Talk Morgan Forums Morgan Sports Cars Morgan Plus Four, Supersport & Plus Six (CX & CXV Generation Vehicles) My23 brakes

My Morgan is of mid 80`s vintage has no ABS or servo and other than the pics kindly posted here by others I have not even seen the brake system that folks are having issues with, and I am NO expert on brakes, just thinking in type in the hope it might help.

MogCX, interesting that you think HEAT could be an issue.... The servo design is to multiply the pressure applied to the brake pedal, and IF it`s internal diaphragm was failing then I would expect the brake pedal to feel HARDER in that it would require more pressure to slow the car down.

Thierry Again it seems heat could be an issue..? Rarely used vehicles can have sticky brake action caused by corrosion build up on wheel related components, pads, pins, wheel cylinders, hand brake linkages, any one of which can cause the pads/shoes to rub the disc/ drum which can build up heat, and which over time can transfer to the brake fluid. If the brake fluid has aged to the extent that it has water content then the water content can boil creating a soft pedal, or the pedal can go all the way to the floor.

With a sticky brake action it may be noted that one wheel has more brake dust on it than the others.

Another check perhaps worth trying is to go for a drive with minimum use of brakes pull over and if you can reach in and touch the discs or drums with a pre-wetted finger tip to compare the disc/drum temperatures....If you burn your finger tip, don`t be too surprised.. (-:

A sticking brake can do so intermittently.

Last thought would be to look for any brake pipe that could gain heat from the exhaust or anything else...

Highly unlikely would be a brake pipe section acting as an earth and carrying enough current to cause it to heat and pass that heat to the brake fluid..

Barry, in general terms air in the system is usually associated with brake fluid loss, which can provide a clue as to where the issue might lie, as well as reduction in brake fluid level over time...With no fluid loss the expectation might be that the master cylinder might be suffering a seal failure.
As has been mentioned previously be sure not to mix brake fluid types,

After having my Plus Six back from the dealers following the master cylinder replacement, my brakes felt the same, so I bleed them again and now they are operating as they should.

this will be done next week

I don't think residual air in the system would lead to fluid loss, this is only possible if it leaks out somewhere (which could be where the air is getting in). Air not removed during bleeding a system with no leaks would lead to the compressible air making the brakes feel soft. this air could be anywhere in the system and may sometimes be more noticeable than others depending on where it is and whether it is in the form of. bubbles or micro bubbles spread throughout the fluid.
Some cars are notoriously hard to bleed and the Morgan CX may just be one of them

My Plus Six arrives back from the dealers today after further work on the brakes. They are driving the car back round 180kms so it will have a good test run. In order to properly bleed the brakes they borrowed a power bleeder - conventional methods could not get all the air out of the system. I will let you know how they are myself after a good long run.
Kerry

Residual air...??? I`m guessing for that to exist that the suggestion might be that system may not have been properly bled... As I have typed previously, I have bled an ABS system using gravity only, which worked well enough.

I guess with ABS it may be possible that if part of the system has been drained, air could be trapped behind a closed valve and not released back into the system until the ABS is activated for the first time after the drain down...?

On the CX, it is impossible to purge by gravity. The ABS system is placed too low.

Gaston thanks for the heads up on that. I`m guessing that for gravity bleeding not to apply I suspect that the fluid reservoir would require to be lower than the bleed nipples on the callipers..?

I appreciate that the ABS unit may be lower than the nipples but would expect that not to have any bearing relative to gravity bleeding.... However I have been wrong before, and will be again, thus more than happy to be corrected.

Looking at the routing of the lines, it is quite possible that the bleeding is the problem.

It appears that all Morgan dealers will have to invest in modern vacuum bleeding equipment which they wouldn't have needed for the trad cars.
Most specialist performance companies will already have this, but I would guess most Morgan dealerships probably don't.
Vacuum bleeding should solve any residual air problems, but it won't be any good if any braking components are fault/leaky.
The more I think about it, the more I think most of the braking problems described in various posts on here are due to inadequate purging of air, possibly due to the brake line plumbing and/or positioning of the ABS unit.
I don't think leaky seals will cause a soft pedal feel (except maybe in extreme cases) unless they are also allowing air back into the system as the fluid weeps past the seal.
I know there was a faulty batch of brake components during early CX production, but I think all the "brake feel" issues discussed here are likely to be due to inadequate bleeding leaving some air in the system.