Snake Eater CVT
- Thread starter kerf
- Start date
Took a good hilly ride this morning and have decided to go with the 11/72 - 18.82:1 final drive ratio. Gotta let my beast breathe, a little higher cruise RPM but I want the added performance.
There was a slight wobble on my clutch drum, as I recall but it seems to have no ill effect. I took my cover off this morning, while I was making the gearing change and the bearings on the belt section are still tight. I've been expecting to have to replace them but thought I would wait till they begin to get loose. I'm running synthetic Mobil 1 / 75-90 in the gear box, it stays cooler than any other part on the trans.
The only part, other than belts and weights, that I'm aware of is the shaft on the spring pulley. Fancy Scooter has those.
There was a slight wobble on my clutch drum, as I recall but it seems to have no ill effect. I took my cover off this morning, while I was making the gearing change and the bearings on the belt section are still tight. I've been expecting to have to replace them but thought I would wait till they begin to get loose. I'm running synthetic Mobil 1 / 75-90 in the gear box, it stays cooler than any other part on the trans.
The only part, other than belts and weights, that I'm aware of is the shaft on the spring pulley. Fancy Scooter has those.
I went with higher rpms too. Spent more on belts in a thousand miles than I have on nexus jackshaft that is installed now which is getting close to a thou'
I bought a full set of bearings, then the clutch-bells starting breaking.... I never found the point where something doesnt break. Found better belts, bearings, bells, etc, but just got over it sadly... Wish it was different., Locking up the CVT with a shredded belt only killed my engine. I cant imagine what that's like without a freewheel cog on my rear wheel assembly!
I bought a full set of bearings, then the clutch-bells starting breaking.... I never found the point where something doesnt break. Found better belts, bearings, bells, etc, but just got over it sadly... Wish it was different., Locking up the CVT with a shredded belt only killed my engine. I cant imagine what that's like without a freewheel cog on my rear wheel assembly!
Well, it's a train wreck and looks like kerf is finished, maybe for good. The outside plate on the variator has cracked where the shaft goes through. It doesn't appear to have the beef to handle the load. I MIG welded the crack but but another appeared on the other side. Unless someone has an idea, I may be through with the whole MB concept altogether.
Actually, not so much. The clutch drum needs to run pretty true but if you think about how a centrifugal clutch works, it will conform to the drum. I'm not talking about an out of round condition, or the drum not being centered on the shaft but maybe not perfectly perpendicular to its shaft.
Ok, long story short, the failure was mine when I overstressed the trans, going up a very steep hill with too high a gear ratio. The amazing thing was, the bike ran for several rides before the failure showed up. I pulled down the input, replaced the bearings with ones of better quality, turned the shaft and squared the shoulder back up and installed the necessary washers to give the proper spacing. I MIG welded the cracks in the outer variator sheave, on both sides, and built up the shaft hole with welds. A little work with the die grinder and a couple of small files and it now is a press fit on the shaft. It again is the sweetest ride I've ever had.
I hope the repairs hold so I can get some idea of how long these trans should last.
I hope the repairs hold so I can get some idea of how long these trans should last.
Hi Kerf,
FWIW, my CVT is going on 3 years old. Although most bearings have been upgraded practically from the start. These are obviously NOT the highest quality-built item. I don't know anybody who is REALLY USING this CVT that only owns 1. I bought another one earlier this year so that I could do some experimenting with my old one. 2 weeks in and the variator shaft snapped the threads off at that shoulder where yours ate the outer sheave. So I went back to the 3 year old but put the belt in it from the newer one just because. The original belt is still good so I keep it for a spare.
I can't imagine, the poster above with all his problems and eating belts and such, what he must be doing to his bike to have such rotten luck.
Longevity-wise, I keep the gear oil changed every 6 months. That's about it for maintenance!
I am running at 16:1 final ratio. ( I can't believe that 18:1 is lugging yours--odd.) At about 6400RPM it will give me 30MPH. I cruise at about 5500RPM at about 25MPH. The bike, motor, and I fell most comfortable there. I've had it easily going 35MPH at 7300RPM. All on the HF 52cc pump engine. It started life with a Subaru 33-4 stroke. Great engine but gutless. I figure I'm only getting to a 4:1 CVT ratio not the 3. something that it's capable of but I've got the weights and contra spring matched to give me higher RPMs off the line.A little higher weights in the variator gets it moving faster but the belt slips on take off and I don't like the idea of that and the results that could come (as you've seen). I don't have to pedal off the line but I always do. Most of my riding is flat-nuts Florida, but there are a couple of high bridges I have to climb to get on and off the beach. The bike will drop to 23-25 MPH depending on conditions but the engine still revs in the low to mid 5Ks.
Oh, and also FWIW, I ride to work a couple of days / wk. at about 30-40 miles / day, weather permitting. So, yeah, I guess it gets used a lot. Without looking at my log (yes, I keep a mileage and maint. log) the CVT has well over 3000 miles on it so far.
Hoping the above info will help someone else out there.
Good Luck!
(your results may vary)
FWIW, my CVT is going on 3 years old. Although most bearings have been upgraded practically from the start. These are obviously NOT the highest quality-built item. I don't know anybody who is REALLY USING this CVT that only owns 1. I bought another one earlier this year so that I could do some experimenting with my old one. 2 weeks in and the variator shaft snapped the threads off at that shoulder where yours ate the outer sheave. So I went back to the 3 year old but put the belt in it from the newer one just because. The original belt is still good so I keep it for a spare.
I can't imagine, the poster above with all his problems and eating belts and such, what he must be doing to his bike to have such rotten luck.
Longevity-wise, I keep the gear oil changed every 6 months. That's about it for maintenance!
I am running at 16:1 final ratio. ( I can't believe that 18:1 is lugging yours--odd.) At about 6400RPM it will give me 30MPH. I cruise at about 5500RPM at about 25MPH. The bike, motor, and I fell most comfortable there. I've had it easily going 35MPH at 7300RPM. All on the HF 52cc pump engine. It started life with a Subaru 33-4 stroke. Great engine but gutless. I figure I'm only getting to a 4:1 CVT ratio not the 3. something that it's capable of but I've got the weights and contra spring matched to give me higher RPMs off the line.A little higher weights in the variator gets it moving faster but the belt slips on take off and I don't like the idea of that and the results that could come (as you've seen). I don't have to pedal off the line but I always do. Most of my riding is flat-nuts Florida, but there are a couple of high bridges I have to climb to get on and off the beach. The bike will drop to 23-25 MPH depending on conditions but the engine still revs in the low to mid 5Ks.
Oh, and also FWIW, I ride to work a couple of days / wk. at about 30-40 miles / day, weather permitting. So, yeah, I guess it gets used a lot. Without looking at my log (yes, I keep a mileage and maint. log) the CVT has well over 3000 miles on it so far.
Hoping the above info will help someone else out there.
Good Luck!
(your results may vary)
My issue was too much power and too high rpm's I tried every belt available I could find. I loved the power off the line. Plus I dont have any peddles to help propel with and I live in hilly washington state. With a new belt, I could pop wheelies with pure acceleration off the line.
I'm about 90% sure I know what caused my failure, that being the belt pulled too far into the variator and spreading the sheaves. I think it may have happened when I went up the hill above my house but I can't prove it and here's why. As I stated in my thread, I couldn't know the "high" ratio of the trans without obtaining imperial data, from actually riding. I went up that hill with a chain ratio of 5.14:1 but I actually started riding with a 4.5:1, all way too high. When my 11 tooth came in, I tried a 5.72:1 and finally settled on 6.55:1, which is the correct ratio. After obtaining data, I calculated that with my final gearing, my total high speed ratio would be 18.82:1, based on a variator overdrive ratio of .775:1. I now know that that number is incorrect because in my first test ride since the repairs, I reached 30 MPH at less than 6500 RPM, not the 7125 my formula had predicted. The road I was on has an almost imperceptible grade and I was going down hill with the 6500 rpm. Coming back, at 30 MPH, she was turning about 7100-7200. That indicated that the CVT is capable of more than a .775:1 overdrive, which is fine with me. By the way, my low speed ratio stands at 45.90:1.
WayneC, thanks for the input, you're the first to give any insight as the potential lifespan of our little Chinese "jewels". After a few thousand miles, if I need a replacement, I won't feel ill used.
WayneC, thanks for the input, you're the first to give any insight as the potential lifespan of our little Chinese "jewels". After a few thousand miles, if I need a replacement, I won't feel ill used.
Ahhh, that explains a lot. LOL I'm notorious for babying everything I own. That could spell the difference.
Kerf, although the HF 52cc is SUPPOSED to be a TLE clone, I know it can't compare in quality OR power. You may be right about the belt PUSHING the outer sheave past it's limits. Obviously the belt won't go anywhere; and the variator inner face is more solid than the outer face. So, yeah, it could have added enough stress and strain to bugger up the relatively flimsy outer sheave. Factor in the hit-or-miss quality of these guys. Or should I say, "Chinese Jewels". HA HA. That moniker just might stick! Why not? We have China Girls; why not China Jewels?!
BTW, I wouldn't be too quick to downplay the importance of the main drive shaft components not being in PERFECT symmetry/true/balance. If the clutch bell was off, that would radiate down the shaft to all components to the other end. It would be just like the drive shaft in an automobile from input to output. In auto parlance they call that Dynamic/Harmonic balance and if it's off can spell disaster for a drive train.(The reason for marking orientation when removing a drive shaft). The slightest 'wobble' on a spinning mass will multiply itself exponentially to the opposite end. I know you know this, but it's important to make others that may read this thread in the future aware of what some might call a 'slight' imperfection and it's implications down the line.
Well, regardless, glad you didn't give up.
Happy trails!
Curt, NOOOOOO! Don't give up! Where else can you get a multi-speed transmission for $70? Add in some bearing upgrades (for your own good and
of mind) and take care of the "jewel" and I believe its a definite contender for a drive system.Heck man, Minnesota? Ya have 6 months to figure it out and put it together! LOL
I took her out this evening, was running about 32 and gave the R460 WOT, felt something jump. Thought I had torn up the variator but everything was still just like I had put it together. Belt slip or a chain jump? Gonna put it back together tonight and head out before daylight tomorrow. Getting ready for my 4:30 AM ride by the cemetery Sunday morning, been look'n for a "haint" down there.
Don't worry, kerf's never alone!
Don't worry, kerf's never alone!
Hi Kerf,
More'n'likely, chain jump and it's trying to tell you something. Don't go far without whatever you need to put the chain back on and get home.
On my rack mount CVT drive I had to develop a Power Side chain guide in addition to a Slack Side
tensioner. Think timing chain guides/tensioners.
Every one of those thumps will add stress to the chain and stretch (wear) it out in no time.
Beware!
Good luck!
More'n'likely, chain jump and it's trying to tell you something. Don't go far without whatever you need to put the chain back on and get home.
On my rack mount CVT drive I had to develop a Power Side chain guide in addition to a Slack Side
tensioner. Think timing chain guides/tensioners.
Every one of those thumps will add stress to the chain and stretch (wear) it out in no time.
Beware!
Good luck!
Will continue on. I have a 50cc Honda got staton clutch shoes. Last spring my neighbor gave me a chunk of aluminum so this winter I will put it in the leath and spin a adapter for it. Fun Fun. At the same time I am going to see if I can streighten the chutch drum. What I think is that the treads were put on crocked it makes the drum high on one side and low on the other? Like it was said I can drill and tap.
Yep dead center of the state Brainerd.
Yep dead center of the state Brainerd.
Added a little more spring tension to the idler last night, this morning she got a good up hill workout with zero issues. Even with 11/72 chain gearing, she is still hitting 30 mph below 6400, with light loading. Under a moderate hill load, she still maintains 30 but the tranny downshifts to allow 7100+.
Since I've been busy, I haven't ridden in about three weeks, until this past Sunday. Ride went great but I noticed some belt slippage on the way back home, keep in mind the bike was a little oily from previous runs. Yesterday, I pulled down the tranny to see what was up and found the variator just like I left it but there was a light oil film on the belt and sheaves. That's when I noticed engine oil, from the exhaust all over the back side of the tranny. I had drilled 4 1" holes into the front and back edge of the belt cover for cooling and it looks like the back draft has been pulling exhaust oil into the back edge holes. I cleaned up everything with brake parts cleaner and applied aluminum tape to the vent holes on the back side of the cover.
A quick test ride confirmed that there was no slippage and everything is back to normal. Want to take her for an extended ride Sunday morning but it's going to be cold, down to 34 degrees. Time for the arctic gear I guess.
A quick test ride confirmed that there was no slippage and everything is back to normal. Want to take her for an extended ride Sunday morning but it's going to be cold, down to 34 degrees. Time for the arctic gear I guess.
Since patching up my transmission, I’ve been riding a lot and the tranny has performed great. I’ve had some modifications in mind and waiting for an excuse to try them out. There are several weak points to the design and several weak components that I’ve felt could be improved. The guys over at Go Ped Nation had identified problems with bearings and seals and I had found a couple that may be unique to a bicycle application. The two main issues I’ve had involved the variator back plate stop system, which was a thin washer riding against the bearing shoulder on the variator shaft and the outer variator sheave plate. As you may recall, by over stressing the tranny on a hill climb, the back plate stop washer failed and allowed slack in the variator assembly, causing my outer sheave to crack and wallow out.
Checking over my bike after my ride last Sunday, I noticed the Chinese seals were leaking on the gear box, so I decided it was time to pull the trigger on repairs and modifications. When pulling the tranny down, I found play in the variator shaft bearings and my outer sheave plate had again cracked. The gear box bearings still look good, probably in no small part due to running Mobil 1 Full Synthetic gear oil in the gear box. Finding the two shaft bearings wasn’t a problem, as Motion Industries, here in Birmingham stocked them in several brands, so I bought two SKF 6002-2RSJEM bearings. The two gear box seals were a different matter and MI drew a blank. I searched the internet until I found Harwal Oil Seal Co, that could supply them in a high quality product and MI was one of their distributers. On Tuesday of this week, I had Motion Industries order one 12mm x 24mm x 7mm and one 15mm x 25mm x 5mm Viton seals from Harwal, in Denver and had them shipped directly to me. Having secured the necessary parts, I started with the other modifications.
The attached photos will be helpful in explaining the following:
The variator shaft has a shoulder that the two bearings ride on and there is a forged flange, on this shoulder, that spaces the two bearings. I decided that this flange would be a robust stop point for the variator back plate and I built a spacer from a 5/8” bronze flange bushing to take the load from the back plate and transmit it to the flange, through the bearing inner race. I cut the bushing down to .210” thick and reamed it to a snug fit in the shaft shoulder. I then MIG welded the cracked outer sheave but I wanted to add some redundancy. This part is stamped from steel plate about 1/8” thick and is heavy enough except where it mounts the shaft. The shaft is keyed to this part by flats milled on both sides of the shaft and I believe the metal is too thin to handle this method of lock up. I had changed the variator spacing to allow the sheave to slide another 1/8” onto the shaft, so I set about building a “hub” on the sheave plate. Taking a 5/16” steel flat washer, I carefully cut the center hole to match the flats on the shaft end, so that the hole in the washer matched the hole in the sheave. After putting the sheave on the shaft, I placed the washer on the shaft and tightly clamped them together. While still on the shaft, for alignment, I MIG welded the washer and sheave together. This created a hub, just under ¼” thick. A little work on the welds with a die grinder and the washer just disappeared into the sheave. It was Friday afternoon and I finished just in time for UPS with my seals. That night I reassembled the tranny and this morning I filled it with oil and remounted it on the bike.
Today, Sat. 1/8/11, I’ve taken three test rides and it seems to be flawless. I’ll probably try another one in the morning (20 degrees) but snow is supposed to move in that afternoon, so I’ll be cooling my jets for better weather.
Checking over my bike after my ride last Sunday, I noticed the Chinese seals were leaking on the gear box, so I decided it was time to pull the trigger on repairs and modifications. When pulling the tranny down, I found play in the variator shaft bearings and my outer sheave plate had again cracked. The gear box bearings still look good, probably in no small part due to running Mobil 1 Full Synthetic gear oil in the gear box. Finding the two shaft bearings wasn’t a problem, as Motion Industries, here in Birmingham stocked them in several brands, so I bought two SKF 6002-2RSJEM bearings. The two gear box seals were a different matter and MI drew a blank. I searched the internet until I found Harwal Oil Seal Co, that could supply them in a high quality product and MI was one of their distributers. On Tuesday of this week, I had Motion Industries order one 12mm x 24mm x 7mm and one 15mm x 25mm x 5mm Viton seals from Harwal, in Denver and had them shipped directly to me. Having secured the necessary parts, I started with the other modifications.
The attached photos will be helpful in explaining the following:
The variator shaft has a shoulder that the two bearings ride on and there is a forged flange, on this shoulder, that spaces the two bearings. I decided that this flange would be a robust stop point for the variator back plate and I built a spacer from a 5/8” bronze flange bushing to take the load from the back plate and transmit it to the flange, through the bearing inner race. I cut the bushing down to .210” thick and reamed it to a snug fit in the shaft shoulder. I then MIG welded the cracked outer sheave but I wanted to add some redundancy. This part is stamped from steel plate about 1/8” thick and is heavy enough except where it mounts the shaft. The shaft is keyed to this part by flats milled on both sides of the shaft and I believe the metal is too thin to handle this method of lock up. I had changed the variator spacing to allow the sheave to slide another 1/8” onto the shaft, so I set about building a “hub” on the sheave plate. Taking a 5/16” steel flat washer, I carefully cut the center hole to match the flats on the shaft end, so that the hole in the washer matched the hole in the sheave. After putting the sheave on the shaft, I placed the washer on the shaft and tightly clamped them together. While still on the shaft, for alignment, I MIG welded the washer and sheave together. This created a hub, just under ¼” thick. A little work on the welds with a die grinder and the washer just disappeared into the sheave. It was Friday afternoon and I finished just in time for UPS with my seals. That night I reassembled the tranny and this morning I filled it with oil and remounted it on the bike.
Today, Sat. 1/8/11, I’ve taken three test rides and it seems to be flawless. I’ll probably try another one in the morning (20 degrees) but snow is supposed to move in that afternoon, so I’ll be cooling my jets for better weather.
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By the way, this will be our second snow of the season. I live in the deep south for crying out loud, where the heck is global warming when you need it.
