Motor mounts in my yamadoo.. considering the solid inserts?

[Ski-Dooin' it]

Well, after 1000 miles and getting the power built on the sled, I bent the crap out of my first gen motor mounts, so bad that 100 miles per belt wasnt even realistic by the end of the season. My issue was that the brackets to the rubber mounts worked pretty well, but having only a bolt throught each of the rubbers allowed the bolt to twist the bracket and torque the rubber mount, combing this with all 4 mounts and the motor is basically just floating around in the chassis. My questions are relating to those who have the solid insert type motor mounts. My idea was to machine a peice of aluminum stock the same size sa the rubber mounts, so it would press in, BUT< just make the rear on a long solid stick and then weld arms down off of it to attach to my bolt holes in the chassis from the doo mounts(they are big cast guys riveted to the bulkhead, so a good mount point)

I was curious if this would be possibly to rigid or what? I feel like my current setup allows to many bolt interfaces and rubber mounts allowing a little slop in a lot of places, so I would like to simplify things and just make a big arse mount that just locks it all together.

 

[mulot30th]

do you have pictures of current engine mount point in your chassis?

I might have an idea for you .

 

[Ski-Dooin' it]

I dont, but here is a picture of the old 1000 motor in place, and as you can see, at the rear of the large cast motor hanger/mount there is the edge of the rubber motor mount and then a little bumper behind it. The big cast block that the jackshaft mounts into, along with one on the other side have threads cast into them and work really nicely as they are almost directly underneat the rear yamaha mounts. I was planning on a tube sort of deal that went throught then had arms off it down to the build in ski-doo mounts.

 

[dirk_03]

Plates

You need to do the same thing I am doing. I know it will work for you as well. Just wait until this weekend and i should have them done and try to get some pics up by monday. It will make it wicked strong. You also need to use the full length bolt that yamaha uses i am pretty sure. As motor mounts are not made to handle flex like your talking about. I think that the front could benfit front a full length cross bolt too.

Either way you will like what I am doing.

 

[Ski-Dooin' it]

I definately will be going with the full length bolts front and rear as the individual bolts tweak slightly and the full length one should help deal with the issue. I am excited to see what sort of crazy contration you have made up.. I kinda wish I had a vector motor, the rubber parts just bolt to the motor.. just take those off and bolt it on from there.

 

[dirk_03]

I will have some pics for u in the morning of what you should do. I don't have internet at home right now so can't post pics tonight.

 

[dirk_03]

I will have some pics for u in the morning of what you should do. I don't have internet at home right now so can't post pics tonight.

 

[Ski-Dooin' it]

perfect.. I was also looking at things, I plan on running a brace from the big cast jackshaft holder up to the top of the shock tower where the steering arm comes down, I feel like this should help keep the bulkhead from flexing backwards allowing the front mounts to move. also should help somewhat in the whole chassis flex department.

 

[dirk_03]

plates

Nick, Here are some pics of what I am doing. the poster board will be cut out to 3/16 aluminum. Then have several cross shafts. This will provide a sturdy stucture to achor to. It should be as solid as a yamaha chassis with these in place.

 

[mulot30th]

Dirk, that is the exact same way I would do it

 

[dirk_03]

Thanks

Dirk, that is the exact same way I would do it

Thank you. I was trying to get away from doing this, to save a little weight, but in the end it is worth a few lbs as a catosprhpic failure out in the middle of nowhere in waste deep snow i would be thinking that the 9 lbs that it adds would not be a big deal. Oh and yeah I need the weight up front to keep the front down! ahaha.

 

[madsledder]

Id like to see progress of this keep us posted

 

[Ski-Dooin' it]

Unfortunately, there are issues with this setup on the RT chassis, first off, the HUGE freakin cast hunk by the secondary, second, I already welded chunk of aluminum angle under the bulkhead below the primary, also has a LOT of huge rivet heads on the side of the bulkhead for the factory bracing not on the revs.. and another, the front ofthe bulkhead has a big peice across the front that bolts to the bulkhead. and the way the RT chaincase has the brake outside with the cae VERY tight to the bulkhead, again creating issues with strength. I dont give a crap about weight added, I just feel like that setup on an RT is a logistical clusterf***. I am going to be running a sort of arm from the jackshaft to the shock tower, so that should help. Now im just working on something big and sturdy to hold the SOB down.. Also, another issue I forgot about on the motor that leads those mounts to not work, with the gear reduction setup and the water pump location on the rx1, I only have like 1" below them on the bulkhead, so those big braces would have a huge weak point there wanyways on the clutch side. included is a picture of the motor before I mounted it, I had to notch the bulkhead a fair amount, there is now some aluminum angle welded in there that really stiffens it back up, but the water pump sticks out past the edge of the bulkhead, thus killing the benefit of those mounts.. I spent a lot of time mocking mounts up like yours but strayed away for a reason.

here are some pictures of my current mounts when first installed.

I am still VERY tempted on the rear mounts to just take 2 big chunks of aluminum and weld arms off the bulkhead for the rear mount Im just affraid if they arent spot on, they never will be, there welded. I like the bolt in ones.. Im just finding it harder to make it strong that way.

The front mount could use some gusseting out to the brace tips, then just a long bolt from side to side, its rather strong and has an nice good mounting surface, jsut the arms to the motor are almost 6" long, so they bend easy.. some bracing could easily fix that all up.

 

[Ski-Dooin' it]

here is a quick model of the rear mount I am looking at building, the large shaft would be a throught type shaft that is the same ID as the motor mounts, obvious some of hte middle material would be machined out just to deal with some extra weight, and thread holes into each end of the tube so the two tabs just bolt onto the long rear insert and thus holdthing the motor VERY still.. allowing minimal play in the rear portion of the motor.. just food for thought.

 

[dirk_03]

yamaha

I like the fact that ur thinking outside the box but, really what you need to do here is think about what works on the yamaha. No need to reinvent the wheel. If you mount the the top of the bulkhead your going the have flex because your bolting to a piece of steel metal. While if you bolt the the flat surface your using now and then bolt through the upright bulkhead side. This will give you the most strength. This is what j tab did. You don't need to use full plates like I am though.