More SV subframe stuff...

[dwilson]

I've been going over my new-to-me 2000 SV and I can't believe the subframe, steel with cast steel ends  ???  The previous owner layed it down pretty hard on the left side, luckily the sliders saved everything except where the passenger peg mounts got beaten up pretty bad.  The sub-frame is bent up and has a crack.  I have to pull it, should I repair it and cut off all the un-needed tabs and brackets or make a new one from aluminum?  I want to be legal in stock classes, what is the best thing to do?  I also thought about pulling it all off and cutting off everything behind the vertical line of the axle, just leave it bare with number plates mounted but no bodywork.

[tzracer]

I have an 03. The stock subframe is very heavy. I made my own out of aluminum. If you know how to weld aluminum it is not difficult, just time consuming.

[dwilson]

I was planning on doing all the fabricating and taking it to a welder to have him zap it all together.  I got a stick welder and a oxy/acy torch but nothing for aluminum.
If I make a custom subframe does that violate the stock frame requirement for stock classes?  If no one knows, who can I ask?

[Zac]

Nothing about SUBframes mentioned anywhere in the rules so it legal  ;)

I made an aluminum subframe for my wife's MZ, and yes, it is quite time consuming.  It would be pretty hard without a TIG nearby, becuase the way I did it I fit up and fixtured everything on the bike and tacked it on the bike, then pulled it off for the full welds.  Going in stages, I think I had the thing on and off the bike half a dozen times during the build-up.

-z.

[MZGirl]

I made an aluminum subframe for my wife's MZ, and yes, it is quite time consuming.  It would be pretty hard without a TIG nearby, becuase the way I did it I fit up and fixtured everything on the bike and tacked it on the bike, then pulled it off for the full welds.  Going in stages, I think I had the thing on and off the bike half a dozen times during the build-up.

-z.

Here's how Zac did it (article on p. 6-7):  http://members.cox.net/strikeracing/bullseye03/bullseye_sept03.pdf

[dwilson]

The SV subframe is pretty simple, just 4 ptraight pieces of rectangular tubing, only 2 simple bends.  I weighed the entire setup on my bathroom scale, it came to 9.5 pounds.  I ordered 8 feet of 3/4" X 3/4" square bar which weighs 5 pounds if I use it all (stock subframe uses 6.5')...  I plan to vice-grip it all together with a piece of .100" thick aluminum diamond plate on top for a seat and have the local shop weld it all together.  I'll leave a small piece of the diamond plate on the back for the regulator/rectifier, ECU and rear brake master cylinder.  I'm also going to get rid of the big-chunk-O'-steel gas tank mount.  I just ordered a hole bunch of aluminum and can't wait... I'm also going to make some custom rear-sets and misc bracketry...

[MZGirl]

One thing that I need to mention about the MZ subframe is that it snapped after a few races.  The designer neglected to account for fatigue of the material due to vibration environments that the subframe experiences.  He went back and added the appropriate reinforcement.  So the subframe design is now on Rev. A.

The SV probably doesn't vibrate as bad as the MZ, but little stuff like this can crop up when going to different materials.

[Zac]

Yeah, we had a little low-cycle fatigue problem.  We used the stock MZ oil tank, which sits up under the tailsection.  The oil tank was basically cantilevered off the back of the subframe, and had a bit of displacement under vibe, which broke the subframe just to the rear of where it was triangulated at the rear seat mount.  A couple of additional tubes to triangulate the rear oil tank mount, which stiffened up the structure and eliminated the excessive displacement, and it's good to go.

-z.

[tzracer]

You may want to make at least 2 subframes. If you have one, you are bound to destroy it. If you have 2, you will never need the second one ;)

Making a jig can be easier than using the bike. I used my bike as the jig for the 2 I have made. I plan to use the stock subframe to make a jig for any future subframes I may have to make.

[dwilson]

I'm still trying to figure out how I can make a sub-frame that has no welds but bolts together.  When I crash I can just cut, drill and bolt on another piece and it's done!  I'm not 100% confident that it wouldn't crack along the bolt holes though so I'll have it welded...

Depending on how much the welder charges I may make a few to start putting on Ebay.  I'd like to start making my own belly pans, sub-frames and rear-sets.  It would be nice if I could actually get some of my money back out of this sport, god knows I'm not getting it out of contingencies  8)  

[DAmico]

Sounds like a lot of time and money being wasted! Go out and ride a dirt bike or cardio train, something that will actually make you faster.

[Super Dave]

Sounds like a lot of time and money being wasted! Go out and ride a dirt bike or cardio train, something that will actually make you faster.

LOL, my thoughts exactly.

Even if you could drop 30# off the bike, it probably wouldn't substantially change your lap times.  

But as long as you're having fun....
 ;D