Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Bleeding Brakes!

Hi there,

As per my posts about my caliper rebuild and finally getting a new brake pipe today I took the car our around the block. I knew the brake pedal felt soft and had more travel then normal. The brakes were largely ineffective, so I came back and tied to bleed them again.

I had fitted new bleed screws in to the calipers and found they never quite tightened, so I switched them for the originals (and noted the hole at the bottom had become slightly oval).

I re-bled the car, a couple of tiny bubbles only. Tonight I took it for a spin around the block and the more it was driven the better it felt. At low speed if hitting the brake hard (coming out of the garage I could get the wheels to lock up).

I cannot find any leaks and can see each caliper piston moving etc. so I believe all is OK there.

Some questions:

I have to loosen the bleed nipples by more than 1/4 of a turn, and up to 1/2 a turn to get any fluid in to the bleed pipe. But often some leaks out around the nipple too at the same time; I assume this is not normal. Any tips? Is there just a sweat spot?

I cannot believe there is any air in there (hit the callipers with a rubber hammer to free any bubbles). What else can I try or is it possible (likely) that as the new pads and dics bed in the brakes will feel firmer?

I have gone from passenger rear- driver rear - passenger front - driver front as the sequence (with the master cylinder on the drivers side).

The master cylinder is quite new so should be OK or have I done damage somehow?

The brake pedal just feels "wrong"....

Thanks,

R.

Are the bleed nipples at the highest point on the calipers?

Bleed nipples are quite sensitive to position, and old ones are often blocked with scaly deposits. There may be slight weepage around the threads and I wouldn't worry about that. The important thing is that they tighten properly - but not too much force!!
If you can access brake grease you could smear a bit on the threads. There are two ways of bleeding and each method suits different systems. The standard method is slow methodical strokes, up to five or so, before tightening & checking the master cylinder. But the method which worked best on the MGB and which I used on the Roadster when I changed the fluid is three rapid strokes, then on the fourth, hold it down and get an assistant to tighten the bleed screw. The theory is that rapid fluid movement will dislodge bubbles.If you have bleed tube with a non return valve you should be able to do this on your own.

Thanks Dave.

Yes the bleed screws are at the highest point. I did read about removing the calipers and "rotating" them around to free any trapped air; I have not tried this yet. I have wondered if getting some heat in to the system might have the same effect?

I do have a bleed tube with a "non return" valve at one end.

Cheers!

Richard

you can check for " brake travel" on each corner with this type of tool

http://www.ebay.co.uk/itm/BRAKES-FUEL-HE...=item3a73830010

Not necessarily when you have disturbed the braking system will it result in air trapped, many parts move from the pedal to the Pad, even callipers can "twist" and rear brake equaliser arms can wear, only a .001 inch can result in big movements at the pedal, recon rear shoes in the 1980s were popular but although the refurbishing firms relined the shoes they did not renew the ware on the metal arms, hence it was sometimes necessary to put a spot of weld on the arms at the point the shoe body rests.

By using this type of tool, you can detect where the travel is and concentrate your efforts on that corner, unless you have already tried may I suggest you hold slight pressure on the pedal and see if it slowly creeps to the floor

if so you could be looking at the wrong end

(master cylinder issues)

Thanks Dean. Good suggestion re the clamp.

My rear shoes are new (circa 200 miles ago) and the front pads (and discs) are brand new).

I am wondering if the Gunson Ezibleed as done some damage to the relatively new (circa 6 months) master cylinder. It said a maximum pressure of 20bar but I lowered the tyre to 15bar so hopefully not!

...as a thought I used the Ezi Bleed to clear the system of the old fluid. Do I need to bench bleed the master cylinder or can I do this by bleeding the whole system?

i.e. just takes longer if no bench bleeding of the master cylinder?

I am wondering if the Gunson Ezibleed as done some damage to the relatively new (circa 6 months) master cylinder. It said a maximum pressure of 20bar but I lowered the tyre to 15bar so hopefully not! [/quote]

surely you PSI? 15bar is 217psi

I do indeed - good point

I'm not a big fan of eezibleed. The pressure has the potential to squirt fluid all over without a great deal of care. On the MGB I used about 8psi, which was enough. I don't think I've used it since.

I had read that elsewhere....mine seemed OK but today I could not get the cap to seal....