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An Unscientific Survey to Record Bent Sub-Frames

Bent Sub-Frames and Other Bits

  • '08, Replaced by dealer / Yamaha

    Votes: 0 0.0%

  • '08, Replaced by your children's college fund

    Votes: 0 0.0%

  • '09, Replaced by dealer / Yamaha

    Votes: 0 0.0%

  • '09, Replaced by your children's college fund

    Votes: 0 0.0%
  • Total voters
    0
Something interesting is that the Skidoo XPs have a very similar problem to our bent subframe. They bend the points were the a-arms mount to the "S module". It looks like more of a pain in the butt to change the s module on a xp then a subframe on a nytro BUT a ton of aftermarket companies have jumped on the problem and are making reinforcement kits that WORK!
 

The pole should have a vote for "never bent the subframe" You must have to bottum the front shock pretty hard to bend the subframe.
 
mjaremko said:
The pole should have a vote for "never bent the subframe" You must have to bottum the front shock pretty hard to bend the subframe.
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Nope. My sense is the frame does well at supporting loads in the vertical and axial directions but is weaker laterally and in torsion.

The frame was designed to be sacrificial in order to save other components (i.e. the tunnel and die-cast panels) from damage. I get this idea, but would be happier if the frame then cost just $250.
 
The substandard frame should not be designed as sacrificial structural part as the A arms should be like every other manufacture... The substandard frame is embarassingly weak and should not be bending with normal trail riding...
 
I would have to agree "dooed" on this one. My right lower control arm is pushed back about 3/4" right now. The impact I took was a direct front impact as I hit a rock under the snow. The impact was not enough to make me immediately think I bent my subframe, however, owning an 07 Phazer with the same weak subframe integrity, I wasn't surprised to say the least.
Whether it is an ego thing, which all engineers seem to have, or not, I can't figure out why most manufacturers haven't looked strongly at Cat's design (I can't believe I just typed that). I have a few buddies with 09 M8's and they seem to have the double wish-bone truly figured out...no doubt over many years of evolution.
Looking at the construction of the subframe, the lack of material in the pocket where the lower control arm bolts in is essentially pathetic. The holes the bolts pass through on the subframe are very prone to elongation over time with multiple moderate impacts to the front suspension.
I would agree somewhat with others on here that the Nytro can take the big bumps when the load is applied to the front suspension in more of a vertical direction, but Yamaha's subframes can't take the frontal impact that I've seen the M8's (or others) take. Sometimes I wonder if Yamaha engineers need to take the approach of "if you can't beat'em, join'em"....refering to the front suspension of course...definitely not the engine.
 
Yamadooed said:
The substandard frame should not be designed as sacrificial structural part as the A arms should be like every other manufacture... The substandard frame is embarassingly weak and should not be bending with normal trail riding...
Click to expand...

There are a couple of ways to look at this problem. You could start at the spindles and work your way inward increasing the strength as you go. This would suggest less expensive components are sacrificed before the sub-frame. But, if you consider the implications of one of these parts failing then it makes sense to have the sub-frame be the weak link as it's less likely to fail catastrophically than a system of fewer individual components.

To design an a-arm to be the weak link in the system you have to bracket its strength between being just adequate for the anticipated loads and yet below the level that would transfer damage to the sub-frame. Determining where the lower level of strength should be (and neglecting fatigue) is the tricky part from an engineering perspective. If it's too weak and bends or snaps in a hard turn you're toast. If it's too strong, then you've defeated the purpose of your design intent.

In my experience - and in retrospect - I am more comfortable with a sub-frame that bends but does not fall apart than I would be with a spindle or a-arm on the edge of failing. A bent sub-frame is easier to recover from than a spindle or a-arm that might let loose and put me in the trees.
 
arteeex said:
Yamadooed said:
The substandard frame should not be designed as sacrificial structural part as the A arms should be like every other manufacture... The substandard frame is embarassingly weak and should not be bending with normal trail riding...
Click to expand...

There are a couple of ways to look at this problem. You could start at the spindles and work your way inward increasing the strength as you go. This would suggest less expensive components are sacrificed before the sub-frame. But, if you consider the implications of one of these parts failing then it makes sense to have the sub-frame be the weak link as it's less likely to fail catastrophically than a system of fewer individual components.

To design an a-arm to be the weak link in the system you have to bracket its strength between being just adequate for the anticipated loads and yet below the level that would transfer damage to the sub-frame. Determining where the lower level of strength should be (and neglecting fatigue) is the tricky part from an engineering perspective. If it's too weak and bends or snaps in a hard turn you're toast. If it's too strong, then you've defeated the purpose of your design intent.

In my experience - and in retrospect - I am more comfortable with a sub-frame that bends but does not fall apart than I would be with a spindle or a-arm on the edge of failing. A bent sub-frame is easier to recover from than a spindle or a-arm that might let loose and put me in the trees.
Click to expand...

I agree, you can put a lot of miles on a bent subframe but not a borken a-arm or spindle. What I don't like is how weak these subframes really are, I mean I could use wood/plastic spindles and a-arms and the subframe would still bend before the wood/plastic would break. When I am going down a trail at 5mph and the carbide hits a rock under the trail I should not have to replace at 400 dollar part.
 
yamahaboy701 said:
When I am going down a trail at 5mph and the carbide hits a rock under the trail I should not have to replace at 400 dollar part.
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$800 Cdn up here.
 
My problem is no other sled I currently ride with or any I have ever ridden on myself in my life has ever bent a frame on a groomed trail... Yet now with age I've managed to mysteriously bend two up with not knowing... All in all the Yamaha Substandard frame is what it is "a factory defect" not an engineering anomaly...
 
subframe

Yes factory defect. Is Yamaha going to be like Toyota they never seem to admit to anything until people get killed. They have supposedly have upgraded this part for 2009 and again in 2010. I guess they need to pay us real trail riders to test these upgrades because there little engineers can't seem to get it right. Ive driven my 06 apex for 9000mi and I have not bent an a arm. Now I have bent my subframe on my 2010 Nytro and these subframes have been on backorder for over 4 weeks. If I took the same hit on my apex I don't believe I would have bent an A arm, so I conclude that the Subframes are to week I would rather bend and replace an A arm than a subframe. I am not an engineer I just a trail rider that rides 3000mi a year on rough trails on Tug Hill.
 
Re: subframe

srx900 said:
Yes factory defect. Is Yamaha going to be like Toyota they never seem to admit to anything until people get killed.
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Ummmmm, I seriously doubt anyone is going to be killed as the result of a bent subframe, considering all of the ones I've seen are still drivable afterwards (and mines got 4000 Km on it while being bent due to my own actions). Sticking throttles on the other hand...........
 
Backorder LOL I was told I was the only one with this substandardframe issue... I'm guess'n as the 2k10 season comes to an end the flow of still ridable bent substandard frames will hit the repair centers... On the brightside maybe you will get an upgraded 2k11 substandardframe...
 
That's what I'm hoping for. Tweeked it last year and it has survived this year. Not sure how long a person can wait till the real fix comes. And when it comes, will it even be compatable with the 08-11 Nyrto's
 
yamahaboy701 said:
Something interesting is that the Skidoo XPs have a very similar problem to our bent subframe. They bend the points were the a-arms mount to the "S module". It looks like more of a pain in the butt to change the s module on a xp then a subframe on a nytro BUT a ton of aftermarket companies have jumped on the problem and are making reinforcement kits that WORK!
Click to expand...

Ten of us went riding in Montana this past weeekend. Rode Friday in Yellowstone park, then Saturday and Sunday in the mountains. Had guides all three days.

We rented 800 Summits 154's. Before we rode we had to inspect the sleds. Almost all the sleds had their shocks tweeked either forward or reaward of center of the A Arms. I talked to the tech. He said he replaces lots of front end bulk heads on these sleds.
 
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