bottom engine mount bolt

rgrigutis · Jan 8, 2010

trying to remove complete gearbox and can, get the bottom bolt past the lower frame tube. anyone have any advive. thanks, rick

BrianK · Jan 8, 2010

Try putting the bike on the side stand. The engine moves. If it moves too much, have a helper SLLLLLOOOOOWWWLY take it from side to center stand. At some point in the transition, you should have clearance.

EDIT: I just gave you a GREAT tip for a completely different problem (aligning the bolt holes in the cradle and engine).

I had no issues with getting that bolt out, so I'm completely guessing here, but perhaps with the nut out and the bolt pulled back a little (at least enough to clear the bolt hole on the right side), you can rotate the top of the gearbox to the right side enough to "lift" the bolt path past the frame rail?

Good luck. Best news is whatever you're doing to the gearbox, right up to a complete rebuild, getting the box in and out of the frame is by far the toughest part - the actual gearbox work is a snap.

maylar · Jan 8, 2010

Remove the head steady and the front iso thru-bolt and lift the engine a bit. That lower 5/16 bolt won't clear the frame otherwise.

rgrigutis · Jan 8, 2010

well the bike has no center stand. reckon i'll remove headsteady and iso thru bolt. thinking about just removing the engine also for a good clean and paint matbe some head work. the nooks and crannies look pretty groady so nows the time i guess. thanks for the tips guys. rick

dave M · Jan 8, 2010

Isn't that bottom mounting bolt meant to be a stud with a nut on either end? This makes it easier to get in and out. In fact all the mounting bolts should be studs according to the 750 Commando parts book that i have just looked at.

BrianK · Jan 8, 2010

Operating from memory, I believe that's right Dave. I remember being concerned about lining up the amount of threads exposed outside the nuts at each end (this is on a 73 850). I know I had zero problems clearing the frame in any event.

lcrken · Jan 8, 2010

dave M said:
Isn't that bottom mounting bolt meant to be a stud with a nut on either end? This makes it easier to get in and out. In fact all the mounting bolts should be studs according to the 750 Commando parts book that i have just looked at.

lEarly 750s had studs with nuts at both ends for the engine mounts, but for the 850s and later 750s, they changed to bolts. I'm not sure when the change was made, but I'm pretty sure all the 850s had bolts.

Ken

ILLF8ED · Jan 8, 2010

Hi Ken,

My parts books for early 750, late 750 early 850 and 850 Mk2/MkA all show the bottom gearbox mount is a stud.

I just completed a gearbox inspection renewing some gear bushes and o-rings. I needed to remove the bottom stud to get at the quadrant and selector shaft o-rings. Came out with no interference problem.

dave M · Jan 8, 2010

Illf8ed, I think the question was about the lower engine mounting, in order to move the engine forward a bit to get the gearbox out through the very tight slot in the cradle. I always wondered why they didn't engineer this a bit differently at the factory as it's only the slightest bit of additional clearance required to get the gearbox out.

BrianK · Jan 9, 2010

Mine's a Mk I 850, one of the first (#427) of the 850s, and it has a stud in that location - and it was no problem at all to remove it.

maylar · Jan 9, 2010

Mine's a MKII and all 3 are bolts. It's even a chore getting a torque wrench on the lower one because the frame rail is smack even with it.

rgrigutis · Jan 9, 2010

sorry to cause the confusion guys. it's a stud. don't know why i referred to it as a bolt. w/ headsteady out and isolastic out hopefully i can get clearance. can't understand why some of you have had no probs getting the lower bolt out and some of us do. thanx, rick

BrianK · Jan 9, 2010

Good luck to you Rick. Let us know how you make out, please.

rgrigutis · Jan 10, 2010

well i finally got it out. put a bottle jack under the motor and it lifted enough to clear. pulled the motor as well. might as well clean and paint everythingand do the mods. don t want to mess with it again. thanks for all the help rick

BrianK · Jan 10, 2010

Excellent, good work Rick! PITA, but worth it.