I am doing a ground up build and seeking advice on which route to take.
If you had to pick between the 86/87 2 bolt/swingarm pivot bolt style rear engine mount, or an 88/89 style single bolt frame mount, which would be the better of the two options for strength and reliability? This discussion should ignore swingarm length as it will be the same in either case.
My initial impression is the 86/87 style puts the least torque strain on the engine cases and other frame mounts since it turns the 2 bolt points into a solid swingarm mount like used on newer ATV's (TRX450R). I'd take a guess this would be useful for higher power motors. However, since the 86/87 design splits the swinger pivot into two pieces, I could also see this causing more flex/torsion forces on the frame and pivot bolt during suspension movement. The 88+ design decouples the motor completely from shock forces going through the swingarm and may prevent vibration/stress from being transmitted to the engine under hard impact.
These are all theories (wild ass guesses) and I'd be interested in knowing how the design change translates to real world results. Does either style have a notably different track record? How do most racers pick between frame styles to do their build?
Are there any other factors to consider one over the other?