Front btake imbalance.

[57traveller]

I'm back.
For the past couple of years, at MOT test, the brake testing machine has always picked up an imbalance in my Traveller's front brakes (only the front). Never enough to attract a failure. The first time it was put down to unequal adjustment. The second time, last November, I made sure the brakes were adjusted as close to the same as possible but still there was/is this imbalance to the right. I removed the drums and checked the wheel cylinders, the left side were very tight, almost seized, so renewed both left side. Right side seem o.k. Still there is the slight tendency to "pull" to the right when braking. Also renewed left side flexible and pipe from tee piece to cylinders and connection pipe between cylinders.
Sometimes, usually when applying the brakes for the first time after say an overnight stop they work fine. Not everey time though.
Would anyone agree that the problem might now be with the other front cylinders (right side) and it could be worth changing them? I'm thinking they might not be releasing full for some reason. Maybe change the right front flexible at the same time? I'm sure the brake shoes are a complete similar set of four, i.e. same make and material, with no contamination.
Any ideas? Sorry for the long post.

[Peetee]

Could it be that the brake lines are past their best? The line to the left cylinder is longer and if slightly corroded the internal passage will be restricted. Brake fluid may not travel along this line as effectively as to the right wheel.

[Alec]

Hello 57

a pull to the right normally means that the left is not working effectively. (By the way, adjustment makes no difference, there is no hydraulic pressure developed until all cylinders are working, i.e pressing against the drum unless one is very seized, of course.)
The other issue that will cause a pull is a supension problem, either worn bushes or some misalignment, maybe due to some accident a long time ago. However, I don't believe that the MOT brake dynamometer will be affected by that. Presumably the difference is slight for the brakes to pass?
If you cannot see any suspension problems then a carefull check of all components is the way to go. Flexibles are well worth changing as they do deteriorate. Are the drum faces in good condition? etc.

Alec

[57traveller]

Petee - I wondered about the left side pipe because of the almost seized wheel cylinders, i.e. fluid not getting through to them, therefore I renewed it along with the flexible.

Alec - all of the front suspension bushes were renewed a couple of years ago, poly, as were the swivels and trunnions. However as you say the brake testing equipment only indicates the efficiency of each side. Yes, the difference was/is within specified limits.
Yes, drums and linings are fine with very little wear.
I'll definitely change the right side flexible and wheel cylinders anyway after which all the front hydraulic components will be new and "newish."

Thanks both for comments.

[chickenjohn]

Check the front suspension nuts and bolts for tightness- eg a loose tie bar on one side and not the other might affect geometry slightly and the car may pull to one side if the bushes are not equally compressed.

[bmcecosse]

Swop the shoes and/or the drums over - if it now pulls to the left then you can mix and match the shoes - ie put one from each side on the other side. As already said - adjustment has no bearing on this - and neither does suspension problems, although that make make it pull on the road - it has no effect on the rollers. Could just possibly be the tyres (although fairly unlikely) - you could swap them about too. But my money is on the shoes !!

[Willie]

Go for a run and feel the heat at the hub caps after a mile or so. If one side
is considerably hotter than the other then you have the dreaded 'failing to
release' disease! I have had this before and did all the obvious things like
check wheel cylinders, change rubbers, change the flexihoses,change shoe
springs etc but the problem remained.....adjust brakes to just allow free spin
of the wheel, apply brakes, wheel now dragging. The only answer was to fit
NEW wheel cylinders which cured the problem immediately. This would only
apply in your case if the MOT brake test took place whilst your 'dragging'
side was still too hot and thus suffering from brake fade on that side.

[bmcecosse]

Good point Willie ! I have had that too - when I had the poor old 8" drums. In fact - to get a decent balance I had to fit one of the springs on one side in the 'longer' hole position - all the others being in the short position. This balanced it up nicely for MOt - but they were still hopeless brakes. Needless to say (and i know many will have been anxiously waiting for me to say this) the bigger 9" Wolseley brakes have no such problems - and pull up in a dead straight line. The lad at MOT time marvelled at how good the brakes were on the test machine !

[57traveller]

Thanks for replies.
I've just about exhausted all the possibilities mentioned except, as I stated, renewing the right side cylinders and flexible pipe. Yes, I'll check for any differences in hub temperatures Willie, not tried that. I think I'll fit a new set (both sides) of brake shoes at the same time, genuine Unipart. Something else I didn't mention was that the right side front brakes "squeel" when applied fairly hard at very low speed.
It's not exactly the end of the world because each time the car has past MOT without problems except for the within limits imbalance. It's just more frustratinging knowing that somethiong is not quite right and not being able to determine the cause. Moreso after thinking it was the nearly seized left cylinders and changing them would sort it.
Did have similar on the rear but that was oil contamination from leaking rear axle seal and very obvious on removal of drum.

[bmcecosse]

Probably the rhs have been through a high heat cycle (because the left was seized) and so they are now glazed - hence the squeal - or at least the coeff of friction has changed. Still think it will be enough to mix and match the shoes you have - but even after I had tried all that - I still had to fiddle the spring to get it right - and I had tried new shoes too!

[rayofleamington]

yeah - for last years MOT on the traveller I changed the shoes and drum until it was within MOT limits (standing over winter is not good for brakes), but it still pulled!!
After a few days driving, it was fine

This year she's got new shoes, cylinders, springs, flexis, pipes m/c and fluid! she doesn't pull at all, but she doesn't stop too well either
I can't wait until they're bedded in properly!

[bmcecosse]

I really do think the modern non-asbestos brake shoes are just hopeless. Mine glazed over and then started to form crazy-paving effect all over the surface. They are maybe ok on the rear of cars where they do very little actual braking - just parking brake duty.

[rayofleamington]

Mine glazed over and then started to form crazy-paving effect all over the surface.

your 9" ones?

[57traveller]

I'll post the results, maybe a few weeks to work up the enthusiasm, after renewing RH wheel cylinders, RH flexible and L & R shoes. Probably fit new "pull off" springs, L & R, at the same time. I'll go to MOT test station I always use, I'm sure he'll test the front brakes for me - fortunatley a very Minor friendly place. MOT testing only, owned by Arriva bus company so "no axe to grind" with regards repairing cars as well.
A couple of years ago he checked and adjusted my saloon's headlight beams for no charge as long as I removed the chrome bezels beforehand!
If all that doesn't sort the problem then back to the drawing board.

[bmcecosse]

No Ray - you are just winding me up here! They have nice thick old-style linings and will likely see me out!

[Willie]

I should have kept quiet! yesterday my car suddenly started pulling to the
right on braking, and yes, the near-side front was too hot to touch whereas the off-side front was just warm. It was easy to prove that it was the rear most wheel cylinder which would not return to rest position unless considerable pressure was applied by hand and,because this cylinder has the
bleed nipple on it it was easy to eliminate any problems caused by back pressure/faulty flexihose/faulty Master cylinder etc by just opening the bleed
valve. Fluid came out but the piston still would not return meaning that the
fault was actually in the wheel cylinder itself. This wheel cylinder has only
done 6,000 miles from brand new, is a non pattern part and looks to be in
perfect order. The bore looks fine and there is no apparent reason for it to
refuse to retract. The pull off springs are newish and unstretched and are in
the 'Furthest' holes to give more pull off pressure. I have removed it twice
and can find nothing amiss the interesting thing being that I had the same
fault on both fronts before and after methodically changing parts one at a
time I found that fitting NEW wheel cylinders was the only way to cure the
fault. Has anyone else suffered this condition?i.e. is there a problem with
modern wheel cylinders?

[rayofleamington]

after methodically changing parts one at a
time I found that fitting NEW wheel cylinders was the only way to cure the
fault. Has anyone else suffered this condition?i.e. is there a problem with
modern wheel cylinders?

Chris Morley had this about 18 months ago - and got it again on the replacement cylinder too

[Willie]

Thanks RAY, I knew that Chris had this trouble as it happened to him just
after my first experience of the problem, but didn't know that it happened to
him again. Since the only actual friction contact in the cylinders is between
the piston rubber and the bore it would seem obvious to renew the rubber
but I did this before and had no improvement. .....Good! my parts have just been delivered so I can see what happens with a new cylinder.

[Willie]

Re the 'brake not freeing off', a new wheel cylinder cured the problem imm-
ediately,as it did 6000miles ago. During this exercise I made a (to me)
surprising discovery. THE BRAKE ADJUSTERS ARE DIFFERENT ON THE 7" and
8" BRAKES. Like many others I uprated to 8" front brakes on my 1957 car
but it never crossed my mind to change the adjusters and I now find that the
difference is considerable. The adjusting screw spindle on the 8" type is a
much larger diameter than the earlier type which means that it contacts the
brake shoe IMMEDIATELY on the first click from rest. The 7" type had lots
of free play before it even contacted the shoe which then gave 9 clicks of
adjustment. The 8" type gives 14 clicks of adjustment on the same shoes!
The adjustment slot now lines up correctly with the hole in the brake drum too
where before it was well off centre so, if you run out of adjustment before the
shoes are actually worn out check which type of adjusters you have. The 8"
type are 10mm diameter at the screwdriver slot---the 7"type are only 7.5mm.

[57traveller]

Sorted
Don't know 100% what the problem was but I'm fairly certain it was the right side wheel cylinders. When the imbalance was first apparent, and as stated in my first post, I found the left cylinders just about seized and thought that was the problem solved. I should have checked the right side as well they were in the same condition. Possibly not releasing properly but o'k. momentartily after an overnight stop. Now renewed along with new shoes, flexibles and pull off springs.
Now all I need to do is bed the new shoes in, the brakes are really "springy" and considerable notice is required to stop.
I'll still go along to my MOT man for a check when they've run in a bit.