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Offline porcupinewhoa

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  • Bike: '19 Z900
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Self replacing front tire advice needed
« on: July 10, 2019, 05:38:57 PM »
Hey y'all, I'm more of a lurker than an active forum user but I haven't been able to find what I was looking for so I'm stepping out of the shadows and here's my first post! I recently punched a hole through my rear stock Dunlop with a drill bit because, well.. stupidity. Good news is now I get to replace the stocks since the stock tires are trash in my opinion and never belonged on there in the first place. I procured a set of Battlax S22's because I have an undying trust in the opinions of Ryan F9, and replaced the rear last night. It was my first time replacing a tire on a street bike but it wasn't that much different than a dirt bike tire change and went pretty smoothly. My concern is the front, I don't want to damage my front rotors when putting pressure on the tire during removal and installation using spoons. The manual warns you not to even lay them down without something under them to keep the rotors from touching anything. Should I remove them? I assume they are probably locked with red threadlocker. I like to do my own work but is it a better idea to just bring the bike to a shop and have them do it on an actual stand to avoid risking damage? I never intended to change my own tires on this bike anyway but after the local shop gouged the wheel on my R6 when changing tires last month I decided to try it myself but the front wheel on this strikes me as a lot more easily damaged than an offroad wheel. Sorry if this is too long winded, my ADD shows up whenever I start typing. I appreciate any advice, I've been impressed by the wealth of knowledge held by you guys. Cheers!

Offline TricksOfTheTrey

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Re: Self replacing front tire advice needed
« Reply #1 on: July 10, 2019, 06:29:56 PM »
I haven't changed the tires yet on the Z but here is two methods I rigged up in the past.

I have an old couch cushion that I keep to sit on when making repairs or working on the ground. I once put the wheel directly on the cushion in a pinch. Not as great of leverage as a solid surface but prevented any warping of the rotor.

The other method I did was using a nice solid card board box with a surface area larger than the rotor. I cut a hole the size of the rotor, allowing the wheel to sit on top while the rotor was suspended in the box. When laying flat with the wheel on top, the size of this box was only about 4 inches from the ground up to the wheel. That small size made it easy to beef up the strength of the box by folding other boxes or using 2x4 pieces of wood to add support inside the edges and corners to prevent it from crushing while working on the tire. Under the rotor I had blocks of styrofoam so that as the box did lose a little rigidity, the rotor was only pushing into styrofoam. ....I randomly came up with this idea in the moment as I had a bunch of boxes that needed to be thrown out.

I'm sure someone can offer more professional solutions than mine, but thought I would share to maybe help spark an idea of how you can make it work for yourself. Good luck! Tires can be a serious PITA sometimes.

Offline porcupinewhoa

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Re: Self replacing front tire advice needed
« Reply #2 on: July 10, 2019, 08:41:50 PM »
Thanks for the response, I've decided to build a small box just for this purpose, in the mean time I brought the bike up to a local independent shop that charges 4 times as much but has a far better reputation than the dealership. The riding season is too short in Maine to be missing days screwing around. I'm basically going to do the same thing you did but in a more permanent manner and I think it will work out well. Thanks again, cheers!

Offline zed9

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Re: Self replacing front tire advice needed
« Reply #3 on: July 11, 2019, 12:03:41 AM »
Welcome.  :821:
You really don't need a box. Just lay a couple of 4x4's on each side of the rotor.

This bike uses a threaded axle casting so when you reinstall the front wheel be mindful of making sure it's lined up real good. Wouldn't want to ruin those threads. Use an anti seize to prevent galling.

Offline porkchop

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Re: Self replacing front tire advice needed
« Reply #4 on: July 11, 2019, 03:25:16 PM »
*Originally Posted by porcupinewhoa [+]
Thanks for the response, I've decided to build a small box just for this purpose, in the mean time I brought the bike up to a local independent shop that charges 4 times as much but has a far better reputation than the dealership. The riding season is too short in Maine to be missing days screwing around. I'm basically going to do the same thing you did but in a more permanent manner and I think it will work out well. Thanks again, cheers!

Friends change their own tires so the tools are bountiful to me, 2 have HF stands so it's clamped down and not touching but the ole carpeted 2x4 box trick worked nice for years.
I felt bad "using" them for the equipment so bought a MOJO bar for us instead of the spoons, long fat pinch bars or screwdrivers  :001:
One buddy runs Dunlops on his Goldwing and has some really stiff ass sidewalls, he'd struggle to spoon them and took both of us at times, PITA.
First time I introduced the MOJO to him + the modified HF stand he was like "no more F'in around, that is staying here"... It does, I know where to go.
We also use balance beads, easy as well.

It's not the cheapest tool for the # of times it may get used but good ones are an investment + way more managable than that POS HF bar and "work smarter, not harder"... We go ride!   :028:

https://www.mojotiretools.com/mojoweb.htm

"The ride is the reason"

Offline Cazzy_R

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Re: Self replacing front tire advice needed
« Reply #5 on: July 11, 2019, 05:50:43 PM »
*Originally Posted by zed9 [+]
This bike uses a threaded axle casting so when you reinstall the front wheel be mindful of making sure it's lined up real good. Wouldn't want to ruin those threads. Use an anti seize to prevent galling.

 The Service Manual specifically states:
 "Do not apply grease to the threads of the axle"

Cazzy_R

Tighten it 'til it strips then back it off half a turn.

Offline zed9

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Re: Self replacing front tire advice needed
« Reply #6 on: July 11, 2019, 05:59:27 PM »
*Originally Posted by Cazzy_R [+]
The Service Manual specifically states:
 "Do not apply grease to the threads of the axle"
Don't listen. Use anti-seize and torque to spec. I say so.  :169:
You'll be crying when you gall those threads.

Offline Cazzy_R

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Re: Self replacing front tire advice needed
« Reply #7 on: July 11, 2019, 06:34:09 PM »
*Originally Posted by zed9 [+]
Don't listen. Use anti-seize and torque to spec. I say so.  :169:
You'll be crying when you gall those threads.

 That's fine I just wanted to let everyone know what Kawasaki explicitly instruct. Not recommend. Instruct.
 Forum members can can decide for themseves who knows best.
Cazzy_R

Tighten it 'til it strips then back it off half a turn.

Offline zed9

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Re: Self replacing front tire advice needed
« Reply #8 on: July 11, 2019, 08:41:08 PM »
*Originally Posted by Cazzy_R [+]
That's fine I just wanted to let everyone know what Kawasaki explicitly instruct. Not recommend. Instruct.
 Forum members can can decide for themseves who knows best.
I think they don't want the axle to back out. It won't, especially if the clamp bolts are properly torqued (I anti-seize those as well  :005:).
I cannot even imagine what harm it would do.

Offline Cazzy_R

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Re: Self replacing front tire advice needed
« Reply #9 on: July 11, 2019, 11:07:56 PM »
*Originally Posted by zed9 [+]
I cannot even imagine what harm it would do.

It is tensile load which applies the clamping force into a bolted joint NOT torque. We cant easily measure the tensile force so it is converted to a torque figure for convenience and practicality. The torque figure to apply a given amount of tensile force is determined from known values, calculation and testing. There are various factors which come into play when determining a suitable torque value such as materials, thread diameter, thread pitch, thread form and significantly friction.

A torque wrench can only measure the effort (resistance) required to tighten a fastener and as we all know when you lubricate a thread it is much easier to turn. Therefore in the case of a lubricated thread the resultant tensile load can be significantly higher than that of a dry joint because due to reduced friction the bolt will have turned through a greater angle before the wrench goes click.

In the case of the Z900s front axle we have a large diameter steel bolt engaging with a significantly weaker aluminium thread.
Although galling is undesirable ripping that thread clean out of the fork leg is significantly more serious.
If you lubricate the thread it you WILL IMPART MORE TENSILE FORCE than Kawasaki intended.

I too apply anti-seize to some threads and it is my assumption, rightly or wrongly, that it is expected that most threads get lightly oiled and that is included in the torque setting calculations. However in the case of this safety critical joint requiring a high clamping force and correspondingly high torque setting: When the manufacturer explicitly states not to grease the thread I will do as they say.

When I fitted my Metzelers I reassembled the front axle dry and it didn't gall. Just sayin. :150:

Oh yeah no additional or undesireable (in Kawasaki's eyes) tensile forces were inparted either. Just sayin  :038:
Cazzy_R

Tighten it 'til it strips then back it off half a turn.