Thread: 40 MPH Club
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Old 02-20-2015, 08:29 AM
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Davezilla Davezilla is offline
Motorized Bicycle Elite Member
Join Date: Mar 2014
Location: San Antonio Texas
Posts: 2,710
Default Re: 40 MPH Club

Wow... did one of your mounts work loose? or did a bolt snap?
I got a few tricks up my sleeve for the rear mount so it's totally trouble free...
First, ditch that steel strap that holds the rear mount to the frame and replace it with a second aluminum mount block like the one that connects the engine to the frame. You can belt sand or mill these blocks way down either to set the engine closer to the seat post tube, not for clearance issues, but so you can also use shorter studs that can't bend or flex, then use a set of high grade studs and the double nut method to hold everything together. Once that's done, the engine will not move.

For the front mount, it's a little tricky because of so many different frame tube diameters and shapes, but if you can get a front mount like the ones MassDrive in here makes, it's a lot stronger and more rigid than those steel adapters and muffler type clamps. I can't see which type front mount you got for sure in the pic, but if it's the one that bolts a plate to the engine and uses a slightly offset muffler clamp it can flex under load and can't hold the engine in place if the rear mount does slip or fail to hold for any reason. You can replace that flimsy adapter plate with a piece of 1/4" aluminum plate stock and drill it up to fit on the engine and hold the clamp, or if steel is all you got or can get, I'd copy the existing plate in 3/16" steel. That'll eliminate that flex point.

I'm not sure what kind of tooling you got, but the strongest and most rigid way to mount is to weld tabs or brackets onto the frame and bolt the engine directly to the mount tabs.

I don't have any pics specifically of my rear mount, but you can see how I used 2 of the rear mount blocks to sandwitch the frame in this pic... This alone will hold the engine rigidly in place and you may also be able to see that I milled down the mount block on the engine side so it can use shorter studs but also because I needed as much clearance is I could get since this is a really small frame. I'll need to take better pics of my mounting system when I get the chance...

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