Brake problem

[S6 Devil]

I have just picked the car up after having new calipers fitted. The mechanic asked if the brakes had been spongy before as now when I push the pedal down there is almost no resistance. If I press a second time they firm up. He tells me he used an eazy bleed to bleed the brakes but questioned whether the master cylinder seals were the problem.

The brakes were fine when I dropped the car off, apart fom a sticicky caliper. What needs doing...re-bleed?

[nawarne]

Mike,
Definitely sounds like air in the system, if the brakes respond to pumping.
Should be easy enough to do...probably better with a helper to check the level in the master cyl. resevoir and pump the pedal. Just keep an eye on the tubing ex the bleed nipple for air bubbles.

Also, IIRC on the Tuscan front caliper there are two bleed nipples - wonder if this might be the problem (missed by your mechanic)?

Nick

[S6 Devil]

Thanks Nick, that's a relief as I believe changing the brake master cylinder is a pig. It was the rear calipers that he replaced, do we need to bleed front and rear?

[Walford]

change the fluid then bleed all six nipples, as the new fluid wont have the small amounts of moisture, that damage the system in older cars

[scotty_d]

Speaking of master cylinders guess what i have been removing all day after trying to bleed my brakes........


My symptoms in the cerb.

I removed all the air for sure out the System every caliper had a flow of fluid from ever bleed point so i am 100% no air in there as i put around 2L through it.

The pedal had little resistance and if you pumped firmed up a little but always goes to the floor.

So it is out now and hope to pick up a new one in the morning.

[S6 Devil]

Walford said:

change the fluid then bleed all six nipples, as the new fluid wont have the small amounts of moisture, that damage the system in older cars

The fluid was changed 2000 miles ago.

Just had an email from my mechanic saying he has bled the system using all 6 nipples. We are going to re bleed it on Tuesday.

[S6 Devil]

scotty_d said:

Speaking of master cylinders guess what i have been removing all day after trying to bleed my brakes........


My symptoms in the cerb.

I removed all the air for sure out the System every caliper had a flow of fluid from ever bleed point so i am 100% no air in there as i put around 2L through it.

The pedal had little resistance and if you pumped firmed up a little but always goes to the floor.

So it is out now and hope to pick up a new one in the morning.

It was your post that I was reading!

My pedal has little resistance but does stop the car. The second pump firms up and brakes the car as normal. The pedal doesn't go to the floor as does yours, this makes me think it is air not the seals on the BMC. I hope!

Did yours suddenly go or was it a slow deterioration?

[scotty_d]

The car has been off the road for 7 months and no fluid in it as i replaced lines/hose's so this was my first go at filling it up and bleeding it this week. I am sure the seals have dried up and must be passing now. Was not to bad to remove i got at it through the soft patch on the Cerbs inner wing. But your's does sound like air being compressed if it is not hitting the floor.

I use a easy bleed as well. great for doing 80% of the work but i always finish with help.

[S6 Devil]

Thanks mate. I didn't think by BMC seals could have deteriorated overnight. It must be air!
I can't think of anything else it could be. There don't seem to be any leaks from the hoses and all was fine with the BMC before the caliper change.

[stuthemong]

You'll often get a bit of air in after such shenannigans. Normally, provided good calliper design, the little air bubbles you get migrate toward the bleed nipples as you use it, so if you bleed it again now you'll be sorted. If you've never done it before, it's not hard - do it with a mate one evening for a beer.

On the old lotus elises you had to unbolt the calliper, repeatidly tap it with a hammer, whilst you span it around upside down, back and fro, to get the air to the bleed nipple. Then reattach calliper.

[nawarne]

S6 Devil said:

Thanks Nick, that's a relief as I believe changing the brake master cylinder is a pig. It was the rear calipers that he replaced, do we need to bleed front and rear?

My 2p's worth!

OK, consensus is that it is air in the system. Agree that if the BMC was fine before the caliper change, it is unlikely to have failed so suddenly.

I believe the perceived wisdom is to start bleeding at the N/S rear then the O/S rear then N/S front and finally O/S front. Maybe a few taps with a hammer will encourage air to migrate to the bleed points.

Nick

[S6 Devil]

Thanks for all your input. I've just dropped the car off with your recommendations. I will feedback when I hear!

[scotty_d]

HA HA i just changed my BMC for no reason other than i am a idiot. I fitted the new one to remember this car has 4 and 2 pot brakes with 2 nipples per caliper.

What a day 14 hours of graft the day before my Mot that was not needed. Hope you get sorted out soon.

Scotty

[S6 Devil]

Well, the system has been bled 3 times now. There was air in all 4 calipers but the brake pedal still isn't right. It is better than it was but I don't feel confident to drive it spiritedly.

Looks like I will have to take it to Andy at APM to get it done once and for all.

[S6 Devil]

scotty_d said:

HA HA i just changed my BMC for no reason other than i am a idiot. I fitted the new one to remember this car has 4 and 2 pot brakes with 2 nipples per caliper.

What a day 14 hours of graft the day before my Mot that was not needed. Hope you get sorted out soon.

Scotty

Interested to know your thinking here. Why was it a waste of time to change it if the car has 4 and 2 pot brakes with 2 nipples per caliper?

[nawarne]

^^ Mike, I think scottyd means that he forgot that the front calipers are 4 pot and have 2 bleed nipples - so he assumed the master was letting air in rather than bleeding both sides of the front calipers.

IIRC, when I was last at STR8Six, they had a pump to get/change fluid into the hydraulics. I guess that way, they are sure that all the air is displaced...and they have clean fluid at the caliper. I'm sure Andy will sort it though.
Nick

[S6 Devil]

nawarne said:

^^ Mike, I think scottyd means that he forgot that the front calipers are 4 pot and have 2 bleed nipples - so he assumed the master was letting air in rather than bleeding both sides of the front calipers.

IIRC, when I was last at STR8Six, they had a pump to get/change fluid into the hydraulics. I guess that way, they are sure that all the air is displaced...and they have clean fluid at the caliper. I'm sure Andy will sort it though.
Nick

Thanks mate. I'm sure Andy will sort it, it's just frustrating as I can't get to him for 2 weeks so am stuck with decidedly spongy brakes. It can't be that hard to bleed can it? Thinking of trying my local garage to see if they can sort it.

[Basil Brush]

I've done my own with a gunsons easy bleed a couple of times, first when rebuilding a rear caliper and then again when I replaced the master cylinder. It was easy enough and just ran plenty of fluid through to make sure.

[S6 Devil]

Basil Brush said:

I've done my own with a gunsons easy bleed a couple of times, first when rebuilding a rear caliper and then again when I replaced the master cylinder. It was easy enough and just ran plenty of fluid through to make sure.

What were the symptoms of a failed master cylinder? I'm just trying to rule out other possibilities!

[fredd1e]

Of the master cylinder failures I've experienced, one was unable to build up any pedal pressure at all and the other was able to build up pressure via pumping the pedal but when held firm the pressure on the pedal bled away . Ps both occured after many miles of use and a full bleed that allowed the master cylinder to go through the full stroke (ie pedal to floor) which it probably hadnt done since new.