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If you are going to mod it for the Final Drive Mod, then yes, this is what has to be done to the C90 shaft to use it for now on the mod...
 

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I have been reading a lot about the Mod of adding a C90 drive to a C50.
A lot of threads to read and go thought but I think I got all the info to make drawing of the parts that need to be modified or made. I'm going to post the drawing and see if any of you Volusia riders would double check me on my drawings.
One drawing is of the shaft mod.
One is of the Bushing.
One is of the spacer.
Be careful about dimensioning from BOTh ends on this sort of drawing. The critical dimensions are overall length and the length to the shoulder where the driveshaft enters the U joint.
The correct Dim is 15 3/4 to the shoulder. I have a drawing on a sticky of a C50 shaft and how that's machined so the two should correllate.
Just an FYI to really watch the overall length and to the shoulder!
Cheers and enjoy the drive!
 

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Dave,
Assuming my calculations are correct, the difference in the shaft drawing in this thread and the one you have created are as such:
Overall length - this drawing is .25" shorter
Length to shoulder - this drawing is .052" shorter

Are these within tolerance enough that it shouldn't make a difference one way or another or is the overall length a critical measurement as well? I suspect that it is not.
 

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I am not speaking for Dave (Because with his age and mine as a comparison...he's still wet behind the ears...) but I have a hard time seeing .052" much less measuring it but with the variable compression of the shaft spring, I see this as being of no consequence...JMO
 

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Disclaimer:
I mean I don't claim to be the expert but if'n it was mine, I'd be happy within that range...there are people that deal with that being a "Grand Canyon" type discrepancy...
 

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Travis- The shoulder plus minus 1/16 is not a worry. but the length of spline needs only to be 1.2 -more than that and it sticks past the splines end and into the U joint- See the drawing on the U joint to driveshaft. The .098 is taken off to make sure no interference with the inside spider of the u joint.
I suspect others have not machined the length but I would! to make sure I would make the spline part that goes into the U joint 1.2" only as the splined portion of the C50/M50 U joint is only 1.08" long total.
Lots of differing info on this- But I did spent quite a while and triple checked all the dims while doing those drawings.
Cheers,
 

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At one time we were trimming 2mm off the u-joint end of the driveshaft splines.

Theory being, if the shoulder get's moved back .200, the splines insert into the joint .200 further and would that conflict with the knuckle action of the joint.

After looking closer, I don't think that 2mm is critical and it does effect "overall lenth" in the drawing.

The critical measurement is from the coupler end of the drive shaft to the shoulder,...15.75 inch, achieve that, and you've got it.
 

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Thanks again. I'm trying to figure out all my options. I bought a VL1500 Final Drive and drive shaft on e-bay today. I have e-mailed Dave Hillis to get pricing info for the shaft chop/weld, but I also have a friend who has a fabrication shop whom I believe could do the work as well. I just wanted to provide the most straightfoward drawing for him to use in the modification. I may take the drawing depcting the chop/weld and demention it with the measurements from Dave's C50 'shaft mod to get most clear version of what I need.

Is the length of the splines a critical measurement? Again, I would assume not but I could be wrong.
 

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Hi travis- Its not critical ..its just the splines on the Ujoint are only 1 082 long so anything more than 1.2 on the driveshaft splines (accounting for a chamfer on the splines) will stick out the end of the Ujoint splines and into the area where the spider resides. I do not KNOW catagorically if it interferes, but the extra spline does nothing for you it just sticks past the Ujoints splines- Personally I would trim it off..
Thats me tho! :) I am a non certified machinist- Spent many years machining since I was 16 and I'm 48 now (BB says I'm wet behind the ears...LMAO).. machine shop in my basement...LOL
its not a big deal to trim the end!..
 

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A C90 driveshaft stub inserted the same depth as a C50 spline. Note the angle of the u-joint.



Same stub inserted full depth (ballz deep, as we like to say). Again note angle of joint.



Look at how far past the yoke the splines enter. Note, this is a C90 driveshaft spline in a C50 U-joint.



These are the pics that started the discussion.

btw that lathe actually was a piece o crap.
 

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Yes, but understand this to, you can reverse the u-joint...and put the long side towards the driveshaft...
 

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Ahhhh Bird... Yes However you could (if you REALLY wanted to) Put your front wheel on the back... But it doesnt make it right!
What Viper showed is what can happen. So there's zero risk and all the benefits of taking that 1/4" or whatever it is OFF- of you risk Serious damage.
All I am pointing out is there is ZER0 benefit leaving the splines on - they stick into an area without splines so theres no need for them to be there other than crowding the U joint- Hack it off! Be safe
 

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A C90 driveshaft stub inserted the same depth as a C50 spline. Note the angle of the u-joint.



Same stub inserted full depth (ballz deep, as we like to say). Again note angle of joint.



Look at how far past the yoke the splines enter. Note, this is a C90 driveshaft spline in a C50 U-joint.



These are the pics that started the discussion.

btw that lathe actually was a piece o crap.
Great pics! Man I wish I saw these before..Nice illustration.
BTW My lathe is a POS as well... Cheap N nasty with a milling machine attachment- BUT I can get some wonderful results fron it- All depends how you set it up..
Thanks for these pics Viper- Nice...
Dave
 

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That is a great set of pics and exactly the information I was looking for! So it seems that for the C90 shaft to work even with the length chop and weld, a 1/4" of spline needs to go as well.
 

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Bingo!
 

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Well it just so happens that I have a C50 u-joint and a C90 driveshaft setting infront of me.

U-joint spline lenth = 1.0 inch

C90 spline lenth = 1.35 inch

I think lopping off .25 off would be perfect.
 

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I was only stating a fact that I believe now has been proven that you can use the u-joint to affect some of the modification needs...and the front tire/rear tire wasn't a good analogy...don't make me...
 

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Bringing it back

If I were to bring these dawings to a machine shop are they detailed enough for the shop to know what to do? I am not savvy enough to explain this to the shop so I am hoping that these drawing will speak for themselves.

Thanks in advance.
 

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I would certainly think so.

Those are clear accurate drawings and the procedure is straight forward.

Cut, shorten, sleeve, reweld and true up.

Critical measurement is drive end of driveshaft to u-joint end shoulder.
 
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