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Installing a Cudney Racing Clutch Kit

12/23/2003

Cudney Racing Clutch Kit Installation

One of the most popular mods that sledders make to their machines is a clutch kit. There are several good kits out there, but one of the most popular kits discussed on DOOTalk.com is the Cudney Kit from Cudney Racing. As with all modifications, there are always the questions like 'How hard is it to install?' and 'What will it do for my sled's performance?'. This article will attempt to answer some of those questions.

I will admit that I am not an expert mechanic. I can get through a lot of the basics, but working on clutches has always been something I've avoided. So when it came time to install the Cudney Kit on my '03 600 HO, I enlisted the help of my friend Corey who is often found turning wrenches at Jere's Repair, one of our DOOTalk Sponsors.

The Cudney Kit consists of Instructions, Helix, Primary Spring, Secondary Spring, and an Adjustable Pin Kit. The instructions are very clear and easy to follow. And as any of you know from dealing with Bill at Cudney Racing, his phone number and email are included with the kit.
 
The first step was to remove the belt cover, belt, and pull the primary Clutch and RER Secondary Converter from the sled. To give us more room, we removed the entire side panel of the REV. With the primary Clutch, we just pulled off the movable half. Here you can see that Corey has removed the movable half and is pulling off the Secondary Converter.
 

The next step is to replace the spring and pins in the primary clutch. You will need to have button retaining clips when removing the Governor Cup and a tool to compress the spring when removing the spring cover assembly. We used a tool fabbed by Jere at Jere's Repair for our work. Open the spring cover assembly and replace the stock spring with the primary spring included in the kit. Put the cover assembly back on using your spring compression tool and make sure that all alignment arrows line up.
 
  

 
Next remove the stock roller pins and replace them with the 3 adjustable pins included in the kit. Start out with the weight recommended for your sled in the instructions.
 

Now it is time to work on the secondary converter. You will need to use a tool to compress the secondary converter spring and remove the retaining clips on the helix. Replace the stock spring and helix with those in the kit and reassemble the secondary converter. You will notice that the Cudney spring is much longer than the stock spring you are replacing. The trickiest part of this operation is getting the splines lined up as you compress the spring. Note: You will notice that our closeup of our spring compression tool does not show the retaining clips and ring that hold the helix in place. We also noticed that right at the point where those parts were needed :-)

  

Reinstall the Primary Clutch and Secondary Converter to the appropriate torque specs, replace your belt and cover, and get ready to try it out. Cudney Racing recommends that all pin weight tuning be done with your TRA clickers in setting number 3.
 
So, the question you've all been waiting to have answered, is what does it do to the sled. On my 600, the first thing I noticed was that the engagement was now at about 4300 RPM's. The other thing that was immediately noticeable is that the sled feels more responsive all through the powerband. It backshifts sooner and keeps the RPM's higher at slower speeds so the power is always available right at your thumb.
 

To further test out the performance of the kit, I needed to line it up against another sled. My main riding partner rides a 2002 ZR 800. Last season, we lined them up several times to see how they compared in various conditions. So this was a perfect test to see how the sled was now performing. Prior to the kit, my 600 could run with his 800 up to about 75 MPH. I know, there's no way a 120 HP sled is going to run with a 140 HO sled. But, after many side by side runs last season, we attributed my success to the 100 LB advantage I had between sled and driver weight and the fact that the REV would hook-up with very little track spin. All the power produced by the REV was moving the sled forward. What's it like now you ask? Our tests were run on a slight uphill run of about 400 - 500 ft in low snow conditions. The Cudney Kit is definitely putting more power to the track, but now there's a lot of track spin. The good news was that even with track spin, the REV still stuck with the ZR up to the 75-80 MPH point on repeated runs. The REV is not yet studded , which should help, and there are suspension adjustments that can be made to help the hook-up of the REV off the line. With the proper hook up, the REV should give the ZR a good run. The next test we did was a rolling start. The ZR is very strong in the midrange and the expectation was that the REV would be beat. I was very happy to find that in a rolling start of about 25 MPH, the REV ran side by side with the ZR right to 80 MPH. The advantage of this kit is really felt in the midrange of the powerband. There was not enough room to get a feel for any difference on top speed performance. I set my kit up with the recommended pin weights for my sled and I was running about 7800-7900 RPM's as full throttle.

The Cudney Clutch Kit is a very easy modification that, with the right tools, can be installed in about an hour. The results are a more responsive sled that is very strong in the low and midrange. For those of you that are looking to spend a lot of time dragging other machines, you may need to work on getting all that new found power to the ground instead of throwing snow at the spectators. I had a few questions before and after my installation and Bill at Cudney Racing was always quick to respond and help out with all of his clutching knowledge. Overall, this project was a great success.

Report submitted by REV-Rider