help with gearing

stomper · Feb 12, 2015

I have a 91 indy 400 and I want to lower the gearing so I can pull grooming equipmet for crosscountry ski trails. According to the service manual it has 19/35 gears in right now. What would I have to go to for the added low end torque.

volcano buster · Feb 12, 2015

What track are you planning to run?

stomper · Feb 12, 2015

Well right now I am running the stock 121 track but I have a 144 x 1.25" That I am going to put on. I know that is too much for the small 400 but I have a fresh 500 setup that I will eventually be putting in. I don't care about top end but I am looking for more bottom end torque

volcano buster · Feb 12, 2015

I've got an 18:41 with a 66 chain in my '93 440 liquid. I have the 133.5 x 1.5" SKS track in it and it pulls fine. I'm not sure you can go much deeper gearing than this so you just might be limited. I think that 400 will surprise you with the larger track and geared down.

stomper · Feb 13, 2015

That sounds promising. thanks

NapaMatt · Feb 13, 2015

these are perfect for the job ur after!!

put a 136" 2" under a 440.. geared way down.. so light u could go any where!!

Tons of torque!

Have fun!

id like to see your cross country ski ... Groomer..

stomper · Feb 13, 2015

Thanks. I will try to remember to take some picks of the drag and track setter tomorrow. I made them myself so they are basic but they do a good job.

stomper · Feb 13, 2015

So will I have to do any thing to my clutches when I reduce the gearing

volcano buster · Feb 14, 2015

I think I just moved the spring in the secondary to the next hole causing more pressure when I put the 136 x 1.25 under my 340.

Merlin · Feb 14, 2015

stomper said:
Well right now I am running the stock 121 track but I have a 144 x 1.25" That I am going to put on. I know that is too much for the small 400 but I have a fresh 500 setup that I will eventually be putting in. I don't care about top end but I am looking for more bottom end torque

You may want to consider installing smaller drivers when you perform the track swap. I went from 9 tooth to 7 tooth on my son's Indy Lite when I upgraded the track. I used combo drivers & an anti-stab kit on my install but probably could've gone the cheaper route & just used involute drivers. The machine was already equipped with 16/39(2.44:1) gearing so by installing the smaller drivers, bottom end performance was improved significantly.

In your application where travel speed while grooming will be relatively slow while pulling a heavy load, I would speculate that you should have the lowest final drive ratio possible to keep the CVT operating in it's efficient range & to keep belt / clutch temps. in check. Looking at the service manual I have for the '96 - '98 machines, gearing combos for the short chain case as low as 2.98:1 are possible & 2.41:1 for the longer case. Obviously top end performance would be reduced but short of having a 2 speed transmission like some of the wide track / utility machines, you can't really have your cake & eat it too. LOL

stomper · Feb 17, 2015

Thanks for the replies guys. Looking in my parts bin, the largest gear I could find was a 39 tooth and the smallest is a 22. It would be good to use what I already have, that would work, if I could. So what could I use to make the 39 tooth gear work. This way I only have to buy one gear. If I could come up with an 18 or 17 tooth, would this work. As for the chain, I have a few to choose from, 64 link and 66 link. That will obviously depend on the gearing. I don't want to get too crazy with the low gearing as I still want to play a bit in the powder with this sled. Sorry for all the gearing questions but when it come to gearing and clutching I have limited experience.

stomper · Feb 17, 2015

NapaMatt said:
these are perfect for the job ur after!!

put a 136" 2" under a 440.. geared way down.. so light u could go any where!!

Tons of torque!

Have fun!

id like to see your cross country ski ... Groomer..

Heres some groomer pictures I promised. The drag is just made from 2x2x1/8 angle and is really easy to pull. and the track setter is made from 1/4" steel. I also made it. It was light and would not dig deep enough to set track in harder snow so I welded some posts to the top of it so I couls add weights to get perfect tracks. I am going to modify it this summer so that the track setter and the drag is all one unit. The setter will pivot up and sit on a frame ontop of the drag when not in use and pivot down when needed. This way I can groom the diagonal trail in one pass.

retiredpop · Feb 17, 2015

stomper said:
Thanks for the replies guys. Looking in my parts bin, the largest gear I could find was a 39 tooth and the smallest is a 22. It would be good to use what I already have, that would work, if I could. So what could I use to make the 39 tooth gear work. This way I only have to buy one gear. If I could come up with an 18 or 17 tooth, would this work. As for the chain, I have a few to choose from, 64 link and 66 link. That will obviously depend on the gearing. I don't want to get too crazy with the low gearing as I still want to play a bit in the powder with this sled. Sorry for all the gearing questions but when it come to gearing and clutching I have limited experience.

16/39 will give 2.44 ratio and you need a 64 link chain. I think it would be close to what you want for pulling your groomer and still give you some track speed too.

1992rm250 · Feb 18, 2015

check this out

http://www.turboaddictionparts.com/catalog/snowmobilecalculator.html

TRS · Feb 18, 2015

I'm sure your looking for 11 plate chain setup? I'll look to see if I have any 11 plate gears left. I think I tossed them, but you are welcome to them.

Edit:
Tossed them, sorry.

volcano buster · Feb 18, 2015

I would like to give credit to the person who put this together, but I have had it long enough I don't remember who that was.

stomper · Feb 18, 2015

Those are handy charts and calculators. Thanks guys, but what am I shooting for for a decent gear ratio. My local polaris dealer has a 17 gear and can get a 15 but says tha a 16 will be hard to get. Could I go with a 17/39 or a 15/39. I still want a bit of speed but I am more concerned with bottom end torque. Sorry for all the questions. Just trying to get the best I can with what I already have without too much extra work.

Merlin · Feb 18, 2015

The chart below will give you an idea of what speed you can expect from a given gear combo assuming you are running 9 tooth drivers(7") & the CVT is at a 1:1 ratio.

You could try pulling the contraption using the 17 / 39 combo & see how the sled works. It should be a significant improvement over the 19 / 35 that you're running now.

retiredpop · Feb 18, 2015

I think the 17/39 combination would work just fine. You can use your 64 link chain. It gives you a ratio of 2.29 which is decent for speed but will give good pulling power. By looking at the pictures the most snow you will be moving will be 2.5" by whatever width it is so in reality it isn't going to pull very hard even with the track setter hooked on behind.

stomper · Feb 18, 2015

I will give it a try thanks

help with gearing

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