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MG Midget and Sprite Technical - Brake Bleeding

Just finished replacing brake cylinders, shoes, calipers, pads and two front flexible hoses.

After manual bleeding with clear plastic hose until no air bubbles remain in expelled fluid on an early 1500 midget, I am struggling to get rid of all the air.

The first press of the pedal pushes down around a third further than the next push which results in a good firm pedal, but after being left a few seconds the pedal on first push is again too low and again recovers on second press.

Just looking for any tips as I presume it is air trapped somewhere in the system or should I try running a few miles to bed the new pads and shoes etc in and then re bleed.

Each wheel was bled after replacing its cylinder/caliper and then re bled in sequence starting again from the furthest away from master cylinder.

Tim Lynam

Non bedded in pads or shoes would increase the movement of the pedal, but it would be risky to go for a run until you are sure everything else is OK!
I have changed all the brake components on my 1500 a couple of times over the last 15 years and after bleeding (single handed, using the hold down the pedal with a broomstick method) the pedal has always been reliably firm.
Is your master cylinder perhaps sulking that it has not been changed too? ( Maybe you have changed it as well, but I assumed you haven't).
JB Anderson

Just check you have the calipers the right way up when i bled mine PO had fitted the calipers on the wrong sides bleed nipple at bottom instead of top.
mark 1500 on the road Preston Lancs

Although the Master Cylinder appears to be the original it has not been changed, so yes it could be having a sulk and saving a bit of air as pay back!

The Calipers are the right way round I hope, bleed nipples on the top.

One thing that is awkward is the front nipples are larger than the rear ones with the front nipples being a perfect fit for spare clear windscreen washer hose I had, but the smaller nipples on the rear cylinders being much smaller and does not give a nice tight seal, maybe best to find some nice fitting hose and re bleed from the back again.

Tim Lynam

If they are working well enough, then go for a drive, preferably on uneven bumpy side roads. Then leave it to stand until the following day before then a re-bleed. The vibration and movement from using the car will shake the air bubbles and help them coalesce after which the second session bleeding will clear them properly out of the system.
Guy W

I've had the same problem with mine in the past. On both occasions it turned out to be the Union of the rigid pipe to th flexi. Worth checking as the symtoms were exactly the same.
Pete Ottewell

Thanks Guy, no problem finding bumpy roads around Mansfield after all the recent snow leaving plenty of pot holes, so been for a run after finding the air problem not as bad as first feared yesterday, but still not right.

Will try re bleeding tomorrow after hopefully dislodging the remaining last few air bubbles.
Tim Lynam

Thanks Pete for the tip, I did initially have to battle with both connections between the rigid and flexible hoses, how did you resolve?
Tim Lynam

I found some bits of the old flexi linings were in the nearside front cylinder causing mine to be spongy. I think the debris was restricting the flow in and out of the cylinder somehow. Fished it all out with some bent wire (cylinder off car).

Mine had been off the road for nearly 10 years at this point but just shows how something quite small and easily overlooked can affect the brakes.

btw I use easibleed as the attractive assistant is usually at work when I am fixing the car. Found it made life much simpler.
Dave Squire

Unfortunately I tried a cheap one man bleed kit from Halfords, which did not last more than one wheel before breaking, after reading the archived messages it looks like the EasyBleed is the favoured optioned most go for. Had to resort to the 2 man option which gave an even bigger issue of having to prise a teenage son from the computer.

The old front flexible hoses were not too bad but decided to change them whilst renewing calipers etc so hopefully no similar issue but it's good to know I'm not the only one to have experienced bleeding issues.
Tim Lynam

It sounds like your using my method of bleeding

Hook up.a clear hose to the caliper, and dump it into the master cyl reservoir and pump.the peddle till no more air is in the clear hose

A couple of notes,

Dont pump the peddle fast, only slowly and evenly

put the end of the hose no more then 1/2 way into.the cly or else you will recirculate the air if its at the bottom of the reservoir

If the hose is loose on the zerk fitting ...definatle problem use a bread tie to make the hose tight to the zerk fitting or getting a smaller size ID clear hose

Another big problem area thats probably more common then we probably realize, is the zerk fitting to the caliper...if this is to loose if can suck air past the tread fittings...and its hard to see it as the air is hiding out in side the solve this us plumbers (ptfe) TAPE, not the paste ! That will fill in any gaps in the threads

Also.. I only crack the zerk about 1/4 to 1/2 turn just enough so the brake fluid passes freely

Prop and the Blackhole Midget

Never had a bleeding issue over the last 50 years of car maintenance use the single handed broom handle to hold the pedal down technique.
Tried eezibleed type things but no better than the simple method.
JB Anderson

Prop, I did not have enough hose to put one end into the master cylinder and as I had no idea how long the old fluid had been in the car I wanted to flush out the old and add new fluid. Not sure how much fluid is in all the lines? although I am sure it will say somewhere in the Handbooks.

But after taking it for a run yesterday it does seem to have pushed a fair bit of air back up to the high spots and now after another bleed today the brakes seem allot better, there is a fair bit of satisfaction gained by seeing those bubbles floating out of the tube that did not want to come out yesterday.

So thanks for everyones tips, maybe I was a bit impatient but after a second bleed and well over a litre of fluid later the brakes are much better with no air and new cylinders, calipers pads and shoes.
Tim Lynam

I thoroughly recommend Easibleed if doing the job on your own. Also having bled the brakes of possibly hundreds of cars over the years (with and without a helper)I can say that very often the master cylinder is the next weak point to fail after many other components have been changed; the ones on Minis (old type)being the most prone to failure in my experience - either that or Mini owners liked my cheap prices! I imagine the Midget items are typically Leyland too so I put new seals in my Midget masters as a matter of course to save time, fluid and extra work later.
Nick Nakorn

Hey tim,

The end of the hose has to be submirged in fluid ither in a catch can or the master reservoir or else air will be sucked back into the lines

Prop and the Blackhole Midget

Glad you are happier with it now Tim.

As everything beds in the feel will improve, and you can always give it a quick bleed in the near future to finally eradicate any residual air that may still be causing a problem, if any.
JB Anderson

Just a side note... I found a similar issue when I fitted new pads and callipers. In my case it was I believe due to the calliper seals dragging on the pistons. I had the identical symptoms of having to press the brake pedal twice in order to get a firm pedal.

I resolved this by installing the old pads (which were of course thinner than the new ones), bleeding, then installing the new pads. The installation of the new pads involved pushing the pistons back in to the callipers... then all was fine for me.

Good idea Tony, I will bear that in mind if the last bit of air cannot be removed, its interesting to hear the ideas on what to most will be a relatively easy task in bleeding the brakes.

Prop, second time around I used a hose with a non return valve on one end which did make the bleeding easier.

But may need a 3rd bleed to finally get rid of the last bit of air after its done a few miles.
Tim Lynam

JB Anderson

Do you have any tips for the single handed broom handle method?

M Wood

I think it is quite a common method for those, like me, who have a SWMBO that will not set foot in the garage under any circumstances so all jobs have to be done single handed!

I start at the left rear, connect a rubber/plastic pipe to the bleed nipple and immerse the free end in a container with some fluid in it(a non return valve on the end in the container may help but is not needed as long as there is enough fluid in the container), make sure the reservoir is full, release the bleed nipple, pump the pedal steadily a number of times then keep the pedal down and hold it down with a broom handle or similar jammed against the seat.
Tighten the nipple, release the broom handle and repeat for the other brakes.

Hope that makes sense.
JB Anderson

Sorry tim,

I didnt catch that you had a bleed valve

Prop and the Blackhole Midget

No problem, I probably never mentioned it.

Has anyone found a good source for plastic clear tubing for the back two bleed nipples?

The windscreen washer tubing fits nice and snug on the two front nipples, but the back two being much smaller are difficult to get the same pipe on nice and tightly.

I bet someone has found an answer!
Tim Lynam

Clear hose for aquariums? I think that's what I have in The Shed. You can buy it by the metre online.
You can even get a little in-line non-return valve for it, which is meant to stop your fish tank air pump flooding if it stops for any reason.
I wonder if that would work with brake fluid. Anyone tried it?
RS Hughes

Is that thinner than the windscreen washer hose?
If so it could well be an easily available option.
Tim Lynam

Looks skinnier to me Tim. I haven't measured it but looks a bit smaller. Also seems to be a bit more flexible.
If your hose is a bit slack on the nipple would it seal if you used a couple inches of copper wire (recycled offcut from twin and earth power cable for example) to wirelock it in place?
Just a thought........
RS Hughes

I had some fuelpipe from a model aircraft nice fit
mark 1500 on the road Preston Lancs

Good idea Mark.
I just found out that old VW buses/campers sometimes have 4mm bore hose for the washers, but some use 2.5mm bore hose. Part number for 2.5mm hose appears to be N018 057 1, in something called ETKA which turns out to be an online parts catalogue. Some bloke with a VW camper was moaning because he bought that hose and then found out he needed the 4mm type after all.
Google knows everything!
Maybe that would work, depending on how small your nipples are (so to speak).
RS Hughes

Another thought. If you're anywhere near a supplier of hydraulic components (example: Hydrasun) you might be able to get some hose called BT7-2, made by Beattie Hydraulics. We use miles of this offshore for pilot hoses etc.
It has a nominal bore of 1/8", which is roughly 3.2mm.

Under the American "dash size" system the dash size denotes the nominal bore in multiples of 1/16" so BT7-2 is 2 x 1/16" or 1/8". This is also used for American standard hydraulic connectors (JIC). So a No.6 JIC is 6 x 1/16" or 3/8" nominal bore and a No.12 is similarly 3/4".

MAybe a little off-piste as BL didn't use JIC (their hydraulic connectors appear to be all BSP or BSPT) but brake hydraulic connectors are sometimes listed as No.2 or No.4 etc. and this what the numbering convention means.

Good luck with your brake bleeding. I always found it a pain - maybe I just never found the right technique.
RS Hughes

I get my clear hose from the big box stores ...home depot, lowells, menards, ect ect

I use a bread tie to tighten the hose to the zerk...and a strand of wire will do the same

The draw back the vinyl hose deterioates after several days because of the brake fluid ... so im sure the fish tank one way valve would be eatten as well with in a few days

But the stuff is cheap... maybe 10 cents per foot, so I just toss when im done

I remove the zerk to match up the tube in the store

Prop and the Blackhole Midget

Well what an imaginative lot you are, I would have never thought of some of those ideas, but there are some good ideas to try, thanks.
Tim Lynam

plenty of model fuel pipe on ebay cheap
mark 1500 on the road Preston Lancs

Good tops on hhe glo-plug model aircraft engine hose.

JB - thanks for the broom tips. I have similar lack of additional helper (and my gunson Easibleed has expired)

M Wood

This thread was discussed between 02/01/2015 and 22/01/2015

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