front brakes binding

[shedrool83]

Got an mot failure for brakes binding and brake lights staying on .(car had sat for about 4 years so no surprise ) So i stripped the calipers ,checked the slider ,pistons coming out and going in with no corrosion on the bits that matter as far i as i can see.Put back together wheels spinning free. Adjusted the brake pedal bar abit so it hit the brake switch and it failed again guy said the front drivers locked up on the ramp (2 min drive to the mot place was fine although the brake pedal was hard .

Been awhile since i have driven an e30 but i'm not convince the calipers are at fault i'm thinking its servo related or what would be the symptoms of a failed check valve on the vacuum pipes to the sevo?I did notice a change in the engine when pressing the brake pedal.
Car at a mates being stored so wont get back to it till Saturday but any input would be appreciated.

[flybynite]

Did you clean and grease the pad sliders? That and the pistons are the only thing I can think of.

If you think the servo is holding pressure somehow then just disconnect it. Brakes will be heavy but still work, see if it binds then.

[fixedwheelnut]

I did two calipers on mine this year for exactly that, tried lubing pads and sliders first but still sticking after a road test so renewed the calipers, Autodoc are good price if you can wait, if not try Eurocarparts or Cotswold.

[shedrool83]

I did clean and grease the sliders also pushed the pistons out as far as i would dare and they are free of rust .I will try pulling the hose off to the servo .

I saw the calipers on autodoc and have them sitting in the basket just incase .

Thanks for the replies .

[shedrool83]

Been having a look at this . If I disconnect the hose off the servo I can blow into the engine put can't suck which I think is right and the check valve is working . If I apply the brake with the hose off (car jacked up )the brakes work and release ok . If I connect the hose with the engine running and apply the brakes the brake locks up and pedal doesn't fully return but it does with the hose off the servo. So am I looking at servo or master cylinder ?

[flybynite]

I have not had this but thinking logically it could be the booster not releasing the vacuum.

It could be a seal in the mc turned but unlikely as brakes did not lock when you tried it witout the booster. Did you press the brake really hard wothout the booster when it did not lock up?

[shedrool83]

Looks like the bar/ master cylinder bar have been adjusted at some point , If i back the bar running from the pass side to the drivers off the front brakes don't bind (still a wee bit drag but not excessive imho)

Question now is is there a way to do a factor reset on the brake adjustment bars/rods?
Is Brian still about i need help ?haha

[paultv]

There's drawings and measurements in Bently if that helps, not sure if its also in the Wiki?

Paul

[steve_k]

There's drawings and measurements in Bently if that helps, not sure if its also in the Wiki?

Paul

i've just had a quick look in the bently manual & can't seem to find any mention of the brake bar, unless i'm missing it?

[flybynite]

There's drawings and measurements in Bently if that helps, not sure if its also in the Wiki?
Paul

i've just had a quick look in the bently manual & can't seem to find any mention of the brake bar, unless i'm missing it?

There won't be anything about setting up a bar in the Bently as the LHD ones didn't have that contraption. Nothing in the RHD manuals I have either though (Haynes etc)

However the measurements to the centre of the clevis pin can still be used, doesn't matter if there is a pedal or RHD Bar attached to it.

[paultv]

Doh! of course..it was the freeplay and pushrod measurements I remember in Bently!

Paul

[DanThe]

The length adjustment on the bar is for nothing other than adjusting the pedal height

[fixedwheelnut]

The cross bar usually does pedal height as Dan says there is adjustment on the push rod in to the servo, make sure when you push the clevis pin in that it can be done freely, if you have to push the rod in to the servo to enable the pin to fit then the rod needs shortening at the servo as in the lower servo in this photo.

[shedrool83]

Thanks guys . I did disconnect the pin from the push rod side the other week while trying to source the issue and i did have to align the holes to get the pin back in . I will adjust the servo end fit a new brake switch adjust the bar across to suit and cross my fingers .

[fixedwheelnut]

Thanks guys . I did disconnect the pin from the push rod side the other week while trying to source the issue and i did have to align the holes to get the pin back in . I will adjust the servo end fit a new brake switch adjust the bar across to suit and cross my fingers .

It will only need adjusting if you have to push the servo rod in towards the servo to align it as if applying the brakes, moving the linkage towards the servo to align it is normal and adjustment accounts for pedal height.

The problem is if the servo rod is already under pressure with no application of the pedal then it is like driving with your foot on the brake and they will bind

[shedrool83]

Today i have fitted the new brake switch , released the pin from the servo side ,adjusted the brake pedal to be inline with the clutch pedal , adjusted the servo end and refitted the pin .

Still got the problem of the brakes locking on after i press the pedal. if i lift the pedal with my foot the release . its like the vacuum when the engine is running is holding the pedal down slightly as it seems fine when the engine isn't running .

Would a burst diagram or weak spring in the servo cause this issue ? I have also read there is a air filter on the servo under the rubber boot inside the car . By the looks of mines there is no filter there ,not sure if that would cause the issue tho .

Tia

[DanThe]

Adjusting pedal height is the last process before setting brake light switch position

You need to ensure the servo pushrod is set to the correct position relative to the master cylinder before even fitting them to the car. On E30 servos the pushrod is usually flush with the face of the servo

[shedrool83]

Adjusting pedal height is the last process before setting brake light switch position

You need to ensure the servo pushrod is set to the correct position relative to the master cylinder before even fitting them to the car. On E30 servos the pushrod is usually flush with the face of the servo

Sorry for being think Dan ,do you mean when the master cylinder is off the servo the push rod should be level with the servo ?

[DanThe]

Yes, the pull bar at the back of the servo should be disconnected too when checking this

[shedrool83]

Yes, the pull bar at the back of the servo should be disconnected too when checking this

Thanks Dan i will check it out .

[shedrool83]

Still getting the brakes binding after pressing the pedal with the car running .

Brake pedal just not returning enough about 25mm short. If I stick my toes under the pedal and lift it up the 25mm the brakes free and the brakes light switch works until the next time i press the pedal .

Running out of ideas here without blindly swapping parts. I did think I was missing a retaining spring looking at realoem but an I right in thinking a face-lift pedal box doesn't use no 15 spring in the position marked blue in the pic it uses 16 and 17 ? (Which I can't see either when looking at the pedal box on the car. )

Tia

[fixedwheelnut]

I think it is the servo side that is more critical to be aligned correctly, see the two images I have screenshot the two purple distances should be equal so that the servo is not under pressure causing the servo to actuate before the pedal is depressed, also make sure the carpet isn't fouling the cross bar behind the heater box not letting it release fully.

Servo

pedal cross bar linkage.