DiabloScott

Agreed - the serial number location under the dropout ended about 1990. The "top of the tube" downtube shifters ended in the mid-80s. I don't have comprehensive serial number decoder but the number is about the right time frame as well. I *think* the C might mean "custom" because the similar ones in my database start with S or P.

Pantah

I had the opportunity to get a bunch of bike work done this weekend.
The old Quantum, the one getting the fork repaired, got further teardown. Removed the stem from the handlebar, which means stripping the bar tape and pulling the shifter on at least one side. Fully cleaned the cassette, chain and chainrings plus a general cleaning. It wasn't terribly dirty to begin with as I keep all my bikes relatively clean as I'm nitpicky about my maintenance but made it squeaky clean. Working on a clean machine is far better than working on a dirty one.
It also needed minor repair to the driveside rear dropout. It's become ever so slightly oblong over the years due to the soft nature of aluminum, causing the tire to sit closer to the non-drive side chain stay. I built it up with a bit of JB Weld and will do some filing to make it perfect later in the week. This is a repair I've done before on a Cannondale with good success.

The new Quantum II got a full teardown to a bare frame. The exception being the headset bearing races are staying since I'm re-using the very nice 6400 headset and the bottom bracket bearings. They feel ever so slightly no perfect but after pulling the seals and finding the bearings and grease to be spotless, I squirted some fresh grease in there and called it good.
I left the internally routed cables in place to make running new ones vastly easier.

Two silly things I found during disassembly. First, the crank bolts were obviously generic hardware store purchases, no idea what happened to the originals. Second, the newer Thompson Elite seatpost had a wingnut for one of the saddle bolts in place of the original log shaped nut, probably got lost.

Here's a photo of that wingnut plus the frame fully disassembled before cleaning.

WaveyGravey

I purchased an older Klein several years ago. I believe it is a 1986 Quantum Racing. But it has no head badge and I always wondered if it may have been altered in some way. Thanks.

Force 

Pantah Thanks for the information about this frame.

masispecial

The bearings need to be C3 tolerance or they will tighten up when pressed into the BB shell.
BITD we used Loctite 608 on the axle and bearings

Pantah

Not much to update on the '91 Quanutm with the broken fork steerer. I've done all the prep I can on the frame and fork for the threadless conversion. Brand new 1" threadless FSA headset arrived a couple of weeks ago and I've got the cups installed on the head tube. Removed the old crown race from the fork and now just waiting on the frame builder to get the time to do the work. He's a busy guy so it might be a while.

In the mean time, I've working diligently on the Quantum II so I can finish it and start riding the thing. I forgot to take a picture of the current status but it's looking like a bicycle again. Cranks, brakes, headset, rear derailleur and wheels have all been gone through, thoroughly cleaned, regreased and installed. Didn't actually overhaul the front hub as once I got the bearing pre-load set correctly, it was buttery smooth so I left it alone. The rear hub felt not precisely perfect and I could feel the grease had thinned out so that got a full service.

As for the rear derailleur, had a bit of fun with that. Since I converting to a triple crank, I need medium cage rear derailleur (a GS cage in Shimano speak). I really wanted to retain the look of the original Shimano 600 6400 but those were only ever made in short cage. Thankfully, the mid-90's was still a time when Shimano components could be extensively disassembled and everything shared a great many similarities and even identical engineering. So, I picked up a mid-90's RX100 A550 medium cage rear derailleur with the plan of grating the two together.

Start with two:




And make one. I present the never made RD-6401GS:




It's installed on the bike but I'm going take it off this week for one more modification to the pulley cage plate. I'm not a fan of the relatively low quality and lack of seals on the A550 pulleys. The 6400 pulleys are much higher quality and sealed well so I'd like to use those. I tried, but the A550 pulleys are wider at the center than the 6400 versions and due to this difference, the pulley cage plate is slightly different. The g-pulley fits and works fine but the lower pulley gets just barely pinched and won't spin. A few minutes with a die grinder will solve that problem.
My other complaint, which is minor, is that the A550 pulley cage plates are stamped steel compared to the aluminum of the 6400 and is significantly heavier. No way around that, is what it is.

I'll have a photo later this week of how the Quantum II currently sits. I should easily be able to have it completed by the end of the month. The final big hurdle is up next with the rebuild of the original STI shifters. It's been a while since I've done a set but I remember it being fairly straightforward.

romperrr 

That is a very cool work you're doing on the rear derailleur conversion. It's inspiring me.

Pantah

Conversions and modifications like this are something I particularly enjoy. It's all about the details.

I'm in the process of doing the same thing to the shifters. I can use the original 8 speed 6400 rear just fine but the double shifter has to be replaced with a triple. The 6400 series was never made as a triple so I have to run a 1055 shifter. All the first generation Shimano STI shifters share the same fundamental design and engineering but there are subtle differences that make some of the key components not interchangeable. I do know that the main shifter housing and hoods share identical dimensions, even if the finish/texture is slightly different. So at the least, I can run the 1055 shifter in the 6400 housing with the 6400 hood, both have a different finish. I'd love to run the 1055 triple internals with the 6400 levers and front plate (the forward facing part that has the series designation printed on it) as those are different between the two but I believe that's where I'll run into compatibility issues. I'm picking up the tool today from my brother to remove the proprietary 4 prong nut that holds the shifter internals together on the back side of the levers. I'm going to have to take apart both the double and triple to compare and see what can be interchanged. They have to come apart anyways thanks to the classic case of factory Shimano grease having turned to peanut butter. Same with the rear shifter, though that also has a tiny spring on a pawl that has magically popped out of place on one end, something which makes no sense given the lack of space for that to happen. I'll post a picture when I dig into it but it really is bizarre. My brother and I are both scratching our heads about it because common logic is that the spring would break first, or at least bend significantly, before being forced out of place in the way it did.

romperrr 

Pantah , very interesting thank you. I look forward to your investigation. I have a few brifters that I need to take apart and refresh. I've never done anything like that before, but I figure if they're already not working, me tinkering around in there can't hurt!

daverup 

Pantah There is an old guide for the A410 RSX STI levers on here,
https://www.bikeforums.net/bicycle-m...ti-levers.html
Those are pretty close to the 1055 Levers, so maybe that would help.
I've never been into the 6400 levers, so I can't help with those.
I did recently have to get into a ST-6500 lever since it had stuck pawls, that one was more difficult than the A410 to re-assemble.
Good luck

Pantah

I've actually rebuilt a set of 6400 levers before, though that was 10 years ago. Still, I did it back then with no instruction manual or walk through, I'll be fine this time around.
Additionally, my brother is a wizard with these first generation STI shifters, he's rebuilt every version ever made and knows them inside and out. If I do run into any issues, I can just talk to him. If there's any broken parts, we both have a stash of parts shifters.

The 9 speed shifters are tricky in that they can't be fully and completely disassembled in the way the 8 speed (and 7 speed first gen RSX) can be. They've got more plastic in them so they're also not nearly as durable.