2009 YZF-R6 front suspension on the FZR

[Cafe Racer]

Thought that there would be some FZR folks interested in this modification.

Check out link for build video. Or check out my Gallery.

http://www.youtube.com/watch?v=W10eCgrq2Aw

Miguel

[thatkid]

Overall a very nice build. I'd disagree about how to did the stem for the front suspension though. As I understand it, you took the stem out of the R6 and put the fzr stem in the r6's place. however it was too small to fit so you added a ring of chromoly I believe you said. And then you pressed it all in and it fit time. My issues comes from now having 3 different metal type in contact with each other, which is bad enough, but then, these pieces have the ability to spin on each other under load. I don't see if a very safe option. I would have gone with the welded el=nd of the FZR stem and turned it down to the right size and then had it pressed in. Less chance that anyone up front is going to go wrong. Beyond that, very nicely done. Bike is clean and ready to be ridden.

[DonTZ125]

My issues comes from now having 3 different metal type in contact with each other, which is bad enough, but then, these pieces have the ability to spin on each other under load. I don't see if a very safe option.

I agree with the potential for bimetallic corrosion, but I have to disagree with the risk of having the components spin relative to each other for the simple fact that, due to the steering head bearings, there is almost no torsional load on the stem. The steering and braking rotary loads are transferred side to side via the triple clamp plates; no torque is applied to the frame due to the bearings. The transverse loads (steering, braking, gravity) are transferred to the frame through the bearings by the stem in shear. The major axial (tension) load on the stem is clamping the bearings into their seats.

I see little risk of spinning the insert, and even less effect.
Any other engimaneers wanna chime in and tell me I'm full of it?

[yamaha_george]

Hmm,
me personally I would be worried about corrosion, I would hate adding any part that is one more thing to go wrong.

[Freestyle72]

My issues comes from now having 3 different metal type in contact with each other, which is bad enough, but then, these pieces have the ability to spin on each other under load. I don't see if a very safe option.

I agree with the potential for bimetallic corrosion, but I have to disagree with the risk of having the components spin relative to each other for the simple fact that, due to the steering head bearings, there is almost no torsional load on the stem. The steering and braking rotary loads are transferred side to side via the triple clamp plates; no torque is applied to the frame due to the bearings. The transverse loads (steering, braking, gravity) are transferred to the frame through the bearings by the stem in shear. The major axial (tension) load on the stem is clamping the bearings into their seats.

I see little risk of spinning the insert, and even less effect.
Any other engimaneers wanna chime in and tell me I'm full of it?

I agree with you. The only real concern is the aluminum rusting the steel. In an ideal world the stem actually see little to no force of any kind as that is the bearings job to transfer these loads to the frame.

I am civil engineer though, what do I know LOL.

[yamaha_george]

I am civil engineer though, what do I know LOL.

Hmm providing you did not design THAT bridge down south, or work for the company that built nuclear power stations in Japan, I would say your opinion is as good as most of us

[Cafe Racer]

Thanks. Those are all excellent opinions.

I will respond shortly. I just got off of a 48 hr shift at the firehouse.

Miguel

[Cafe Racer]

Overall a very nice build. I'd disagree about how to did the stem for the front suspension though. As I understand it, you took the stem out of the R6 and put the fzr stem in the r6's place. however it was too small to fit so you added a ring of chromoly I believe you said. And then you pressed it all in and it fit time. My issues comes from now having 3 different metal type in contact with each other, which is bad enough, but then, these pieces have the ability to spin on each other under load. I don't see if a very safe option. I would have gone with the welded el=nd of the FZR stem and turned it down to the right size and then had it pressed in. Less chance that anyone up front is going to go wrong. Beyond that, very nicely done. Bike is clean and ready to be ridden.

Thanks to all that responded.

The issue of using different types of metals together, or "Dissimilar Metals" is well taken. Yes, it is understood that the use of dissimilar metals in certain applications can result in corrosion.

Corrosion may result if the dissimilar metals are used in series while conducting an electrical current. Or, corrosion may result is if there is an additional property involved. This being something referred to as an "electrolyte". A generic example of an electrolyte would be salt water.

It order to prevent this phenomenon a simple barrier would need to be used. A barrier such as a shim or sleeve between the differing metals would work. This could also be performed with paint or plastic or...?

Another way to prevent corrosion is to isolate the two metals from exposure to the third property.

In my application, I feel that the use of dissimilar metals would be fine since they are not exposed to any types of acidic base nor are they exposed to any current.

Certainly, the unit could be more isolated from the enviroment. So I am fabricating a plug/cap to fit underneath the lower triple clamp. The cap will also enclose a grease plug. This should even further isolate the steering stem from any exposure to the environment.

Come to think of it, our bike is made and lightly based on dissimilar metals. Aluminum frame? Any worries about those "mixed metals"?


As for the thought that the sleeve itself is detrimental to the structural intergrity of the unit. I would have to disagree. The steering stem is not subjected to load bearing torque. It does not spin. Nor, does it move vertically. It is a static part of the bikes front suspension.

The lower triple clamp is engineered so that the steering stem cannot be removed vertically (upward) when in place. As well, it cannot be removed toward the downward postion when the steering stem in secured at the upper clamp with the steering stem nut.

The I am quite content in thinking that the unit as a whole is very secure. Fyi... the 4130 CRMO sleeve was heated in order for it to be pressed onto the steering stem. It is an extremely tight application.

I appreciate all of your inquiries.

Miguel

[yamaha_george]

Miguel,
Yes our bikes do have mixed metals and those who use stainless bolts in alloy engines will be most aware of the hassle.
Whilst our comments on using dis-similar metals may seem to criticize you and your work it is not the case, many people on the board are not that technically aware and none of us know it all . This is why we mention such details such as inter-metal corrosion, just to bring others up to speed and develop the knowledge base here.

The idea of adding a grease barrier to prevent the ingress of moisture is sound in principle.

By the way the fact that two material in contact will always have an electrical circuit going on ,that is the very nature of things, and any kind of damp atmosphere will just make the electrical circuit more active.

[Cafe Racer]

Miguel...

Whilst our comments on using dis-similar metals may seem to criticize you and your work it is not the case, many people on the board are not that technically aware and none of us know it all . This is why we mention such details such as inter-metal corrosion, just to bring others up to speed and develop the knowledge base here.

The idea of adding a grease barrier to prevent the ingress of moisture is sound in principle.

By the way the fact that two material in contact will always have an electrical circuit going on ,that is the very nature of things, and any kind of damp atmosphere will just make the electrical circuit more active.

I realize that I am new to this community. So it is obvious to me that others may think I was upset. Not the case at all.

If there is one thing I have adopted in my life as a fireman in San Francisco is being able to appreciate. Appreciate family, friends, colleagues and everything that comes with it. Be it comments or advice.

I love the collective "brain power" of the many different forum boards. As long as the comments continue my progress continually improves.

Cordially,

Miguel

[yamaha_george]

Miguel,
glad to hear it, as you say we all contribute in some way and absorb the thoughts of others and knowledge continues to grow.
S & F
Y-Geo.