Wheel rub ponderings - thoughts appreciated

[davecymru]

I'd appreciate hearing your thoughts and ponderings on something that I'm encountering on the Countach.
I've not focused on it yet as I've had other things to sort out first, but it's playing at the back of my mind so i thought i'd mention it while i sort out other bits.

I have (what i believe are) Granada rear drums on the back of the car and the rear drivers side makes a rubbing noise occasionally.
I did a quick look into it a while back and from what i can see so far it's the inner edge of brake drum rubbing on the brake backing plate, if that makes sense? 
(i'll try and get a photo up to soon so that it makes more sense!)

From what i can figure, it's got to be moving/flexing under load and/or going over bumps and what I'm wondering though if it's something simple such as  the bearing having some play in it? Or if it's something more serious?

I suspect that what ever is wring, it's mainly caused by the stupidly large wheels on the back!  But i thought i'd put this out-there in case anyone else has experienced anything similar over the years which perhaps could save me some time when i do get around to this?

Dave

['The Gaffer']

Have you tried jacking up the rear wheel and seeing if there is any play or knocking when jiggling the wheel around? That might highlight bearing or shaft wear.

[bluehornetrider]

With wheels as wide as yours it puts a lot of stress on the rear wheel bearings, especially if they were never designed for the sort of cornering forces your putting them through.  Might be time to upgrade to a beefier set up.

[davecymru]

Thanks for the ideas guys.

I had a quick run-out the other day to make sure it's still an issue (it is) and then I jacked it up.
There is no play that i can feel, but when i took the brake drum off i could see where it was rubbing, i just don't know for how long that's been a problem
So i've smoothed that down, painted it black and i'll do another run and then re-inspect.

Here's a pic of after i smoothed it down so you can see what i'm talking about.



I'm starting to wonder if the alignment is right? Given the size of the rear wheels, that may be contributing?
For those who think their cars are a bit of a bu**er to work on, here's what i have to deal with!

[paintman]

I know this might sound a bit crude but why not bend the backing plate so they don't foul the brake drum.....5 minutes work and a lump hammer!!!

Or put 4 washers on the studs to hold the drum off the back plate (not so drastic maybe).

    Tony

[davecymru]

I know where you're coming from and i have ground a mm or two off of the backing plate before i painted it to see if that 'cures' it.

But I'm very conscious that it's addressing a symptom rather than the cause?

[Camber Dave]

Try moving the spring to the inside of the shoes. B***h to fit but pulls shoes in to the back plate.
Could be the photo but the anchor plate (below rivets) looks bent out. It should be flat to hold the shoes in.

[davecymru]

Cheers for that, i'll give it a go.

[YellaBelly]

I'm with Dave on the springs, the way they are fitted in the piccy will tend to pull them out toward the drum. I've never seen any in front of the shoes, always behind (well on the jallopies I've worked on anyhow )

[benchmark51]

The position of the backplate is 90 degrees out. The shoes should be vertical on the backplate and not horizontal. At least they are on escort, cortina, and sierra. I haven't got a granada manual so could be wrong. Also the return springs are on the outside of the shoes according to my manuals. I would check this and check the drums for warp.

[YellaBelly]

Good point about the drums, I was too busy looking for other issues! Benchmark51 is right, normally the slave cylinder will be at the top or thereabouts.

[Bulldog Bri]

Just another thought, are these the correct pads for the drum could be just they are a fraction to wide. Is there a difference in the pads of the Mk's of the Granada, Could even grind down the outside edge of the pad a shade.

[Hairy Santa]

I wouldn't be surprized if at some stage the drum had been stuck on to the hub assy and someone has been at it with a large hammer and at the same time welted the backplate a few times instead of the brake drum

this is a norm for this type of single leading shoe brake  - you do have to let the handbrake cable right off, lots of people get caught on this one

normally the backplate is 90% rotated to how the picture is on most veh's but this wont make any difference to the operation of the shoe's or brake efficiency, but if there is the slightest of play in the bearing then due to the shoe's being top and bottom they possibly could rub

because the shoe's are being pulled in to the backplate by springs then it wont make any difference if the pull back springs are on the inside or outside as long as they have clearance on the hub and not rubbing

use a drift and hammer to knock the backplate back if you think it is out of alignment or make a shim or two (like a wheel spacer) to go between the hub and the brakedrum, (that's what old beer cans are handy for) this should sort the problem

mostly the same as what every one else has said, so I'll got back up the garage now     

[davecymru]

Brilliant thanks guys! 

If i hadn't promised to babysit (apologies, I've been reliably informed that it's not babysitting if they're your own kids!) look after  my boys and take them for a hillwalk I'd give the shim approach a go as a good start.

I hadn't noticed the 90 degree 'thing', but that is something that i will certainly look into the next time i have everything apart as it should be quick to address.  Assuming the original builder hasn't done anything "interesting" fitting them!