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Tim2809

front brake upgrade?

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Have you checked the hoses are in good order?  Internal delamination or bulging under pressure would cause pressure loss in the calipers.

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right sorry to reserect this post. 

brakes still poor if i try an emergency stop its like driving an old series on drum brakes thats just been through a flood.

its had new discs and ferrodo pads, new delphi wheel cylinders and mintex shoes. new goodrich braided hoses and a new trw master cylinder. 

the caliper pistons pushed back ok so initially ruled out but now not sure.

vac pump is good as replaced for know good pump. 

brakes adjusted and bled out several times over last 3000 miles since doing the brakes. 

would calipers cause the issue im experiencing? 

any advice appreciated

tim 

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You do have the calipers & rear  brake cylinders on the correct sides with the bleed screw at the top ? if not you'll never get all the trapped air out. 

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the calipers are still original and nipples at the top. sure i fitted cylinders on correct side but will double check.  pedal goes 1/3- 1/2 way down and feels firm but at this stage im thinking of making a parachute as nothing else seems to work. 

i feel its got to be something obvious that im missing. 

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1 hour ago, Bowie69 said:

You don't mention the servo?

if i turn engine off and go back 5 mins later it still has vacuum in it and needs 3 pumps to expell all thats retained so assumed its good. 

i ve not tried turning engine off whilst moving and expell the vacuum and see if they get really hard. 

have a private drive at work so could try it safely 

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15 hours ago, Tim2809 said:

im thinking of making a parachute as nothing else seems to work.

Now that I would like to see 😂

My brake pedal firmness isn't great, but it did improve a bit with new front calipers. Did you bleed the master cylinder on the bench before fitting? This is one of the only things I've got left to try having replaced all else.

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17 minutes ago, dailysleaze said:

Now that I would like to see 😂

My brake pedal firmness isn't great, but it did improve a bit with new front calipers. Did you bleed the master cylinder on the bench before fitting? This is one of the only things I've got left to try having replaced all else.

filled it up with no pipes connected and used a pressure bleed to push fluid through. then connected the pipes

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17 hours ago, western said:

You do have the calipers & rear  brake cylinders on the correct sides with the bleed screw at the top ? if not you'll never get all the trapped air out. 

this is the o/s/r. cylinder viewed from the rear of the wheel 

61A649D3-230D-4CF5-AEED-D27B74BA8D5C.jpeg

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Do you have the shoes installed correctly and adjusted correctly?  It is really easy to get them wrong as the correct fitment is not obvious and not shown in the workshop manual.

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18 hours ago, Red90 said:

Do you have the shoes installed correctly and adjusted correctly?  It is really easy to get them wrong as the correct fitment is not obvious and not shown in the workshop manual.

initially i had them wrong as would not adjust up, now i can adjust so they lock the drum. 

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So reading through the only thing you have not looked at is the stuff in the brake lines.  Not sure what you have as it varies, PDWA, bias valve and/or G-valve.

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47 minutes ago, Red90 said:

So reading through the only thing you have not looked at is the stuff in the brake lines.  Not sure what you have as it varies, PDWA, bias valve and/or G-valve.

its fitted with the pdwa or was. ive taken it out as it only indicates a pressure loss on a 110  

only thing ive not done is calipers and servo. 

may have to take the gamble. 

ive got new tyres going on at the weekend so may take pads out and check the pistons again and try re bleeding again 

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right i think i finally sorted it thanks to everyone who commented 

took front pads out and i dont know why but when i pushed pistons back in i can only assume some seals had twisted and when i tried pumping the pedal without the pads in only 2 each side actually came out. 

ive got all pistons to move out and poured some fluid on them as i pushed back in by hand. now pedal is at the top and now when i brake i actually stop and can lock front brakes. 

once again many thanks to you all 

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That's good news, but I would be budgeting for a new pair of calipers...

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And Zeus pistons.

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Years ago I had problems on a 300tdi 90 which had poor brakes. I traced it to the pattern callipers which had been fitted prior to my ownership - only the inner two of the four pistons were operating on both front callipers. I dismantled the callipers and found that the rubber seals between the two callipers halves on both sides had completely swollen up and blocked the passageways to the outer callipers halves.

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17 hours ago, Bowie69 said:

That's good news, but I would be budgeting for a new pair of calipers...

now i know what the issue is i am ordering new calipers on monday 

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Let us know how you get on.  For what it's worth, I prefer to refurbish the calipers with Zeus stainless pistons and genuine seals rather than replace the caliper with new - the new units will have rusty pistons within a few years, even if just used on the road, and then you're back to seizing pistons or leaking seals.  It is a fiddly job to get the dirt seal retainers in, so fitting the Zeus pistons to the new calipers will save you that job but preserve the new parts in just the same way.

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Britpart do stainless pistons for the callipers and they are surprisingly very good indeed and far cheaper than Zeus were who I have also used in the past. I changed the pads on my old 90 yesterday and the britpart stainless pistons are like new after 5 years by the sea.

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