brake problems i give up now!!!

[steve_k]

Hear me out mate, Try fitting stock calipers and see if anything changes.

Process of elimination, if not then master cylinder ,then other stuff until things do change.
I know it`s a load of graft but maybe bit by bit is the way to go?

Mart.

true, worth a try, i'll dig in the shed see if i've still got some original calipers.

[steve_k]

i forgot to add,

when i hold the peddle down as far as it will go with the engine off (not very far at all) & try to turn each wheel in turn by hand they will not budge.

also there is a slight bit of drag with the peddle released.

[fixedwheelnut]

i forgot to add,

when i hold the peddle down as far as it will go with the engine off (not very far at all) & try to turn each wheel in turn by hand they will not budge.

also there is a slight bit of drag with the peddle released.

That still sounds like the cross bar between pedal and servo is not adjusted correctly if the brakes are dragging,, look at the two screenshots the pin that connects the servo rod to the cross linkage pivot should go in easily without needing to put pressure on the servo rod, that way the brake is not in the depressed position with the pedal at rest.

With engine off the pedal should be firm, if you start the engine with your foot on the brake you should feel the pedal go down a bit more as the servo assistance comes in. when you switch off the servo should hold enough vacuum for two pumps before the pedal goes firm again.

[steve_k]

i forgot to add,

when i hold the peddle down as far as it will go with the engine off (not very far at all) & try to turn each wheel in turn by hand they will not budge.

also there is a slight bit of drag with the peddle released.

That still sounds like the cross bar between pedal and servo is not adjusted correctly if the brakes are dragging,, look at the two screenshots the pin that connects the servo rod to the cross linkage pivot should go in easily without needing to put pressure on the servo rod, that way the brake is not in the depressed position with the pedal at rest.

With engine off the pedal should be firm, if you start the engine with your foot on the brake you should feel the pedal go down a bit more as the servo assistance comes in. when you switch off the servo should hold enough vacuum for two pumps before the pedal goes firm again.

i'll have a look at that bar in the next few days soon as i get chance, also, when i fitted the servo the fork lined up perfectly with the linkage & didn't need to be moved at all,

[steve_k]

well i've had a look at the pedal & cross bar this morning,

there is about an 1 inch "free play" in the pedal (it moves freely back & forth) before i can feel any resistance or pressure, i wasn't able to adjust the cross bar/linkage as i couldn't find my 7mm spanner (off to get a new one soon),

but while i was there, laid across the seats, i noticed that if i press the pedal down i can see the linkage & pushrod working as as soon as the pedal is pressed the pushrod moves forward.

still at a total loss

[steve_k]

well i managed to find my 7mm spanner,

had a look at the pushrod for the pedal/servo & when i took the old servo out i marked the position of the pushrod with paint in case i needed to adjust it & it is near as damn it still in the same place.

also, after an early morning rush to a local motor factors (for a part for my other car) i picked up 2 brand new m10 speed bleeders for the front calipers & 2 m7 ones for the rear & a new one of these

https://www.halfords.com/tools/hand-too ... 21141.html

(under £5 so why not?),
got back & swapped the old bleeders for the new ones,

then went to bleed the brakes again,

got plenty of air out the system & checked the pedal after doing each corner,

at the end the pedal feels a lot lot firmer with the engine off,
i'll find out either tomorrow or over the weekend how the pedal feels with the engine running once the battery is charged up,

fingers crossed.

[martauto]

Lets hope it all works out for you mate

Mart.

[steve_k]

Lets hope it all works out for you mate

Mart.

thanks, i hope this wind quits before i try again as i've already been in the back of the head today when the wind took the bonnet

[steve_k]

well i've just been out & had look & all the unions are dry, all the bleed nipples are & the pedal is still firm so fingers crossed.

[martauto]

Could this be the day ????

Mart.

[steve_k]

not yet

had to spend the day changing the locks & the front & back doors at the house due to someone trying the door last night.

[steve_k]

well ive spent today with the help of a mate, trying & checking a few things in regards to the brakes.

first off, we took each calliper off in turn & pressed the pedal a few times to check that the pistons weren't seized & that there were no leaks,

al four checked out perfectly,

next, while i pressed the pedal my mate checked all the unions & they were nice & dry, as were all the bleed nipples,

next step was to check the servo, now this is where it gets a little "odd", with the engine off i pumped the pedal & it was nice firm & would only go down about half way (if that) & stayed the same each time we tried it.

we also tried with the engine running & the results were near as dammit the same.

also because i didnt have any standard calipers in the shed we tried the mk3 mondeo st220 calipers & redrilled A3 290mm discs, again the same results.

so, in an attempt to rule out the servo we tried all 3 of the e9x servo's (incl the one on the car) i have, each time the result was the same, & each time there was no need to adjust the pedal,

so after that were tried a spare (old) e9x M/C to see if the new one was faulty or not, guess what? exactly the same result with either of them.

i was unable to drop the car down as the tyres need pumping up & i couldn't find the pump attachment for my compressor & the audi (daily) is sulking as it need the rear coolant flange on the back of the engine changing due to a coolant leak (should get that done on monday/tuesday when the part arrives),

so thats where i'm upto today , still totally stumped.

[flybynite]

One thought, have you tried a basic e30 servo and M/C? Shouldn't be a problem as you are still M20. Just wondering if the e30 brake contraption as it is set now might be pushing the e90 MC too far possibly inverting the seals.

[steve_k]

One thought, have you tried a basic e30 servo and M/C? Shouldn't be a problem as you are still M20. Just wondering if the e30 brake contraption as it is set now might be pushing the e90 MC too far possibly inverting the seals.

nope the old servo & M/C are long gone, both were scrap,

as for the set up/pushrod pushing the e90 m/c to far? thought about that (forgot to add it up top though ) s i undid the 2 bolts to see if the m/c would move forward but nope nothing, if i pull the m/c forward off the mounts & then push it back there's no resistance if you know what i mean?

if i get a chance next week when the audi is fixed i'll move that out the way, pump the e30's tyres up
& move it up & down on the drive & see how the brakes feel then,

fingers crossed.

[steve_k]

welll ive had a quick look at the brakes again today (didn't get chance yesterday as i was in too much pain after a 2hr physio session on my shoulder & it's still bloody sore today ) & it looks like the brakes could be binding/sticking on slightly,

so it looks like soon as my shoulder stops throbbing i'll be having a look at that pushrod from the pedal to the servo,
i'm beginning to think that could be a lot of the problem even though it all lined up when i fitted the e9x servo.

i wont be able to move the car nuch as i'll have a skip sat behind it for the next 10 days.

[steve_k]

forgot to add, i also tried the brakes again by holding the pedal down as far as it would go & tried to turn each wheel by hand,

safe to say none of them would turn & i was at risk of popping my shoulder out as i was pulling as hard as i could.

[steve_k]

could it be? could i finally have brakes on the bmw that work?
i changed the servo non return valve for an inline, universal one, started the engine with the brake pedal as far down as it would go, as the engine started the pedal went down a little,
left the engine to run a little while & tried the pedal, it has started to firm up nicely but i do think there's still a little air in the system so i might try bleeding them again just to be sure,
the car is currently on axle stands with a skip behind it so i can't try the brakes on the drive yet but it's looking hopeful.