Knee Dents (hammering a tank)

R

rlarkin70

New Member
hi all. I just thought I would put up a couple of pictures and the method I used to bang some knee inserts in the sides of my 76 CB550F tank. I would encourage anyone to try it, since it was very easy, and took less than 15 minutes. I was terrified of doing this because I figured I would ruin the tank, but I went slow at first and it was easy to get the hang of.

1. with the tank on the bike sit in your riding position and use some masking tape or something to mark where your knees lay agains the tank
2. cut out a cardboard template that matches the outline
3. use the template and a Sharpie to trace the outline of your inserts on the tank
4. using a deadblow hammer (I used a 24 oz. with a plastic head) hammer in the main shape, starting in the middle. keep in mind the tank will cave in several inches ahead of where you make your blows, so take this into account.
5. work outwards and forward. the tank sides will start to cave in just along the ridge where the top meets the side of the tank. work slowly and check your progress as you go. you can always make more blows. its hard to take them back though!
6. use the edge of the hammer head to work around and shape/blend the edges
7. finish by looking at it under light, and hitting any high spots. keep hammering until the contours are smooth
8. repeat for the other side. compare from top/side/rear views and use template again to match the sides so they are the same

I am no expert, and this is the only tank I have done this to. I just thought I would share since it was pretty easy to do once I got past the intimidation of taking a hammer to the gas tank. Next step is removing the old paint (I think I will use aircraft stripper) then use some Bondo and sanding to blend in the dents, and cover up the badge area. Then prime and paint.

-Ron
 
Sweet. Been thinking of doing the same to my tank, but have been scard of the first blow. Nice Job!
 
WOW...I think I should just send you my tank to do!!.. LOL...
A couple of things though...
1. Could you mark on the tank, (with an x1), where you made your first hit, then with an "x2" where you made your 2nd hit?
2. Just to confirm, you used the plastic side of the hammer?
3. You used the metal side of the hammer to smoothen out the sides?

Thanks for the post... I'm gonna do the exact same thing on the black cb750f thank thats on my bike now. I guess I should take the tank off the bike huh??!!...

Thats awesome..
 
basically I started out at 1, hit there and around that area about 10 times maybe. I used the flat part of the plastic hammer head. then at 2, hitting that area working out from that spot out in a small circle. at this point the side of the tank started to fold in. then at 3 I worked with some hits up the front of the insert area. this is the place that you need to be most careful, since the other borders almost define themselves, but the front you could go too far with. then using the edge of the plastic head I worked along the top of the tank. at this point it almost naturally folds in along that seam, and it is just a matter of making it look even. then I used the edge of the plastic head and worked around the whole perimeter of the indents evening things out. you can hold it up to the light and see any high or uneven spots, then tap those.

I always used the plastic head, never the metal one. you will see when you start to hit that the tank just slowly starts to cave in as you go and before you know it you have a decent indent. then its just a matter of going over it again and again, making it a bit deeper, and smoothing it out by hitting the higher spots. the edge/corner of the hammer is great for the edges.
 
its a lot less dented than I thought it would be. but I will definitely use some bondo and sand it down before I prime it. I thought about using a rubber pad, but seems like too much trouble to find something, and cut it to size...AND make it look good.

-Ron
 
hi again Zixxer-

You asked about the dents, and using Bondo....

I used some bondo around the perimeter, then sanded it and primed it. then sanded again to see where the low spots were. I applied a bit of Bondo spot putty over them and haven't sanded that off yet. I figured I would take a photo now in case I forget to shoot one before I prime it.

I stripped off the old paint off with aircraft stripper and lightly sanded before I put the Bondo on. It should turn out OK I think. I am not trying to get it perfect, just fill in the dents and smooth the transition a bit.

-Ron
 
I picked up a used tank for 5$ and started hammering it, Im having a problem with the lower seam and it poking my legs. any tips? My indents are more uhhhh severe then yours are..
 
I agree, if you really want to tuck in your knees the lower seam is a problem. But I don't think you can (or would want to try to) bang that in with a hammer. I would imagine it would need a cut/weld type solution.

Here is a pic of the tank on the bike. Taken at night, and all black, so hard to see the tank very well! I will post a better picture of the final product, but I am happy with how it turned out.

The bike is still coming back together, with most work on the electrics and engine right now. Next "cafe" item will be to chop the rear fender, and bring in the tail light to behind the seat. Speaking of which, if you think it looks a bit off...you're right. I just threw the seat on there to take the picture, the cover is just loosly fitted to it at the moment. =)

-Ron
 
I pretty much used this same method except i worked from the outside in...i felt i was able to control where the edge lines were going a little better since i was using a ball peen instead of a deadblow. The finish isnt as smooth as it pocks a lil where the peen hits it, but its going to be bondoed anyway, so i wasnt too worried about that...good project. Its ALOT easier than you think its going to be...just be patient and carefull about what youre doing...My slopes arent as gradual as his, i wanted a sharper edge, so i worked about a half inch inside my lines..starting along the top seam..and again, watch that you are fairly even and level as you go (dont get one part way deeper than another or it will crease..) His pics pretty much tell the story, and as long as you work the top and in a radial fashion there is no FIRST shot thats better than the other...
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light
    • www.jadusmotorcycleparts.com
    www.lostapostle.ca/
    www.sparckmoto.com

    Spread the Love

    Back
    Top Bottom