Bicycle Mechanics - adjusting old shimano 600 derailleur

hey all,

i recently began switching the shimano 600 group from my salvaged but unusable kabuki submariner to a pretty nice shogun frameset.

everything has been going smoothly until i attempted to rotate the cranks backwards (the drivetrain is completely installed), it seems lke there isnt enough spring tension left in the derailleur because the chain sags and slides along on the front d. cage (remember this is rotating the cranks backwards). when i hold the rear der. tight with my finger this solves the problem. is there anyway in increase the spring tension? (aside from getting a new spring)

another problem-- when i shift into the largest of the rear cluster the derailluer pulley is pushing the chain up against the cog, so its not very smooth or quiet. i figure this problem could be adjusted using the b-line screw, but there isnt one! it seems like removing a link from the chain might alleviate both problems, but then when im in the big ring i might be limited to fewer gears if the chain is too short....

come on rev. chuck, i know you have the answers i need!!!

... adjusted using the b-line screw, but there isnt one! ...

Missing screw or no B adjustment at all? What ring and cog are you on when the chain sags and touches the FD? Are you sure the chain isn't too long?
I measure my chains using Sheldon's method. http://www.sheldonbrown.com/derailer-adjustment.html

Measure the distance between the BB center and the dropout on each frame. If it's (significantly) shorter on the new frame, then BR is right, and the chain is too long; you'll have to take off one or more links to compensate.

ive already removed a link b/c when i first installed it, it was obviously too long. if i take out another link i think it may be too short.

blastradius-- no B adjustment at all!!

If the chain is the correct length, then perhaps the only thing to do is to keep out of the small ring/small cog combos.

If you put it in the big/big is it dead tight? You may yet have room to shorten the chain. You may also just be suffering saggy der. disease, the spring is worn and loosing its spring. If it mainly happens when back pedaling you could be having some binding in the freewheeel or freehub(Lube might cure this) The der should pivot freely on its mount bolt, sometimes this can cause your problem.

i tried shortening the chain again, but it was too short... everything is well lubed and moving freely, so i definately think its saggy der. disease :(

i have a more recent shimano 600 with a long cage that isnt nearly as cool looking, i think i may try and take the spring from that if its compatible.

thanks for all the replies, ill let y'all know if it works out!

instead of swapping springs i took apart the der. im using and set the spring in the other hole for more tension....its a little better, but still has some sag. it backpedals okay in the large chainring, but still cant be backpedaled well in the small chainring. the chain jumps up the the next largest cog when backpedaling in the small chainring, can anyone explain this? the bike is rideable at this point, as long as i dont backpedal in the small chainring. anyone have any last suggestions before i start riding it without backpedaling in the small chainring ever again?!?

That sounds like a chain line issue. I think yo should follow your signature mantra and ditch those gears and ratchets for some fixed piece of mind.

Beat me to the punch Rev! Anybody with a signature like that ought not to be "backpedaling" unless they're rolling backwards.

i already have enough singlespeeds, fixed gears, and coaster brakers. i need a nice friction shift setup to ride sometimes, and to add a little variety to the stable!

anyhoo, how would i go about diagnosing and correcting this chain line issue?

If you are running a double up front then from the first ring to the middle cog in back should be a straight line. If not then your b.b spindle is too long, or the b.b cups need to be adjusted.