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Brand New Drive Ring Destroyed

5.5K views 77 replies 19 participants last post by  l008com  
#1 ·
So last year I was fixing up this old MTD machine. Its drive wring was worn almost completely away. No biggie, they're easy to replace. So I replaced it with a brand new one. Then packed the machine away for the Summer. This Winter, we've had four smallish snow storms. I fired the machine up and used it to clear my driveway. Its not that big of a driveway, I live in the suburbs, not out in the middle of nowhere.

So here are the results, pure madness:

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The original worn out drive ring that needed to be replaced ^

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The new replacement drive ring installed and looking ready to go ^

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The new drive ring after four small snow storms, about 4 total hours of use! ^

What the hell??? How does this even happen? These drive rings are supposed to last YEARS. This one failed spectacularly after just a few hours. Yes, it also gouged the hell out of the friction disc. Those strips are, I assume, the rubber. It didn't wear out, it just peeled away into these strips.

Has anyone seen this happen? This seems like complete madness to me!

Also if you noticed, the first two pics are youtube screen captures. I actually made a video about the repair process. MEANING I have a very detailed history of exactly what I did and how I did it. Although I can't think of any possible way to mess up, that would cause this??


I don't even know what to do. I mean I can replace the rubber again, but will it just look like this again after just a couple of hours of use?
 
#29 ·
I had a newer wheel go on me in a similar fashion. I was pushing the machine through some very wet berm along the curb which was backed up and causing flooding from snow melt. In my case it probably was slipping due to water intrusion on the disk drive. The heat build up (like YR mentioned earlier) was what caused mine to fail I am pretty sure. The drive just quit and the blower would not move. It looked very similar when I took the bottom pan off. With the exception of an undamaged disk. I got lucky with that.
 
#31 ·
Here are my thoughts on this one.

When i see your video at 1:28 i see the drive lever moving the drive disc / plate forward to make contact with the friction wheel rubber, at 13:25 i see you buttoning it all back up.

What i do not see is the drive disc/plate return spring (bottom right) that is supposed to retract that drive disc / plate back into position off of the friction disc rubber when not engaged. That might make the drive disc/plate rub the friction disc rubber continuously, not enough to drive the machine forward as it has no mechanical leverage with the cable to engage the drive mechanism but enough to prematurely wear the rubber itself.

Attached is a picture and you can see the plate return spring (bottom right corner), alongside 2 other springs one to engage via drive lever (bottom right) and a third brake (centre).

When you buttoned up the machine i did not see these two springs at all.

Cheers,

Image
 
#32 ·
Welp, I just looked up the cost of a new friction disc and **** a brick.

What do ya'll think about taking the disk out and sanding it smooth? Its aluminum so it should sand fairly easily. It will be thinner when I'm done but despite the number of alumium chips we can see, I don't think THAT much material was removed, so I think it should be thick enough to still work. With a palm sander, some medium grit fallowed by some fine grit, I should be able to get it pretty damn smooth.
 
#33 ·
Well I guess I left out some key details and my last reply . . . lol

So I'm not sure if the missing springs are what caused this. Like on the one hand, they pull the parts away from each other, so I can see how having them missing could cause a problem. At the same time, with nothing pulling the parts together, I would expect the fiction created to be minimal at best. Who knows. If I had the time I could do a bunch of long tests and see how much wear was created with and without the springs. But I don't have that much time.

Also maybe the ebay rubber drive ring was fine, and it wore out due to the missing springs. Or maybe the missing springs weren't really a problem, and the drive ring was just made of really cheap rubber? Again, who knows.

So I'm going to go ahead and replace both missing springs (the return for the friction drive and the return for the auger belt engager), and I'm going to replace the friction wheel with a genuine MTD ring.
HOPEFULLY this was just a minor speed bump, and the machine runs well, and reliably, after this!

And as previously mentioned, I'm not going to replace the friction disc, but I will sand it smooth as long as it seems salvageable once I remove it.

Anyone have any other thoughts? I don't. Zero additional thoughts. Other than the thought that I can't wait to get this machine out of my life so I can move on to the next one :D

Oh speaking of the friction disc, there are a million youtube videos for removing the friction RING but I can't find any for removing the friction DISC. Seems like there must be some trick to it since you can't hold the "other" side of the bolt because its on a bearing behind the disc.
 
#36 ·
Ok with the new springs on the way, I look a peak at the drive train today. Actually what I did was zip tie the friction plate AWAY from whats left of the wheel so I could start up the engine without making things worse.

While I was in there, I was looking at where the springs are going to go. The auger belt tensioner spring is very clear. Its the yellow line in my image.
But the drive plate spring is another story. Where is it supposed to go? I can see where it hooks on to the plate carrier itself, but there doesn't appear to be any place to hook the other end. Is it supposed to ALSO connect to the auger belt tensioner? I guess that would work if the length of the spring is right. Its pulling so perpendicular-ly, that its probably not going to make it work any better or worse. Is that the secret?

Image
 
#39 ·
While I was in there, I was looking at where the springs are going to go. The auger belt tensioner spring is very clear. Its the yellow line in my image.
But the drive plate spring is another story. Where is it supposed to go?

View attachment 238041
I’ll unbutton a unit and take a picture for you of the connection point a bit later this afternoon, likely you can just put a small diameter hole in the side metal for an anchor point if needed. Seeing you have a bit of time however i will get a pic up shortly. Cheers.
 
#42 · (Edited)
That spot is more than adequate to the task long as the spring has enough tension, one could also just drill a hole near the same location if one was worried. The unit i took the picture of is a 1994 model so the spring has been effective at its intended purpose for 30 plus years, so no reason to change something that has worked as intended and can likely still do another 30 years.

Last powder in my area will be tomorrow with an anticipated 4 inches and that should be it.

After that i have in hand OEM auger & drive belts, Stens friction wheel rubber all ready to be installed as part of a wider off season maintenance regime this season. I thought about a complete teardown and repaint however on this unit the juice isn’t worth the squeeze, waiting for the right prospect (Yamaha, Honda, Ariens) to come in my door and with no ethanol free gas in my neck of the woods for the last year and a half i should come across something interesting shortly.

Cheers.
 
#43 ·
I have 2 of those mtds, one since 1992 and no issues with ring. Got a freebie from a friend and rubber gone in no time. PO owned it a long time but gave to me when electric start failed. No mention of friction wheel issues. I did have to replace a return spring. There was also something that I thought had side play that might have affected the drive. I eliminated that play but I've still used up another wheel with little use. My replacements were aftermarket so next one would be oem mtd but that blower didn't get pulled out for use this winter.
 
#48 ·
Update:
Well, half update, not a full update.

I ordered a new drive ring and new springs months and months ago, and I just today got around to installing them. I didn't replace the friction disc itself but I did spend a LONG time sanding it down and got it pretty smooth.

So I replaced the rubber ring, again. And then I installed both springs. Its very clear and easy to see and feel the job those springs do. So between those springs and the new rubber, hopefully the problem is fixed. I also adjusted the shift position a bit so it was further out from center. Although the machine was moving at a normal, acceptable speed so I'm not sure that was actually a problem.

I haven't tested it out yet though. I have some other parts that need fixing first. Then my plan is to fire this beast up and let it idle for maybe a half hour. If its not a windy day, I may put a fan on it so its not idling in the hot sun.

I'm pretty confident it will have no problem with that since the spring is pulling the disk well away from the rubber now. So whether or not it was a problem before, I doubt it will be one now.

Then I'm going to put this guy into gear and drive it up and down my lawn a bunch of times. What I really want to do is drive it all the way up and down my street, but my neighbors will think I'm even more nuts than they probably already think I am. But my lawn is long and I disengaged 2 wheel drive so its just one wheel, so it shouldn't tear up the grass at all. I'll just go back and forth until I'm bored out of my mind. Then flip it up and check the rubber. And if all looks good, I'll call it done. And if its torn up, then I'm baffled and I'm not sure what I'll do.

It would be nice if I had a foot of snow to really test the repair out with. But sadly/thankfully were many months away from that :D
 
#49 ·
1008com, I adjust my tension / engagement of the drive so that with half the distance of movement of drive lever handle pressed you will be touching the friction wheel to the drive plate. Hope that makes sense, please update us as you test it out.
 
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#50 ·
Glad you finally made the decision to proceed with the spring, manufacturers do not put in extra springs in for no reason and i would put my money on you being good to go now.

Let us know after you have tested the beast and let us know if llama is good….

Cheers.
 
#51 ·
Ok full update. Here's what I did today to test. Note: Its august, so not exactly snowblower weather, but it wasn't too hot out and there was a steady breeze so things should have been ok temperature wise.

So I fired it up and let it run for 15 minutes.
Then I shut it off, tipped it up and checked out the transmission. The rubber ring looked untouched, as you would expect since it is not in contact with the friction disc anymore, and I DID NOT pull the drive lever all all for this first part of the test.

BUT heres where things got weird. I was feeling around in the transmission and the friction disc was BURNING hot! It was crazy how hot it was! Everything else in there was warm, but this thing was pretty much too hot to even touch.

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How could that happen? Theres no source of heat down in there. Its not like it was caused by friction, the transmission was never engaged! Its not like the bearings are seized, I was able to turn the disc by hand when it was off. It didn't turn easy because it was also turning the engine, but it didn't feel stuck at all, it felt like the only resistance on the thing was the belt turning the motor.

Any ideas what is up with that?

After this test, I put it back down, fired it up, and then drove it under its own power up and down the yard a bunch of times, using every gear. This was probably like 7 minutes of constant driving.

After that test, I tipped it up again and looked and the plate felt a LITTLE bit cooler, but not a whole lot cooler. The rubber drive ring didn't look like it had any premature wear on it. Of course when your'e snow blowing, it takes a lot more than 6 minutes.

But is there something going on that is causing the friction plate to overheat? And maybe thats what peeled the rubber right off the drive wheel? Looking at how this system works, I don't see what it could possibly be though.

Also, fun fact - just now while exporting that photo out of photoshop, I was zoomed in enough to see that the remains of the original auger return spring are still there rusted in place :D haha
 
#52 ·
Unless you have the exhaust blowing on that plate, the only other way it could get too hot to the touch would be rubbing on something, which you should hear or see, or heat transfer, say from a bad bearing, which would be unlikely.
 
#57 ·
UPDATE TIME

And a very unexpected update at that.
I thought for sure the bearings were going to be shot. The heat has to be coming from somewhere, and its either going to be belt rub, which seems unlikely since the belt is supposed to rub as it turns the disc, or the bearings.

So I removed the belt and then spun the disc by hand (the metal disc, not the wheel with the rubber ring).
It spun - dare I say - perfectly. Smooth as ice, no resistance at all. The heat couldn't possibly be coming from there!

Video:

Then I took a closer look at the belt. The belt looks like garbage! Total trash, ready to be replaced. But of course, just like the rubber drive ring, this belt was BRAND NEW and I just installed it last Winter. So this belt has the same 4-5 hours of use on it.

Also odd, its the INSIDE of the belt that is chewed up. But how could it even get like that? The pulleys are all V channel pulleys so they don't even touch the inside of the belt, just the sides. And the tensioner touches the back of the belt. And yet, THIS is what the belt looks like!?



This really is the repair that never ends!

So what do you make of this? It was a "heavy duty" replacement belt, not OEM but made for this application. I can see a cheap belt not lasting as long, but I can't see one dying after 4 hours and also heating up the disk so much that it melts the friction ring? Is this the cause of all of this??

Also the first guess is probably going to be "was the belt too tight or too loose?" It seemed fine to me. The tensioner was keeping it tight and the tensioner didn't seem maxed out or under used. It all seemed right.

I plan to buy the new belt from at least a slightly more reputable source than ebay. But still. this seems crazy.

Thoughts?
 
#58 · (Edited)
That cam shaft drive sheave looks awful shiny, which is not normal.

Some belt on some machines are cogged from the factory.

I would also make sure you get the right size belt, i.e., length
, width and pitch.

You probably want to clean that engine while your in there.

fwiw ... most of my machines get the D&D Blue Kevlar or the Green Gates Power Rated. Off Road Belts's is my go to site for belts.
 
#59 ·
So, what exactly is a "cam shaft drive sheave" ?

I ordered the belt based on part number, I believe this is the exact belt:

I do have one of those OffRoad Belts in my ebay history, that must have been what I put into my yard vacuum. blue offroadbelts are good quality? Of so ill grab another one of those for this snow blower.