brake problems i give up now!!!

[steve_k]

evening folks looking for a bit of help & advise.

i recently changed my brake servo & M/C from the clio servo 7er M/C to a dual diaphragm e90 servo & 25/23mm M/C as the clio servo had bust & the seals on the 7 M/C had gone.

anyway, i bled the brakes & i've no noticed that the brakes are binding & the brake lights are on all the time.

when i installed the new servo & M/C i had to push the clevis fork forward about 5mm (or so),

so my question is this, would adjusting the bar from the pedal to the clevis stop the brakes binding & stop the brake lights from being on all the time?

if so how would i go about adjusting the bar?

any help/advise/tips would be fantastic as i've got the mot coming up in a few weeks & want to make sure it's all as it should be.

thanks in advance folks.

[MrBenn]

Steve. Pretty sure the bar that links the pedal to the booster has one type of thread on one end and the reverse on the other. SO just just undo the nut near the clutch pedal and spin the bar and that changes the adjustment.
I hope that makes sense.

[steve_k]

Steve. Pretty sure the bar that links the pedal to the booster has one type of thread on one end and the reverse on the other. SO just just undo the nut near the clutch pedal and spin the bar and that changes the adjustment.
I hope that makes sense.

Yep that makes sense,

Will have a look tomorrow & fingers crossed.

[DanThe]

If you had to push the bar/clevis to get the holes to line up that is why you have problems, the pull bar should be adjusted so the clevis pin drops in easily, then you adjust the brake light switch afterwards if needed

[steve_k]

If you had to push the bar/clevis to get the holes to line up that is why you have problems, the pull bar should be adjusted so the clevis pin drops in easily, then you adjust the brake light switch afterwards if needed

cheers dan,

i had to push the clevis fork forward by about 5mm at most, hopefully adjusting the bar will bring it all back in line.

[steve_k]

Well all sorted now,

After getting my hand stuck, then realising I was winding the bar the wrong way (thank god I marked it) after 5mins & 10 mins calling myself every name under the sun,

Its all back to where it should be,
Pedal is back to its normal height, brake lights are now off & the wheels turn freely.

Thanks for the advise folks.

[flybynite]

Well all sorted now,
After getting my hand stuck, then realising I was winding the bar the wrong way (thank god I marked it) after 5mins & 10 mins calling myself every name under the sun,
Its all back to where it should be,
Pedal is back to its normal height, brake lights are now off & the wheels turn freely.
Thanks for the advise folks.

Glad it's all sorted

Have to let us know how the brakes feel with the new setup

[steve_k]

Well all sorted now,
After getting my hand stuck, then realising I was winding the bar the wrong way (thank god I marked it) after 5mins & 10 mins calling myself every name under the sun,
Its all back to where it should be,
Pedal is back to its normal height, brake lights are now off & the wheels turn freely.
Thanks for the advise folks.

Glad it's all sorted

Have to let us know how the brakes feel with the new setup

i will do, fingers crossed they feel a lot better than the previous set up as i'm now using the larger rear callipers from a touring & a wilwood bias valve.

[MrBenn]

Glad you got it sorted Steve.

What is different about touring rear brake setup?

Removing the standard rear brake bias valve and plumbing it to somewhere/something controllable within arms reach was on my list...... Be interested in what you used to achieve it.

[steve_k]

Glad you got it sorted Steve.

What is different about touring rear brake setup?

Removing the standard rear brake bias valve and plumbing it to somewhere/something controllable within arms reach was on my list...... Be interested in what you used to achieve it.

The rear callipers on a touring have slightly bigger pistons (33mm compared to 37mm).

As for the bias valve, its a wilwood/Tilton style screw type mounted in the factory location, I use it because I've got hi spec billet 4 callipers (4x42mm pistons each calliper) with 284mm discs, also the fact the factory bias valve was knackered.

You can get a remotely operated bias valve but they ain't cheap.

[steve_k]

well i'm back with this one again.

after nearly a years lay of from it (due to other ongoing projects & family problems) i'm still struggling with these brakes.

a little bit of history & what the braking system consists of,

the brakes on this car consist of.

non abs (removed years ago due to it not working properly if at all,

front brakes, fully rebuilt Hi-spec billet 4 calipers (4x42mm pistons per caliper) DS3000 pads, 286mm x 24mm drilled, grooved discs, speed bleeder valves/nipples, 1 piece braided steel lines to the M/C.

e90/e87 servo & 25.5 M/C, tilton screw type bias valve in place of (knackered) original bias valve, braided steel line to new T piece.

rear brakes, fully rebuilt rear calipers with ds2500 pads & drilled & grooved discs, one piece braided steel lines to T piece, speed bleeder valves/nipples.

now the problem i'm having is a soft brake pedal, i've bleed the brakes using both a pressure bleeder & the 2 man method, flushed the fluid several times & used royal purple (dyed) 5.1 fluid so i could tell when the new fluid was coming through.

at first i thought it could be an internal issue with the M/C so i replaced it with a new one & bled the brakes 2 again afterwards but still the same,

i replaced the check/non return valve on the servo as it appeared to be sticking, new vacuum hose to the TB,

still the same.

does anyone have any ideas? as this is the only thing stopping me from getting the car mot'd & on the road.

[ChrisHC]

Did you adjust the pull bar that runs across the car from the pedal to the masrer cylinder as was suggested by Dan The?
On my car adjusting that cured the spongey brake problem that felt just as though the brakes needed bleeding.

[steve_k]

Did you adjust the pull bar that runs across the car from the pedal to the masrer cylinder as was suggested by Dan The?
On my car adjusting that cured the spongey brake problem that felt just as though the brakes needed bleeding.

i honestly can't remember
i'll have a look today & keep my fingers crossed.

[steve_k]

Right, before I check the pull rod, does the brake pedal have to sit level with the clutch pedal? Or is it slightly lower?

[ChrisHC]

According to the wiki, the pull rod can be adjusted to control pedal height. There's a small rubber buffer on the lowest part of the bracket that holds the brake light switch, and the rod should be shortened until the arm of the pedal all but touches this buffer.

To adjust the brake pedal, slacken off the lock nuts and turn the pull rod using a 7mm open-ended spanner on the flats near the clutch pedal to adjust, until the brake pedal only has a small bit of upwards free movement to its stop. One end of this rod has a reverse thread, so turning it changes its length.

Be careful though. If you over-tighten things, so that the pedal is touching the buffer and moving the master cylinder push rod, the brakes are likely to lock on.

[steve_k]

cheers chris,

well i've just had a look & there's is zero upwards play in the brake pedal.

looks like i'll have to get the spanners out & see if i can adjust the pedal & get a bit more play in the pedal & go from there.

[steve_k]

well i'm back with this problem again.

i adjusted the pedal to it's original height (marked the push/pull rod before i changed anything), bled the brakes (again) & still the same.

so far it's had a brand new M/C, new non return valve & new fluid,

while trying (& failing) to sort this i had a look on both realoem & bmwfans.info to see if the e90 servo had a non return valve, from wat i can see all it has is a vacuum pipe & no mention of a non return valve (unlike the e30 servo),

i even had a look on there at the e30 servo & the part number for the non return valve comes back on a google search as a straight connector, even the likes of turner motorsports etc show it as a simple straight through barbed connector, got one on the way to try & keep my fingers crossed.

also, when i removed the vacuum pipe & valve from the servo there was a slight HISS as if air was escaping as i removed the valve.

i'm really at my wits end with this now as it's the only thing stopping me from getting the car on the road.

[steve_k]

forgot to add, the TB on my engine has 2 vacuum ports on it, one is blocked off with a bung so i'm wondering if i swap the ports over could that help?

[steve_k]

well i'm now leaning towards the tilton screw type adjustable bias valve could be at fault or need proper adjustment.

my reasons? well when i reverse the car then use the brakes there's plenty of bite, my thinking there is thats because the car is going backwards on a downward slope, correct me if i'm wrong.

yet when going forward te brakes only bite when i lean on the pedal,

i'll have a look at that valve & later today or tomorrow & go from there.

if anyone has any ideas based on these updates then please post them.

[flybynite]

Good brakes in reverse? Opposite of what drum brakes used to do. You sure you haven't put upside down drums on by mistake

I have heard of a few cars do that when the shift in engine position when in reverse closes a crack in the vacuum pipe.

Hard pedal one way and good the other shouts vacuum to me, have you done a leak check with brake cleaner or something?

[martauto]

well when i reverse the car then use the brakes there's plenty of bite
yet when going forward te brakes only bite when i lean on the pedal,

Silly thing but is the bias valve the wrong way around giving bias the wrong way ??

Mart.

[steve_k]

Good brakes in reverse? Opposite of what drum brakes used to do. You sure you haven't put upside down drums on by mistake

I have heard of a few cars do that when the shift in engine position when in reverse closes a crack in the vacuum pipe.

Hard pedal one way and good the other shouts vacuum to me, have you done a leak check with brake cleaner or something?

i'll dig out the brake cleaner tomorrow (if it's not snowing again) & check for any leaks between the servo & TB,
but the vacuum pipe is a brandnew silicone one,

[steve_k]

well when i reverse the car then use the brakes there's plenty of bite
yet when going forward te brakes only bite when i lean on the pedal,

Silly thing but is the bias valve the wrong way around giving bias the wrong way ??

Mart.

can't hurt to check, knowing my luck quite possibly.

thats 2 things to check tomorrow.

[steve_k]

Just a thought.

I've had a look at a diagram of the e30 vacuum line from the servo to TB & it appears that the non return valve is placed closer to the TB than the servo,

Well mine is the other way round, so tomorrow I'll move it closer to the TB & try again,

Whether it's position affects how the brakes work is yet to be seen,

But, it can't hurt to have it as close to stock now can it?

[BenHar]

It is the right way round I hope?

Ben

[steve_k]

It is the right way round I hope?

Ben

Both the bias valve & non return valve are the correct way round,

Going to try the brakes again tomorrow & check for any vacuum leaks.

[steve_k]

Well it looks like there could be a break through in this one.

I checked the servo by keeping the break pedal pressed while I started the engine & it did go down a little, left the car running to get up to temp then moved it backwards on the drive & tried the brakes a couple of times.

Plenty of bite each time, moved it forward & tried again, pedal went soft of a couple of times but if I pumped the pedal they worked fine,

So, with the engine running I sprayed carb/brake cleaner along the joints on the vacuum hose from the servo to the TB & the only place it appeared to be sucked in was the grommet on the servo, also the engine note changed slightly which leads me to think it was being sucked into the inlet.

Also when I switched the engine off there was a hissing sound coming from that area,

Now, correct me if I'm wrong but that says to me the grommet has either failed or is on its way out.

I'm sure I've got some spare grommets somewhere so I'll dig them out & try again over the next few days.

If anyone has any other ideas then please let me know.

[steve_k]

Good brakes in reverse? Opposite of what drum brakes used to do. You sure you haven't put upside down drums on by mistake

I have heard of a few cars do that when the shift in engine position when in reverse closes a crack in the vacuum pipe.

Hard pedal one way and good the other shouts vacuum to me, have you done a leak check with brake cleaner or something?

thanks for the idea of using brake/carb cleaner to check for a vacuum leak

[martauto]

Now, correct me if I'm wrong but that says to me the grommet has either failed or is on its way out.

Sounds that way Steve, just a bit curious why you have still got better brakes going backwards?
Or, is it because you have mega size brakes up front and the servo cant manage them but can the smaller rear brakes with a "reduced" servo efficiency?

Mart.

[steve_k]

Now, correct me if I'm wrong but that says to me the grommet has either failed or is on its way out.

Sounds that way Steve, just a bit curious why you have still got better brakes going backwards?
Or, is it because you have mega size brakes up front and the servo cant manage them but can the smaller rear brakes with a "reduced" servo efficiency?

Mart.

My brake set up is hi-spec billet 4 piston calipers up front with 286x25 discs, standard rear discs with rebuilt calipers,

The servo is off an e90 335d with 25.5mm M/C so should be more than up to the job,

I'm beginning to think that if the grommet on the servo has gone that it's slowly losing vacuum, also that could be the reason for the hissing sound in that area after I switched off the engine.

That's why I'm going to replace the grommet with a new one & try again.

[martauto]

That's why I'm going to replace the grommet with a new one & try again.

Sorry ,thats what I was trying to say

Go on, do it now Steve, it will only eat away at you, all night, until you know

Mart.

[steve_k]

That's why I'm going to replace the grommet with a new one & try again.

Sorry ,thats what I was trying to say

Go on, do it now Steve, it will only eat away at you, all night, until you know

Mart.

If my back eases off enough on the next hour or so I will do,

[flybynite]

thanks for the idea of using brake/carb cleaner to check for a vacuum leak

No worries If it is not what you have tried already then it must be something else. Not that easy when you are actually there looking

Sounds that way Steve, just a bit curious why you have still got better brakes going backwards?

I still think it could be the shift in engine position when in reverse temporarily closing the leak. happens quite a lot.

[steve_k]

thanks for the idea of using brake/carb cleaner to check for a vacuum leak

No worries If it is not what you have tried already then it must be something else. Not that easy when you are actually there looking

Sounds that way Steve, just a bit curious why you have still got better brakes going backwards?

I still think it could be the shift in engine position when in reverse temporarily closing the leak. happens quite a lot.

i never thought to try it till you mentioned it so thanks again,

as for the shift in engine position when in reverse? i'm doubtful as they are these from strongflex

https://strongflexuk.com/product/031761 ... 1-e30-e12/

i fitted them only just before christmas & there is near enough zero movement in them,

i'm leaning towards the rubber grommet being on it's way out due to the hiss i heard when i shut the engine off,
going to prise it out & check it over & replace it with a brand new one i've got & try again.

[martauto]

i'm leaning towards the rubber grommet being on it's way out due to the hiss i heard when i shut the engine off,
going to prise it out & check it over & replace it with a brand new one i've got & try again.

Fingers crossed for you mate

Mart.