• Don't miss out on all the fun! Register on our forums to post and have added features! Membership levels include a FREE membership tier.

poo primary on a doo?????

ragincajun

Well-known member
Lifetime Membership
Nov 26, 2007
2,960
491
83
34
Great Falls Mt
hey guys,
my doo primary is toast and it is gunna cost a sheit load of cash to fix. i like how simple the poo primary is, makes less heat and how cheap it is! anyone get the taper machined to make it fit on a doo? if so how well did it perform and how did you like it? please PM me with any info!
thanks!
 
D
Oct 13, 2008
768
148
43
Have not done it but I here they work well. The problem is that the vibration destroys them from what some on here say. Sounds like if you can get a billet one they hold up fine, but I would not use a stock one.
 

winter brew

Premium Member
Lifetime Membership
Nov 26, 2007
10,016
4,332
113
56
LakeTapps, Wa.
that is not true. The weight difference wont hurt your crank

Can you explain more?
I did one on my '07 and lost the crank 3 rides later. I want to think this was just a coincidence. We've all heard the stories of crank failures over the years but I have also heard of alot of long-term success stories and that is why I chose to go with the P-85 on mine. To be honest, I would have gone back to the TRA even if I hadn't lost a crank, I didn't find enough gains to warrant the vibration and cost.
I see alot of P-85 guys going to great lengths to add mass (ring gears, machined steel rings etc...) to avoid the harmonics that MAY be damaging to the Doo crank.
 

evandaigneault

Well-known member
Lifetime Membership
Oct 13, 2008
566
51
28
40
Portland,OR
i ran one for a long time and know a few other guys who ran their p-85's and 4-pro's for a long time no problems. They had less problems than they did with their TRA-7's, which dont work worth beans
 

evandaigneault

Well-known member
Lifetime Membership
Oct 13, 2008
566
51
28
40
Portland,OR
there is only like a 1.5 lb difference i believe between the 4-pro and the TRA. I think it might be like a 2 lb difference with the p-85 and the TRA. The polaris 800 has a similar crank to the 800R and the m-cat 800 runs a similar style primary, those 800's can handle lighter primary's. Its the cranks themselves that have been creating the problems on doo. Too many out of spec cranks were out there to begin with and were wrecking things left and right. The most important thing to do if you are putting a polaris primary on your ski-doo is to make sure you balance it with the weights and spring it before you put it on. That should help cut down on harmonics. The harmonics come from a crank that is out of spec or an unbalanced primary running at high rpm over time.

Thats how i see it anyways

Evan
 

AKSNOWRIDER

Well-known member
Lifetime Membership
Dec 25, 2007
8,882
4,431
113
62
anchorage
Can you explain more?
I did one on my '07 and lost the crank 3 rides later. I want to think this was just a coincidence. We've all heard the stories of crank failures over the years but I have also heard of alot of long-term success stories and that is why I chose to go with the P-85 on mine. To be honest, I would have gone back to the TRA even if I hadn't lost a crank, I didn't find enough gains to warrant the vibration and cost.
I see alot of P-85 guys going to great lengths to add mass (ring gears, machined steel rings etc...) to avoid the harmonics that MAY be damaging to the Doo crank.

winter I would think to run a different clutch you would need to balance both the clutch and the crank..I bet that would fix any vibration/longevity problems..
 

winter brew

Premium Member
Lifetime Membership
Nov 26, 2007
10,016
4,332
113
56
LakeTapps, Wa.
The P-85 I ran was 6lbs lighter than the TRA7 with ring gear. Some guys are running the lightened TRA or the factory lightweight race dept TRA which is pretty darned light. I also had my P-85 spin balanced. It vibrated alot just due to the loss of damping from the 6lb lighter clutch....it was like one of those foot vibrators at the county fair! :beer;
I got the TRA7 on the '07 working as good as ANY clutching on any sled I have ever been around so I ditched the whole P-85 thing. JMO-
 
Premium Features