Author Topic: Bleeding brakes  (Read 627 times)

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Offline Roger

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Re: Bleeding brakes
« Reply #15 on: Thursday,January 04, 2018, 08:34:54 AM »
Yes mine does have that but surely it's impossible to reach the bolt heads from there....
No it isn't,  with a longish ring spanner (box-end wrench).
Before you put them back,  drill holes in mild steel strip and brazen the bolts in them the strip needs to be long enough to stop the bolt rotating when you tighten the nuts. You'll never have the difficulty again.

Offline Gmg31

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Re: Bleeding brakes
« Reply #16 on: Saturday,January 06, 2018, 08:51:35 AM »
Apologies to anyone who has seen this moaning tirade on other pages, I’m running out of ideas and patience.

1970 S2 Europa. Full restoration every component of the braking system is brand new, no servos.  I have spent weeks trying to bleed the brakes and I cannot get a pedal at all.

Normal manual bleeding 10 or more times. Nothing
Pressure bleeder, nothing.
Following advice Here.
I disconnected the pipe from the MC that goes to the T piece and added a bleed valve to the end. I then bled the MC. With the bleed valve shut the pedal was rock hard so clearly the seals inside the MC are holding.
I then connected that same pipe directly to 1 front wheel and bled that, all ok working fine.
Reconnected the pipes as they should be and bled the whole system half a dozen times, manually, with an eazi bleeder and with the pressure bleeder. Nothing.
Adjusted the connecting rod from the pedal to the MC tried it shorter and longer nothing.  There are 4 flex unions on the rear non are leaking, 4 flex’s unions on the front non are leaking 2 Brass T pieces neither are leaking. Rear cylinders new, checked not leaking. BTW When I say ‘nothing’ I mean absolutely nothing, the pedal just goes straight down to the floor, not even a soft spongy pedal.
Question with no visible leaks how can air be getting into the system, surely even the slightest air leak would cause fluid leak.

Offline EuropaTC

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Re: Bleeding brakes
« Reply #17 on: Saturday,January 06, 2018, 09:30:58 AM »
gee, this is getting a bit serious. No need to apologise for having a good old grumble, we all do it, that's why we just love these old cars so much  ::)

Firstly, if you can get a hard pedal with the m/cyl outlet blocked then it isn't going to be an actuating rod problem, so let's park that for the moment. It might need adjusting to get full travel or pedal position but shouldn't stop the brakes working. And the m/cyl has been ticked as well.

OK, get me up to speed with your layout....

I'm assuming you have a single circuit m/cyl with a line going from the m/cyl to a 4 way union just in front of the crossmember ? 

From the 4-way you have 1 line outlet to each front caliper and then a single line going down the spine of the chassis to the rear ?

At the rear you have another 4 way union located on the chassis with one inlet from the front, outlets RH rear, LH rear and then brake pressure switch ?

If that's right and you're getting nowhere with the usual "bleed the furthest away first" method I would be tempted to isolate the front calipers by going to the front 4-way and replacing the outlet to the rear/central spine with your bleed nipple.   Try for both front calipers working.

Is that ok ? If you can get a solid pedal on the front calipers we're chasing a rear problem and the transfer line is the first target. It's a long line and could easily trap an air pocket if you don't get a good flush there.

So replace that central line and if you can easily get to the rear 4-way,  crack the front/rear transfer line so that as you push fluid through you can see it appear before re-connecting. Messy so you'll need a rag to stop the chassis paint getting attacked.

In fact if you have easy access to the 4-way I'd be tempted to remove the brake switch and use the bleed nipple to get all the air out up to that point. You can leave the nipple in place once it's clear and go for the rear brakes now, furthest away first.

Don't get too down about it.  With the lines going up and down the car (even more with a servo system) there are plenty of opportunities to retain air bubbles in the lines.  I aim to do a single line at a time and don't get hung up about flushing a complete reservoir full out at one go with my pressure system.

Yes, I waste a lot of fluid but it's cheap if you buy the big 4/5L cans from Halfords. £20-£25 ? well worth wasting a few quid to preserve your sanity !



« Last Edit: Saturday,January 06, 2018, 09:35:02 AM by EuropaTC »

Offline pto

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Re: Bleeding brakes
« Reply #18 on: Saturday,January 06, 2018, 09:33:14 AM »
Hi

Not to insult your intelligence, but when it comes to the rear cylinders, you've connected the pipes to the bottom, not the top?  If you've connected to the top you'll never bleed the air out of the cylinder.

(Why are you messing with the pedal when you know when the rears are disconnected it works fine?)

Jack
« Last Edit: Saturday,January 06, 2018, 09:35:05 AM by pto »

Offline E Paul

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Re: Bleeding brakes
« Reply #19 on: Saturday,January 06, 2018, 10:18:24 AM »
If you have boosters SpeedBleeders are your best friend.

Offline Gmg31

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Re: Bleeding brakes
« Reply #20 on: Saturday,January 06, 2018, 10:23:00 AM »
Europa TC yes you have described my system perfectly.  i will work through your suggestions.
I don’t have Boosters, (Servos in the UK).  A FB friends has suspected that the brake switch is a high point and can trap air.

Thanks for your suggestion everyone
« Last Edit: Saturday,January 06, 2018, 11:16:50 AM by Gmg31 »

Offline jbcollier

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Re: Bleeding brakes
« Reply #21 on: Saturday,January 06, 2018, 04:34:28 PM »
Have you adjusted the rear brakes?  The first time, you should adjust them with the handbrake cables disconnected.

Offline EuropaTC

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Re: Bleeding brakes
« Reply #22 on: Sunday,January 07, 2018, 12:55:05 AM »
A FB friends has suspected that the brake switch is a high point and can trap air.

Following on from your friend's suggestion, if your rear 4-way is arranged like the first image with the base horizontal then I'd put money on it being the culprit. Nowhere for the air to go.....

It sounds like your system is the same as mine used to be. I mounted the 4-way on the vertical section of the rear Y so it was like the second image, brake switch on the bottom.

Brian

Offline Gmg31

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Re: Bleeding brakes
« Reply #23 on: Saturday,January 13, 2018, 02:48:37 PM »
Spent another whole day on this today. Turned the brass union at the back the other up so the switch is in the bottom. Bypassed the union at the front and connected the MC straight to the rear. Perfect rear brakes excellent.  Connected the front on their own perfect.  But Re connected them all together NOTHING.

have decided to do away with the front union and split the feed into two senate brake circuits using 3 T joints  with their own bleed nipples. This is absolutely driving me mad.

Offline EuropaTC

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Re: Bleeding brakes
« Reply #24 on: Saturday,January 13, 2018, 11:44:17 PM »
have decided to do away with the front union and split the feed into two senate brake circuits using 3 T joints  with their own bleed nipples. This is absolutely driving me mad.

Gee, this is crazy. Front works in isolation, Rear works in isolation but all together and it's not working ?  I can understand your frustration, by now my swear box would be overflowing and there would be chunks missing from the workshop walls where missiles had collided.

But however bad it seems, you are approaching the problem in a logical manner. You've proved that the m/cyl, front calipers and rear drums do work independently, so it's got to be something about the line connecting front & rear.  Somewhere there must be a hold up of air which isn't being taken out during the bleed process.  If you can stand yet more questions.....

1. Did you take any photographs of the brake lines during the build so we can see how they run ?  I have no idea how it will help but seeing the geometry might just trigger something.

2. When you connected the m/cyl directly to the rear brakes did you use the front to rear line on the car and if so, how did you get it working ? (layout)

If it's any consolation then you're not the only one stumped here. Without a servo and on a single circuit, this is a frustratingly simple set-up. It's crazy how air is being held up even with pressure bleeding. It's just a pity you're not closer to Lincolnshire, this is worth an afternoon of looking at.

Brian

Edit to add;  following on from subsequent comments regarding m/cyl bore and travel, a further question. When you got either the front or rear working singly, how much travel was there on the pedal ?  I would guess it should be around an inch or even less to fully apply either front or rear brakes. If it goes much further and won't reduce with pumping, then there is some mileage in checking the m/cyl bore you've got is correct. I'd be looking for 0.7", IIRC early cars had smaller ones but I'd expect you to be fine with 0.7" and no servo.
« Last Edit: Sunday,January 14, 2018, 08:50:12 AM by EuropaTC »

Offline cwtech

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Re: Bleeding brakes
« Reply #25 on: Sunday,January 14, 2018, 05:14:20 AM »
Is it possible that the master cylinder does not displace enough volume to activate both the front & rear brakes at the same time?

This could be caused by an undersized master, or not enough stroke on the correctly-sized master.

While bleeding the brakes, does the pedal go all the way down to the floor/carpet?  ...If so, you may not be utilizing the full stroke of the m/c.

Offline jbcollier

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Re: Bleeding brakes
« Reply #26 on: Sunday,January 14, 2018, 07:38:12 AM »
A few bubbles of air will give a slightly soft pedal, not no pedal at all.

A few questions:

- All new parts means what?  Please describe exactly what was done.  New? Overhauled?  Parts sourced from whom?

- New master made by whom?  Bore size?

- Did you confirm that the pushrod is not preloaded?

- Did you check that your rear brakes were properly adjusted?

Offline Gmg31

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Re: Bleeding brakes
« Reply #27 on: Sunday,January 14, 2018, 01:53:17 PM »
New MC, new Callipers, new rear cylinders, all new pipes, new brake switch. Everything from Banks Europa Engineering. The only things not replaced are the two brass unions.

I’ve repositioned the rear union so the brake switch is at the bottom and this worked perfectly if ONLY the rear is connected up. Same at the front so the only part that is added when connecting everything is the Brass union at the front. So my plan is to ignore this and use 3 T pieces and create a duel system.  Parts are on order so hopefully I’ll update this thread next weekend.

Offline jbcollier

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Re: Bleeding brakes
« Reply #28 on: Sunday,January 14, 2018, 05:00:28 PM »
You should not have to change the lines from stock.  Something else is wrong.

It’s my understanding that you have a single circuit m/c and that you have tried it with attached only to the front and then only to the rear.  You say the brake pedal was then fine.  Could you describe fine?  Given the isolation of half the system, the pedal should have been very high and rock hard.  Was it?

One other thing to look for is the wrong seals in the front calipers.  I have only seen a couple of times but sometimes the calipers seal is too stiff and it retracts the pistons too far leading to a very low/non-existent pedal.  Again it doesn’t happen often but it worth checking.  Have your beautiful assistant apply the brakes while you watch the movement of the calipers pistons.