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Robem Engineering Subframe


Spatt

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Almost 1 year ago we built our first subframe for the FZ07.

I never really like the way it worked and the plugs that went into the tubes.  I know others have since made other solutions that I found equally difficult or more so to install or service.  The original design was 3 pieces allowing to replace any item that bent separately and also allow the subframe to be installed without each part being in tension.  I still never really loved the design and only built a few.

image.thumb.png.48934972ec8376bb2ca6cb61352e2c5a.png

Move forward a year.  Going to try and add plugs to weld to the frame and allow the entire piece to be removed as one unit.  So far I've machined the aluminum part for the subframe side and working on the steel slugs with matching interlocks.

image.thumb.png.2c379e404e4c6adbe39a0895395d3719.png

We will test it on our SV's first but I think I can pass it along also to the FZ riders if all goes as planned.

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Get your MT07 & FZ07 racing parts at https://www.robemengineering.com/fz-07-products

 

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21 minutes ago, MiniFZ said:

A “plug and play” ish, subframe frame would be awesome!  Consider this a not so subtle hint. :D 

It will require one to weld the opposite plug into the frame but from there you’d be able to bolt the subframe on like a regular subframe.  
 

I’m trying to work out 3D printed guides that snap together as cut guides.  
 

The idea for the connections is stolen from some offroad bodies door bars and sections of removable roll cages.  

82220FCF-35E0-4A71-94B7-D0F57C42B9D6.jpeg

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Get your MT07 & FZ07 racing parts at https://www.robemengineering.com/fz-07-products

 

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How about undercutting those connection points, so they slide together from the side and dovetail? Not sure if that's a possibility with the full unit being installed, but possible.

Just a thought to strengthen up that joint . . .

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19 hours ago, Spatt said:

Almost 1 year ago we built our first subframe for the FZ07.

I never really like the way it worked and the plugs that went into the tubes.  I know others have since made other solutions that I found equally difficult or more so to install or service.  The original design was 3 pieces allowing to replace any item that bent separately and also allow the subframe to be installed without each part being in tension.  I still never really loved the design and only built a few.

image.thumb.png.48934972ec8376bb2ca6cb61352e2c5a.png

Move forward a year.  Going to try and add plugs to weld to the frame and allow the entire piece to be removed as one unit.  So far I've machined the aluminum part for the subframe side and working on the steel slugs with matching interlocks.

image.thumb.png.2c379e404e4c6adbe39a0895395d3719.png

We will test it on our SV's first but I think I can pass it along also to the FZ riders if all goes as planned.

Real nice!  Those are 6061, correct?

I like the idea of welding a steel piece to the stock frame.  A cleaner "factory" setup in the long run.

Craig Mapstone
Upstate New York

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Just now, blackout said:

Real nice!  Those are 6061, correct?

I like the idea of welding a steal piece to the stock frame.  A cleaner "factory" setup in the long run.

Correct 7075 doesn’t weld.  Steel just gives stronger threads and a permanent  connection to the bike and make the fuss with having to mess with the frame side a one time ordeal.

This solutions like most of my parts won’t be for everyone but it will be a nicer clearer looking bike.  

 

 

 

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Get your MT07 & FZ07 racing parts at https://www.robemengineering.com/fz-07-products

 

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57 minutes ago, phanomenal07 said:

I'll start googling how to cut off the existing subframe. This looks dope

port-a-band and a steady hand😄

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1 hour ago, phanomenal07 said:

I'll start googling how to cut off the existing subframe. This looks dope

Might want to look at a small tubing cutter, or maybe "modify" a small tubing cutter (depending on how close yo need to get to frame) Good luck-

""W.O.T. until you see god, then brake"

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3 hours ago, sansnombre said:

How about undercutting those connection points, so they slide together from the side and dovetail? Not sure if that's a possibility with the full unit being installed, but possible.

Just a thought to strengthen up that joint . . .

As soon as you load the joint its physically bound.  There is .012" clearance and (5) 90 degree connections you have to overcome add it (2) M6x20 fasteners.  Look at it from this angle, with the green insert fixed and weighting the red trying to pivot down.

Think about it this way one a typical sportbike subframe you're relying on on the shear strength of an M8 or M10 fastener.  Only reason for 2 fasteners per connection is redundancy, on the race bikes I doubt we will use both. 

image.thumb.png.f0d3679dc834f7a75f572cfa1dc2a616.png

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Get your MT07 & FZ07 racing parts at https://www.robemengineering.com/fz-07-products

 

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I'm not sure of the loading here, and what you say is correct, but if you have a lateral load (up/down in this picture), only the threads of the bolts contain the parts, which would be a design no-no.

But if no load trying to separate the parts in the vertical direction, then no problem. As I'm sure you all have already considered . . . .

Cheers.

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55 minutes ago, sansnombre said:

I'm not sure of the loading here, and what you say is correct, but if you have a lateral load (up/down in this picture), only the threads of the bolts contain the parts, which would be a design no-no.

But if no load trying to separate the parts in the vertical direction, then no problem. As I'm sure you all have already considered . . . .

Cheers.

Threads carry loads all the time.  Not sure I understand the problem.

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Craig Mapstone
Upstate New York

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It's considered substandard to have threads directly retaining loads, and, yes, it happens all the time. Generally because it's easier, cheaper, or the loads don't require something stronger. If it can be avoided, it should be. It is better to have the bolts secure the parts that restrain the loads - as they do in the other directions in this design.

If you look at the graphic above, you would have to have significant shear forces to compromise the joint in the left-right direction or the in-out direction, but in the up-down direction, you just have to compromise the threads on the two bolts, a much, much easier thing to do. So if there are significant loads that would try to "lift" the red section off of the green section, it would be relatively easy to do.

Again, if there are no/low loads in that direction, there is no problem. If there is, than a dovetailed joint would add profoundly to the strength in that direction, and also make the joint more robust along the other separation lines as well.

IMHO

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Even with those two bolts just run in finger tight, the aluminum sub frame tubes would buckle before the fasteners/joint would fail. That joint is actually overbuilt for what's needed, which makes it perfect. 

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14 hours ago, shinyribs said:

Even with those two bolts just run in finger tight, the aluminum sub frame tubes would buckle before the fasteners/joint would fail. That joint is actually overbuilt for what's needed, which makes it perfect. 

Then . . .

17 hours ago, sansnombre said:

the loads don't require something stronger.

I'm out.

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  • 2 weeks later...
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On 2/6/2020 at 7:33 AM, sansnombre said:

Then . . .

I'm out.

I actually agree with you here, making the joint stronger with dovetails would be more ideal, and its what i would personally do because i dont believe theres such a thing as over-engineering.
 In this case it seems as though the loads the joint would see are the weight of the fairings, and subframe, with partial rider weight, and whatever tiddly bits are packed inside. these loads will be compressing the joints via gravity and centrifugal forces together rather than separating them, which may in turn cause premature bolt failure from unloading when braking or whatnot but it seems unlikely.  

ATGATT... ATTATT, two acronyms I live by.
 

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  • 2 weeks later...
On 2/17/2020 at 3:06 PM, sorkyah said:

I actually agree with you here, making the joint stronger with dovetails would be more ideal, and its what i would personally do because i dont believe theres such a thing as over-engineering.
 In this case it seems as though the loads the joint would see are the weight of the fairings, and subframe, with partial rider weight, and whatever tiddly bits are packed inside. these loads will be compressing the joints via gravity and centrifugal forces together rather than separating them, which may in turn cause premature bolt failure from unloading when braking or whatnot but it seems unlikely.  

So you believe the fastener is being subjected to dynamic axial loading...so we would be solely relying on the fasteners tensile strength at that point correct? 
 

We are sharing that load with up to 8 fasteners with a tensile strength of 70,000 psi dividing the load.  If that’s your argument. 


I guess there will be a hole in the market for someone to make a dove tail jointed subframe in the future.  Won’t be me.

Sorry for the late reply.  Been in the shop and not really doing much on the board 😁

Edited by Spatt

Get your MT07 & FZ07 racing parts at https://www.robemengineering.com/fz-07-products

 

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@Spatt

Im not doubting your work, just my penchant for over-engineering things.  I have a bad habit of looking at things and attempting to improve them in my mind. Not necessarily for the better/easier solution. 

ATGATT... ATTATT, two acronyms I live by.
 

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2 hours ago, sorkyah said:

@Spatt

Im not doubting your work, just my penchant for over-engineering things.  I have a bad habit of looking at things and attempting to improve them in my mind. Not necessarily for the better/easier solution. 

No worries.  

Get your MT07 & FZ07 racing parts at https://www.robemengineering.com/fz-07-products

 

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  • 2 weeks later...
phanomenal07
15 hours ago, Spatt said:

V2 of the subframe is on the bike and looks killer. 
 

Definitely not a modification I would suggest but some the the bikes on the MotoAmerica grid will be sporting it for sure.  

828088E0-33E4-497C-959E-62ADE4D30CDA.jpeg

95854F24-B343-4C50-98AD-79A319F810F0.jpeg

Why wouldn't you suggest this mod?

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