900 motor mount bolt

SnowPro · Dec 10, 2009

My bolt supplied with the compfusion kit broke. I am putting in the new pucks and want to install the best bolt. I did a search and did not come up with the bolt size. What has been working best ? Have grade 8 been sheering ? Do you want rolled or cut threads ? Thanks in advance.

Dogmeat · Dec 10, 2009

http://www.snowestonline.com/forum/showthread.php?t=166387

check that thread out, should have what you need in there.

guidoxpress · Dec 10, 2009

correct me if i am wrong but rolled bolts are stronger..

grade 8 is perfect for the motor mounts..if you break them..you have a problem somewhere else..

here is the bolt info from compfusions instructions..

3/8 x 2.25” bolts, and torque the support assembly to engine @ 40 ft/lbs.

guidoxpress · Dec 10, 2009

also be sure to use BLUE LOCKTITE on ALL motor mount bolts...

CompFusion · Dec 10, 2009

To date I've only had discussions with a couple guys about the 3/8" bolt failing. After discussing it for some length we came to the conclusion that over-torque was likely the prime suspect. Once the assembly is bolted to the engine the 2 washers and spacer fit together metal to metal. All that is required is enough torque to prevent this assembly from loosening....I would be using red threadlocker on those suckers as you can always apply heat for removal if needed. Any excess torque beyond that is only putting unnecessary load on the bolt but serving no real purpose.
Also remember that adding a higher strength bolt does not mean you can torque it down tighter. You are limited to the load capacity of the aluminum threads in the crankcase. I've seen a few guys strip out the threads in the rear PTO case mount from tightening things a bit too much. If you have good clean threads, the right locker, and hit 30-40 ft/lbs you should be good to go.

guidoxpress · Dec 10, 2009

colin..your the MAN!

High Velocity · Dec 10, 2009

CompFusion said:
To date I've only had discussions with a couple guys about the 3/8" bolt failing. After discussing it for some length we came to the conclusion that over-torque was likely the prime suspect. Once the assembly is bolted to the engine the 2 washers and spacer fit together metal to metal. All that is required is enough torque to prevent this assembly from loosening....I would be using red threadlocker on those suckers as you can always apply heat for removal if needed. Any excess torque beyond that is only putting unnecessary load on the bolt but serving no real purpose.
Also remember that adding a higher strength bolt does not mean you can torque it down tighter. You are limited to the load capacity of the aluminum threads in the crankcase. I've seen a few guys strip out the threads in the rear PTO case mount from tightening things a bit too much. If you have good clean threads, the right locker, and hit 30-40 ft/lbs you should be good to go.

All very good advice from an experienced Polaris tech. However, the one point I have to respectfully disagree on is the use of red (permanent strength) locktite. I don't believe you need anything more than blue in this application. No offence intended Compfusion, but my 28 years experience as an automotive and H/D mechanic as well as experience on my own 900 tells me that red locktite is serious overkill for this application.

f15ejedi · Dec 10, 2009

High Velocity said:
All very good advice from an experienced Polaris tech. However, the one point I have to respectfully disagree on is the use of red (permanent strength) locktite. I don't believe you need anything more than blue in this application. No offence intended Compfusion, but my 28 years experience as an automotive and H/D mechanic as well as experience on my own 900 tells me that red locktite is serious overkill for this application.

How often do you change your motor mounts? The red loctite is suggested because you shouldn't have to change your motor mounts every season after you install Compfusion mounts. Get it?

High Velocity · Dec 10, 2009

f15ejedi said:
How often do you change your motor mounts? The red loctite is suggested because you shouldn't have to change your motor mounts every season after you install Compfusion mounts. Get it?

I don't have a clue what your mechanical background is, so I was just going on mine. Experience tells me red locktite isn't necessary and will be a pain in the butt down the road. As far as changing my motor mounts, I did put Comp's mounts in my sled and pulled them out the next season because they were completely pounded out. I reinstalled my original stock mounts at that time. GET IT !!!!.

f15ejedi · Dec 10, 2009

High Velocity said:
I don't have a clue what your mechanical background is, so I was just going on mine. Experience tells me red locktite isn't necessary and will be a pain in the butt down the road. As far as changing my motor mounts, I did put Comp's mounts in my sled and pulled them out the next season because they were completely pounded out. I reinstalled my original stock mounts at that time. GET IT !!!!.

I'm sure your mechanical background is greater than mine. That is apparent because you let everyone know what it was in your first post. My apologies.

High Velocity · Dec 10, 2009

I'm not trying to start a pissing match. I was only expressing my opinion in my original post and trying to do it with no respect to Compfusion. I've both appreciated and benefited from his advice. I agree whole-heartedly with Comp that over-torquing is the cause of most bolt failures and that is the prime reason I believe that permanent strength locktite is not necessary. I've yet to hear of motor mount bolts falling out, so IN MY HUMBLE OPINION, blue locktite is more than sufficient and if for some other reason, chit goes bad, the blue is much easier to deal with. f15, you could talk to twenty different techs and get twenty different opinions. I was only expressing mine. Once again, no offence was intended.

f15ejedi · Dec 10, 2009

High Velocity said:
I'm not trying to start a pissing match. I was only expressing my opinion in my original post and trying to do it with no respect to Compfusion. I've both appreciated and benefited from his advice. I agree whole-heartedly with Comp that over-torquing is the cause of most bolt failures and that is the prime reason I believe that permanent strength locktite is not necessary. I've yet to hear of motor mount bolts falling out, so IN MY HUMBLE OPINION, blue locktite is more than sufficient and if for some other reason, chit goes bad, the blue is much easier to deal with. f15, you could talk to twenty different techs and get twenty different opinions. I was only expressing mine. Once again, no offence was intended.

Exactly. Read the highlighted portion.

High Velocity · Dec 11, 2009

????????????

ghostwhite · Dec 11, 2009

High Velocity said:
????????????

You typoed the highlighted potion HV. It should have read "no dis-respect" its pretty easy to understand what you're trying to say but some of us are blowing this out of proportion, so can we just agree to disagree?

I have comp mounts and love them but MY engine vibrates like a mother and I do expect to turbo soon so I do see myself having to change out the pucks eventually.

High Velocity · Dec 11, 2009

Oops !! My bad !!Definitely should have read no disrespect.

CompFusion · Dec 11, 2009

Just a typo...no biggie, we all make'em. I've always used the higher strength locker in structural locations like these (where it is easy to get heat in there for removal) just to have the greatest security that a job I do won't came back for something as small as a bolt backing off. I guess it's just erring on the side of caution.
I have seen techs reassemble clutches without threadlocker and if was me the half clutch would probably spin right out through the bellypan.
I don't doubt that blue would be just fine but I've never been willing to take the chance on something that shakes like many 900's do..

Anyways, guido is right 3/8NC x 2-1/4" is the size you need. This size gives maximum thread engagement into the case without bottoming. Be sure to clean out any threadlocker in the case as there is little room once it goes together. Not cleaning it out will cause an issue as well.

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