377 or 391
- Thread starter ski-doo25
- Start date
The 391 is a softer belt than the 377....so the 377 will show more RPM all else remaining the same...so you may need to make some clutching changes with a different belt.
If the 391 lasts, I see no reason to change....a more flexible/softer belt has the potential to put more power through the clutches by lessening slippage.
If the 391 lasts, I see no reason to change....a more flexible/softer belt has the potential to put more power through the clutches by lessening slippage.
Since we are on belts I also have a question. I happen to have 3 brand new 166 belts in my trailer. Would I be able to run them on my 2009 with boost? It just sucks to have $300 worth of belts just sitting there. If I could use them for a little bit I'd be good with it.
Brew is it similar to the 288?
Last edited:
B
badass1000
Well-known member
the 166 is a narrower and I believe longer belt then the 377. the 166 is for the older rev's. I ran some 166's on my 08 xp when it first came out. I believe it was the belt that came on the sled and the recomended belt for the xp when it first came out. They didn't last very long at all. Some as low as 30 miles and up to 100 miles max in bottom less powder. this was on a pretty much stock engine, stock sled. Even when I got the clutching down (with stock engine) the 166's didn't last very long. I would try to sell the 166's to some one on a rev. Even if you sold all 3 to buy one 377, the one 377 will probably last alot longer then 3 166's on a xp.
288
Paul, is the 288 and the 391 about the same?
Marc
Paul, is the 288 and the 391 about the same?
Marc
O
oerthtop
New member
The 391 belt was out last year. BRP used it for all the 800 short track and flat land sleds. We ran them on our summits last year and had about the same luck with the 377. The 377 seems to give you more RPMs and stays more constant(hot or cold). When the 2012 Summits were released this year the 377 were still on back order. We didn't get initial orders till after sleds were being shipped so maybe the change was just due to lack of the 377's around. BRP still recommends 377 on the prior model years? The 391 and the 377 are listed as hard in Ski-Doo charts but the 391 is definitely more flexible than 377. Maybe it is just due to all the clutching changes this year. Time will tell, for now we have a lot of both of them. hope that helps.
Hmm The 391 is a softer compound. I like that much better. Relying on a hard belt and slippage to keep RPM,s up dosnt wash in my opinion. I use a med compound and clutch accordingly,Hence the 288 belt and 433 ramps for altitude
Last edited:
thats my point. Poor clutching will require a belt that slips to maintain RPM,s[377] change setup to run a med compound belt and no slip .adds performance and stays much cooler.
Exactly....despite what Doo says, the 391 is physically more flexible and acts softer than the -377....and the 391 shows less RPM all else remaining the same so whether it's the construstion, durometer or materials used it "acts" like a softer belt.
With the changes in clutching, gearing and the cooling duct, the temps seem to stay low enough to allow the 391 to last, where in previous years the more durable -377 was needed.
391 is not like the 288.
Last edited:
D
dennis
Member
391 vs. 377 belts
Parts folks at the Doo dealership said BRP has quit "making" the 377; 391 is it's replacement. 391 has same dimensions as 377 and can be used on all XP's. 391 is suppose to last longer, provide better torque and fray less. Keep'em and clutches clean and see for yourself. Ulti-max makes a belt of the same dimensions and sells for about $120. Some of the custom builds in our area (mtns, MT) at 180 to 250 HP use the Ulti's and find them great. I've got 2 on order for use on my '08 & '12 XP's. Especially if you mostly "cook" your belt under the hood most of the time, why have a $165 getting ruined by constant heat, kink and no use?
Dennis
Parts folks at the Doo dealership said BRP has quit "making" the 377; 391 is it's replacement. 391 has same dimensions as 377 and can be used on all XP's. 391 is suppose to last longer, provide better torque and fray less. Keep'em and clutches clean and see for yourself. Ulti-max makes a belt of the same dimensions and sells for about $120. Some of the custom builds in our area (mtns, MT) at 180 to 250 HP use the Ulti's and find them great. I've got 2 on order for use on my '08 & '12 XP's. Especially if you mostly "cook" your belt under the hood most of the time, why have a $165 getting ruined by constant heat, kink and no use?
Dennis
Part Number Description Dealer Parts B/O Avail Qty.
417300377 DRIVE BELT COM 2012 0 4076
I just checked BRP has (4076 "377's") and (1819 "391's") And both are current 2012 belts. They told dealers last year to only use 377's on summits (not 391's). I would say to stick with stock belts because "WE" as dealers can warranty a belt if it is defective or with clutching problems if the belts are stock type. Also BRP looks at what they sell to what regions to determine if there is a problem with a belt or sled or whatever. If you replace with non OEM parts they don't see big failure #'s and don't think there is any "REAL" problem. In 2008 BRP saw a huge amount of 166 belts failing and then came out with a new stronger belt and they also let us warranty tons of them. BRP does try to help but rely on dealers to get numbers and feedback for them. That being said I do realize some times it is harder for the consumer to get help... both belts have worked well for us if the sleds are setup right.
