Saturday, November 30, 2019

Suntour Accushift Derailleur Overhaul

I bought a well used Suntour Alpha 4050 rear derailleur that could use some help. I have this same model on a 1988 Schwinn Letour, and it shifts very nicely.


Time to take it apart. I'll start with the mounting pivot. It's spring loaded, which is unusual for Suntour. There's a small C-clip that can be pried out with a screwdriver:


That clip will go flying. After retrieving it from across the room, you can slide out the mounting bolt and spring:


To service the pulley knuckle, remove this philips screw:


Now let the pulley cage unwind, and find the right position to slide it out. You need to rotate it just right so that it will slide out of the knuckle:


There are 3 positions for the spring beneath the plastic cover, I'll just use the middle one for reassembly.


The pulley screws are 9 millimeters. A socket works best for the screw on the back of the cage, since it is recessed into the plastic cage plate:


Pulleys disassembled:


Exploded view:


Now I can clean everything.  For reassembly, I added grease to the knuckles and slid the springs into their mounting holes:


Next I reinstalled the mounting bracket by rotating it against the spring and pressing it into the knuckle. Then I secured it with the C-clip (I pressed it in with a flat screwdriver, but it's easier to use pliers).


Now I reinserted the pulley cage plate into the pulley knuckle.  First I had to insert the spring into the middle mounting hole, then wiggle it a little bit while pressing it into the knuckle. The toughest part was installing the cage stop screw while holding the knuckle back against spring tension.


Next I reassembled the pulleys:


 And screwed the cage back together:


 All done. I considered sanding out the scratches and touching up the paint, but I actually like the worn look.

Sunday, November 24, 2019

Single Pivot Brake Caliper Overhaul

My new-to-me Miyata has sticky brake calipers that don't move freely.  These Dia-Compe single pivot calipers are very common on older bikes, and I'll show you how to take them apart to clean and grease the moving parts.

Before getting started, grind down a cheap 10mm wrench so that the open end is thin enough to fit the inner locknut without touching the outer nut. Alternately, you can buy Park Tool CBW-1, which is rather inexpensive. You won't be able to retighten the locknuts afterwards without a thin 10mm wrench, so don't try to do this without that special tool.

First I loosen the two locknuts with my thin 10mm wrench on the inner nut, and a normal 10mm wrench on the outer nut:

A thin washer will be next. Slide that off, and you can remove the brake arms after you unhook the spring from the back side:

Keep everything in order. There should also be a plastic washer between the two brake arms, and another washer on the back.

Here's the order for reassembly (left to right):
Acorn nut
Small locknut
Washer
Long brake arm
Plastic washer
Short brake arm
Washer
Spring








Clean all of these parts, and add grease to the washers and the pivot bolt before reassembly:
  

The reassembled brake pivot needs to be adjusted like a wheel bearing. You want the brake arms to pivot freely, but you also don't want them to wobble around because the brake will feel sloppy. I will screw the small locknut on until it is snug, then back off a little bit and check. Then I will screw the outer acorn nut back on:

The most important step is to tighten the locknuts against each other to secure the caliper. Again, you'll need that special thin 10mm wrench for this step. Put the thin 10mm on the inner locknut, and tighten the outer acorn nut against it to secure the adjustment (like a wheel bearing, but less torque).

Finally, you can hook the spring back into the nubs behind the brake arms, and then you're done:
 

Sunday, September 9, 2018

Simplex Front Derailleur


I've come across a fair number of vintage bikes with Simplex components, but the front derailleur would be made by a different brand.  I read that the original Simplex front derailleurs used a plastic clamp that was prone to breaking, and people would have to replace them when they inevitably broke.  My brother bought an all original 1970s Peugeot from a thrift store with one of these mythical Simplex derailleurs.
Sure enough, there's a crack right in the weakest part of the clamp:


My guess is that these front derailleurs all failed within the first 100 miles or so, and got replaced with whatever metal derailleur that the bike shop had in stock.

Thursday, December 29, 2016

Cleaning Rusty Chrome

I have an old Colombia 3 speed cruiser that I left outside for at least a year. I guess I lost interest in riding it after the rear tire got a tear in it. After getting another 26x1-3/8" tire, I decided to fix it up again (this would be the 4th time I've reconditioned this bike, it's had a hard life). Anyway, I used some wet aluminum foil to clean the chrome fenders that had rusted pretty badly:


There's a lot of pitting on these fenders, and they're in bad shape. I won't be able to bring them back 100% but I still tried out my aluminum foil trick:


After a few minutes of scraping and rinsing off the rust, here was the result:


Not perfect, but a lot better than what I started with. The pitting went through the chrome into the steel underneath, which is why those specs are still visible. If the chrome was only surface rusted then the wet foil would leave it looking perfect. Oh well, cheers.

Friday, December 9, 2016

Seized Schwinn Seatpost

I was restoring an old women's frame Schwinn Varsity and I couldn't remove the seat post. I'm not sure how it rusted in there so badly since the rest of the bike looked like it was never really used, but that post might as well have been epoxied in place. I used penetrating oil, my propane torch, and a pipe wrench, and the post wouldn't budge. I was actually bending the top of the post with the pipe wrench.


Finally I tried spraying the inside of the seat tube with Lime-Away to try to dissolve the rust holding everything together. After a few hours I hit it with a hammer to see if it would move:


It did. Very slightly, but enough to break the rust bond. When I started turning it with my pipe wrench it made the most satisfying cracking sound that I've ever heard.


Progress:


Victory!


Grease your seatposts. That is all.

Monday, November 21, 2016

Polishing Bearing Cones

You'll probably think I'm crazy for doing this, and that I should just go buy new parts. Sometimes that just isn't an option. My Schwinn Traveler had some very worn bearing cones (maybe the wheel was submerged, and then ridden for a while without grease to protect the bearings):


It was bad enough that I would hear a very noticeable rumbling sound if I spun the wheel off the ground. I was debating re-lacing the wheel to a new hub, but I thought I'd try this instead. I pulled the axle out, and tightened the bearing cone and locknut on one end of it. Then I used a drill to spin the axle while I held sandpaper up to the bearing surface:

I used several different grits, starting with coarse emery cloth, then 400 grit, then 1000. It took a while to clean up the pitting since these cones are made of pretty hard steel. My last step was polishing the cones with my fancy metal polish:

Now they look like Deore XT bearing cones:

The wheel spins quietly now, so I guess this worked. Time will tell if they start pitting again (probably not, I used some decent grease). If the bearing cups inside the hub were badly pitted too then I would just replace the hub, but in this case they were fine. Plus I didn't have to spend any money. Cheers.

Sunday, November 20, 2016

Schwinn Traveler Rebuild

A couple years ago I showed how I used drain cleaner to dissolve an aluminum seat post that was hopelessly stuck inside an old Schwinn Traveler frame. After dealing with that nonsense, I built a lightweight set of wheels for that bike, and gave it to a good friend of mine. I always liked how it handled, it was extremely agile and fast. Anyway, I found another identical bike at a garage sale this summer, and this time I'm keeping it for myself. This one needs some repairs (of course):

The bike was missing a cassette, but came with another rear hub with a freewheel mounted to it. I'm guessing the previous owner tried to fix the bike, but gave up on it when they figured out that freewheels don't work on cassette hubs. The freehub body itself would spin freely in both directions, so either the pawls inside it were broken or just stuck. Time to deal with it:

Axle and ball bearings removed:


After removing the dustcap, I flooded the freehub body with motor oil. After a few minutes it started working normally again. Now I can repack the hub bearings and install a new cassette:



Time to do something about the dork-tastic handlebar setup. This one has steel brake lever extensions, a head light screwed onto a reflector bracket, an extra reflector bracket on the front brake caliper, and worst of all - foam handlebar grips (yuck). I removed the brake extension levers first:

Next I stuck an allen key inside the brake lever to loosen them from the clamp on the handlebar:

Then I slid those old disintegrating grips off with soapy water:

Now it's time to remove the dork light. I unscrewed the handlebar stem, then removed the top nut from the headset:

With the headset disassembled for cleaning, this was a perfect opportunity to remove that extra bracket too:

The bottom bracket is next. The lock ring came off easily, but the adjustable cup on the left side put up a fight. I had to break out the penetrating oil (I'm much more used to using this stuff on rusty cars):

Since I don't have the proper pin spanner for this kind of cup, I had to improvise a bit:

That worked. After cleaning and repacking the dried out bearings, I could reassemble the bottom bracket (with a hammer and punch, again. I need to stop misplacing my normal tools):

Crank reinstalled:

I also repacked the headset bearings and reinstalled the fork and front brake:

Now the handlebars and brake levers can go back on:

After reconnecting the brake cables and putting on some proper handlebar tape, here's where I'm at now:

This bike handles as well as the last Traveler I had. I love these late 80s cro-moly Schwinns. They are incredibly light, agile, and they usually have indexed shifters. Unfortunately this one was in pretty bad mechanical condition (wobbly wheels, gummed up freehub, pitted bearing cones on the front axle, and missing a cassette), but it's back to normal now.