It should even out when pads were in

perfect, just waiting on that adjuster to arrive and then few more things before i can get her registered :)

Gl with it! Those parts came to :) ta

You'll probably find that it sticks if there's any corrosion on the drums - which can happen if they have been sitting for a while - with part of them more exposed to the air than the sections the old shoes were rubbing on (or close to rubbing on). Additionally, brake pads and shoes actually deposit some material on the disc/drum surface (part of the bed in process and they stop better as a result). What can happen is if someone has done a very hard stop and heated them up a lot, then sat at the lights, with the brakes on hard (for example) well there'll be a hell of a lot more deposited in that section because of it, and so they grip, slip grip etc when free-spinning. On discs it's also responsible for a lot of the symptoms that most people think must be warped discs, and they go and drop money on disc machining which isn't worth it almost _ever_ .

http://www.stoptech.com/technical-sup ... rake-disc-and-other-myths

is a really good article from a guy who literally wrote the book on race car engineering (several books in fact)

I can't remember if he covers it in the article, but if not, the 'reason' brake machining on a lathe only works 'emotionally' (by which i mean people feel better about it, thinking it is safer etc) is actually quite simple. brake discs, whilst very well made (for the most part) still have some minor differences in composition on any one spot of each disc. Add to that natural variation, overheating causing them to be harder and softer in various spots - well if you attack that with a brake lathe, with a cutting tip, well it will cut the softer stuff away a lot better than the harder, so although it looks and mostly measures up as even, in fact at a more microscopic level it is never truly flat.

To do _that_ right one would still use a brake lathe of some sort, but grind the surfaces with stones, not cutting tips. grinding or machining discs also makes them thinner and so it will be sooner that you get to minimum thickness, and have to replace the discs more often.

Believe it or not, if you have used discs, that are actually in usable condition, and bed new pads in properly, they'll work just as well well some ridges/grooves on them as they will without.

Since discs for most cars are still easy enough to source it's not as big a concern, but if other older car brands are anything to go by, sourcing drums will get more and more difficult. So I'd _really_ urge anyone to avoid getting drums machined unless they were so badly corroded that they wouldn't bed properly and continued to grab in one section..

Having said all that, a lot of brake places will tend to do one of two things - either put more pad material onto the brake shoes they re-line (to account for the strong likelihood that most people's drums by now are a mm or two bigger inner diameter than they were new. The other thing they can do is to alter the backing plate. The easiest way to do that is simply weld up the edge that ridss in the slot on the wheel cylinder (or something along those lines depending on brake wheel cylinder design).
So it is not at all uncommon to find things are a tight fit with new shoes.

Another little tid-bit - although I've cautioned against machining brake drums, there is _one_ thing I do think is worthwhile. On a lot of drums, you find that they wear where the shoes are, but of course that inside edge doesn't wear, so there is a big lip. It's a tight fit over the shoes till that lip is all the way past, then they are loose. You can adjust them up but then they are impossible to get off. So what i might suggest here is that you get the lip itself machined down. Make sure to only remove material from the lip, not all the way across 'just to smooth it up' or you lose more drum thickness. You don't even have to go to a brake and clutch place to do it, you can - using some washers as spacers, put the drum on the axle and tighten it firm (but not ridiculous) and with the rear of the car in the air, and safely on stands, and with the front wheels chocked etc, start the car up and have it in first, and let it idle along, the drum spinning (at an ok speed, but nothing ridiculous, idle in 1st or 2nd gear is enough) and then use a drill or die grinder, and a tungsten carbide tip and gently remove the lip. Once you get near to fully removing the lip, swap in a drill bit with a grinding stone on it (or use a dremel or whatever) and do the last little bit with the stone. WIth the drum spinning, it'll ensure a smooth even removal, no high and low spots. Make sure you come outwards as flat as possible, with just a very slight taper right on the outside of the drum surface. That's not totally a safety issue per se - but i do recall once when getting a roadworthy, and I have rediused the outside with a bigger taper - and they initially failed teh drums, thinking they were as thin as that tapered edge. But once they were actually measured they were ok.

If that sounds like I'm speaking in an alien language (and that's quite possible - because sometimes the printed word falls short of communicating the full message, whereas a diagram, even a dodgy one done with mspaint - can make it clear in a couple of seconds) let me know and I'll knock up a couple of diagrams

thanks for the input jmac!

im just a little unclear of the lip getting machined down, this is the lip that rests over the backing plate?

no - on the drums themselves,. There's the area where the shoes rub on, then there's a small area where the edge of the drum surface doesn't contact the shoes, and it doesn't wear down, leaving a lip or ridge.

http://datsun1200.com/uploads/photos/24173.jpg




Here's a rough diagram to help show it. I basically grabbed the first image I found on google and edited to suit. By pure chance the link happened to be to nissan brake drums (though I think perhaps not for a 1200!, but don't know for sure)

http://bonamotor.en.gasgoo.com/auto-products/1013954.html

I'll add another closeup of the original photo (a small section of it) because it shows on the 'new' drums there's actually a slight taper right on that edge to help the drum slip on easier. you could copy this, but i'd re-iterate that going too far will leave that edge thinner than ideal, esp if a roadworthy tester thinks it is how thin the rest of the drum is. So rather than copy that taper right at the edge of that new drum, put a slight taper or radius, a little less severe as that one.

http://datsun1200.com/uploads/photos/24174.jpg

Your ms paint skills are exceptional jmac. Puts some photoshop people to shame

That's cos Jmac is old skool dos man! No offerce Jmac I am to

thanks jmac all clear now!