Rear Brakes Binding

[Pete Lewis]

Yes Doug that illustration is very wrong 

with the square hole at the top of the rear shoe the lining position on the shoe looses its" leading" profile 

and a leading shoe ha a s self  servo effect to help braking by adding contact force to the drum  

a trailing shoe wants to lift away from the drum 

fit the shoe upside down and you will fail the MOT efficiency %

Pete

[johny]

1 hour ago, Pete Lewis said:

if you have to use a bolt it needs a shank to contact the wear points and always fit a bolt so if the nyloc/nut lets go the bolt wont drop out 

but agree clevis and R clip or split pin is the std  fit 

having said that it a lot easier to remove a nut than a rusty siezed spit pin 

Pete

Rust!!! This car wont see any rust ever again🤣

As for skimming drums I think thats a lost art because I struggled to find anyone prepared to take it on. Needs a suitable mandrel and not available nowadays. Pity as I think an old skimmed drum has much more chance of staying round than a new pattern part....

[dougbgt6]

Yes Pete you are correct, but my brake shoes always look like this.                                                                                                 

 And not this

Doug

[Pettifordo]

1 hour ago, dougbgt6 said:

And not this

Do you think I have the wrong type of brake shoe ?

I still a bit confused about the leading / following part as my brake shoes seem to be identical

[johny]

It looks like the issue of pattern parts quality has raised its ugly head again! What effect the difference will have is unknown but the leading edge of the front shoe worries me as it looks more vulnerable to catching on the drum with the risk of being pulled away. Chamfering it certainly appears to be a good idea.... 

[Pete Lewis]

the lining should /must be fitted to align with the end of the shoes leading edge 

so the expanding effort makes the lining grab the drum , if its late it just rubs it and does not gain any rotation load to aid the contact

its called self servoing   

those bonded look awfull    there is no leading trailing  action 

Dougs top picture is spot on 

[dougbgt6]

4 hours ago, Pettifordo said:

Do you think I have the wrong type of brake shoe ?

I do, but I'm not sure it causes binding? Certainty what Pete said, but what do the gurus think? 

Doug

[Pettifordo]

1 hour ago, dougbgt6 said:

I do

I purchased the shoes from Rimmer Bros about 6 months ago……so I can rule it out I will buy new ones and also replace the springs and then I can check the movement of the slave cylinders - I will update you on progress next week

[AlanT]

Had same issue on my rebuild @Pettifordo 

File down the end edges of the friction material. It solve the issue. Handbrake may need to be a bit less tight than you’d eventually like until worn in.

[AlanT]

By the way @Pettifordoit’s well worth getting Mintex front pads whilst sorting your brakes. A recent discovery for me (courtesy of our experts) and transformational vs standard. 

[chrishawley]

This could be rather repeating what has been said above....but here goes...

The orientation of the shoes is an interesting matter. Reffering to the WSM and Haynes they in accordance as to which way up the shoes should go. But it's sort of impossible to fit the front shoe incorrectly because the cut out from the lever for the handbrake has to be at the top. Note that the drawing in the WSM, although unlabelled, refers to the left hand unit.

Then there's the matter of 'unisex' shoes - those where the friction lining is cut away equally at both ends. Had some from Fitchetts and questioned them about it. They said 'it's fine'. So I fitted them and they were indeed fine.

If the brakes are rubbing periodically on each rotation and always in the same position(s) that does rather point to the drum being slighty out of round. But if only one side is problematic then a diagnostic test might be to swap the drums over: If the rub transfers with the drum (once adjusted up) then that would be even more suggestive.

 

 

 

 

[Pettifordo]

So I think I have the rear brakes working now - set them as 1 full turn back from where they stop the brakes and making sure the leading edge was shaved…….

so that’s great but now the front Nearside brake is really tight 😩😩😩😩 I can turn it with the wheel on but it is stiff and with the wheel off I can’t turn the hub - it’s like the breaks aren’t letting off…..the calliper is a new one from RimmerBros 😤😤😤 new disks as well and new wheel bearing - soooo frustrating 

[Pettifordo]

Brakes working now - think it might have been the slave cylinder not moving freely……

But then the front ones were sticking and this was caused my my “fix” to get the brake lights to go off meaning the brake pedal didn’t travel back fair enough to let brake fluid back into the master cylinder.

Car was rolling and stopping nicely !!

Phew

[Pettifordo]

But I have ordered new shoes and new springs anyway as I don’t want problems later on 👍

[PeteH]

On 28/10/2022 at 12:03, johny said:

Rust!!! This car wont see any rust ever again🤣

As for skimming drums I think thats a lost art because I struggled to find anyone prepared to take it on. Needs a suitable mandrel and not available nowadays. Pity as I think an old skimmed drum has much more chance of staying round than a new pattern part....

That IMHO, is largely because your average workshop no longer has tradesman Turners. A company I am familiar with, the owner served his apprenticeship with me, has had a request out for over 6 months for a Turner, No takers, the guy who retired creating the vacancy, still goes back to do the odd job that no one else can cope with, he`s now into his 70`s.

Pete

[johny]

Yes then that in turn pushes up the cost so it cant compete with new drums from a low cost labour country...

[johny]

Not very green either is it☹️

[Pete Lewis]

i got some replacement drums for the 2000  machined like an old thrupenny bit  obviously held in a lathe chuck with created some serious lobe effect  complete rubish

and they were from a place that normally knows better  had them in stock too long to return them so they went up the tip 

i would just burnish the braking surface and realy clean both mating faces and the hub may be the cause of any runout 

they do get bent with age and years of furious removal methods , si i would check the hub face runout 

Pete

[johny]

I believe cast iron also has a habit of distorting after casting so should be left a while before machining (please note this aftermarket manufacturers!).

The problem for refacing the braking surface is how to hold the drum to ensure its centred on the axle axis rather than the outside and I would have thought an old modified half shaft could be used. With a short section of half shaft held in the chuck the drum could then be reverse bolted to the hub and machined....

[Pete Lewis]

yes in manufacturing we stored cast drums outside for months to age them 

and these were 20" dia and brake surface 8" wide    used to be made by Qualcast  back in the days when we had an industry .

not long back we were given synchro baulk rings machined in a chuck to make three lobed useless parts supply 

its the loss of skills and basic understanding that we suffer at the wallet these days 

Pete

 

[Stratton Jimmer]

On 01/11/2022 at 09:57, Pete Lewis said:

we stored cast drums outside for months to age them 

In steam locomotive preservation, the cast iron brake blocks are similarly left outside to weather for several months before use. I recently delivered a new set to the GWS at Didcot and added them to their "weathering pile".