Topic: Dent on frame rail

[bultaco59]

Hello people, does anybody out there have any ideas how pull a dent out of the frame, its right in the front, and it really pisses me off because know matter how much work goes into the build that's the first thing there gonna see, if anyone has a trick up there sleeve please let me know. I'll post a pic.

Thanks
Bob in burbank

[Vinhead1957]

Drill a  hole, use a dent puller and weld the hole

[Retro Rocket]

And have the frame checked for straightness....   I have a K2 frame with a dent in the same spot and after having it fixed I'm having it put on a frame jig and checked...

[754]

That is from the 20$ hiway bars it  used to have.. Some bondo them, pita to fix.

[Icarus]

I'm a brazing guy so I just say lay some brass in there to fill it up an then a quick sanding.  Classier than bondo and powder will stick to it.

[lucky]

If you heat the center of the depression with a torch to dull red it initially expands. May pop out wards.
After it cools it will shrink just slightly. It should look slightly better.

Do not put water on it. Just let it cool at room temp.


If you drill a hole in it and use a dent puller it could look worse because the tent puller will make a protruding volcano shape. I would not do that.


If you weld the hole that the dent puller requires that will cause shrinkage as it cools. It will just look worse.

I think I would go with the Bondo myself. It will look perfect.

[kghost]

I would TIG weld it then grind to match........but I have a welder

[bultaco59]

Hey guys thanks for the response, I guess the best way for me is to lay some brass in the dent.
one question, does map gas get hot enough to melt brazing rod ? since I don't have a turbo torch.
If not I'll have to bring are tig welder from work home and try that. I now have options, thanks again.

Bob in burbank

[Vinhead1957]

If you heat the center of the depression with a torch to dull red it initially expands. May pop out wards.
After it cools it will shrink just slightly. It should look slightly better.

Do not put water on it. Just let it cool at room temp.


If you drill a hole in it and use a dent puller it could look worse because the tent puller will make a protruding volcano shape. I would not do that.


If you weld the hole that the dent puller requires that will cause shrinkage as it cools. It will just look worse.

I think I would go with the Bondo myself. It will look perfect.


You have never pulled a dent I see.  Yes the hole will pull high like a volcano but you hammer and grind it back down and then fill the hole.  You can fill with lead (old school) fill with brass(braze) or weld with steel.   Bondo on a frame for only cosmetic dings only.  Frames flex and the inconstant densities. Bondo (soft) steel (hard) will crack at edges.

[Powderman]

JB Weld, sand and paint. JB Weld can be powder coated, Bondo can not. Is there another reason for fixing the dent other than cosmetic?

[754]

A split die for 1 inch tube, may reround it, but its tricky..and involves heat..
What I mean is 2 square blocks bored to one inch id.. Like we use on fork straightening.

[70CB750]

Auto body guys use lead bars to fill dimples, like this:

http://www.newegg.com/Product/Product.aspx?Item=9SIA1NW0F40630&nm_mc=KNC-GoogleMKP&cm_mmc=KNC-GoogleMKP-_-pla-_-Body+Repair+Tools-_-9SIA1NW0F40630

easier to work with that brass.

[lucky]

I would TIG weld it then grind to match........but I have a welder

The TIG weld would make the least heat input with the most penetration but
there would still be shrinkage and you would still have to bondo it after sanding.
Never use a grinding wheel on a 1/16-.060 thousandths thick frame tube.

One touch of the grinding wheel and 1/3 of the material could be gone.

[mec]

my way: drill a hole opposite side of the tube, hammer the dent, weld the hole.

mec

[cosmicvision]

Is there another reason for fixing the dent other than cosmetic?

I read a topic on here once about the guy that had a weird fork angle & couldn't figure out why, and ruled it to be the frame being slightly skewed. It was intense, replete with the horror stories of off-kilter frame geometry sending you into a tank-slapping fiery blaze. Not sure how much effect a dent of that size would have...thought it was worth mentioning though.

[Retro Rocket]

my way: drill a hole opposite side of the tube, hammer the dent, weld the hole.

mec

Good thinking Mec....

[lucky]

my way: drill a hole opposite side of the tube, hammer the dent, weld the hole.

mec

  That sounds very interesting. I like it.

[Vinhead1957]

Mec that is not a bad idea!

[kghost]

I would TIG weld it then grind to match........but I have a welder

The TIG weld would make the least heat input with the most penetration but
there would still be shrinkage and you would still have to bondo it after sanding.
Never use a grinding wheel on a 1/16-.060 thousandths thick frame tube.

One touch of the grinding wheel and 1/3 of the material could be gone.

I would build it up with the TIG.

I agree don't use a huge electric grinder.

After build up.......sand it back with a rol-lock disc on a 1/4 air grinder aka the wheeng wheeng tool lol

[Don R]

If you tig, it use phosphor (EDIT) SILICON bronze rod. It's easier to sand down and requires less heat causing less shrinkage. It worked fine on mine. Most of the above ideas work too.

[Dave Voss]

If the frame is not bent or distorted in any way, then that dent is not enough to warrant any repairs.  Although it could be straightened out, the drilling of holes, pulling/pushing action on the metal tube, etc. will weaken the frame, which then is dependent on the quality of the repair to restore the original strength.  Even then, it will be very difficult to remove the dent such that it won't still be obvious where it was, in which case some filler will be required to hide it.  So if this is being considered for cosmetics, then I would recommend just filling the dent as-is, instead of trying to remove it first.

[lucky]

If you tig, it use phosphor bronze rod. It's easier to sand down and requires less heat causing less shrinkage. It worked fine on mine. Most of the above ideas work too.

Most welding suppliers only sell silicon bronze filler wire.

[CapeCafe]

Dent the other side to match

[Don R]

If you tig, it use phosphor bronze rod. It's easier to sand down and requires less heat causing less shrinkage. It worked fine on mine. Most of the above ideas work too.

Most welding suppliers only sell silicon bronze filler wire.

I stand corrected,  thanks.

[bultaco59]

If none of the other options work, that to is an option. granted not the best option,but an option none the less.

[Garage_guy_chris]

heat and air pressure inside?  water inside and freezing? those are my two contributions

[mpacey]

I just bought a 72 cb500 with the same issue. It never occurred to me that it was because of the crash bar I threw away on my way home from buying the bike.
So what was the final verdict and solution? How did the fix work out for you?

[Vinhead1957]

The easiest solution is to strip and grind the paint in that area and use body filler and primer repaint.

[750K]

If its just dented from the crash bar and not a bent frame from something else I'd use fiberglass strand body filler, it will flex if it has to and not crack unlike the plastic filler. Fill sand and paint, forget about it.

[mpacey]

Plastic filler sounds like a plan.
I was looking forward to my build, and was bummed about scrapping the frame and having to part it out. Winter project is back on!!

[Don R]

JB weld would be my option. Relax and enjoy your build. Some of the suggestions although well intended are a bit extreme.

[lucky]

If you heat the center of the depression with a torch to dull red it initially expands. May pop out wards.
After it cools it will shrink just slightly. It should look slightly better.

Do not put water on it. Just let it cool at room temp.


If you drill a hole in it and use a dent puller it could look worse because the tent puller will make a protruding volcano shape. I would not do that.


If you weld the hole that the dent puller requires that will cause shrinkage as it cools. It will just look worse.

I think I would go with the Bondo myself. It will look perfect.


You have never pulled a dent I see.  Yes the hole will pull high like a volcano but you hammer and grind it back down and then fill the hole.  You can fill with lead (old school) fill with brass(braze) or weld with steel.   Bondo on a frame for only cosmetic dings only.  Frames flex and the inconstant densities. Bondo (soft) steel (hard) will crack at edges.

The frame is much thicker than sheet metal of a car.
The frame is .062 thousandths thickness.

[BeSeeingYou]

I just bought a 72 cb500 with the same issue. It never occurred to me that it was because of the crash bar I threw away on my way home from buying the bike.
So what was the final verdict and solution? How did the fix work out for you?

Just use JB Weld like DonR and powderman recommended.  You can buy it for a few bucks in the small quantity you need.  I think it's better than "Bondo" type fillers for small areas like this.  Dries fairly quickly, is hard but sands easy and feathers out nice.  It's a modified epoxy so it really holds on.   I used it to smooth out all the ugly welds on an XS650 frame....didn't have any dents but the XS has (had) some pretty ugly welds on this part of the frame.  I don't understand why it needs to be complicated by welding, brazing, grinding, drilling, pounding......  keep it simple and easy.  I got it in a set of 1 oz tubes (resin and hardner) and it was enough for the whole frame.

[BeSeeingYou]

heat and air pressure inside?  water inside and freezing? those are my two contributions

  Don't even consider it.  Water expands 10% when it freezes...so how do you control it and make it apply pressure to the dent only.  Once in awhile you see these "techniques" mentioned for gas tank dents too...usually by people who have never tried it themselves.  Only trust the advice of those who have subjected themselves to their own advice. 

[commando1954]

Build up the dent with lead then file off.

[Lostboy Steve]

I usually build up the area with some weld and then grind, file and sand.

[Retro Rocket]

my way: drill a hole opposite side of the tube, hammer the dent, weld the hole.

mec

This is the way i would do it....