Paxmanmerv

Paxmanmerv

Active Member
Never come across this before, but theres a first time for everything!
1974 SER3 swb with some odd brake problems. Hopoefully someone has come across this before & can advise me.
Brakes were pretty much shot so replaced the lot. Cylinders, drums, shoes & return springs. Bled them all through, pressure bleed, vac bleed & traditional pedal bleed but pedal still pumps up, good on second pump. Adjusted them all up, lock & back 3 notches, still pumps up & good on second pump. Pedal goes down about 2 1/2" on press 1 & 2" on press 2. Also, as these are lead & trail shoes front & rear, there is a return spring on the front shoe but no return spring on the rear shoe which tries to lock the wheels when rotated in a reverse direction. Put a lead slope on the rear shoes but made no difference. There is a spring in each wheel cylinder that pushes the pistons out. Should this be removed?.
Any ideas? Really got me stumped.
 
The spring is supposed to be there in the wheel cylinders.
Maybe you're slacking off too far. Do the snail cam all the way up to lock the wheel, then slack out off a notch at a time until you can hear the brakes 'just catching' as you spin the wheel
There is a spring at the top for the leading shoe and one at the bottom for the trailing shoe
 
Sounds like the springs are in the correct places so thats a good starting point. At 3 notches each of the brakes are still binding slightly. Is it simply the nature of the beast? With it parked on a flat hard surface it can be pushed forwards, but doesnt want to be pushed backwards as the trailing shoe becomes the leading shoe & bites into the surface of the drum. Would anything be gained by fitting a light spring to top of the trailing shoe or drill a hole higher than the existing hole for the spring at the bottom of the shoe? :vb-confused2:
 
The lower spring should pull the trailing shoe into the cylinder enough to hold it in place. Maybe it's stretched/lost its spring?

The pedal shouldn't 'pump up'. Maybe it's related to the weak lower spring?
 
On our S2 I put a chamfer on the shoes to stop the brakes binding in reverse. I found the best way to drive ours was to press the brake pedal once and on the second press they would be perfect. This was after quite a bit of faffing around.
Also found after market snail adjusters worse than useless if that is what you have.
I was using Britpart drums and Delphi shoes.
 
all of the above advice, plus when bleeding the brakes push the shoes in so the brake cylinder pistons are pushed in, refit drums then bleed brakes. Mine was same as yours with less travel second pump of brakes before I did that.
 
If doing the above use plastic tie to keep them in. Personally I do not see how this helps.
 
Last edited:
Have you got the springs attached as shown
manual recommneds using 3 clamps on the flexis to isolate both fronts and the rear when bleeding
with all clamps on the pedal should be hard
then try removing one of the front clamps and check again

with new shoes I would also check how they mate with the drum just sliding them around or check with feelers
and when fitted if not braking as good as what it should be then some chalk lines across shoe every inch show where itโ€™s contacting drum when you drive and brake

as said back off the adjusters bleed till no air , then adjust as below , tap drum with rubber mallet to help centralise below says back off 2 clicks rather than 3 but easy enough to spin wheel and see when it drags .

with one side done with good pedal then do other side and then rear flexi

have you fitted the anchor plate correct way round
have you used the corrrect cam on the adjusters

can also test shoe square to hub with a small square , this can be adjusted by the screw post on backplate
IMG_3220.png
 
steve2286w said:
Have you got the springs attached as shown
manual recommneds using 3 clamps on the flexis to isolate both fronts and the rear when bleeding
with all clamps on the pedal should be hard
then try removing one of the front clamps and check again

with new shoes I would also check how they mate with the drum just sliding them around or check with feelers
and when fitted if not braking as good as what it should be then some chalk lines across shoe every inch show where itโ€™s contacting drum when you drive and brake

as said back off the adjusters bleed till no air , then adjust as below , tap drum with rubber mallet to help centralise below says back off 2 clicks rather than 3 but easy enough to spin wheel and see when it drags .

with one side done with good pedal then do other side and then rear flexi

have you fitted the anchor plate correct way round
have you used the corrrect cam on the adjusters

can also test shoe square to hub with a small square , this can be adjusted by the screw post on backplate
View attachment 309890
Click to expand...
Thats great! Thanks for that. All looks as it should. Will get measuring & re-bleed then see what happens.
 
I had this, found it was one of the springs on the rear which was pulling the cylinder back in. Check springs :)

Mine was 3 & 8 on the pic above. rather than go to the stud on the back plate the spring went shoe to shoe

HTH
 
Sooo.... Kept digging & found the problem. The new shoes are 6mm wider than the old ones so the unmachined part of the Drum catches on the shoe & pulls it on as soon as it goes backwards. Front shoe not a problem because as you know theres a substantial spring holding in in place.. Not expecting that with all new parts but there we are!
 
Paxmanmerv said:
Sooo.... Kept digging & found the problem. The new shoes are 6mm wider than the old ones so the unmachined part of the Drum catches on the shoe & pulls it on as soon as it goes backwards. Front shoe not a problem because as you know theres a substantial spring holding in in place.. Not expecting that with all new parts but there we are!
Click to expand...
Are they the wrong ones or just badly made?
 
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