How much would you pay to get your subframe straightened

[Rx1M5]

I've been dissecting my Nytro this weekend and of course I have the bent subframe. After taking endless measurments etc I know exactly where and how much mine is bent. The only way I can see to straighten it out properly is to build a jig where I can use rams etc to push it true. I was wondering if there would be any interest from anyone in having their frame straightened. If there is I may build a more elaborate jig that I can straighten any damage right, left, up down twist etc. If not I'll just do mine which is bent to the right with a more simple jig. Anyways if there was some interest what would be a fair price to have the job done including bracing it up to make it stronger? I don't see any point in buying a new one from Yamaha if it's just going to bend again. Looking at it with the subframe off there are some other options for stregthening it. I'd love to have a $1800 cro mo one from Diamond S but that's a little rich for my blood.

Rx1M5

 

[skyboz]

I would consider having you straighten mine and reinforce it!! If it were bent!! What kind of $$$ are you talkin'??

 

[2008 Nytro RTX]

Where exactly should I measure to see where they are bent?

 

[Rx1M5]

I would consider having you straighten mine and reinforce it!! If it were bent!! What kind of $$$ are you talkin'??

This is my question. I'm not looking to get rich here but it'll cost a few bucks to build up the jig and take some time to do each frame. Is it worth it for me is what I'm asking or will it just turn out to be a giant PITA? I'm thinking by the time you pay for shipping 2 ways and I make a bit it would have to be in the $150 - $200 range?????


To check your frame:

The first thing you need to check is pretty obvious, if your shocks are not centered in the upper A-arms and/or your ski tips are uneven then something is tweaked. The bottom A arm is a pretty beefy piece I'd be surprised if somebody bent one of those so chances are it is either the upper a arm or the subframe. My money is on the subframe. On my sled the subframe is bent from the lower half down. The upper a-arm mounts are in the right place and are even with one another. It is as if somebody grabbed the two lower A arms and just cranked them to one side like a giant set of handlebars. Mine has no up down twist it's just bent to the right. I think if you were to hit the perfect bump or whatever it'd bend back straight again. When you start to measure it up I think you will find that not only is the one side pushed back but the opposite side will actually be slightly forward as well. This sounds bad but it is actually good because it means that the lower A-arm mounts are strong enough to work off of. In order to straighten it I need to make a heavy steel jig that I can bolt the frame to and apply pressure to the lower A-arm mounts. I've got some ideas on how I will do it.

The next tell tale sign on mine is on the short/bent side right where Yamaha riveted the tie rod boot to the subframe (stupid idea drilling a hole at a stress point duh) there is a wrinkle in the subframe tubing you can feel with your finger. Compare your sled from side to side for this bump in the tubing. Clearly the metal is compressed on the short side and stretched on the longer side.



Rx1M5

 

[nytro23]

for what is worth

I was told by my dealer here in Alaska that a new subframe upgrade would be around 650 bucks dealer cost...I didn't ask the details but I'll have one coming. Dealer tells me it will make it an 09 after I install it.
I'm talking with the dealer this next week, I'll get more info.

 

[arteeex]

Re-bending the sub frame is a not great idea and this is why; once bent a metal will resist bending in the opposite direction to a greater degree than in the same direction. Bending it back to its original condition will cause additional dislocations in the material and thus make it weaker in both directions because you must exceed the yield strength of the material again in order for it hold the new shape. Due to localized yielding of the material its Young’s modulus (a measure of material stiffness) has been reduced in that region and therefore you can expect subsequent failure under much lower forces. Think about bending a wire, it gets easier with each subsequent bend. Heat treating after re-bending would be an option if the material was, say, 4130 but this is more likely to cause the entire weldment to get jacked out of shape when internal stresses are normalized.

And, just to complete my treatise; welding in gussets would only be a good idea if you know for certain the direction and degree of the forces seen by the sub frame. Some flex (strain) in a structure is necessary for redistributing stresses. If you eliminate all flex and create a very stiff structure stresses become concentrated in small areas and can easily exceed the ultimate yield strength in tensile, torque or shear. Given the contorted configuration of the sub frame it is best left to the professionals to determine where and how to strengthen this structure.

The End.

 

[nytro23]

very well put

nicely said, as much as I beefed up the race sleds I just moved the weak point somewhere else. Haven't found where it was moved to as of yet. Hit a log and tree so hard it sheared the lower A arm bolt, and sub frame still appears straight.
Some gusseting is needed if your planning to abuse the sled. I did the race sleds last year with input from Yamaha.

 

[Rx1M5]

Re-bending the sub frame is a not great idea and this is why; once bent a metal will resist bending in the opposite direction to a greater degree than in the same direction. Bending it back to its original condition will cause additional dislocations in the material and thus make it weaker in both directions because you must exceed the yield strength of the material again in order for it hold the new shape. Due to localized yielding of the material its Young’s modulus (a measure of material stiffness) has been reduced in that region and therefore you can expect subsequent failure under much lower forces. Think about bending a wire, it gets easier with each subsequent bend. Heat treating after re-bending would be an option if the material was, say, 4130 but this is more likely to cause the entire weldment to get jacked out of shape when internal stresses are normalized.

And, just to complete my treatise; welding in gussets would only be a good idea if you know for certain the direction and degree of the forces seen by the sub frame. Some flex (strain) in a structure is necessary for redistributing stresses. If you eliminate all flex and create a very stiff structure stresses become concentrated in small areas and can easily exceed the ultimate yield strength in tensile, torque or shear. Given the contorted configuration of the sub frame it is best left to the professionals to determine where and how to strengthen this structure.

The End.

I just thought I'd throw it out there and see if anyone would be interested but I can see that in fact it will be a PITA. One querstion though, and by the way I worked auto body for many years. why do we have frame machines for straightening our car frames which we use to carry our families? So in summary I don't think I will bother I'll just fix my own. Thx

Rx1M5

 

[maxdlx]

Car frames don't ussually end up in Hi stress situations. A few years back we bent the frame on our dirt modified the first week out. Put it on a frame machine, and was like new. About 3 weeks later it stopped driving perfect. Fame was bent again, so back on the frame machine, then back to the track, 3 weeks later smae thing. After 4 times on the frame machine it would bend every night out. New chasis no problems. You can straighten them, and gusset them, but they will be weaker. Maxdlx

 

[Early Rider]

A freind in Labrador City got his covered by Yamaha,
I have one that needs replaced and have not yet tried to get it covered
As any one eles heard of this?

er