Topic: Cb350F fuel tank repair

[brianc]

Last task on my 350F restore is the paint work. The tank revealed its little surprise once I got the paint and bog off. A bit ugly. I see an 'easy' way of getting out the dents (LOTS) plus a couple of drilled holes? is if the outer (top) part of the tank can be separated from the lower. I thought I read somewhere (on this forum) of someone doing that, but I can't find it now.
To me it looks like a long old fashioned puddle weld on the joint as opposed to the continuous roll / spot weld of later tanks. Careful Dremel / grind with appropriate fuel awareness (no fuel in the tank for years) should get it apart, panel and repair holes and reweld. Might need a jig to make sure of alignment.

Anybody done something along these lines? Thanks

[Trevor from Warragul]

http://forums.sohc4.net/index.php/topic,181154.0.html

[RAFster122s]

Jeff at Godfrey’s Garage does tank repairs and modifications, not inexpensive work. But good tanks are very hard to find on many models and getting harder to find.

[brianc]

Thanks for that link, I'll follow it to see if the poster replies on the final question.

[calj737]

Cutting the shell loose from the tunnel and welding it back is an ENORMOUS amount of work. A far easier approach is to do a “paintless dent repair” technique by pushing the dents out from inside. Solid rods bent and hooked into differing angles can allow you to reach anywhere needed. At worst, cut an access hole in the bottom that can be welded back up.

Distortion and shrinkage from welding the shell is a significant issue and cleaning a very irregular piece of thin sheet steel is a major PITA. Believe me, I did a couple for friends and if I had charged an hourly rate, they could have bought a new bike for the price.

[brianc]

Thanks, I'll have a good think over a beer or two. It certainly sounds tricky, but the tank is pretty crappy. I might have to buy back one of the tanks I sold! Doh!. This one looked good until the paint came off.

[calj737]

They always look good until they get naked… 

Just have the dents pulled by a PDR guy and apply a skim coat of filler. Then sand that down and paint it. It will be perfect and the modern fillers and paint will adhere properly.

[Mark1976]

They always look good until they get naked… 

Just have the dents pulled by a PDR guy and apply a skim coat of filler. Then sand that down and paint it. It will be perfect and the modern fillers and paint will adhere properly.

++++1
Unfortunately when it comes down to the cosmetics of these bikes today, it's neither quick nor inexpensive, and anyway you look at it, it'll be less expensive than doing it the cheaper way twice.

[newday777]

Most PDR guys will probably say that the metal is too thick to massage the dents out, good body guys will say they can spot weld dent puller pins on and pull the dents mostly out, then filler to smooth it out before repaint.

[calj737]

Most PDR guys will probably say that the metal is too thick to massage the dents out, good body guys will say they can spot weld dent puller pins on and pull the dents mostly out, then filler to smooth it out before repaint.

Speaking from personal experience, that is completely untrue. I have fixed dozens of these vintage tanks by PDR. I have also cut and welded them back together. The latter is far more work and the results are equal.

[RAFster122s]

A lot of PDR guys don't have the jigs to hold the tank and a setup that levers against anything other than the filler neck.

I've seen guys ruin a compound curving shape with the weld on pins as they don't have the skills and experience and stretch things way out of shape trying to get movement with too much force at too few pins. Then they have a real mess.

Face it, most people don't have the patience to learn how to work metal and are more of a plaster with body filler than a metalsmith.
They aren't taught the art.

[ozm29c]

brianc,
Re separating the two halves of a CB350F fuel tank. Frustratingly my reply to you disappeared when I pressed the post button?
I have sent you a PM so that I can forward the details to you.
Cheers
John W.

[newday777]

Most PDR guys will probably say that the metal is too thick to massage the dents out, good body guys will say they can spot weld dent puller pins on and pull the dents mostly out, then filler to smooth it out before repaint.

Speaking from personal experience, that is completely untrue. I have fixed dozens of these vintage tanks by PDR. I have also cut and welded them back together. The latter is far more work and the results are equal.

As I said,  MOST WILL PROBABLY SAY. All I did was to state the facts.
How can you say it COMPLETELY UNTRUE???
You may have the experience to make it happen, but there are lots of PDR shops that don't.

[calj737]

As I said,  MOST WILL PROBABLY SAY. All I did was to state the facts.
How can you say it COMPLETELY UNTRUE???
You may have the experience to make it happen, but there are lots of PDR shops that don't.

And you know that MOST won’t how? That’s uninformed speculation on your part. The metal is not that thick and is very easily moved, pulled, pushed. Of the 10-15 PDR guys I know, everyone of them has done these types of jobs many times. It’s no big deal.

[newday777]

As I said,  MOST WILL PROBABLY SAY. All I did was to state the facts.
How can you say it COMPLETELY UNTRUE???
You may have the experience to make it happen, but there are lots of PDR shops that don't.

And you know that MOST won’t how? That’s uninformed speculation on your part. The metal is not that thick and is very easily moved, pulled, pushed. Of the 10-15 PDR guys I know, everyone of them has done these types of jobs many times. It’s no big deal.

Great! But you haven't encountered the ones I have.  Chill out.

[70CB750]

I soldered with soft solder holes on the bottom of a fuel tank.  Easy enough and lasts forever.§

Body work to fill dents - spend the money on a pro level filler, do not use walmart bondo.