Onthemotorway

Hello there,

I'm new to the forums and from the UK! I recently purchased a 1979 Schwinn Varsity off an American gentleman who'd imported it to the UK in the early 90's.

I'm having trouble adjusting the rear derailleur, it's GT510 derailleur and looks like this:



At the moment I can't get the chain to engage the lowest gear, I understand there is an H and an L screw which allows for this adjustment but I don't know which one is which.

Any help much appreciated!

thanks

Tim

ColonelJLloyd 

I just finished the overhaul on my friend's 1976 Varsity. I'm having the exact same issue. I only see one adjuster on the RD, though.

Also, this RD does not move on the mounting bolt axle, correct? It is fixed in its forward/backward position.

Flying Merkel

I had a Varsity back in the day. It never could shift into the small or large sprocket reliably. There's rumors that the problem was with the shifters not having sufficient travel- can anyone confirm or deny?

Seeing that derailleur brought back many frustrating memories. Maybe some day another Varsity will come along so that we can try again. Fun all-around bike, despite it's flaws. Nothing brings back the 70s for as the sight of a Lemon Yellow Varsity with dork disc & turkey wings proudly on display.

Doohickie

Not sure if they had different shifters on there by '79, but my 1973 Varsity uses every bit of the travel to get through the range. I was having trouble with the original GT100 deraileur, so I replaced it with a Suntour AR from a later Schwinn. It works, but like I said, there's almost no extra travel.

Zaphod Beeblebrox 

I can safely say I've never bothered on any Varsity/Continental that's passed through my hands. The Schwinn Approved derailleurs get replaced with Suntour and thats the end of the problems.

ColonelJLloyd 

Ha! That's the correct answer, but not the one I want to hear.

Doohickie

Slap an old Suntour on there and you should be good to go. I even swapped out the wheels and put on a set of alloys with a 6 speed freewheel and it shifts okay.

cycleheimer

Proper tension/slack in the cable? Cable moving smoothly through the housing? Everything cleaned and lubed? No fraying of the cable inside the cable housing? With any deraileur, just see which of the screws it starts bumping up against when you physically move it outward and inward, and then adjust accordingly in small increments.

ColonelJLloyd 

^
Proper tension/slack in the cable? Yes
Cable moving smoothly through the housing? Everything cleaned and lubed? No fraying of the cable inside the cable housing? It's all good. I installed new cables and housing.
With any deraileur, just see which of the screws it starts bumping up against when you physically move it outward and inward, and then adjust accordingly in small increments. I only see one adjuster. It is the outward (small cog) adjuster. I have it all the way out and it still won't shift to the smallest cog.

Zaphod Beeblebrox 

I had a similar issue with a Deore RD last weekend. Turns out the parallelogram was just really gummed up....I'd put the shifter into the highest gear and the RD would move to about 4th on a 7 speed cassette and not go to any smaller cogs. Hosed it down with WD-40, and worked it back and forth until it was clean, lubed it up, adjusted the cable and its fine now.

michael k

Edit; Good thought Zaph ^

The pic above shows 2 adjustment screws, ( center for highgear and bottom for low)Same on the ones I have.

First I look at the derailer from the rear to make sure its not bent.

Then loosen the cable and manually shift the derailer by hand while turning the crank and make the nessesary adjustments on the set screws.(Hi-low)

Tighten the cable adjusting screw on the rear all the way down(in), reattached the cable and adjust the cable tension if need be removing any slack.

ColonelJLloyd 

Can you point it out? I don't see the second one.

Also, can anyone answer my question in post #2?

michael k

Theres the screw head on the main body (high gear) then there is one near the bottom-right (low gear)slightly above where the cable attaches.

ColonelJLloyd 

Ahh. I see it now. Thanks!

ColonelJLloyd 

For posterity's sake - I made sure the lower limiting screw was all the way out. It came closer to shifting to the lowest cog, but still wouldn't get there. I used my hands to, ahem . . . adjust the RD outward. It'll shift into all 5 cogs now.

Sprint75

The GT500/510 is supposed to pivot freely forward/backward on it's mounting bolt. If it doesn't, then the bolt is too tight.

cycleheimer

Sometimes you need to slightly unbend these things.

BlankCrows

Ugh, looking at that GT-510 RD is giving me a headache. I've got a nice ladies Varsity in the garage with one of those demons on it -- the darn thing wont take up any slack. I'm just going to put a Suntour on it.

mplotkin

as an old Schwinn mechanic that worked in shops in 1979 here are your options.
the suntour derailleur is a good option if you don't care what type is on the bike.
If you are restoring the bike here are some tips. first remove the cable and then manually check to see if you have the full range of shifting. if it won't go into high gear with the limit screw all the way out, use a set of channel locks or a large crescent wrench to bend the hanger outward slightly. the pivot point is the bolt and nut at the bottom of the hanger.
this was pretty common in the day as bikes would fall over and the derailleur would be bent inward ever so slightly.
another option is to add a washer between the frame and spacer nut.
then readjust the limit screws.