Brake drum removal bolt size 5/16 NC or 3/8 NC

So here is the problem, A late 1984 series 3 SWB, I can remove the rear brake drums by about 1 cm and then they catch solidly although spring back slightly, they both spin although one was binding badly and the MOT had them down to 10% efficiency. I suspect the problem is they have worn a grove and are now catching. Is there a way to get around this and to remove the drum? Can I put a lever in to try and force the pads back over the lip.
But lastly and most importantly can any please tell me DEFINITAVLEY what the size the bolt is that goes in to assist removal. I now have 2 opinions/ opinions ; 5/16 NC and 3/8 NC both of with are difficult to find and to purchase individually and not bulk. Any help or words of wisdom gratefully received.

I thought they were the same thread as the drum screws

You can backoff the shoes using the adjuster bolt head, accessible behind the backplate. They turn a snail cam, which adjusts the resting position of the shoes.

Regarding the drum assistance removal bolt - sorry, I don't know, although I recall it was the same screw that's used to hold the drum in place, so if you actually have one of those available (they are often not fitted), you could try that....or at least measure it.

Adam

Probable on the shoe without a spring [ trailing ] the slave piston is partially seized and is not returning. I have a bolt with a handle welded to it for this job but can not remember the size/type I am afraid. Do not think it is the same as drum retainer screw.

Bolt is 3/8" Whitworth.

I tried the 3/8 Whitworth bolt but the tread was to fine hence the confusion.

Disconnect the pipe to the slave cylinder (you'll be replacing it anyway...) and see if you can get a screwdriver in the 1cm gap and knock the shoes back a bit.

Thanks, that's good advice I forgot that the pipe would need to be disconnected. I will try and get in there and push bake the pads. I have ordered new drums as they are going to past it so nothing to lose now. One thing sealing of the old pipe what is a good method. I had problems with the front when doing this and no mater how much I squeezed and bent it a small leak was present.

bultacobob said:

Thanks, that's good advice I forgot that the pipe would need to be disconnected. I will try and get in there and push bake the pads. I have ordered new drums as they are going to past it so nothing to lose now. One thing sealing of the old pipe what is a good method. I had problems with the front when doing this and no mater how much I squeezed and bent it a small leak was present.

Click to expand...

You can get plastic brake pipe clamps. They look like pliers and you clamp the flexible pipe nearest to the pipe you are disconnecting, which reduces the amount that leaks.
I would factor in two new brake cylinders as well as thyey often seize, which would also explain why the drums don't want to come off.

I have used a small pair of molegrips with a piece of leather in the jaws to protect the flexible pipe for this purpose. As said by others back off the adjusters and then use hide hammer for the drum problem.

Thanks, I was so focused on the brake pipes I forgot about the flexi on which is an obvious one to clamp. I am going to replace everything and start again right the way back to the PDWA .

Throw the PDWA valve away as well as the resevoir has two compartments on the master cylinder.

Years ago I remember fitting new drums to my 109 and the new drums did not have the same thread in those bolt holes as the old did.
I drilled them out to the next size up to metric fine and retapped.
First thing I did on the 110 was fit a disc brake Salisbury, I dislike drums.