fancy buying some more just to check that. I spose I could lift them off and use a block as you said.

It deffo can't be wheel bearings now. There is no play at all up front.....

I can't see why turning has an effect though. And it doesn't happen forward then reverse when driving in a straight line.

 

[trax]

Thanks Trax.

They rock a fair bit in the caliper, possibly 3 to 4mm. This is with new Ap calipers and pads fitted at the same time.

I've thrown away my old flexis, and don't fancy buying some more just to check that. I spose I could lift them off and use a block as you said.

It deffo can't be wheel bearings now. There is no play at all up front.....

I can't see why turning has an effect though. And it doesn't happen forward then reverse when driving in a straight line.

with the wheel off, see if you can push the pads in by hand. should indicate if the rocking is the possible cause.

 

[ONE LIFE LIVE IT. D90]

with the wheel off, see if you can push the pads in by hand. should indicate if the rocking is the possible cause.

Just tried that as you said mate. I couldn't really push the pistons back. So maybe it's not that. There's nothing left though 😠.

Do you think it's worth trying a different brand of brake pad with different retainers? Possibly ferodo? ... There are leading and trailing chamfers on the front pads though.

I even tried a long tough screw driver in the vents of the disc (bad I know) to try and see if I could get any leverage to create movement. But nothing! All calipers torqued up correctly too.

 

[trax]

Just tried that as you said mate. I couldn't really push the pistons back. So maybe it's not that. There's nothing left though 😠.

Do you think it's worth trying a different brand of brake pad with different retainers? Possibly ferodo? ... There are leading and trailing chamfers on the front pads though.

I even tried a long tough screw driver in the vents of the disc (bad I know) to try and see if I could get any leverage to create movement. But nothing! All calipers torqued up correctly too.

sorry, you know what i think... dump the braided for rubber and clamp em off to make sure it's the calipers

 

[ONE LIFE LIVE IT. D90]

sorry, you know what i think... dump the braided for rubber and clamp em off to make sure it's the calipers [emoji14]

I would do that mate but I don't think they do extended ones do they? It can only be the front axle too if it happens when turning. Looks like I'm going to have to live with it

 

[trax]

I would do that mate but I don't think they do extended ones do they? It can only be the front axle too if it happens when turning. Looks like I'm going to have to live with it

can't find any m10 end stop.

you got a welder.. maybe soldering iron?

you could always get a m10x1 female and solder/weld the end to make an end stop.

stick it on instead of the caliper to isolate it. you could maybe use copper pipe folded a few times instead of welding.

 

[nrgserv]

read the lot, then re read the first post.
gut feeling is still wheel bearings, and after a load of Guinness, gonna offer a non tried, hairbrained idea.
using 4 matches (unused), cable tie or securely affix by other means, one to each side of the front disc to within a fag paper packet distance of contact.
go for your drive, taking in a few corners.
have a gawp underneath and see if any matches are dead due to striking contact with a disk.

failing that, I'm with trax, and clamp the pipes individually.

edit.
drunken ramblings.
ya cant fix a match to the outer edges

 

[trax]

read the lot, then re read the first post.
gut feeling is still wheel bearings, and after a load of Guinness, gonna offer a non tried, hairbrained idea.
using 4 matches (unused), cable tie or securely affix by other means, one to each side of the front disc to within a fag paper packet distance of contact.
go for your drive, taking in a few corners.
have a gawp underneath and see if any matches are dead due to striking contact with a disk.

failing that, I'm with trax, and clamp the pipes individually.

edit.
drunken ramblings.
ya cant fix a match to the outer edges

i think he's saying BURN IT. BURN IT. BURN IT. :flame: :flame:

 

[Kwakerman]

Have you tried driving in circle or whatever you need to do to make the fault appear but don't press the brake pedal. Come to stop (use handbrake gently) then whip the wheels off with the brakes in the 'fault condition' to see which caliper has the pads pushed back. A bit of hassle but may get you down to one corner for a start?

 

[TheMunster]

Have you checked disc runout? Something must be out of line somewhere. If not and your calipers are true to the swivels and there's no play in the wheel bearings then you have a faulty component.

Has it had anything touched with the vac system? Egr removed? Is the vac pump to servo pipe totally sealed? Had this on a mates disco, he hadn't sealed up the vac feed to the egr valve after he removed it, left the ecu and actuator connected under the bonnet so whenever he was coming off the power and the egr valve would of opened he lost his servo assist.

 

[ONE LIFE LIVE IT. D90]

i think he's saying BURN IT. BURN IT. BURN IT. :flame: :flame:

read the lot, then re read the first post.
gut feeling is still wheel bearings, and after a load of Guinness, gonna offer a non tried, hairbrained idea.
using 4 matches (unused), cable tie or securely affix by other means, one to each side of the front disc to within a fag paper packet distance of contact.
go for your drive, taking in a few corners.
have a gawp underneath and see if any matches are dead due to striking contact with a disk.

failing that, I'm with trax, and clamp the pipes individually.

edit.
drunken ramblings.
ya cant fix a match to the outer edges

I think I'll use the matches for the same thing trax is thinking instead hahaa.

Thankyou for the reply. I see what your getting at, and if all else fails it's worth a try.

 

[ONE LIFE LIVE IT. D90]

Have you tried driving in circle or whatever you need to do to make the fault appear but don't press the brake pedal. Come to stop (use handbrake gently) then whip the wheels off with the brakes in the 'fault condition' to see which caliper has the pads pushed back. A bit of hassle but may get you down to one corner for a start?

That's a really good suggestion Kwakerman. I like the sound of that, certainly worth a try. It's a ball ache as you say, but the wheels have already been off a million times already, few more times isn't going to hurt.

Have you checked disc runout? Something must be out of line somewhere. If not and your calipers are true to the swivels and there's no play in the wheel bearings then you have a faulty component.

Has it had anything touched with the vac system? Egr removed? Is the vac pump to servo pipe totally sealed? Had this on a mates disco, he hadn't sealed up the vac feed to the egr valve after he removed it, left the ecu and actuator connected under the bonnet so whenever he was coming off the power and the egr valve would of opened he lost his servo assist.

Thanks mate. I haven't checked disc runout, I assumed it was okay been as in a straight line and general driving the brakes are okay.

Servo, vacuum pump and one way valve replaced. I beleive it wasn't fitted with an EGR out the factory, and there is no T piece off the vacuum hose.



You all seem convinced it's wheel bearings. And so was I untill I replaced 2 of the four stub axles and bearings (passenger rear and drivers front). The other front one has been checked today several times with a pry bar at 6pm levering the wheel in every way. Even stuck a large screw driver in the vented disc to lever the disc and detect some play. Nothing!

Could the bearings/stub be good to feel at a standstill, but when moving have play?

And do you guys think it's the front axle or rear? Bearing in mind that driving in a straight line forward and reverse is perfect.

Thankyou all. Appreciate your efforts to help this annoying problem. Now, where are those matches haha

 

[boguing]

Could you check that the whole lengths of the front brake flexi pipes aren't getting caught or stretched as you turn the steering from lock to lock?

I may have missed it, but in the first post you mentioned a clicking noise - has that gone with the fettling you've done since?

 

[ONE LIFE LIVE IT. D90]

Could you check that the whole lengths of the front brake flexi pipes aren't getting caught or stretched as you turn the steering from lock to lock?

I may have missed it, but in the first post you mentioned a clicking noise - has that gone with the fettling you've done since?

Thanks for reply.

Checked the flexis and solid lines today. No issues, snagging, stretching rubbing or chaffing of any kind.

The clicking does seem to have gone, the only thing I can hear clanking now is the brake pads when the wheel is turned back and forth.

 

[trax]

Thanks for reply.

Checked the flexis and solid lines today. No issues, snagging, stretching rubbing or chaffing of any kind.

The clicking does seem to have gone, the only thing I can hear clanking now is the brake pads when the wheel is turned back and forth.

they clank? yeah that doesn't sound right.

you got the pin and springs in?

 

[nrgserv]

Have you tried driving in circle or whatever you need to do to make the fault appear but don't press the brake pedal. Come to stop (use handbrake gently) then whip the wheels off with the brakes in the 'fault condition' to see which caliper has the pads pushed back. A bit of hassle but may get you down to one corner for a start?

I think this may be what I was trying to say last night until beer got in the way

ya say you've got vented discs on the front? are they standard for model or upgrade / aftermarket fitment?
do you have wheel spacers fitted or large offset rims?

somethings allowing the pads to be pushed back to cause the excessive pedal travel after cornering by what you say.

where are you?

 

[ONE LIFE LIVE IT. D90]

they clank? yeah that doesn't sound right.

you got the pin and springs in?

Yeah they are rocking forward and back in the caliper housing. Dissapointing considering the calipers, discs and pads were all new at the same time.

I have got the pin springs in (possibly a crap brand). But I've ordered a set of these to try too....

http://pages.ebay.com/link/?nav=item.view&id=400489078394&alt=web

 

[trax]

but you have

in?

i've got the old style so i dunno how much they move tbh