Which DD gears for the mountains?

[ripsass]

Going to put a 141 x 2.25" PC on my CF8SP. Pretty much only ride mountains or deep snow and don't mind missing some top end.

Stock is 60/60, thinking of either 57/63 or 55/65. What it the theoretical top speed with stock vs these ratios? Thinking of it this way will help me relate it mentally.

Will the stock clutching be affected by the gear change?

 

[hatchers]

i hear a 2010 has stock 55/65....this is what i did last year and loved it!

 

[Destroyer]

Ha, it looks like there's a select few of us doing up Cf's for deep stuff. IMHO i think the 57/63 is the ticket. Dropping gearing will lower belt temps. and you will still pull some good top speed. If you gear to low you will really hurt the midrange pull of your sled.

I'm going to start working around the suggested stock helix angles. (0-6000 46-40) (6000+ 36.) According to the info on the net the stock clutching is pretty decent.

http://www.mxzx-revzone.com/article/tuning-laws-118.asp

There is a **** load of good reading on this website.

The doo guys will tear me a new one for letting this info out.

I've never owned a cat but...It doesn't matter where you ride, you can adjust rpm's with pinweight and engagement and shift rpm's with springs etc.

 

[black swan]

i hear a 2010 has stock 55/65....this is what i did last year and loved it!

oh, your pulling me leg, Jimmy! quit thinkin w/ your dipstick



Jimmy....

 

[ripsass]

Oh ya, meant to add this.

non-Reverse case gears (fits 2005-2006 models & 2009-2010 engine reverse models)
PART # INPUT/TRANSFER GEARS EFFECTIVE RATIO PRICE
66852* 68/52 1.62 $199.95
66753 67/53 1.67 $199.95
66654 66/54 1.73 $199.95
66555 65/55 1.79 $199.95
66456 64/56 1.85 $199.95
66357 63/57 1.91 $199.95
66258 62/58 1.98 $199.95
66159 61/59 2.04 $199.95
66060 60/60 2.11 $199.95
65961 59/61 2.18 $199.95
65862 58/62 2.26 $199.95
65763 57/63 2.33 $199.95
65664 56/64 2.41 $199.95
65565 55/65 2.50 $199.95
65466** 54/66 2.58 $199.95
65367** 53/67 2.67 $199.95
65268** 52/68 2.76 $199.95
* = High speed gears, case modification may be necessary.
** = Snocross and Mountain Applications.

 

[PCDOC]

My 08 M8 came stock with 57/63 gears and I changed to 54/66. Pulls nice.

If you plan on ordering new gears get them from Black Diamond. (they are the guys that invented the diamond drive) Their gears are a one piece design and are stronger than the welded stock cat gears.

 

[CuzzinOlaf]

I put in the BDX Lites in my sled. I think they're 55/65. Definitely helped with the bottom end. I think my top speed on my M8 153 Power Claw is 80 or 85.

 

[YooperScott]

Stock M8 gears '07-'09 - 57/63 top speed around 90
Stock M8 gears '10 - 55/65 top speed around 84
56/64 around 87
54/66 around 81
53/67 around 79
52/68 around 76

Might be able to get used 57/63 cheap from guys that went lower on M8's. I have 55/65 on order for my '08 M8.

 

[Destroyer]

If you can achieve full shift you should get more than 90 out of the 57/63. At 2500' my buddies stock 09 M8 had no trouble hitting 93-95 and he was not running efficient by any means. I rode his sled and he blew apart 5 belts in 800 miles.

 

[ripsass]

Sweet. Great info guy's, thanks.

Think I'm sold on 55/65's then. Don't mind paying for new ones from BDX as they are only $200 bucks.
Sounds like a good idea to get as many OEM parts as possible out of that DD unit.


Ordering my new 2.25" PC from free agent!!!!!!!!!!!!!!!!!!!!!! Wooooo. This is gonna rip.

 

[CuzzinOlaf]

Sweet. Great info guy's, thanks.

Think I'm sold on 55/65's then. Don't mind paying for new ones from BDX as they are only $200 bucks.
Sounds like a good idea to get as many OEM parts as possible out of that DD unit.


Ordering my new 2.25" PC from free agent!!!!!!!!!!!!!!!!!!!!!! Wooooo. This is gonna rip.

You're gonna love the PC and the gears. I'm doing a pipe this year and hope it wakes the sled up even more. Good luck to ya.

 

[Destroyer]

you boys don't think 55/65 on the 141 is too low? It should pull 57/63 with that length no problem. Last years m8 162's were geared 57/63.

 

[ripsass]

Lower gears = Gnarlier wheelies.

I rode an Assault last spring and have been hooked on low gears since. I only ride the steep/deep now days so I don't care if it "only" does 80 MPH.

I want it to go from 0-80 in one and a half seconds.

 

[YooperScott]

Well then you're in luck cause it'll probably do closer to 85.

 

[Destroyer]

Don't say I didn't say anything. I would probably bet money that two identical crossfires doing 60 mph side by side with pclaw tracks in any terrain, at any elevation. clutched the same...One 55/65 one 57/63...the 57/63 will jump out it front instantly.

 

[Destroyer]

and...lower gears does not = better wheelies. If geared to low you will run out of gear to hold the wheelie.

I had a 07 rev gear 23/45 hold wheelies for ever and ever and ever...and ever ski's staight up.

then gear 21/45.. out of the hole pops em up real quick. then holds it for a bit and then the front end comes back down to the ground and you have no acceleration. sure you could run a steeper helix to help it out. but as a system you max out sooner than necessary. = hurts performance.

 

[ripsass]

I was pondering the acceleration part today actually too. It's no fun if you lose all your forward momentum...

My buddy with 57.63's swears by them.