anyone know why a T140 seat loop cracks just rear of the top shock mounts - seen several over the years - just wondering if there is an established reason
Just happens to vibrate more at the rear.I get shattering of the mudguard on my T120.Most parts that loosen are also at the rear.I have noticed that just using a different exhaust will make a big difference to vibration and where it occurs in the rev range.One thing i did notice is that the standard exhaust for 1971 is very heavy and that is the smoothest ride.
On a good note,i have not had any frame cracking,and the rear mudguard and indicators are the cracking parts.
On OIF bikes that is a weak point of the frame. We used to see it all the time a the shop I worked at thirty plus years ago. I suspect that is one reason the 1979 T140 rack had a sticker that said 15 Lbs. maximum. We used to see it on bikes with sissy bars. Guys would tie a loaded backpack to them or their girl friend would lay pack on the pad. What happens is the mounting point for everything is the rear fender and shock mounts. All pressure is behind the shock mount and downward. Ride down the road hit a bump more stress added to an unsupported point. Metal fatigues and frame breaks.
I had one crack at the rear portion of the OIF tank at the place it attached to the top frame.
I later found out this caused by the top engine stay having been removed which allowed some type of tweaking in the frame cracking it at that location. The rear shock one, I've never witnessed myself. I've noticed some sloppy welding in front of or behind the shocks on those top frame rails.
Have noticed other bikes cracking in that area on the sub frames, most often from them having too heavy a load on a luggage rack.
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