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MG Midget and Sprite Technical - Bleeding Brakes

I have fitted new calipers and pads to my 1970 midget, as documented in my earlier thread.
Now the fun bit - bleeding!
I have used my Eezibleed, which has been fine in the past.
I started at the rear - I have not disturbed the drums as did not need adjusting. Brake fluid came through clear straight away on both sides.
The nearside caliper was next - (Bleed nipples on both calipers are at the top).The master cylinder was empty as the flexible goodridge hoses slowly drained when original calipers were removed.
Near side caliper bled as I was expecting, air bubbles to begin with and then clear.Same with offside caliper.
With Eezibleed disconnected first push on the brake pedal was soft straight to the floor, the second push was what I was expecting for the first push. Re connected Eezibleed, got attractive assistant to depress brake pedal and hold down whilst I closed nipples. Did this to both front nipples. Only got a minimal amount of air go through. No real improvement.
Have trawled through the archives for bleeding brakes (there are a lot) and can't see anything jump out at me. Someone had suggested that they would improve once the new pads had bedded in, someone else said they ran their Eazibleed at 30psi as opposed to 20psi stated maximum by Eazibleed.
Any ideas (apart from re-bleeding)
Geoff
Geoff Mears

Only thing I'd say is don't exceed the Eezibleed stated pressure.
I had the bottle of fluid split once at normal pressure, old bottle. Not an experience I'd wish to repeat.
G Hawkins

Geoff, it's not clear but that sounds like you bled clear fluid out of the tests before filling the master cylinder? Maybe I read that wrong. But either way if the M/C has been empty at any stage then you need to bleed an appreciable amount out of the rear to clear any air that might be lurking way up the pipework, near the inner wheel arch junction. Otherwise you are only moving those air bubbles part way down and they won't have arrived at the rear cylinders yet.

On adjustment, the rears do have to be fairly closely set, to the point of dragging slightly if they have been disturbed, to get the system to work properly. They will soon bed themselves in.

And, I always get them as good as necessary to enable me to drive, carefully, and then adjust and re-bleed after a couple of trips of maybe 50 to 100 miles total. It shakes any lingering air into bigger bubbles that can then be bled out.
GuyW

Hi Guy
The master cylinder had been filled prior to starting the bleeding as I wanted to check that the banjo unions were not leaking (which they were not). The back shoes were adjusted up ok.
Geoff Mears

Ok I assumed I had read that wrong! Nevertheless, if there was air in the top end of the pipeline before it was filled it can take quite a lot of fluid to be bled through to the rear of the car, before all that air is expelled and you are genuinely seeing fresh fluid. And its not necessarily all out when the first lot of fresh fluid arrives. Air bubbles can cling in the fittings and pipework despite fresh fluid passing them. Pressing the pedal and wedging it down overnight can help dislodge them though.

I have long wished that fluid was available in a variety of colours so that when flushing and refilling a system you could easily see when the new fluid had arrived. I've mentioned the idea here on the BBS on several occasions now.
GuyW

Thanks Guy
I’ll try wedging the brake pedal overnight and give the rear brake pipes a good bleed.
Geoff
Geoff Mears

Geoff,
I know it won't help you with your bleeding problem now, but...
Before I remove a brake caliper or wheel cylinder, I remove the reservoir cap, put a double layer of cling film over the opening, then replace the cap. My hope is that it will help to stop too much fluid draining out of any open pipework. The cap on its own will not stop the fluid draining, as it has a breather hole.
Jon
Jonathan Severn

If you are sure you have all the air out and still have a long oedal, check how much the caliper pistons are retracting. With new seals and not quite enough lube they need more effort than normal to push the pistons through the seals. This compresses the seals more than normal, so when they rebound after pressure is released they will retract the pistons further than usual. 20 thou per piston is enough to need most of the mcyl stroke to get them & pads back to contact with the discs
Paul Walbran

If the problem persists try putting the handbrake on. If the pedal feel is improved you need to fully adjust the handbrake.
Rob
MG Moneypit

Guy,
Well I blocked the brake pedal last night ready for today. When I started to bleed the rear nearside I almost immediately noticed the level of fluid in my catcher jar jump up. My thinking - the fluid had filled the air blockage, so joy. Ran clear(hardly any airbubbles.) Offside rear, opened bleed valve, and immediately loads and loads of air bubbles - immense joy!....followed by slurpy noise. Much sorrow. I had emptied the Eazibleed reservoir. "Silly me" I muttered. So it looks like I have re-created my problem. Still got slack pedal. Need to order some more Dot4 so a few days off to reduce blood pressure levels. Will do the overnight wedge again, and make sure to check reservoir levels next time!
I'm sure a bottle of wine tonight will help my mental state enormously.
Geoff
Geoff Mears

Oh, sorry Geoff - I think I forgot to mention the bottle of wine. Essential ingredient to consume whilst the pedal is blocked overnight!

But it does sound like a good practice run.
GuyW

When I use my eezibleed I don't put fluid in the container but just use it as a pressurising device. Obviously,that means I have to be careful to keep the M/C topped up and ensure there are no air leaks. It's worked for me so far and means I don't waste fluid that would otherwise be left in the eezibleed container.
Bill Bretherton

Easibleed design fault! If they had used the same screw on cap thread as is used on bottles of DOT fluid one could then either simply use the DOT bottle as the pressure reservoir, obviating the need to decant from one to the other, which possibly introduces air bubbles. Or at least leave fluid in the easibleed bottle and put the cap on for storage until the next time!
GuyW

Reminds me of a very old joke to be told against folk of nearby town/part of town which has friendly rivalry with your neck of the woods: injured bloke from X place walks into the Accident & Emergency Dept (ER) of his local hospital. The doctor asks him ‘Where are you bleeding from?’ to which the man angrily replies ‘I’m from bleedin’ X, where you bleedin’ from?’

Cheers
Mike
M Wood

Hi Guy
Had another practice run today! Pedal blocked overnight. All bleed valves ran clear after a length of time. Kept bottle topped up between each bleed, and re-inflated tyre to 20 each time. First pedal push was slightly better but still went to floor, the second pump of the pedal gave me a firm brake and sustained it. Will have another go in a few days time when there is a dry day.
Geoff Mears

Sounds better!
First stroke to the floor followed by good pressure on the second sounds like either rear brakes not sufficiently adjusted up, or front disc pads backing off too far. The latter may be as Paul (NZ) describes or it can happen if discs are warped or not seated back on the hub correctly. ( You did clean any rust off the hub mating surfaces didn't you?) As the disc rotates it wobbles and nudges the pads back, giving too much clearance and a "long pedal" on the first press.
GuyW

Thanks Guy. Will check disc pads and brake shoes adjustments. When I fitted the new pads they literally flopped in and may not have sat level. I’ll take them out and refit. Paul talked about lube - I just fitted the new callipers without doing any lubrication. Should I maybe spray a bit of WD40 on the circumference of the calliper pistons to see if that helps? Maybe pop old worn pads in to allow the piston to travel further giving more area to lubricate? Not sure how or where to measure for the 20thou mentioned by Paul.
Geoff Mears

Do you have a dial guage, Geoff? You could check on run out on the disc.

As for rear brakes, I always adjust mine up until they are scuffing lightly. Any more than this and they take up all the fluid movement that should be going to the much more effective front discs! The rears will soon adjust themselves to run freely. You also need to make sure the adjuster is centred well "between flats" and to adjust with the handbrake adjustment backed well off, leaving that adjustment until last of all.

Apologies if this is all well known to you Geoff. It's one of the limitations of this form of communication in that it is very easy to sound patronising and end up saying the obvious to people who probably know a lot more about this than I do!
GuyW

Sorry to jump in here at such a late stage, but if I read correctly and you managed to almost get the job done, only to find you had then let new air in at the MC, surely your set up is ok, and its just the "bleeding air" that is your problem?

Like Bill, I run my Eezibleed dry, not as efficient as you have to keep filling the MC, but I had a leak in the pipework once and the brake fluid went everywhere.

Good luck
Graham V

I think if there were still air in the system then although you could pump the pressure up with a couple of quickly repeated strokes, the pedal would then still feel springy under one's foot. I thought Geoff was getting a firm pedal after a second stroke? That said, I never seem to get a really solid pedal feel until after a shake down run and a re-bleed.
GuyW

This 'Eazibleed' seems a right misnomer, often there seems to be air in the brakes after its use. Perhaps things would work out better and more often if it wasn't used.
Nigel Atkins

Nigel, you won't be at all surprised but I disagree. I have used mine on dozens of different cars over a period of 30 years or so. I have never had any problems, no fountains of brake fluid, no added air in the systems. Follow the simple instructions, don't over pressurise, keep the reservoir bottle topped up and its a simple and effective system!
GuyW

Guy
I agree with you. I find a big advantage of eezibleed is that you get continuous pressure down the line.
When you do it by applying pressure with the foot pedal, I find the air has a chance to run back into hiding each time you take your foot off the pedal.
With the clutch, I have found sometimes eezibleed can be the only way that works for me.
Graham V

Hi Guy
Firstly, although I said that I was replacing the rear shoes with the wider Mini ones, when I took the drums off the standard shoes had plenty of life left, so I have left that change for a future date. Also, the adjustment nut for the rear brakes is on the “flat” edge, so ok. I have the 1500 handbrake system which is set up ok (I think). Anyway, it is 100 times better than the original system.
Sorry, I don’t have a dial gauge. A bit of history - I purchased my 1970 car in 1993. It was a hopeless mot failure which I purchased to use as a Heritage re-shell. I used the existing callipers, which means they have had over 40 years use, if they hadn’t been replaced prior to my purchase. I had no sponginess to my braking when I changed them for new callipers. The pads were wearing at an angle which I put down to the pistons jamming. The discs that I fitted to the Heritage shell were new and have done about 35-40k. My thinking is that my current problem probably is to do with the new callipers, along the lines of Paul’s thinking.
From what has been said previously I’m thinking the problem lies within the new callipers, so if there is a way to lubricate to ensure a smooth operation I’d appreciate advice.
Finally Guy, I’m grateful for your comments and advice (and everyone else’s). I have learned a lot here and am grateful for the help.
Geoff Mears

Clutch bleeding for me today for the first time in a number of years.

Having taken on board comments from this and other threads I set about it a bit differently this time.

First thing was to jack the car up one side to put the bleed port on the slave cylinder as high as possible.

Despite having a remote bleed point, I still got in quite a mess last time, so I took precautions this time. I sliced open a couple of black bin liners to make sheets to cover the wing and engine bay, then, just as they do in operating theatres, I cut small holes to access the points to operate on; one for the master cylinder and one for the bleed point. Bin liners were ideal as they are cheap, impervious and disposable.

I used a short telescopic builder's prop to brace the clutch pedal. These props are useful for all sorts of things and I have a much longer, ratcheting one that was invaluable when we were fitting plaster board panels in ceilings.

As suggested in this thread, I filled the master cylinder but left the Eezibleeder empty. It meant releasing the pressure a few times to top the fluid up, but this was much less messy than when the tube from the Eezibleeder is full of fluid that I managed to splash on the wing last time.

All went well with only minimal drippage caught in a paper towel round the bleed point.

After a brief test run there is clearly still a bit of air in there, but at least it gave me a working clutch at the first attempt, unlike my previous efforts which took ages to sort out.

Thanks to everyone who has provided bleeding hints and tips.

Colin






C Mee

Well done Colin. When I bled the Frogeye clutch for the first time (new M/C, pipes, slave and remote bleed) I expected trouble but it almost bled itself with the eezibleed. There was slight seepage at the remote bleed and I wonder if the air had all gradually bled out until I sealed it a day or two later. I left the pedal in the up position and didn't jack the car up. Still has a good pedal.
Bill Bretherton

Maybe I've just been lucky with the EeziBleed. The only problem it's presented has been air leaks at the bottle cap, where tightening the cap further sometimes makes the leak worse... and this is at the recommended pressure. But still, I've gotten a good firm pedal on my own car, as well as on a friend's 61 Midget, with a minimum of fuss.

I realize that this could change next time... keeping fingers crossed. ;-)

-:G:-
Gryf Ketcherside

Gryf,
see the 'Homage to Prop' thread in 'Midget and Sprite General'.
Nigel Atkins

This thread was discussed between 26/02/2021 and 13/03/2021

MG Midget and Sprite Technical index

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