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Old 12-23-2009, 11:50 AM
soccerrj88 soccerrj88 is offline
Motorized Bicycle Member
Join Date: Sep 2009
Location: Florida
Posts: 23
Default Seat tube motor bolts keep breaking?!

Well I have an aluminum bike that has oversized down tube and seat tube. Well the front tube i make a motor mount for that looks just like the ones you can buy online and the back, I did pretty much the same thing. A piece of aluminum with a muffler clamp under and engine studs over. (see pic for all this might help) Well the origninal studs lasted about 450 to 500 miles before they snapped off. And they broke right between the motor and the spacer that is supposed to clamp to the seat tube. Well I upraded to 8.8 metric bolts that i turned into studs and those broke after1 ride. Well then I drilled and tapped to 1/4 20 with grade 8 bolts. They snapped after one ride! What is going on here? Anybody else have these problems.

Last edited by soccerrj88; 12-23-2009 at 12:00 PM.
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