My transmission conversion on a Craftsman Professional - Snowblower Forum : Snow Blower Forums
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post #1 of 17 Old 07-27-2016, 11:26 AM Thread Starter
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My transmission conversion on a Craftsman Professional

I actually found this forum by searching for information on the Craftsman Professional machine that had a known problem with their transmissions breaking repeatedly. My brother had bought this machine just 2 or 3 years ago and it had suddenly broken.



Knowing that I'm a tinkerer, he asked me if I wanted it for free. Well why not?

I found this thread:

https://www.snowblowerforum.com/forum...on-issues.html

That confirmed that just swapping out the transmission with a new one was not worthwhile. With the machine otherwise looking brand new, I thought it would be an interesting project to try and convert it to a standard friction disk type. It's a nice machine, with heated grips and electric chute controls. I took measurements of the transmission box and then started looking up kijiji ads for old snowblowers being sold for parts. I responded to a few ads by asking about the width of the transmission box. Toro machines seem to have rather wide butts, but one MTD machine had one that was actually about 3/8th of an inch narrower. The height was a good inch less and length looked about right. At first I was thinking of taking the various transmission parts and then building them into the Craftsman transmission box but unless the width was almost exactly the same, this would have been a lot of work in getting things shimmed and aligned just right. Then some openings such as the ones for axle bushings are actually punched in a specific shape and flanged. That's when the box-within-a-box idea seemed attractive if it could be made to fit. This seller was right in my neighborhood too so I went over and checked it out. I wasn't interested in the engine and he was willing to remove it to sell it separately, so I struck a deal for $50.



Always sign your snowblower parts donor card!

Last edited by guyl; 07-28-2016 at 12:45 PM.
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post #2 of 17 Old 07-27-2016, 11:37 AM Thread Starter
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So I took the Craftsman machine apart and removed the transmission with it's plastic gears and all.



Here I hadn't removed the axles yet. These are separate axles (this transmission allowed for power steering) and to remove them you need to remove the wheel bearings.



In examining it, I could see that it was actually a CVT design like a snowmobile, and even the pulley on the engine was made of plastic with sheet metal crimped onto the plastic sheaves. Ugh. The speed control enabled reverse inside the transmission, and pushed on one of the driven CVT pulley sheaves to vary its width. The engine CVT pully has a spring loaded sheave and takes up the slack. The gears driving the wheels are also plastic. The transmission housing had broken where the input shaft and pulley enter it, so that pulley was actually flopping around. This caused it to hit the auger pulley and make a nasty gouge in it:



That got straightened out and smoothed.

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post #3 of 17 Old 07-27-2016, 12:57 PM Thread Starter
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The underside of the MTD transmission. Classic stuff.



It got cleaned up and the rust was buffed off the axle. The friction disk was also cleaned up, and a new friction wheel ring was put in. The axle had also developed a crack on one side where the key for the large drive gear is located. Fixed that up with the arc welder and then ground smooth.

This is the MTD transmission box once everything was removed:



Now the same box once I had cut away the front flange, bottom edges (removed almost an inch) and the back end (right to where the large drive gear extended to, about a quarter inch):



Metal cutting was all done with my trusty DeWalt reciprocating saw. That tool is so handy it isn't funny...
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post #4 of 17 Old 07-27-2016, 01:13 PM Thread Starter
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I test fitted the MTD transmission box inside the other box several times. One challenge was getting around the mechanism for the auger control. The friction disk plate's mounting holes are quite close and it had to swing freely. The mounting rails for the Craftsman transmission were perfect for mounting the MTD box. Note how I had to invert the top left bolt, to avoid interference with the large wheel drive gear underneath:

.

For the traction belt, I could not find a standard belt that was close to the required length, but the auger belt from the MTD was just over an inch longer than needed, and I figured that adding an idler would make things just about right. I took the idler mechanism from the MTD's bucket:



And transformed it into a pivoting, spring loaded idler:



Did I mention that it's a tight fit?



The spring pulling on the idler is on the other side, as seen here:



To keep everything easily serviceable, I used hole saws to make large openings in the Craftsman transmission box to allow access to the bearings and bushings of the MTD box:


Last edited by guyl; 07-27-2016 at 01:17 PM.
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post #5 of 17 Old 07-27-2016, 01:37 PM Thread Starter
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Last but not least was adapting the controls. Now I have not had enough snow blowers in my life to say what is standard, but the ones I've known always had the auger control on the left and traction control on the right. Well this Craftsman was the other way around... Since the MTD friction disk was designed with the traction control on the right, I looked into actually inverting the controls, and it turned out to be quite easy.





The pull cable goes down to the relocated pulley at the bottom right. You can see the old holes for it on the left. The auger control's cable now makes a diagonal to the top left. The CVT transmission's control had a bellcrank at the top to convert horizontal motion to vertical, and then another one at the bottom to make it horizontal again. That got removed and the control arm for the MTD friction wheel was extended and offset with flat bar to both make it easier to connect without interfering with the other controls, and to reduce travel over the machine's gear selection lever, because it had greater travel and it was hard to get low speeds without this change. In process control language, I had to reduce "gain". I also had to adjust the "zero offset" so that the friction wheel was over the center of the friction disk when the gear selection lever has set between the forward and reverse gears.

I was able to use the better looking (and much newer) Craftsman wheels on the MTD axle. The axle is bit longer than needed and I ended up drilling new bolt holes for the new wheels. I also applied a coat of anti-seize paste to the axle before putting the wheels on, in an attempt to at least slow down the rust that makes them hard to remove in the future.

I even reversed the control labels on the console:




I now have a machine that should last me many years and with easy to find transmission replacement parts should the need arise.

Last edited by guyl; 07-27-2016 at 01:44 PM.
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post #6 of 17 Old 07-27-2016, 03:37 PM
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Nice conversion!

Garage:
MTD....2 stage(modern 8.5 HP) not my favorite
Honda HS622 TA-B - acquired at an auction- nice machine for it's size.
Toro S-140- Picked it up on trash day... it runs, sort of.
Yamaha YS 240 TB "Ricky" latest Craigslist find- on the bench now.
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post #7 of 17 Old 07-27-2016, 08:32 PM
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nice job! lotta work I'm sure but it comes with the satisfaction of doing the job right!
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post #8 of 17 Old 07-28-2016, 05:56 AM
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Nice write up on that job. All you need now is some snow.

I'm pretty much retired from the forum thing, but I check in every now and then.
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post #9 of 17 Old 07-28-2016, 12:35 PM Thread Starter
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Thanks for the comments! Yes, I get at least as much fun and satisfaction in planning and doing these projects than in using the finished product afterwards.
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post #10 of 17 Old 12-19-2016, 10:41 AM Thread Starter
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I just thought I'd provide an update now that the snow has finally arrived and I've had a chance to test drive my frankenblower a couple of times.

So far so good! These have been rather moderate snowfalls but enough to get a good idea of how things are going. First there was just getting used to the machine. The first problem was that the "up" button for the electric chute control was intermittent. This was an easy fix by cleaning the contacts on the terminals and reseating the connector firmly. I initially had a few apprehensions about things like electric chute controls since they leave you with no alternate way of accomplishing their function if something fails. But the convenience is a luxury that quickly becomes second nature. I always start clearing my driveway by first doing the part near the house where I need to back up often to move the snow farther out, then I go do the heavy stuff at the street that is also full of salt and that is most critical to have done in case I rant into something like a broken belt or other show stopper, and finally I do the part in between that requires long passes back and forth between both ends, both blowing the snow to a single side. Since the ends are already done when I do this part, I basically do it without stopping, just making powered U turns at each end. Blowing to a single side means I have to turn the chute around 180 degrees too. A quick thumb press on the chute button while I turn the machine around makes this really easy.

The second issue was that the auger belt was slipping. I had to adjust the tension on control cable to insure that the spring in line with that cable was at least visibly getting stretched a bit. Both the auger and traction control cables are actually made up of two cables (that I spliced using a homemade cable clamp) from the two original machines. I need to find a more elegant clamp solution than the small metal plates with screws that I used. Any ideas?

The final issue was the control handle interlock that I ended up disabling because it was now "backwards" due to my inversion of the control cable functions (see previous posts). This function is usually handy when you want to free up a hand to adjust the chute position while still moving and blowing snow, but the thumb operated chute controls makes this rather unnecessary.

The one remaining thing is that I don't have a nice slow forward speed. The speed control has evenly spaced notches that must have been fine for the original CVT transmission but that are less suitable for a friction disk transmission, for which the notches are usually more exponentially spaced. I'll have to experiment with the control rod length adjustment to try and get a nice slow crawl in position 1.

Overall it's been a fun experience designing this modification. I'm still wondering what all the other machines sold with this same original crappy transmission have become.
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