I have a Massimo MB200 with the 196cc engine. Earlier this summer the bolt holding my torque converter on broke off in the shaft, spilling the torque converter all over the road. I ordered a new pulley, removed the bolt with an easy out, and replaced everything. Everything seemed okay. Recently while riding the torque converter blew off again. This time rather than the bolt break off in the shaft, the tip of the shaft broke off. What's the best way to fix this? Replace the shaft? Replace the motor? I do have a HEMI Predator 212 as a backup engine for my mini bikes so I can always install that if that's the easiest fix. Thanks guys.
Torque converter flew off, shaft is broken
- Thread starter BreynnMike
- Start date
I'm not a TC guy, don't know much about them. Are you talking about the crank in the motor broke? Just my opinion but if it has happened twice something was not put together correctly whether something is not lined up correctly, to tight, not tight enough or what I couldn't say, but seems to me something wasn't quite right.
I mean the shaft coming out of the motor where the OEM clutch and the current torque converter are attached to. Yes it broke twice but it broke differently. The first time just the bolt holding the torque converter pulley broke off in the hole we tapped when installing the TAV. I'm sure that that is a combination of vibration and not tapping a hole deep enough. I'm absolutely not a machinist. That being said, when tapping the hole, I don't know what an appropriate amount of material you should have around the bolt. It's possible (and I'd say likely) that tapping the hole weakened the shaft. I've enclosed two pictures. Is welding the tip of that on possible? What's the technical name of that shaft that broke? I am guessing that in order to replace that shaft the motor needs to be taken apart right?
That is the crank that broke, you can buy a new crank and change it. You can get it already drilled also. I have not personally changed one but it doesn't seem real difficult. It may very well be that the first time it happened that it weakened the crank causing it to break. I definitely wouldn't weld the original, they are not real expensive and will just break again. Honestly I'd probably just put on the predator with a new TC if I already had it.
That's what I'll end up doing. I did one Predator swap already. Installing this 212 onto my Massimo MB200 should be quicker than installing a 212 on my wife's Moto 80. Might end up being just as quick as replacing the shaft too. I just pulled the Hemi 212 out of the box and see that the shaft is already tapped. That definitely makes it better. Thanks so much for your help.
My son and I swapped out a coleman 200 in less than 2 hours. It was a nice complete bike, the original engine had the govenor zip tied and blew up. We ride mostly roads so I removed the gear reducer and ran it straight chained. The only things I had to buy was a clutch and chain. With parts in hand it flew together.
I baffled as to why you ran new threads in the crank.
I believe when you tapped the crank you took material out of the I.D. which weakened the crank nose and then you used too long of a bolt/ tapped to shallow and stretched the nose again and broke off the end on the crank.
The original bolt is a M8 and the torque is like 17 ft lbs. The nose of the crank will never break under normal operating conditions.
I believe when you tapped the crank you took material out of the I.D. which weakened the crank nose and then you used too long of a bolt/ tapped to shallow and stretched the nose again and broke off the end on the crank.
The original bolt is a M8 and the torque is like 17 ft lbs. The nose of the crank will never break under normal operating conditions.
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