gitaneusa.com :: View topic - 1972(?) Super Corsa stripping, dent, rust

vanhelmont

When my forkless frame arrived, my first thought was it deserved a decent burial. There is no sign of any head-on collision, but the dent on the top tube was worse than it looked in the pictures on ebay. The picture of the dent was blurred (and I have since found that it isn't so easy to get good photos of bike details with a typical digital camera), and it's a little off to one side, so it doesn't show up in the picture below. The listing said the tube was straight, but it looked funny to me. With a plastic ruler I still wasn't sure, so I got my steel rule, and found out it was very slightly bent. I tried to bend it back straight by supporting the tube at the lugs, and pushing on it with a big c-clamp, with a block grooved to fit over the tube. Then I decided the dent might be causing it not to be straight, so I clamped two blocks together, and drilled a 25.4 mm hole. I clamped them on the dented part of the tube, and that pushed in the parts that had been pushed out to the sides by the dent. It also pushed the tube a little out of round, so maybe I should have sanded the hole out closer to 26 mm, but I think the tube is straight, so I was happy.

Also inside the seat tube was a spider web with lots of red dust, so I thought it might have serious rust problems. When I cleaned it out there didn't seem to be any internal rust other than a little in the seat and head tubes. Just to be sure, I sealed up the openings of the frame with electrical tape and put in about 100 ml of an automotive rust treatment, then tipped the frame around so that the stuff would go everywhere. I repeated the tipping a couple of times, over the course of the day, then the next morning emptied it out. Any rust should be converted to an iron phosphate chromate, which provides a sort of protective coating.

I used a water-based gel for stripping. It's safe but much less effective than other paint removers I have used. That might be because it was too runny to get a thick layer on the surfaces. I stuck with it because I could use it inside without ventilation. After removing the paint with a scraper, wire brushes (the little round brass wire brush was a lifesaver for tight places), a scrubbing pad, and steel wool, I did a little sanding with 320 sandpaper to get most of the rust off, then "painted" it with the rust treatment. It turns the rusted spots brown, and showed up rust that I couldn't see in spots I had sanded. My conclusion is, if you strip a frame, unless you really do a lot of sanding, use some kind of a phosphate rust treatment to get rid of any rust you may have missed.

I did a little lug filing. After about an hour with a couple of little files, it's not ready for NAHBS, but I think it's a big improvement.

Hope my experiences will be some use to somebody out there.

Dave
Tampa

verktyg

It's too bad about the dent in the top tube (see links below).

I've carefully checked out the pictures of all the frames and bikes that I bought on eBay. When something didn't look right I asked the seller and requested more pictures or clarification. If I'm not comfortable with the response I don't bid.

Last year I bought an early 80s Motobecane Team frame on eBay. There were no tubing stickers on the frame. It could have been either Reynolds 753 or Columbus SL tubing which would pin down the age.

The seller was local and when I picked it up from him the first thing I did was check out the fork shape to determine if it was Reynolds or Columbus tubing. The fork blades had a strange shape so I immediately looked down at the fork dropouts: Tange! Embarassed

It was a Tange replacement fork! Next thing I did was feel under the top and down tubes at the head tube. There were little ripples under the tubes indicating that the bike had been crashed! (I sensed that the seller was a newbie fixie freak and perhaps ran into the back of a car. I don't think that he even realized that the frame was damaged.)

I renegotiated the price on the spot and got a substantial refund from the seller. Even though I got a great deal on the frame it was still a major disappointment. Team bikes and frames are really rare. The Tange replacement fork is a really good match to the original but it's still damaged goods. A year later the bare frame is still hanging in my basement. Crying or Very sad

I also bought a 1978 Motobecane Team frame on eBay (Sorry Stephan, I have a much larger collection of Motobecanes than Gitanes - Motos are easier to find). The were some spots on top tube in the eBay pictures but the seller assured me that they were just where "the paint had worn off".

When I received the frame I saw that they were dents that had been repaired with Bondo. I got the frame for so cheap that I've kept it for a beater or stationary bike whenever I get some time to build it up.

Back to your frame:

There is a water based paint remover made by 3M that's quite effective. A local frame builder uses it all the time. I haven't been ably to find it in any paint or auto parts store but it's out there somewhere.

I've seen old repairs that were done with brass or lead. Today most frame builders us Bondo or similar 2 part epoxy auto body filler to repair dents in frame tubes. Also, auto body "spotting putty" or compound is great for filling minor dings and voids after you primer the frame.

Lastly, you should check the frame alignment while you are at it. A properly aligned frame makes a world of difference in handling, especially on a larger sized frame.

Check out these links:

http://www.sheldonbrown.com/frame-spacing.html

http://www.parktool.com/repair/readhowto.asp?id=40

http://www.youtube.com/watch?v=xRDfzZsOwZQ

http://www.yellowjersey.org/twist.html

http://www.parktool.com/repair/readhowto.asp?id=43

You can get pretty close without a lot of special tools.

Chas.

greyhundguy

WOW!...what a difference in braze work. This is my Interclub frame after striping. Must have been a 1 liter Lunch the day they made the SC.

I've done NO finish work to the brazing and will repaint it as built. Frame is under 3 coats of primer now. I'm waiting for the humidity to go away so I can paint and clear coat it.

Jay

verktyg

Jay,

It looked like Gitane used rocks in their sand blasting equipment. They blasted away all of the excess flux and braze material on the frames made with heavier gage tubing. This left a bad orange peel finish in the metal.

I don't think that they sand blasted their Reynolds frames.

They applied a heavy coating of white primer to the bare metal and a thin top coat of finish paint. When the primer coat was too thick it resulted in a finish that was very fragile and easily scratched. This was quite common on bikes made during the US Bike Boom days.

Gitane improved their finish quality in 1974 but it was too little, too late because the Boom was almost over by then.

Chas.

vanhelmont

Chas.,

The dent looked bad when I got the bike, but since I squeezed the part that stuck out at the sides back in, it isn't so noticeable. I guess I could get out the propane torch and try to solder it, but I'm going to use a plumbing epoxy.

Thanks for the alignment links. I checked alignment of the front triangle like the Taylor brothers in this video:
http://www.youtube.com/watch?v=TMA8X5pk2kI
At the end they also use string to check something, and I wrapped a string from the rear dropouts, around the head tube, and measured from the string to the seat tube on each side. When I pulled out the right rear dropout to make the two sides even, it went from about 114mm to 120mm between the rear dropouts. I made a crude copy of the Park dropout alignment tool with threaded rod, nuts, and fender washers. It should at least serve for checking, and if it's off I'll take it to the shop.

Yeah, Jay, maybe it was a 1 liter lunch. At least I can imagine the frame was brazed by a happy Frenchman!

Chas. said, "Gitane improved their finish quality in 1974 but it was too little, too late because the Boom was almost over by then."

I wonder if some of the sloppiness could have been because they were trying to build as fast as they possibly could. I can't see that any of it has any structural effect. There was one spot on the lower head lug that looked like it might not have been brazed properly, but when I stripped it the brass was just below the edge of the lug. Then in 1974, maybe because the boom was ending, or they had managed to expand enough that they could take the time to be neater. I'm not going to try to duplicate the thick primer. I may do a tiny bit more of sanding or filing, but I'll remember, it was built to ride, not to look at.

A British guy who worked in one of the many small builders active in the late '40s and '50s said that one guy in his shop did a lot of chainstay replacements on Hetchins, because they would often rust and fail within a couple of years, because they didn't clean out the flux properly after brazing. The best I could see in my chainstays with a little mirror and flashlight there was no significant rust after 30+ years. Even if it looks sloppy, Gitane seems to have taken care of the essential things.

verktyg · Last edited by verktyg on Mon Sep 15, 2008 8:18 am; edited 1 time in total

greyhundguy

Chas wrote:"Gitane improved their finish quality in 1974 but it was too little, too late because the Boom was almost over by then".

Then it wasn't just the rock blasting on my Frame as it is a '74-75 with the Honeycomb rear dropouts.

Jay

verktyg

Jay,

There was a major improvement in Gitane paint quality after 1973. The paint and lugwork on my Gold 1973 Super Corsa was pretty good (by French standards) Laughing

A lot of Gitanes came with "candy apple" or "flamboyant" transparent lacquer on top of the white primer. You could see the surface indentations from the sandblasting or shot peening in the tubes, especially on Gitane Gran Sport model bikes built during the Bike Boom.

Chas.