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Discussion Starter #1
I changed my drive shaft out due to universal joint going bad. I replaced the bevel gear assembly along with the drive shaft. There was a small spring that I inserted into the drive shafts spline closest to rear wheel drive box per OEM diagram. I cannot get the transmission to engage/turn the rear wheel. What would be most likely cause?
 

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So to clarify you get the Bike into 1st Gear but the rear wheel turns free like it hasn't engaged with the Transmission ?
 

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Discussion Starter #3
It sounds like solid gear changes to each gear, but rear wheel spins free. There's no attempt to turn rear wheel at all.
 

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Did the drive shaft engage with the rear drive unit? When you turn the wheel does the shaft turn? The rear wheel will turn everything all the way to the transmission output shaft. If you have one pull the rubber boot at the front of the shaft and see if it turns.
 

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It would be helpful if you provided the exact model and year of your bike. That way we can look at parts diagrams to try to figure out what might have gone wrong.
 

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Discussion Starter #6
Did the drive shaft engage with the rear drive unit? When you turn the wheel does the shaft turn? The rear wheel will turn everything all the way to the transmission output shaft. If you have one pull the rubber boot at the front of the shaft and see if it turns.
I'll do what you suggest and tell you the outcome.
 

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Interesting problem. Can you tell us the symptoms of the u-joint going bad? Was it just getting noisy or were there other issues? Was there any other installation problems that you ran into? Did you install the spring in the correct orientation? I think your spring has a very slight taper and the large diameter faces the pinion gear nut if it is similar to my ZN shaft drive.

Swapping out the bevel gears is a very tricky job and one that I have never had to do. I hope you have a service manual to help with shimming for proper bearing preload and adjustment of proper gear clearances and proper tooth contact.

For reference, here is the exploded view of the drive train.

 

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My son's Vulcan 750 had the splines on the rear drive wear out.(60,000 miles) The bike would not drive and he thought it was the transmission. It would just grind/click. It was hard to hear if it was from the front bevel gear or the rear drive assembly. This could have sounded like the U joint being bad. On that bike the service manual called to remove the drive and grease the splines when you replaced the tire. To make things even worse Kawasaki didn't lube them during assembly. This goes along with my previous post about the rear wheel turning the shaft. We replaced it with a unit off EBay.

With the items you replaced there could be a disconnect at the bevel gear to the transmission, the new bevel gear box gears, the shaft front connection, or the shaft rear connection. You need to find where the disconnect is before you will be able to fix it.
 

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Discussion Starter #10 (Edited)
Interesting problem. Can you tell us the symptoms of the u-joint going bad? Was it just getting noisy or were there other issues? Was there any other installation problems that you ran into? Did you install the spring in the correct orientation? I think your spring has a very slight taper and the large diameter faces the pinion gear nut if it is similar to my ZN shaft drive.

Swapping out the bevel gears is a very tricky job and one that I have never had to do. I hope you have a service manual to help with shimming for proper bearing preload and adjustment of proper gear clearances and proper tooth contact.

For reference, here is the exploded view of the drive train.

For reference, here is the exploded view of the drive train.

[/QUOTE]
Thought it was bevel gear or bearings. Sound seemed to be marbles hitting inside of transmission. Once I got back end off, I saw u-joint was badly chipped, cracked, and had lots of play. Bevel gear and bearings were in excellent shape indicating almost 0% wear. There were no installation problems other than not engaging/turning wheel.

I thought I installed the spring in the correct orientation but that's definitely something I'll check.

I did not swap out bevel gears. I used the complete bevel gear assembly that came with the shaft I ordered and included the exact same shims as my older one.

Thank you!
 

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Is there any chance the shaft/parts you ordered are not the correct ones and that the splines are not engaging?


Even though you have a matched bevel gear set, the backlash, etc needs to be checked and adjusted as well as bearings pre-loaded. Not doing this however, should not be the cause of your issue but it will affect how long those gears will last. Do you have a service manual?

 

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Did you use item 610 in the drive shaft dia. to lock the drive shaft onto the front bevel output shaft? If not the shaft can slide back and disengage from the drive.
 

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Discussion Starter #13
Is there any chance the shaft/parts you ordered are not the correct ones and that the splines are not engaging?


Even though you have a matched bevel gear set, the backlash, etc needs to be checked and adjusted as well as bearings pre-loaded. Not doing this however, should not be the cause of your issue but it will affect how long those gears will last. Do you have a service manual?

The shaft sent to me was an inch too short! The rear splines couldn't reach far enough to engage. The u-joint was so messed up on the old one that I didn't realize the length difference. I ordered another shaft that claimed to be off a 2005 Vulcan Classic 1600A which is exact match. I got bike back together and everything works smooth!!!
 

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Discussion Starter #14
PROBLEM SOLVED!!!

THANK YOU TO EVERYONE FOR YOUR THOUGHTS, POTENTIAL ROOT CAUSES, AND DIAGNOSTIC SUGGESTIONS! I FOUND ALMOST EVERYTHING VERY HELPFUL!
 
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