triple clamps questions for Speeddog

[booger]

S4RT

I have the front Showa fork off for refinishing & cartridge installation; examining the heads of the M8 clamp bolts it appears they have tiny fissure cracks forming underneath? Didn't give me a good feeling seeing that. So, I have sourced Ti replacements for everything on both sides - all 6 M8 pinch bolts, four M10 caliper bolts, the 4 M8 fork bottom axle pinch bolts, and four M6 for the fender mount.

Are these Ti replacements even going to be strong enough for this application (grade 5)? Ti is strong but not as ultimately strong as the original steel. And how am I to torque these Ti bolts? I'm assuming the torques will be different from factory due to the different material. And Grease B as the shop manual prescribes or

Also just how stiff are the Speedymoto triples over stock, are they a noticeable and worthwhile upgrade, and can I use stock caged bearings instead of the tapered roller bearings they come with?

[booger]

..dawg? 

[stopintime]

I've had SpeedyMoto top triple and now have complete IMA Special Parts triples. IMA talks about the correct, not max, stiffness. For me, 98% motivated by design - not function.

Both types of bearings work well.

We're stretching the bolts by screwing them in, but the weak link is the aluminum, so my uneducated guess is that the torque value is decided by the aluminum. In my case, less on the three lower triple IMA bolts than on the stock triples.

My 0.02

[booger]

I've had SpeedyMoto top triple and now have complete IMA Special Parts triples. IMA talks about the correct, not max, stiffness. For me, 98% motivated by design - not function.

Both types of bearings work well.

We're stretching the bolts by screwing them in, but the weak link is the aluminum, so my uneducated guess is that the torque value is decided by the aluminum. In my case, less on the three lower triple IMA bolts than on the stock triples.

My 0.02

Thanks (Lars?)

I forgot about IMA. They have the most beautiful machined alloy products. Are you saying that IMA has the appropriate or correct stiffness and that SpeedyMoto does not, and is more form than function? Good to know about IMA because if I do indeed upgrade the triples, I might seriously consider them especially if I have a better physical case for buying them over the others. And good to see they offer a version for handlebars because I don't do clipons. Would you happen to know if a Pitbull front stand will fit in the steerer tube of the IMA?

I seem to remember IMA being a Swedish company?

[stopintime]

Lars, yes 

IMA is Italian. ISR brakes is Swedish.

I don't know how stiff the SpeedyMotos are. Maybe they're perfect, but then again "perfect" is, at best, subjective. Stiff is good for some bikes/riders/speeds. Softer might be better for other combinations.

Remember: there has to be flex a few places on a bike. As little as possible, but just enough. I think 'harmony' is essential. Similar properties all around the bike. Things that can create harmony: Frame, triples, swingarm, rider, suspension, tires. Or: If the top triple is stiff, something else must be soft. If both triples are stiff, the frame must be soft. If the lower triple is stiff, the top triple can be soft to compensate.

I love the look of my IMA triples. They didn't mind crashing hard twice.

There is hole for a stand under the lower triple. You'd have to ask IMA about the dimension.

IMA will delete the local tax (~20%) for non EU customers and shipping isn't THAT much more these days.

[He Man]

Just throwing my engineering 2cents here cause you know why not.

The fork clamp force is pretty low. If you crank the snot out of those bolts, youll find that the cartridge inside the fork can actually bind. I don't know how sensitive it might be on a street bike, but on a dirt bike you can notice it since the travel on a dirtbike is upwards of 11"+.  So the torque values on these triple bolts are not close to capacity to begin with (maybe on a softer aluminum it might be).

Looking deeper into it, if you compare the modulus of elasticity (basically a measurement of how much it can stretch and rebound back to its original position), titanium is 17,400,000 PSI, aluminum is about 10,000,000 psi.

Since the clamping force on the triple is really how much torque you apply on the bolt, then that means for equal clamping force, the aluminum is  going to stretch more than the titanium. Does this mean that you can torque a ti bolt less? Well, this is where things get interesting.

If you apply the same torque value to both bolts, the titanium one stretches less, but because of the ramp/screw design of the threads you still have to make sure all of the threads on the screw grab all the threads within the hole its going in so you need to torque down to the minimum value that the bolt needs so it doesnt premature fail. Or in this case gouge the threads on your aluminum triple.

Im not a fastener engineer (yes there are engineers that design only bolts) but this is the 100,000 feet in the air description.

Notice I said nothing about strength, were talking about elasticity only. Is the Ti strong enough? Without doing any comparison or calculations, I would venture to say yes because I dont think you are utilizing the bolts full tension strength anyway.

[booger]

Lars, yes 

IMA is Italian. ISR brakes is Swedish.

I don't know how stiff the SpeedyMotos are. Maybe they're perfect, but then again "perfect" is, at best, subjective. Stiff is good for some bikes/riders/speeds. Softer might be better for other combinations.

Remember: there has to be flex a few places on a bike. As little as possible, but just enough. I think 'harmony' is essential. Similar properties all around the bike. Things that can create harmony: Frame, triples, swingarm, rider, suspension, tires. Or: If the top triple is stiff, something else must be soft. If both triples are stiff, the frame must be soft. If the lower triple is stiff, the top triple can be soft to compensate.

I love the look of my IMA triples. They didn't mind crashing hard twice.

There is hole for a stand under the lower triple. You'd have to ask IMA about the dimension.

IMA will delete the local tax (~20%) for non EU customers and shipping isn't THAT much more these days.

A ha! (Norwegian) I was conflating IMA with ISR. Those ISR radial masters are very compelling. I think Ryan Reynolds has them on one of his bejeweled Sport Classics. Thanks for the explanation. One detail I noticed about the IMA triple was the steering tube - apparently it does not get pressed into the lower triple as is conventionally done. it's actually clamped in with three bolts. Does this present any problem in any way?

Just throwing my engineering 2cents here cause you know why not.

The fork clamp force is pretty low. If you crank the snot out of those bolts, youll find that the cartridge inside the fork can actually bind. I don't know how sensitive it might be on a street bike, but on a dirt bike you can notice it since the travel on a dirtbike is upwards of 11"+.  So the torque values on these triple bolts are not close to capacity to begin with (maybe on a softer aluminum it might be).

Looking deeper into it, if you compare the modulus of elasticity (basically a measurement of how much it can stretch and rebound back to its original position), titanium is 17,400,000 PSI, aluminum is about 10,000,000 psi.

Since the clamping force on the triple is really how much torque you apply on the bolt, then that means for equal clamping force, the aluminum is  going to stretch more than the titanium. Does this mean that you can torque a ti bolt less? Well, this is where things get interesting.

If you apply the same torque value to both bolts, the titanium one stretches less, but because of the ramp/screw design of the threads you still have to make sure all of the threads on the screw grab all the threads within the hole its going in so you need to torque down to the minimum value that the bolt needs so it doesnt premature fail. Or in this case gouge the threads on your aluminum triple.

Im not a fastener engineer (yes there are engineers that design only bolts) but this is the 100,000 feet in the air description.

Notice I said nothing about strength, were talking about elasticity only. Is the Ti strong enough? Without doing any comparison or calculations, I would venture to say yes because I dont think you are utilizing the bolts full tension strength anyway.

Great explanation. Makes total sense to me. I would hazard a guess that Ti stretches (elongates) less than steel, is less ductile, therefore more brittle. But as you say, if max torque is already set to much less than failure point (and affecting the internals) then I should be okay.

Not sure if either one of you have inspected the heads of your triple clamp bolts like I have, because you likely have better things to do, but what am I seeing when I see those tiny fissures underneath the heads of the OE bolts? And if I chose to not use the Ti replacements could I go ahead and continue to use the OEs?

[stopintime]

The stock triple bolts are tightened with 20 and 24 Nm. IMA bolts with 7.5 Nm. I guess that's possible because they are twice as many. Be very careful with the back/forth/round tightening pattern. Once the next bolt is tightened, the previous bolt often lose it's grip. Normal procedure, but a lot more complicated than one or two bolt systems.

My triple tree is older, but still available. I used more than 7.5. At least 20. Fork tubes have not been damaged by this.

The new solution with three bolt tightened steering tube is probably smart for the DIY'er.

I would bring allen keys the first few weeks to catch lose bolts.


I wish I needed thumb brakes  Cool upgrade.

[Speeddog]

Moving slow lately, sorry

Aftermarket triples may be stiffer but I'd not pay extra just for that on a street bike.

If you like the looks, go for it.

I like the OEM ball bearing setup, it holds up fine.
If you get tapered roller measure the ID of the cup race and confirm you can get the edge of a punch on for removal.

Ti bolts torques, not sure.
Make sure you lube the threads as Ti galls something fierce.

[He Man]

Do you have pics of the bolts? The way the cracks appear are tell tale signs of failure mode. I highly doubt the fissures have to do anything with overstressing. But I've never inspected mine so I'm not the right guy to ask. I have however replaced many that fell off while riding. I dont like my bolts too tight, but i'm responsible for my own life and I check my triple bolts before each race and every other trail ride. I dont use a torque wrench on my KTM clamps to be honest. Its just tool tight with my finger + 1/4 turn.