dog bones

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erawtik
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dog bones

Postby erawtik » Sat Oct 18, 2008 9:04 pm

Is the steel you find at places like Lowes, Home Depot strong enough for dog bones if not where should i be looking to buy the metal from? And another thing what about cutting the stock bones and rewelding them then reinforce them on the sides?? Or what if i redrill a new hole in the stock bones?

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shredex
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Re: dog bones

Postby shredex » Sat Oct 18, 2008 9:14 pm

erawtik wrote:Is the steel you find at places like Lowes, Home Depot strong enough for dog bones if not where should i be looking to buy the metal from? And another thing what about cutting the stock bones and rewelding them then reinforce them on the sides?? Or what if i redrill a new hole in the stock bones?


I think you need to find some tempered steel. aluminum is known to snap
You can find a couple diff. metals at lowes, just ask to know what kind of metal it is. and make sure its thick enough. dont get sheet metal.
1/2 inch thick should be good
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Re: dog bones

Postby erawtik » Sat Oct 18, 2008 9:18 pm

i buy steel all the time just to have on hand for when i weld something or rig something together. I know it comes in all kinds of thickness and width is usally inch up to like 2 inches wide. Im just wondering if its strong enough cause the stock bones are pretty thin but must be storng metal.

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Re: dog bones

Postby reelrazor » Sat Oct 18, 2008 9:45 pm

How about this?

ImageImage

I have a set on hand. PM me.

EDIT by Y_G as Moderator :-
I added the following photo so that others at a later time can see what weld is required to do this

PLEASE read ReelRazors post in reply to mine to see the SAFETY issues involved and the precautions he took as a Professional Welder !!!


Image
http://www.michiganmobileservice.com/


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Re: dog bones

Postby PIMPMYFZR » Sun Oct 19, 2008 12:31 am

reelrazor wrote:How about this?


I have a set on hand. PM me.


are these supposed to be adjustable dogbones
??
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Re: dog bones

Postby haunter » Sun Oct 19, 2008 1:47 am

1/2 inch is too thick, stock are 1/4 inch I think

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Re: dog bones

Postby thatkid » Sun Oct 19, 2008 2:00 am

Stock are just under 1/4" thick. I use 1/4" aluminum when I make new ones. 6061/7075/2024 it's all strong enough. For steel I would say 3/16" thick is fine. That may be what the stock bones are.
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Re: dog bones

Postby yamaha_george » Sun Oct 19, 2008 5:10 am

reelrazor wrote:How about this?

I have a set on hand. PM me.


Hmm while certainly an idea, the loads on those rather small weld areas in the picture I personally would worry about.

I would be sure and make the weld beads the full length of the hex + top and bottom.

The allen key headed bolt is just plain scary (and does not allow true adjustability without partial dis-assembly.)

How ever I would weld a second piece of hex in its place with a clearance hole thro it and weld as the other one.

Then using a high tensile steel bolt with more threads, put it first thro the clearance hex, then a nut then adjust my dogs to suit by screwing it into the lower hex and lock the position with the middle nut.

That way I hope I would have made an on the move adjustable ride height assembly, that can take the strain.

PS The above description is mine but the idea is from an early GP test bike I saw back in the 90's.

RealRazor neat idea and thanks for reminding me, but please beef up the assembly I hate bad news about bikers.

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Re: dog bones

Postby reelrazor » Sun Oct 19, 2008 9:43 am

yamaha_george wrote:
reelrazor wrote:How about this?

I have a set on hand. PM me.


Hmm while certainly an idea, the loads on those rather small weld areas in the picture I personally would worry about.

I would be sure and make the weld beads the full length of the hex + top and bottom.

The allen key headed bolt is just plain scary (and does not allow true adjustability without partial dis-assembly.)

How ever I would weld a second piece of hex in its place with a clearance hole thro it and weld as the other one.

Then using a high tensile steel bolt with more threads, put it first thro the clearance hex, then a nut then adjust my dogs to suit by screwing it into the lower hex and lock the position with the middle nut.

That way I hope I would have made an on the move adjustable ride height assembly, that can take the strain.

PS The above description is mine but the idea is from an early GP test bike I saw back in the 90's.

RealRazor neat idea and thanks for reminding me, but please beef up the assembly I hate bad news about bikers.


Let me allay you fears, george.

a) the welds were performed by an experienced certified welder (me: A.W.S.- with cert in FCAW, GMAW, SMAW-all positions. TIG in two positions)

b) welds are full length, wrapped corners.

c) weld is cjp where possible.

d) grade 8 allen bolt which has larger cross section than the original dogbone (which is A36 steel btw-low midgrade mild steel)

e) process and welds were initially inspected by my shop's AISC certified Weld Process Inspector.

f) my shop's lead project manager/steel fabrication engineer (who also rides) liked the idea and saw no issues

g) after a couple hundred miles , the ones on my bike were tested using a dye penetrant method with no cracks or strains except for micro-cracking radially
around the original pivot bolt holes
(which were almost certainly caused in the {original OEM die punching process)

h) I have now close to 2000 miles on them with no further distress

i)The weakest link (literally) in the whole rear suspension are the bolts on which the dogbones hang at the swingarm and at the relay arm which are subject not only to tensile loads (such as the dogbones), but also to shear stress. Those bolts are of the same grade and smaller diameter than the hardware I used.

i) I can perform adjustment in less than five minutes with the bike on the swingarm stand and a scissor jack between the tire and seat subframe-and do whenever I have a pillion rider-by removing just the bottom bolt and counting out turns (one turn =4.5mm of tail rise). The units I make allow about 60mm of adjustment in 11 steps (allowing thread overlap at junction equal to 1.5 diameters)


Now on to some of my observations.

I have seen for sale:

Dogbones re-created using aluminum, the grades of some of which is a work hardening alloy (and if it was a a good idea would have been done by Yamaha) patterned after the orig steel units.

Adjustable dogbones with multiple holes, in steel, stainless(also work hardening), and aluminum with 2mm or less of material between the holes. Which, btw, require more "partial disassembly" to adjust

Thanks for your opinion (and concern) tho.
http://www.michiganmobileservice.com/


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Re: dog bones

Postby thatkid » Sun Oct 19, 2008 10:05 am

reelrazor wrote:Dogbones re-created using aluminum, the grades of some of which is a work hardening alloy (and if it was a a good idea would have been done by Yamaha) patterned after the orig steel units.



Not true. Yamaha's goal is profit as is any company. Steel is roughly 5 times cheaper than aluminum. That's a better margin for them.
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Re: dog bones

Postby reelrazor » Sun Oct 19, 2008 10:15 am

thatkid wrote:
reelrazor wrote:Dogbones re-created using aluminum, the grades of some of which is a work hardening alloy (and if it was a a good idea would have been done by Yamaha) patterned after the orig steel units.



Not true. Yamaha's goal is profit as is any company. Steel is roughly 5 times cheaper than aluminum. That's a better margin for them.


Yeah, you are right. Steel is cheaper. My point was that work hardening grades of alloy are not a good idea in any application where cyclic stress is an issue.
http://www.michiganmobileservice.com/


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yamaha_george
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Re: dog bones

Postby yamaha_george » Sun Oct 19, 2008 11:48 am

ReelRazor,
Good, I am glad your engineering skills live up to your nickname and you have tested the goods in a scientific manner and are as safe as you can be on a bike.

I see so much work that while it looks OK you have a nagging doubt about how safe it is, being a belt & braces engineer I do my best to warn others of the likely pitfalls of their design, I have survived nearly 50 years of biking and my own & other engineers tinkering so I know how good life can be and how catastrophic even the slightest corner cutting can be .

Like you I warned one lister who had a pair of multi-hole dog bones and their potential for failure. One thing about this list the members do appreciate sound tech advice , PLEASE always feel free to give it, that is what makes the group so special.

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Re: dog bones

Postby shredex » Sun Oct 19, 2008 11:55 am

after riding on those for awhile, the thread on the bolts might deform and you wont be able to unscrew it anymore
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Re: dog bones

Postby reelrazor » Sun Oct 19, 2008 12:38 pm

shredex wrote:after riding on those for awhile, the thread on the bolts might deform and you wont be able to unscrew it anymore


I'll say again...I have close to 2000 miles on the set on my bike.

I have adjusted (to raise the tail) them each time I have taken a passenger, and then reset the ride height for myself solo six or seven times in those miles.

Tensile failure (breakage)of a 3/8" grade 8 bolt is 12,360 lbs. Yield (stretch resulting in deformation) occurs about 20% lower which equals about 9800lbs.

My bike and I weigh about 590lbs.

I would need a load of 16g's to stress ONE of the bolts to yield.

Keep in mind there are two acting in tandem.

In other words:

Not very likely a valid worry.
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Re: dog bones

Postby haunter » Mon Oct 20, 2008 11:39 am

reelrazor wrote:Dogbones re-created using aluminum, the grades of some of which is a work hardening alloy (and if it was a a good idea would have been done by Yamaha) patterned after the orig steel units.


x2 on kids comment about cost for Yamaha

7075 T6 is marginaly less strong than 403 Stainless, which is stronger than the whatever cheap ass crap metal the stock dogs are made of :deal:


I have nothing bad to say about yours, its a good idea, if I needed that kind of adjustability.


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