B40 1962 - Rear Wheel - fitting new brake shoes

[stevehayward]

Eventually getting back to my B40 after 5 years of various distractions.  The bike has been stripped and is being put back together.  Front end is on and ready for the wheel and the back end is also ready for the wheel - however I came across a problem.

The rear wheel has a new sprocked/brake but I cannot seem to get the rear brake shoe/plate into the hub/sprocket or when i do it pretty solid.

Whilst going through my spares, I found the extra new sprocket/hub that I had purchased (as a spare - like I am lible to need it - not, too many memories of wrecking chains and sprockets on my moped!) and the brake shows fitted easily with this whilst on my bench. So I took the one on the wheel off and put the spare on and thought I was away. Not the case same problem.

Any ideas?

I can provide pics - I am thinking I've done something simple or is that someone simple has done something wrong.

So wanting to get back into this and get it on the road - was supposed to have both wheels back in the bike and handle bars on by 6th Jan (Back to work).  Been looking at other projects as getting my mojo back but not getting distracted by new before this is done and ridden.

Thanks in advance

[neil1964]

Is it the diameter of the assembled backplate stopping it fitting?  Are your brake shoes new/oversize for a new hub?
Do you have calipers to measure both hub internal diameters accurately.
If it is not that I have come across warped brake plates that partly apply the brake (ie cam does not sit squarely and parallel to end of the shoes?
Could also be that the leading edge of the shoes need chamfering.
So couple of things to check.

[rhyatt]

Just to clarify please.
Can you sit the assembled brake plate cw shoes etc into the hub when the wheel is off the bike ?

If so

You then offer the assembled wheel into the bike and it locks up when you tighten the spindle nuts.

Or can't you get that far ?

[DAVE BRADY]

Hi,

It sounds like there is a problem with the brake drums that manifests itself when bolted to the hub.
Assuming that both drums are new and purchased at then same time the fault could be common to a batch.
With the drum off the wheel use a straight edge to check that there is no slight dishing across the. If so, when tightened, it could be that as it is 'flattened' under pressure it is distorting the drum. Also, are there any other imperfections that could prevent the drum from sitting perfectly flat.
If you have managed to rotate the brake when tight in the fitted drum there may be marks on the brake shoe surface and the drum to give further clues.

Dave. 

[stevehayward]

Just to clarify please.
Can you sit the assembled brake plate cw shoes etc into the hub when the wheel is off the bike ?

Yes

If so

You then offer the assembled wheel into the bike and it locks up when you tighten the spindle nuts.

Or can't you get that far ?   Do not get this far

I cannot get the assembled brake plate into the brake drum.

[stevehayward]

Hi,

It sounds like there is a problem with the brake drums that manifests itself when bolted to the hub.
Assuming that both drums are new and purchased at then same time the fault could be common to a batch.
With the drum off the wheel use a straight edge to check that there is no slight dishing across the. If so, when tightened, it could be that as it is 'flattened' under pressure it is distorting the drum. Also, are there any other imperfections that could prevent the drum from sitting perfectly flat.
If you have managed to rotate the brake when tight in the fitted drum there may be marks on the brake shoe surface and the drum to give further clues.

Dave. 

Dave

Was my thinking but both were purchased as new at different times and I thought problem in chair as both items the same or I have assembled the plates/showes wrong.  I am going to have a dig through the old parts and see if I have the old shoes.  I replaced them as I went.

New items - brake drum, shoes & I think springs from memory
Old item - brake plate

I will have a look at the brake drum that is off the wheel and takes some measurements and do the same with the one on the wheel.

I did not notice any issues when tightening up the bolts when putting brake drum in place.

[stevehayward]

BTW thanks for the prompt replies much appreciated. 

[DAVE BRADY]

Hi,

I have found that with some pattern brake shoes the radius that sits on the pivot is too small thus preventing the shoes from sitting fully home.  Even a small amount of material can make big difference. Thre shoe should fully engage with the pivot.

Dave.

[rhyatt]

of course , the thickness of the new shoes may be excessive - many new parts come from abroad manufacturers who do not comply accurately with the original dimensions
try to find the original shoes and see if they go in fine

[DAVE BRADY]

Hi,

The conundrum is why they fit when the drum is not fitted to the hub but not when it is? So it seems that the linings are not necessarily too thick.
The wheel spindle will centralise the brake plate so it looks like it is down to the shoes.
As Rhyatt said, try and find the old shoes for comparison of the accuracy of the shoes and particularly the pivot radius.
What make are the shoes?

Dave.

[Rupert]

Did you slacken the nut on the brake plate on the brake shou fulcrum?
The fulcrum pin has a generous clearance in the brake plate to allow the shoes to centralise in the drum.
Proceedure - hold the fulcrum pin in a vice, slacken the nut, fit the shoes, fit the assembly to the brake drum with spindle in place (jiggling usually needed), apply the brake and hold it on while tightening the fulcrum pin nut.

[stevehayward]

Hi,

The conundrum is why they fit when the drum is not fitted to the hub but not when it is? So it seems that the linings are not necessarily too thick.
The wheel spindle will centralise the brake plate so it looks like it is down to the shoes.
As Rhyatt said, try and find the old shoes for comparison of the accuracy of the shoes and particularly the pivot radius.
What make are the shoes?

Dave.

Shoes are:  40-5525 FERODO FSB-918   (Sold to me as Ferodo - however........and was in 2018)

I have found originals but have been tending to family - New years Day - however off the rest of this week.

[stevehayward]

Did you slacken the nut on the brake plate on the brake shou fulcrum?
The fulcrum pin has a generous clearance in the brake plate to allow the shoes to centralise in the drum.
Proceedure - hold the fulcrum pin in a vice, slacken the nut, fit the shoes, fit the assembly to the brake drum with spindle in place (jiggling usually needed), apply the brake and hold it on while tightening the fulcrum pin nut.

I will be double checking tomorrow as decided to take shoes off and check against originals and then go through above procedure

I just reread this and as I have the back plate in hand with shows and and all bolts attached - I will be trying this first

I cannot remember back to when I fitted them together - life and a house fire stopped me when previously working on bike. So best restart

Thanks

[stevehayward]

Thanks Gents for the responses and the preverbial shove - curiosity got the better of me so sneaked to the garage and fitted the old shoes to the back plate and they dropped in 1st time. No cuts or bruises either.

So the new shoes are bin bound and I think for the moment the old ones will be installed so I can put the wheels back in the frame, handlebars etc etc.  Will contact Draganfly or Kidderminster for a new pair but not needed to do the reassembly.

I did a quick comparision with the old ones and there appeared to be a little difference. The actual brake pad material is shorter than my originals and when I offered them up there was a slight difference in shape.
I will have a better look tomorrow and take some pictures.

It appears I had taken a file to the flat side ficve years ago to reduce the diameter when inserted on the back plate.
   

[rhyatt]

Don't bin them.
I use a pad sander to dress my oversize shoes , so they go in.
You can chamfer the ends easily also.
Chamfer and try , chamfer and try until it drop in and then centralise the back plate as described already.