No brake pressure after master cylinder replacement

[BBB]

Front right side only: replaced disc, pads and both bleed nipples. Then swapped the master cylinder for a GT3 version. 

Pressure bled the front right caliper until clear fluid with no bubbles.

Now I have no brake pedal pressure at all, the pedal just goes to the floor and pumping the pedal doesn’t improve things. Sigh.

Should I just bleed the whole system: rear left, rear right, front left, front right and see if that improves things? Or should I remove the new master cylinder and bench bleed it? Fluid must be getting through the master cylinder as I could pressure bleed the front fight. Or should I press on and do the front left pads/disc and then bleed the whole system? 

Tired, hot, annoyed.

[Paul P]

air in the abs valves ?

icarsoft or equivalent will force valves to open to allow bleeding.......

[BBB]

5 hours ago, Paul P said:

air in the abs valves ?

icarsoft or equivalent will force valves to open to allow bleeding.......

Worth a shot, thanks.

[Cocky]

I actually despite being careful got air in from replacing the MC so yeah go for full bleed inner nips first on each caliper. 

[BBB]

Well that went south quickly. The first inner nipple on the rear caliper sheared clean off. Then the caliper hard pipe to the flexi split. I frickin hate brake fluid.

I managed to get the upper flexi to hard pipe joint undone on both sides and so both calipers are now in the post to Bigg Red for a full rebuild and paint.

One sad-looking boxster on four jack stands, dripping brake fluid into litter trays. Ah well, I’ll take this opportunity to fit new rear pads, discs and braided hoses.

[TROOPER88]

1 hour ago, BBB said:

Well that went south quickly. The first inner nipple on the rear caliper sheared clean off. Then the caliper hard pipe to the flexi split. I frickin hate brake fluid.

I managed to get the upper flexi to hard pipe joint undone on both sides and so both calipers are now in the post to Bigg Red for a full rebuild and paint.

One sad-looking boxster on four jack stands, dripping brake fluid into litter trays. Ah well, I’ll take this opportunity to fit new rear pads, discs and braided hoses.

Whenever you are working on the brake lines, use a piece of wood or similar to hold the brake pedal to the floor. This will stop most of the fluid leaking out 

[Cocky]

On 7/31/2024 at 6:32 PM, BBB said:

Well that went south quickly. The first inner nipple on the rear caliper sheared clean off. Then the caliper hard pipe to the flexi split. I frickin hate brake fluid.

I managed to get the upper flexi to hard pipe joint undone on both sides and so both calipers are now in the post to Bigg Red for a full rebuild and paint.

One sad-looking boxster on four jack stands, dripping brake fluid into litter trays. Ah well, I’ll take this opportunity to fit new rear pads, discs and braided hoses.

I drilled and recoiled my rear nip using the big red kit. Not fun but will be worth it when you get back out on the road. 

[BBB]

5 minutes ago, Cocky said:

I drilled and recoiled my rear nip using the big red kit. Not fun but will be worth it when you get back out on the road. 

I’m not as brave as you, so just handed over the cash.

Trip to OPC today to pick up the rear hard lines from caliper to flexi lines. First time using my Classic Membership for the discount so that helped the pain slightly.

But then got home and noticed that I must have dripped brake fluid over one of the headlights and it’s left a mark on the lens. So now I’ve got to add polishing that out to the growing shyate list.

Edited August 1, 2024 by BBB
spelling

[Cocky]

Better than it being on your paintwork 🤔

[BBB]

And the bad news keeps coming. I really wonder when the brakes were last done properly.

Front left caliper, undid nicely, pads out, cut the hard line to caliper as it was really rusty and I have a new one to go on. Got the caliper in the vice and carefully removed the bleed nipples and remains of the hard line. Then tried to remove the damper plates and neither plate came out easily. One has the smaller cylinder rusted into a piston and the other side has one rusted into the bigger piston. I tried everything I could think of to free them but they are rusted in solid, so I’ve had to remove all the caliper pistons.

Choices: ignore it and put the pistons back in and don’t use damper plates - probably a bad idea. Or buy two new pistons and replace the seals and dust covers while it’s all apart. I’m thinking new pistons but will decide tomorrow.

Rear discs and pads, pins, bolts arrived from @T911UK so at least I have the parts when the calipers come back from Bigg Red.

[Ninesomething]

On 8/2/2024 at 9:28 PM, BBB said:

And the bad news keeps coming. I really wonder when the brakes were last done properly.

Front left caliper, undid nicely, pads out, cut the hard line to caliper as it was really rusty and I have a new one to go on. Got the caliper in the vice and carefully removed the bleed nipples and remains of the hard line. Then tried to remove the damper plates and neither plate came out easily. One has the smaller cylinder rusted into a piston and the other side has one rusted into the bigger piston. I tried everything I could think of to free them but they are rusted in solid, so I’ve had to remove all the caliper pistons.

Choices: ignore it and put the pistons back in and don’t use damper plates - probably a bad idea. Or buy two new pistons and replace the seals and dust covers while it’s all apart. I’m thinking new pistons but will decide tomorrow.

Rear discs and pads, pins, bolts arrived from @T911UK so at least I have the parts when the calipers come back from Bigg Red.

What pads are you using? I just did brembos and they had plates on the back so I didn't reuse the OE ones.

[Ninesomething]

On 7/30/2024 at 10:46 PM, Cocky said:

I actually despite being careful got air in from replacing the MC so yeah go for full bleed inner nips first on each caliper. 

Reckon you'd be pretty lucky to replace the m/c and not get some air in somewhere...

[Cocky]

3 hours ago, Ninesomething said:

Reckon you'd be pretty lucky to replace the m/c and not get some air in somewhere...

To be fair I thought if I got the two lines off pretty steady away despite obviously going in with a empty MC I would be able to top it up and still have a pedal but that didn't happen. 

[½cwt]

On 8/2/2024 at 9:28 PM, BBB said:

And the bad news keeps coming. I really wonder when the brakes were last done properly.

Front left caliper, undid nicely, pads out, cut the hard line to caliper as it was really rusty and I have a new one to go on. Got the caliper in the vice and carefully removed the bleed nipples and remains of the hard line. Then tried to remove the damper plates and neither plate came out easily. One has the smaller cylinder rusted into a piston and the other side has one rusted into the bigger piston. I tried everything I could think of to free them but they are rusted in solid, so I’ve had to remove all the caliper pistons.

Choices: ignore it and put the pistons back in and don’t use damper plates - probably a bad idea. Or buy two new pistons and replace the seals and dust covers while it’s all apart. I’m thinking new pistons but will decide tomorrow.

Rear discs and pads, pins, bolts arrived from @T911UK so at least I have the parts when the calipers come back from Bigg Red.

Get Bigg Red to do the pistons whilst they have the calipers.  BCS swapped 3 of the pistons in my calipers (all pitted with corrosion) as part of a refurb a year or so ago, but then I'd asked them to change all the piston seals (I'd supplied new Bigg Red ones along with new bleed nipples) so it was a cheap add on to the scope of work already...

[BBB]

17 hours ago, ½cwt said:

Get Bigg Red to do the pistons whilst they have the calipers.  BCS swapped 3 of the pistons in my calipers (all pitted with corrosion) as part of a refurb a year or so ago, but then I'd asked them to change all the piston seals (I'd supplied new Bigg Red ones along with new bleed nipples) so it was a cheap add on to the scope of work already...

Unfortunately Bigg Red have my rear calipers and the blocked pistons are on one of my fronts. I have pistons and seals on their way from autodoc and I'll rebuild it myself. I may give it a repaint whilst it's all apart.

[BBB]

To close this off then.

Front callipers rebuilt with fresh piston seals, two new pistons and all new dust covers. In case it helps anyone else, the part numbers from Frenkit were P363201 for the 36mm piston, P403202 for the 40mm piston and 236033 for the seals and dust covers. New Textar pads, vibration dampers and Pagid discs. New stainless steel bleed nipples, painted and new decals.

Rear callipers were rebuilt as a pair by Bigg Red after I sheared off an inner brake nipple. They painted them and put on new Porsche decals. Again textar pads, Pagid discs. The handbrake pads were great so they were just cleaned and scuffed with emery cloth.

Goodrich flexi hoses all round and new OEM hard lines to each calliper. GT3 master cylinder and GT3 air deflector thingies fitted (the plastic things that clip onto the suspension arm).

And then came the bleeding. Three rounds with a pressure bleeder and still no pedal pressure. “Bench” bled the master cylinder in situ, recirculating the brake fluid back into the reservoir using rubber tubing and got loads of bubbles out, refitted, still no brake pressure. Eventually my wife sat in the car and I bled each corner the old fashioned way (pump, pump the pedal until faint pressure, and open each nipple, repeat ad nauseam) and then quite suddenly the brake pedal began to build pressure.

All good now, ABS triggered from some extreme braking and the brakes are now awesome. A painful process, but at least it’s back on the road again.

[bally4563]

8 hours ago, BBB said:

To close this off then.

Front callipers rebuilt with fresh piston seals, two new pistons and all new dust covers. In case it helps anyone else, the part numbers from Frenkit were P363201 for the 36mm piston, P403202 for the 40mm piston and 236033 for the seals and dust covers. New Textar pads, vibration dampers and Pagid discs. New stainless steel bleed nipples, painted and new decals.

Rear callipers were rebuilt as a pair by Bigg Red after I sheared off an inner brake nipple. They painted them and put on new Porsche decals. Again textar pads, Pagid discs. The handbrake pads were great so they were just cleaned and scuffed with emery cloth.

Goodrich flexi hoses all round and new OEM hard lines to each calliper. GT3 master cylinder and GT3 air deflector thingies fitted (the plastic things that clip onto the suspension arm).

And then came the bleeding. Three rounds with a pressure bleeder and still no pedal pressure. “Bench” bled the master cylinder in situ, recirculating the brake fluid back into the reservoir using rubber tubing and got loads of bubbles out, refitted, still no brake pressure. Eventually my wife sat in the car and I bled each corner the old fashioned way (pump, pump the pedal until faint pressure, and open each nipple, repeat ad nauseam) and then quite suddenly the brake pedal began to build pressure.

All good now, ABS triggered from some extreme braking and the brakes are now awesome. A painful process, but at least it’s back on the road again.

👍

[phobospt]

On 8/22/2024 at 10:36 PM, BBB said:

To close this off then.

Front callipers rebuilt with fresh piston seals, two new pistons and all new dust covers. In case it helps anyone else, the part numbers from Frenkit were P363201 for the 36mm piston, P403202 for the 40mm piston and 236033 for the seals and dust covers. New Textar pads, vibration dampers and Pagid discs. New stainless steel bleed nipples, painted and new decals.

Rear callipers were rebuilt as a pair by Bigg Red after I sheared off an inner brake nipple. They painted them and put on new Porsche decals. Again textar pads, Pagid discs. The handbrake pads were great so they were just cleaned and scuffed with emery cloth.

Goodrich flexi hoses all round and new OEM hard lines to each calliper. GT3 master cylinder and GT3 air deflector thingies fitted (the plastic things that clip onto the suspension arm).

And then came the bleeding. Three rounds with a pressure bleeder and still no pedal pressure. “Bench” bled the master cylinder in situ, recirculating the brake fluid back into the reservoir using rubber tubing and got loads of bubbles out, refitted, still no brake pressure. Eventually my wife sat in the car and I bled each corner the old fashioned way (pump, pump the pedal until faint pressure, and open each nipple, repeat ad nauseam) and then quite suddenly the brake pedal began to build pressure.

All good now, ABS triggered from some extreme braking and the brakes are now awesome. A painful process, but at least it’s back on the road again.

could have you used a compressor and a brake bleeder to speed up the process?

 

[BBB]

59 minutes ago, phobospt said:

could have you used a compressor and a brake bleeder to speed up the process?

I used a pressure bleeder, at 15psi, and it was great at getting fluid to all the bleed nipples, but wouldn’t give a firm pedal. It was very useful for filling my system as it was completely empty and the big advantage is that you can do it on your own.

Getting my wife to pump the brake pedal until there was maximum resistance, with me bleeding the rear wheels worked in the end.

This new tool arrived too late, but should make things a bit easier in the future.

https://www.amazon.co.uk/dp/B08F25ZNNY?ref=ppx_yo2ov_dt_b_fed_asin_title

 

[phobospt]

I had similar on my Mercedes when I let the brake fluid completely out on one of my calipers which caused for air to be inside the ABS system...In the end I put a pole pushing gthe break pedal for around 24 hours and tham did 2/3 runs on accross all calipers starting on the furthest to the master cylinder and it was all sorted..

 

Anyway, back to Porsches, got a GT3 MC to fit, so your experience and notes will defenitely help, thank you

[mrf193]

Had a similar nightmare with my 987.2. Wanted to fit the GT3 master cylinder and the OSF inner bleed nipple was broken. Ended up replacing the caliper as needed the car back asap. With flexi lines, GT3 master cylinder + front brake ducts, Castrol SRF fluid and EBC bluestuff pads all round - the brakes are totally transformed!