Snowcat Driving School! Please Help

I have questions.. They might sound dumb to many of you.. but I have no place else to turn.

I have a Manual transmission Tiokol IMP. From memory.. Engine transmission has 3 forward, 1 Reverse gear. Rear Transmission is 4 ranges forward. One Reverse.

So:

1. I plan to groom snowmobile trails. Ideal speed is 10MPH or a little less. What combination of gearing is best? I don't know if 1st on the engine, and 4th on the rear end is better or worse than 3rd on the transmission and 1st on the rear end.

2. Can I go out on swampy grass and brush? I don't have a NEED to run it till snow.. but I would give it a try.

3. Which do you shift into reverse to back up??.. The engine, or the rear end. All things being equal.. the rear end is big money. I think I want to put that in the proper range and be done with it.

Thanks for the assistance.

JP

No input at all?

I'm on vacation when I go home Tuesday.. Going to get the IMP back together.

JP

And I thought I had alot of gears in my last truck with an 18 over !!! What you have there sounds like a old 2 sticker (5&4) in the old trucks. There must be some sort of shifting pattern to it. Should be a diagram of it in the original operators manual...

OT.

I didn't feel I had any info to offer, since I have never even driven an Imp, but since you aren't getting any other answers, I'll offer my 2 cents...

1. No idea of ratios, but you could perhaps test out the ratios in the tranny and diff manually and draw some guesses that way. Otherwise, trial and error with a GPS to get the speed you want. Depending on conditions, there may not be a single ratio that works best for everything.

2. I'd think you could run it on grass, etc., but you will have a harder time turning and will need to use a larger turning radius to prevent the tracks catching and possibly de-tracking. D-shaped grousers seem better for running on surfaces other than snow, I believe.

3. Not sure of proper protocol for reverse, although I'd assume the most convenient shifting would be the preferred method. Typically, this would be the transmission rather than a transfer case or rear end, I believe.

Keep asking, somebody here must have the answers you seek.

Use the tallest gear in the rear end that will allow you to start out in first in the front transmission. Then use the front transmission like a normal transmission. Use the front for reverse when needed. I seriously doubt you will be able to groom at 10mph and will end up in the 6mph range at best with the Imp. Once you find your tallest gear you can run in at a steady speed in the rear you still may have to gear down the rear end for steeper hills as needed. The little Imp is just not a powerhouse for dragging a grooming drag so you will need to adjust to your specific snow and trail conditions as needed. Running on grass is not a substitute for actual snow and trail conditions. As to swamps and brush unless you have a valid reason I would not risk the machine in that environment.

I've had an Imp for a few years now, but have used it for cabin access rather than grooming. My experience may or may not be applicable to your circumstances.

My understanding is that the rear end is the weak link in the system, and I've always assumed that this meant the ring & pinion. If that is true, then the specific gearing combinations of the front and rear transmissions won't make much difference since they all drive the pinion.

I tend to use the rear transmission as a range selector and do most of my shifting with the front.

I rarely use reverse on the rear transmission -- most of the time it is just as a practical joke for new drivers.

I would be reluctant to drive too much on grass. I've got the drop-center grousers and they do OK on hard surfaces and gravel, but I fear that grass would offer too much traction and put a lot of stress on the rear end. Going straight is fine, but too much turning would make me uncomfortable.

Ron

Thanks

This is the kind of info I was looking for.

I guess short of not popping the clutch, there's no way to 'protect' that big ring gear.

I've toyed with the idea of keeping the fluid cool. I guess I should just put in a thermocouple first to see if the fluid is getting hot during grooming operations.

JP