John Nolan 

I'm trying to assemble this Raleigh branded Suntour GT, but I'm missing some understanding, and, maybe, some part. I picked it up at my co-op a couple of years ago, and it may not have all the original fittings. The claw didn't come with it.

I don't understand how to tighten it onto the claw and still allow it to pivot. I've never assembled a derailleur with a claw and a jam nut. I'm not clear what the jam nut is for, since integrated hangers don't seem to need one.

I've included a picture of the fittings placed in the order I've tried for assembly:
pivot bolt, then 2 thin washers, then derailleur body, then thin washer, thicker washer, then pivot bolt threaded into claw, then jam nut. It also had the tabbed washer you see above the thicker washer, but I don't understand what that's for, or where it goes. If I include it there's not that much thread left for the jam nut.

When I pulled this out of my parts bin, I thought this would be a no brainer, but I forgot who I was dealing with.

oneclick 

That tabbed washer is a wheel-axle-retaining gizmo, usually seen on front wheels; the dropout has a little rectangular hole above the axle slot, into which the tab fits, the washer section is placed on the axle inside the nut. If your wheel is loose it (is supposed to) stay(s) in.

I discard them, my nuts are tight.

(It's not part of your derailleur, it came from somewhere else.)

John Nolan 

I know I'd seen them somewhere!

So, one mystery solved.

oneclick 

The integrated dropouts almost always have a slight boss where the derailleur mounts, the derailleur manufacturers (should) arrange matters so that the upper knuckle's inner face is outside the outer edge of this boss. That means the upper pivot bolt can be screwed down TIGHT and the knuckle will still pivot; no jam nut needed. Claws rarely have such a boss, so the necessary clearance for the pivot is done with a locknut on the pivot bolt - you get it just loose enough to swing, and jam it there.

(Some rear mechs have a shouldered pivot bolt and shims to get the same result.)

John Nolan 

Thanks for that...that's what I imagined, but I can't seem to figure out how to keep the adjustment when I tighten down the jam nut.

I installed the derailleur and claw on the frame, adjusted the pivot bolt, and tried to hold the pivot bolt in place with a hex wrench while tightening the jam nut, but things still ended up too tight.

philbob57

I thought the slant-parallelogram ders didn't need to pivot.

John Nolan 

Oh, that would make things easier!

Big Block

the exploded drawing

John Nolan 

Yes, I have looked at the diagram at Disraeli Gears (BTW your link doesn't work for me, i don't know why.) I didn't have exactly the same arrangement of washers, and I couldn't figure out from that picture how to adjust things.

oneclick 

Well, you need to have it a bit looser before tightening the locknut.

Locknuts work because there is clearance - physical space - between the threads of a bolt and the threads of a nut. A nut by itself (usually) has enough clearance that it is loose; it will turn, and it will also move forwards and backwards along the bolt WITHOUT turning, taking up first the clearance on one side of the thread valleys, then on the other. Locknuts work by forcing the main nut against one side of the valleys, while the locknut gets forced against the other side of the valleys. You get them tight and they stay wherever they wind up being wedged against each other..

Adjusting a pair of locknuts to a particular position along a threaded shaft is a bit of an art. You must start with the main nut a little too loose, so when the jam nut forces it a little further along the shaft it winds up in the correct location. One out of maybe twenty or thirty times I'll be lucky and get it just right the first time - but normally it is lock and check and unlock and tweak and lock and check again until is *is* just right.

John Nolan 

Thanks, oneclick. Sounds good—Trial and error, that's right up my alley (especially the error!) Just nice to know the procedure isn't in error.

Big Block

link issue is that SunTour Small Parts Catalog - 1983? scan 2
is being refused as it is not an https but in http form.

John Nolan 

Thanks for clearing that up Big Block.
That page one doesn't exactly match my mech—there doesn't seem to be a recess for the pivot bolt, and I'm pretty sure the very thin washers on mine are original, but they don't appear in that diagram.
Still, it does give the general idea.

oneclick 

The very thin washers are the shims I mentioned. You use just enough of them to get the clearance desired. Again, the sequence is iterative: try a set of shims - tighten - check - if not correct loose and change shims and try again.

PatTheSlat 

These only pivot to make it easier to get the wheel out, so if you can't get it on there where it pivots freely it won't affect operation at all.

John Nolan 

I finally got it adjusted—shuffled around the shims, and worked a bit more carefully. Thanks PatTheSlat: good to know the adjustment isn't too critical.