Understanding Titanium (Lightweight build)

[KootenayD]

To make sure the effect is clear. Here is the math you need to understand...

Say the change in mass between the bolts is 10 percent. So the heavy bolt is 1.1 pounds and the light bolt is 1.0. Change in mass as a percent is:
(1.1/1.0-1)×100 = 10%

Next, say the change in radius is the same relative percentage for 2 bolts of equal mass...say both are 1 pound bolts. Well use inches for sake of discussion since everyone is likely familiar. Placement of the first bolt is 1 inch from the center of rotation and placement of the second bolt is 1.1 inches from the center of rotation. The effect on inertia as a comparable percentage is:
((1.1x1.1) - (1.0x1.0)) x 100 = 21%

So, a 1 unit change in radius has an effect on inertia that is over double the effect effect of a 1 unit change in mass.

To keep things simple, the relative radius of the primary clutch bolt that is used as the basis for comparison relative to all clutch bolts is 1/2 the radius (diameter/4) of the primary bolt thickness (around the axis of rotation). So, the radius of interest is quite small. That means small bolts near the outer edge of the clutch radially are orders of magnitude more sensitive to changes in mass relative to the primary bolt when it comes to changes in inertia. That is what is implied when I say the effect of changes in radius is squared and why it is the first order effect. That relation is why grams in clutch weights are used as the basis for clutch tuning when for performance changes. Best of luck.

You're missing the forest for a whole lotta shrubs here...

I'm not sure how the 2024 updates are holding up but 2022/2023 P22s are breaking bolts and exiting stage left, especially on the 9Rs. No one that rips trusts that bolt, the P22 or the engineering behind it. While Polaris engineers may know what they are doing, it doesn't speak to what the bean-counters and offshore manufacturers are doing to appease the shareholder.

Stock primary bolt: Steel Grade 10.9/SAE Grade 8: 150,000psi tensile strength, 130,000psi yield (permanent deformation) strength at 12% elongation (stretch). TQ 110ftlbs dry
Titanium bolt: Grade 5: 145,000psi tensile, 138,000psi yield at 14% elongation. TQ 75ftlbs with a touch of loctite

The design of the P22 plays an important role in my choice to continue running a Ti primary bolt at the lower TQ spec. It works and that's the not-so-secret sauce...

 

[KootenayD]

no way anyone is noticing the weight reduction from running titanium bolts.
spend that money on some sweet ass monster stickers.

Haha, I took stickers and foam off of my sled to save weight... If TI doesn't give you a slow roaster, you're in the wrong thread!

 

[jcjc1]

Ti is cool as hell. Check out the book “Skunkworks” which among other things, details the construction of the SR71 blackbird. The tooling and crazy engineering that went into the plane because so much of it is (Russian) titanium is fascinating.
As for sleds, it’s a cool niche thing to do but as for meaningful weight reduction, not so much.

 

[Cinno]

Those of you that have used titanium bolts/nuts over the years, can you give some feedback. This summer I started down the path of exchanging out rotating parts to titanium. Primary, Secondary, QD2, clutch cover bolts, weight pins, starter cup bolts. I used blue loctite on these without using a primer.
I then ordered a nextech carbon skid last week and was reading his instructions on installing it. He recommends using primer and red loctite. The primer being used to help the metal interact with the loctite. Also read to not use impacts on the titanium.

My question is, will my "non primed" blue loctited rotating parts be ok? Or do I need to take them all back off and prime and blue loctite? I don't want to use red on these rotating bolts as there is a high likely hood I may need to remove them.

I agree with many others that your money is better spent on power increases, clutching, gearing and less expensive weight reduction techniques.

To put a finer point on rotational inertia not all components in the drive train have the same losses since they don't accelerate at the same rate. The torque required to accelerate them from the motor is also different because of the gear ratios between the motor to the track (CVT, chain case, driveshaft teeth) . The classic formula force(torque)=mass(rotational inertia) times acceleration applies. For example if the typical starting primary to secondary ratio was 3:1 and the primary and secondary had the same inertia(rotational mass), the torque required from the motor to accelerate the secondary would be 1/9 of the primary not 1/3. This is because the secondary only accelerates at 1/3 the primary and the torque required from the primary is also 1/3 because of the gear ratio. The same occurs at the chain case, given a 3:1 there you get another 1/9 reduction in torque to drive the bottom gear. So overall the torque required from the motor to drive the bottom gear of the chain case is 1/81 of the primary. We know the inertia of all these drive components are not the same but given whatever inertia or gearing you pick there is a diminishing return as you gear down from the primary. Now as the CVT shifts from 3:1 towards 1:1 the torque inertia losses go up but now the acceleration rate of the components is set by the overall acceleration of the sled because the torque to accelerate the primary inertia drops to zero when the motor hits the rather constant shift rpm. The overall sled acceleration will be a rather fixed rate because the output horsepower of a CVT is constant. The CVT output speed goes up as the torque does down. When the load HP gets to the given max motor HP the sled stops accelerating.

To summarize the rotational inertia of the primary is more important than the other rotational inertia components, however for overall sled acceleration the lowest cost to performance increase comes for a simple gear change. Up until you hit max motor speed of course.

Cinno

 

[xpturbo600]

You're missing the forest for a whole lotta shrubs here...

I'm not sure how the 2024 updates are holding up but 2022/2023 P22s are breaking bolts and exiting stage left, especially on the 9Rs. No one that rips trusts that bolt, the P22 or the engineering behind it. While Polaris engineers may know what they are doing, it doesn't speak to what the bean-counters and offshore manufacturers are doing to appease the shareholder.

Stock primary bolt: Steel Grade 10.9/SAE Grade 8: 150,000psi tensile strength, 130,000psi yield (permanent deformation) strength at 12% elongation (stretch). TQ 110ftlbs dry
Titanium bolt: Grade 5: 145,000psi tensile, 138,000psi yield at 14% elongation. TQ 75ftlbs with a touch of loctite

The design of the P22 plays an important role in my choice to continue running a Ti primary bolt at the lower TQ spec. It works and that's the not-so-secret sauce...

I'm not missing the motivation. Given my prior description, you should guess that I am an engineer. Yes, the materials have similar capacities. If the steel bolts are shearing and titanium is working at a lower clamping force, then the steel bolt isn't the problem. A way to reduce shear load under vibration is to set the clutch at the factory torque spec. Then, back the bolt off and re torque to a lower number. I did not engineer the polaris primary bolt, so I won't comment on that. If the torque spec is stretching the bolt during operation then someone didn't do their job. The fact a Ti bolt is used with success doesn't indicate the minor difference in material capacity is the reason for that success. There may be machining or manufacturing imperfections that propagate fractures under heavy vibration. That is a question for polaris.

 

[boondocker97]

Here is another nice, calm guide to help when selecting the type and length of your hardware. Same principles apply with Ti. Farmers might want to go ahead and skip this.

 

[boondocker97]

This explains a little about the welding process. So not only is the material expensive, but the welding process is more time intensive.

 

[KootenayD]

I am an engineer.

Since this thread is titled "Understanding Titanium (Lightweight build)"... Ti is a fascinating material that is accessible, strong, light, doesn't rust and can generally be expected to be of better quality than std offshore hardware. Fit and finish are excellent in comparison, diametral tolerances are accurate and repeatable, threads are clean and mic out exactly where they should, heads are well formed and take tooling nicely with little play. Ti can be ordered to custom lengths and profiles and often in anodized, it always looks great. Grade 5 Ti (vs typ Gr 8) maintains greater tensile strength (138ksi vs 130ksi) to a greater (14%) elongation; it's marginal but it's positive. The same goes for weight, where every gram counts and all things being equal, Ti brings an edge.

I'm looking at the BBQ next...

 

[KootenayD]

Here is another nice, calm guide to help when selecting the type and length of your hardware. Same principles apply with Ti. Farmers might want to go ahead and skip this.

Love this guy! Spade is a spade

 

[xpturbo600]

Since this thread is titled "Understanding Titanium (Lightweight build)"... Ti is a fascinating material that is accessible, strong, light, doesn't rust and can generally be expected to be of better quality than std offshore hardware. Fit and finish are excellent in comparison, diametral tolerances are accurate and repeatable, threads are clean and mic out exactly where they should, heads are well formed and take tooling nicely with little play. Ti can be ordered to custom lengths and profiles and often in anodized, it always looks great. Grade 5 Ti (vs typ Gr 8) maintains greater tensile strength (138ksi vs 130ksi) to a greater (14%) elongation; it's marginal but it's positive. The same goes for weight, where every gram counts and all things being equal, Ti brings an edge.

I'm looking at the BBQ next...

A key factor you don't address is stiffness. Ti has several nice properties, yes. But, Ti does not have the stiffness of quality alloy steels or carbon fiber, meaning Ti is susceptible to galling, deflection, and lateral torsional buckling whrn it comes to compressive and shear loading, there are better options. Ti works well when carrying static tensile loads. But so is stainless, chromoly, 7075 aluminum, other exotic alloys, etc. Ti has its place, but billing Ti as a cure all is not accurate. Lastly, anyone can order anything in custom sizes. All you need is a willing machinist and round bar stock. Accuracy and consistency of fastener dimensions has much more to do with the machinist running the mill/lathe and or forming processes than it does with the material used.

 

[xpturbo600]

The only reason I responded was because if you are going to "understand" Ti, then you must also provide information as to what Ti is not good at. So far, little discussion has been provided on why one would not use I titanium. Lastly, as I mentioned in my original post, the weight benefit of Ti as a primary bolt is minimal when it comes to measuring the performance gain in terms of inertia. I did say, Ti has a benefit when it is place at a distance from the axis of rotation. That is true so long as the application does not put the material at risk of galling.

 

[kanedog]

Kootenayd may just be a 20 year old without much real world life experience In all realms. At least thats what I came up with in my exchanges with the boy.

 

[KootenayD]

A key factor you don't address is stiffness. Ti has several nice properties, yes. But, Ti does not have the stiffness of quality alloy steels or carbon fiber, meaning Ti is susceptible to galling, deflection, and lateral torsional buckling whrn it comes to compressive and shear loading, there are better options. Ti works well when carrying static tensile loads. But so is stainless, chromoly, 7075 aluminum, other exotic alloys, etc. Ti has its place, but billing Ti as a cure all is not accurate. Lastly, anyone can order anything in custom sizes. All you need is a willing machinist and round bar stock. Accuracy and consistency of fastener dimensions has much more to do with the machinist running the mill/lathe and or forming processes than it does with the material used.

It's true. 'Stiffness' of a fastener is a product of several factors but as a material in general, alloy steels are 10-30% 'stiffer' than Ti alloys. The eng term is Youngs Modulus. Our sleds are plastic, aluminum and light gauge steel so I think a fastener with some give is desirable. Cast iron head to a steel block... hell yeah; alloy steel all day. Plastic body panels to aluminum structure could probably use an aluminum fastener. The only real advantage of stainless (in this context) is corrosion resistance, although stainless is more readily available than Ti.

If you like steel bolts, you're in luck because a stock sled has em everywhere! Funny thing though, if you buy replacement fasteners from the dealer (because you need to match the profile or whatever), OEM charges more for offshore steel fasteners than you would pay for the same shiny Ti bolt.

 

[KootenayD]

"...I have no ti (or KootenayD) experience so I’m soaking it all in!"

 

[kanedog]

I can tell by your response you have little real world experience In fabrication, metals and world in general. Makes me puke reading your canned, robotic responses like you are sharing some sacred metal knowledge that nobody knows. Barf. Gawd kids are so dumb these days. If you are so smart, how come you aren’t rich?

 

[mrooks17]

Trolls ruining good threads again on this forum. Surprise surprise.

 

[kanedog]

the thread is ruined by misinformation and peeps who don’t know what they talking about, not trolls.

 

[KootenayD]

the thread is ruined by misinformation and peeps who don’t know what they talking about, not trolls.

When you're done vomiting (which might be the most substantial thing that I've seen come from your mouth), maybe you can elaborate... More facts. Less gum-flappin'!

 

[sno*jet]

how stiff is the fancy steel fastener where the nice gold color has worn off and replaced with rust?
assemblies held together with Ti bolts are not failing left and right in the snowmobile industry.
that said I'm still afraid to use them for clutch pins. But what grade steel are the factory clutch pins? maybe they are grade 5 already with a fancy treatment, just like Ti?
Im a fan of using Ti cover bolts and anything rotating. worth every penny. The big clutch bolt too, hanging off the end of your crank adding to the left/right side imbalance.
The "you will never notice it" police make me laugh, as they spend 20+ thousand every year for a sled that's 5 pounds lighter

 

[KootenayD]

how stiff is the fancy steel fastener where the nice gold color has worn off and replaced with rust?
assemblies held together with Ti bolts are not failing left and right in the snowmobile industry.
that said I'm still afraid to use them for clutch pins. But what grade steel are the factory clutch pins? maybe they are grade 5 already with a fancy treatment, just like Ti?
Im a fan of using Ti cover bolts and anything rotating. worth every penny. The big clutch bolt too, hanging off the end of your crank adding to the left/right side imbalance.
The "you will never notice it" police make me laugh, as they spend 20+ thousand every year for a sled that's 5 pounds lighter

Hey Sno, The stock cam arm pins are roughly Gr5. Lots of guys running Ti here without issue but most Ti pins have no coating to protect from abrasion. TJ cautioned me on this (I bet he has a set of coated Ti pins) and I've been keeping an eye on mine. They are wearing faster than the steel pins... With those pins so far from center, I couldn't not run Ti there. Plus they're in a P22 so they'll probably end up on the forest floor before they wear out.