07 M8 DD issues

[Mohabba]

Hi

Looking at a 07 M8 162" with 2500 miles. Last winter the DD grenaded. I know that the owner has no clue to what caused it. He bought a new complete DD and did a few trips rest of the season. He has very little experinece with snowmobiles

Im thinking that the DD blew because of a bearing issue according to some other threads. DD is now completely new but probably standard bearing - i would change it.

I remeber - from that time - they were mentioning issues with the DD flipping in reverse while going forward?

Anyone know of issues with that DD flipping in reverse?

Sled is stock with no updates of any kind. What preventative work should be done to that year model and what decent mods could i look forward to?

He has other priorities now and i should be able to get it for a good price. He wants it out.

I will be keeping it for hopefully several years since i have other priorities too but still want to ride in the deep. I can do all the work on it.

Thank you for your comments

 

[moderatebill]

Great sled if you can get a good price. The drive can be a problem, but not a show stopper.

 

[snowcatter]

Every 07-08 DD we have taken apart shows sign of eminent bearing failure. The bearing they use is very cheap . . . a $4 bearing as opposed to $36 one that was used in the 05-06 DD's The best way to fix this problem and ensure years of future reliability is to replace the cheap bearing with the 05-06 bearing. This requires some simple machining on the gear to make room for the wider bearing. I am in the process of doing this very thing on my 07 M8. I happen to have a lathe, but any decent machine shop would be able to do it for you. Good news for those of us who have 09-10 DD's . . they use the same cheap bearing as the 07-08, but they have a spacer installed on the shaft, so no machining required. Just pitch the spacer and install the new wider bearing 1602-348

 

[89sandman]

Have never heard of one going into reverse by itself, they have a motion sensor on the rotor that prevents this. my experience with the weakness in the diamond drive is the planetary, the angle cut gears put a lot of stress in this area and ends up taking out the brass shimm and the planetary gears lock up. i got just over 4,000 hard miles out of my first one. all you can really do is keep good fluid in it and hope for the best. if your gonna ride the deep heat protection and venting is a must. nosnow running boards by fastlane absolutely rock.

 

[Mohabba]

- Snowcatter
Thanks for your reply. Any pictures of that procedure would be very cool.

His riding buddies told med that the reverse mode alarm sounded when his DD locked up a couple of times and also when he climbed a bottleneck hill to get home and the DD grenaded.

Not sure what to think.

 

[snowcatter]

Ok here are a couple pictures of the process . . Here is what the gear looks like after machining the shaft to accept the new wider bearing.

Here it is with the new Bearing pressed on