Replacing calipers and master cylinder

[fewtrees]

I’ve all the bits, fluid, isocar thing to cycle abs if needed so all cool..

Question is, which order?

I’m thinking master cylinder first, bleed that with the old fluid still in there

Then a Caliper at a time, usual order of furthest distance from abs unit first.

Better to do inner or outer nipple first?

Anyone got some sage advice?

[Nobbie]

Before starting the job, check all the nipples, particularly the inside ones to make sure they’re not siezed. Maybe spray a bit of dismantling fluid around the thread first. A lot of garages only touch the front ones when bleeding. I think I’d do inners first as the outers don’t seem to bleed this area.

[Menoporsche]

Agreed to get all nipples sorted before you start. No point getting half way through then have to sort a stuck/snapped nipple. 

[½cwt]

Usual method is to bleed all the fluid out that you can through the lines furthers from the master cylinder/ABS unit.  You can syphon/syringe some of the old fluid in the  master cylinder reservoir first to save a bit of effort.  Then continue to bleed every nipple (outers first, then inners to also ensure the caliper crossover pipe is flushed) until fresh almost clear fluid rather than the older more straw colours fluid and any bubbles have gone.  Ideally when you've done this once, rebleed each nipple again to be certain no air has now risen to that high point in each caliper.  If you don't let any air into the ABS unit you shouldn't need to cycle it.  Obviously if you are replacing the m/cyl then there will be air throughout the system.

I did a full caliper overhauls and replaced all the brake lines from the ABS pump onwards last summer and had no problems with bleeding.  As I wasn't touching the m/cyl I fully depressed and blocked the brake pedal in place whilst working on the system to avoid the fluid draining completely so avoiding air into the ABS unit.

Edited April 6 by ½cwt

[fewtrees]

Thanks guys, They are all rebuilt calipers, new pins/springs and clips so not worried about the old bleed nipples!

[ATM]

5 minutes ago, fewtrees said:

Thanks guys, They are all rebuilt calipers, new pins/springs and clips so not worried about the old bleed nipples!

You can buy titanium or stainless nips, your choice. So you could add these now and they won't get all rusty.

[Ninesomething]

I just had my master cylinder, flex pipes and some solid pipes done. Would've had front discs and pads too if ECP hadn't sent the base parts instead of the S ones. 🙄 I dropped in while they were doing it and they did the flex cables before they'd touched the master cylinder. Don't know if it matters either way.

[fewtrees]

So today I’ve done the master cylinder. I bench bled the mc first and quickly swapped the units over.. Obvs still got air in there but I went around the callipers and got a load of air out.. Car stops and can lock the fronts but it’s ok.

Tomorrow I’ll replace the callipers in the usual bleed order and see where I get to.
 

Fortunately I have a motive bleeder which makes the job easy!

Titanium/s.steel nips sound very cool - gonna check that out 👍

[BBB]

6 hours ago, fewtrees said:

So today I’ve done the master cylinder. I bench bled the mc first and quickly swapped the units over.. Obvs still got air in there but I went around the callipers and got a load of air out.. Car stops and can lock the fronts but it’s ok.

Tomorrow I’ll replace the callipers in the usual bleed order and see where I get to.
 

Fortunately I have a motive bleeder which makes the job easy!

Titanium/s.steel nips sound very cool - gonna check that out 👍

Was the master cylinder swap straight forward?

[fewtrees]

21 minutes ago, BBB said:

Was the master cylinder swap straight forward?

It was really, I took the carpet out of the front as I knew brake fluid was going to get spilt..

I used a syringe to remove the fluid in the reservoir.

Removing the reservoir proved to be harder than removing the master cylinder itself. The hydraulic fluid lines are not tightly bolted and the 2 holding bolts for the mc itself are not too tight either. There’s room for a 22/20mm socket no problem.

The hardest part is getting rid of the air out of the system. To help with this I bench bled the new mc beforehand so there’s less air to remove.

[BBB]

9 hours ago, fewtrees said:

It was really, I took the carpet out of the front as I knew brake fluid was going to get spilt..

I used a syringe to remove the fluid in the reservoir.

Removing the reservoir proved to be harder than removing the master cylinder itself. The hydraulic fluid lines are not tightly bolted and the 2 holding bolts for the mc itself are not too tight either. There’s room for a 22/20mm socket no problem.

The hardest part is getting rid of the air out of the system. To help with this I bench bled the new mc beforehand so there’s less air to remove.

Thanks for this. I still have a GT3 master cylinder sat on my bench for swappsies, but keep putting it off. Bench bleeding? Is that simple, if I look it up on YT for example?

[Ninesomething]

1 hour ago, BBB said:

Thanks for this. I still have a GT3 master cylinder sat on my bench for swappsies, but keep putting it off. Bench bleeding? Is that simple, if I look it up on YT for example?

The instructions that came with my gt3 m/c specifically tell you not to bench bleed it but then other posts I've read people say they did. I'm thinking there's just more than one way to skin a cat. Poor thing. M/c upgrade is a noticeable improvement though - stand on the pedal and it's rock solid.....

[fewtrees]

So the front callipers are on and I’ve had to do the abs cycle to get the air out (finally).

Verdict: Gt3 master cylinder is ok, solid but I doubt is needed for the road with a well bled system. Should be better on track as the standard unit travelled a lot.

I’ve got matched track pads for the rear now. Theory is the balance is wrong and the front lock too early so that’s tomorrows job plus the gt3 brake ducts..