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I’m putting this information together because it’s nice to have all the information you need is a single place without having to resort to a search engine.

These instructions will explain the basic tools, items and modifications necessary to install a VS1400 drive assembly on a VL800/C50 using a VL800/C50 driveshaft and spacer.

What’s the purpose of this modification?
To achieve a higher/sustainable top speed
To reduce engine vibration from high RPMs while traveling 70+ MPH
To increase fuel efficiency (arguably)

Tools Needed:
Metric box wrench set (up to 22mm)
Metric socket set
*Tork wrench
Metric allen wrench set
Snap ring wrench (straight/inner)
Needle nose pliers
*Rubber or plastic mallet
Several round rat tail files (or a ½” drill bit)
*Corded drill
Small parts brush
Bike lift or equivalent

Items Needed:
VS1400 final drive assembly (SKU: 27300-38845)
VS1400 spring for driveshaft (SKU: 09440-30008 )
C50/VL800 drive shaft (SKU: 27151-41F00)
C50 or VS1400 axel spacer (SKU: 64772-34201 or SKU: 09180-17088 )
VS1400 oil seal (SKU: 09283-30026)
VS1400 circlip (SKU: 09381-40003)
*Cotter pin (SKU: 04111-40308 )
Honda Molly 60 paste (or equivalent)
75W-90 gear oil

* Indicates optional

While the VS1400 drive assembly uses the same diameter driveshaft as the VL800/C50, the C50 driveshaft and spacer will need modifications to work properly with the VS1400 drive assembly. Otherwise, the driveshaft may put undue stress on the bearings.

As you can see, the VL800/C50 driveshaft is much larger than the VS1400 driveshaft:


This is a VL800/C50 driveshaft after it has been machined; modifications from the original driveshaft are noted in red:

(Admin Note - In the above picture the shoulder only gets pushed back 3/16" of an inch, not 3/8", tool used for undercut was 3/8" wide)

The shoulder, measured from the drive end should be 15-3/4" after the shoulder is pushed back as in the picture below.

The original VL800/C50 spacer can be shortened by 2mm, or it can replace it with another spacer that’s 2 7/8” in length. Make sure the replacement spacer is hardened steel. Here’s a stock VS1400 spacer next to a replacement spacer:


A replacement oil seal and circlip should be purchased from a Suzuki dealer. While the original circlip may be in good condition, it’s better to have a spare on hand incase the original breaks during assembly.


Pick up some Honda Molly 60 grease (or equivalent) from a local Honda dealer. Make sure the grease contains at least 44% molly (as recommended by Suzuki). Standard automotive molly grease should not be used as it does not offer adequate protection. The molly grease will be applied using a small parts brush to the splines on the driveshaft and drive assembly. I also applied it to the axel shaft and spacers.


Find a well lit/flat surface to work on; this modification can take several hours to complete so plan for enough time (it took me aproximately 2 hours). Secure the bike to the stand and proceed to remove the drive assembly using the Rusks’ “Checking Driveshaft Lubrication” guide found on the VR site.

It’s a good idea to put something underneath the front tire to help support the bike. When you remove the drive assembly and wheel, the bike becomes front heavy and may try tipping over.


Using a file (or ½” drill bit if preferred), enlarge the mounting holes for the VS1400 drive assembly. Take your time and make sure everything is lined up properly by test fitting the drive assembly multiple times. Forcing the drive assembly onto the frame will damage the threads on drive assembly. I used a rat tail file with a high speed drill to elongate the holes.


Attach the modified driveshaft to the VS1400 drive assembly using the circlip. Slide the seal onto the driveshaft and push it down until it is flush with the drive assembly. The seal keeps the molly grease in and contaminants out.


Slide the driveshaft into the u-joint and secure the drive assembly to the frame. If the shaft will not go back in all the way, try rotating it. If that doesn’t work, pull the drive assembly back out and try using a long broom handle to realign the u-joint that’s inside the bike (you may need to use a flashlight to see if the u-joint is straight). It took me a couple tries to get it to align properly.


Now is a good time to check your rear brakes for wear and/or clean them.


Insert the modified (or new) spacer into the VS1400 drive assembly. Assemble the wheel and brakes in the reverse order of the Rusks’ guide mentioned above. If possible, use a tork wrench and tighten everything up to specification (foot pounds can be found in a service manual). I didn’t have a tork wrench on hand, so I used the ole’ GNT (good n’ tight) scale. Once everything is back together, put the bike in neutral and gently spin the rear wheel. It will spin smoothly if everything is aligned properly. Fill the drive assembly with gear oil and you are done!


Take it easy on the drive for a little while. If something isn’t aligned properly, it will likely present itself within the first ~100 miles. Just like new brakes, gears take a little time to “mesh” together. Also, park the bike in an area where it can be monitored for minor oil leaks.
 

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Discussion Starter #2
I apologize for not getting any pictures of me actually “working” on the bike. I did this modification on my own, so no one was around to take pictures for me. Besides, I might have broken the camera.
 

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Great Post, thanks, actually makes it seem simplier than I prevously thought. I am still a little confused about the shaft though, I was under the impression the shaft had to be cut off then welded back or something
 

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mike in nc said:
Great Post, thanks, actually makes it seem simplier than I prevously thought. I am still a little confused about the shaft though, I was under the impression the shaft had to be cut off then welded back or something
There are a couple ways of doing the VS1400 modification. Basically, all you’re doing is shortening the VL800/C50 driveshaft 3/8” (where it contacts the u-joint) to prevent it from putting stress on the bearings. You can machine the existing driveshaft without cutting. You can cut the driveshaft, remove a small section and weld it back together. You can cut the original VS1400 driveshaft, add a bit of material and weld it back together. All methods have been done and are proven. The method I have shown here is the most DIY friendly and requires the least skill if you have access to a lathe and/or grinder. A couple members have even done it using a die grinder.

I had Aric ([email protected]) machine my driveshaft. He’s very well known and has done many driveshaft modifications. Also, he is very reasonable…
 

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So having the shorter splines on there isn't going to reduce the contact patch enough to cause failure? I would think that it would increase stress on the remaining portions by quite a bit. You're taking over half an inch of length out.
 

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Discussion Starter #7
Actually, you're only reducing the splines by 3/16". With the shoulder machined back, the driveshaft actually pushes further into the u-joint. The splines continue to make contact throughout.

I doubt 3/16” is going to make much of a difference on a hardened steel driveshaft that has very little or no lateral movement. Corrosion from water and heat would be a bigger concern for failure. As long as you continue to lubricate and check it every tire change, it will likely outlast most of the major wear components on the bike.
 

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OregonLAN said:
Actually, you're only reducing the splines by 3/16". With the shoulder machined back, the driveshaft actually pushes further into the u-joint. The splines continue to make contact throughout.

I doubt 3/16” is going to make much of a difference on a hardened steel driveshaft that has very little lateral movement. Corrosion from water and heat would be a bigger concern for failure. As long as you continue to lubricate it every tire change (using the correct lubricant), it will likely outlast most of the major wear components on your bike.
Ok, I was confused on which direction to machine the shoulder. Maybe you could make a note either in the drawing or the write up. Thanks for posting this!

3/16" is actually a lot of area when you look at how many splines there are. I haven't read of any failing yet, so it shouldn't be an issue.
 

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There, I updated the picture to help prevent confusion...

A few members here are running this modification without shortening the driveshaft. While they claim it works fine, I was advised by Aric that I should shorten the driveshaft. I took Aric’s advice considering he’s the machinist for Hamling.

I made the “how to” article primarily as a way of giving back to the community; I’m not trying to convince anyone that one method is better than another; surely I didn’t “invent” this method, nor do I recommend it over another. VR is an awesome community with some extraordinary members. I’m just trying to share…
 

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seawolf06 said:
So having the shorter splines on there isn't going to reduce the contact patch enough to cause failure? I would think that it would increase stress on the remaining portions by quite a bit. You're taking over half an inch of length out.
Take a look at the 1st picture. The lenth of the splines on the "drive end" of the driveshaft are shorter than even the shortened end of the u-joint end of the driveshaft. Every failed driveshaft I have seen has fail at that point and I wonder if it isn't a designed weak point. If it fails at this point, you can disengage that spinning driveshaft via the clutch, if it fails at the u-joint end, it is going to continue spinning until you bring the bike to a stop. Probabaly bovine scatology, but there must be a reason the splines are made that way.

Great write up BTW.
 

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OregonLAN,
Thank you so much for this very informative post.
I'll have my modified parts from Aric next week and will have this printed out and close at hand when I do my upgrade.
Thanks again!
D
 

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I followed the directions of this post

Thanks to all who researched this mod and to this post, I have a better functioning C50. Three and a half hours (1 hour to stab the u-joint) of following the directions (except 1/2 inch diameter bolt holes was still a little small) and I was cruising down the highway learning the best way to use my new drive train.

I read all I could find on the dj drive for months before tackling the project and with a couple of friends and VR's brains, the job wasn't that bad.

Special thanks to those I PM'd and gave needed info.

hd58
 

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Great write up and pics OregonLAN

I have two questions:

Why do you think you will get a higher top speed?

Why do you think the spacer needs to be hardened steel?
 

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Discussion Starter #19
C50std said:
Great write up and pics OregonLAN

I have two questions:

Why do you think you will get a higher top speed?

Why do you think the spacer needs to be hardened steel?
1. Well, I think you can achieve higher top speeds given ideal conditions. However, it takes a really really long straight/flat stretch of land. The fastest I’ve had mine up to is 93MPH (or 98 on the speedometer). I was unable to achieve these speeds before the drive; YMMV.

2. The original spacer is hardened steel. I would assume there’s a reason for it being hardened otherwise Suzuki would have used cheap gray iron. Where I work, we use hardened steel for items that are prone to wear...
 

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My C50 runs 95 mph top speed on a long flat stretch. I can accelerate to 90 mph with quick acceleration. From 90 to 95 is slow.

I like the quick pick up. I out ran a Kawasaki 1500 nomad at the race track. When we reach a speed around 60 0r 70 mph, I really pulled away like he was sitting still.

The C50 it a 805. It was made to wind up fast and tight. Engineers would have given the C50 a different ratio if anything else worked beter.

My C50 runs best at 70 mph. It's very smooth and the stock drive ratio gives me great acceleration at high speeds. Just ask the red mustang which tried to run me at 70 mph on I 40 at Hickory NC. Left it behind.
 
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