can someone explain backshift
- Thread starter ullose272
- Start date
I like to call it "down shift".
Imagine driving a under powered stick shift Ford Pinto up a hill, once you start up the hill you have to down shift to keep to keep from lugging or stalling the motor. When you get to the top, you can up-shift back into a taller gear.
Imagine driving a under powered stick shift Ford Pinto up a hill, once you start up the hill you have to down shift to keep to keep from lugging or stalling the motor. When you get to the top, you can up-shift back into a taller gear.
go down a hard packed trail...then at the same speed quickly stray into the deep powder...your rpms should be close in both instances...thats good back shift
D
drypowder
Well-known member
and by ajusting your belt to 1/16" OF an inch above your sheave will help with the back shift . isnt that right mmsports?
D
drypowder
Well-known member
also tell us more about those turbo kits u sold out of. how much boost, was that price installed , and also is it a pull and go turbo?thx
Kevin, Thanks for all that you do for us in the AC section. It does not go unnoticed or unappreciated. Wish we had a dealer like yours in our area.
X2. The pro's know how to say it.
The rest of us say this; Ride on a hard pack, stand up, let off the throuttle. When your junk comes in contact with the handle bars---Now that is back shifting. LOL
I would say it's a simple as your sled always being in the right gear when you nail the throttle. It really showcases itself when you are climbing a hill and have to get off the throttle for a second for some reason and then nail the throttle again almost immediately. You sled should not bog, it should pull the skis like it down shifted and keep you on your merry way.
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not sure ?
That's more to do with belt deflection not really back shift . Back shift is more about spring tension and helix angle.
When I adjust belt deflection I adjust it till thee is a 2 in of slack. If you had to much then I am sure it could affect you shifting .
That's more to do with belt deflection not really back shift . Back shift is more about spring tension and helix angle.
When I adjust belt deflection I adjust it till thee is a 2 in of slack. If you had to much then I am sure it could affect you shifting .
as it should.
H
high time
Well-known member
I got a lesson last spring.........
at hill drags. I was using my quicker back shift clutching for it and my buddy used flatlander clutching. As we raced, every time we hit a bump my sled backshifted and he jumped ahead. Mine works good for highmarking his worked better for hill drags. Shift up is not all bad, as long as your engine doesn't bog down too much. No such thing as perfect clutching all the time.
Owen
at hill drags. I was using my quicker back shift clutching for it and my buddy used flatlander clutching. As we raced, every time we hit a bump my sled backshifted and he jumped ahead. Mine works good for highmarking his worked better for hill drags. Shift up is not all bad, as long as your engine doesn't bog down too much. No such thing as perfect clutching all the time.
Owen
J
JROD
Well-known member
You will also feel backshift when descending a hill. It feels like engine breaking and in a sense it is but it's because your clutches have "back shifted" to a lower ratio.
In essence, your clutches are constantly changing drive ratio from primary to secondary clutches. When there is a small load on the track, as in going down a flat trail, it's not hard to run a high ratio (primary fully shifted out, belt pulled down deep in the secondary)
When there is high load in the track, as in climbing a hill in deep, heavy snow your clutches need to react in order for the power of the engine to maintain it's optimal power RPM.
Snowmobile clutches are completely load sensitive so in the above instance when climbing the hill, your snowmobile engine does not have enough power to swing the weights that collapse the spring in the primary in conjunction with collapsing the spring and rolling down the helix thus closing the secondary. This is backshift.
Your clutches are always fighting to return to a lower ratio. It is a load from one side of the clutches or the other that inhibits this; the track or the engine.
When adjusting weights, primary or secondary springs, helix etc. you are simply adjusting when clutches react under differing loads.
For instance, If your sled is upshifting too fast (soft springs, high degree helix) it may pull like a freight train on flat ground. Upshifting, meaning, clutches are shifting to a high ratio. However if you take this same setup and put it on the mountain, you are adding another degree of load to the equation. The engine does not have the power to power through this thus resulting in belt heat due to the belt slipping and low RPMS due to the engine not having the power to pull such a load.
On the other end of the spectrum, if your clutches are running stiff springs and lower degree helix, your engine has to fight harder to upshift into a higher ratio. The engine can easily maintain optimal RPM but can also overrev. It also may have a problem not being able to shift all the way up due to such stiff springs. In order to shift out a heavy spring, you must run heavier weights. In order to due this, again, your engine must have enough power to stay in it's RPM range while doing this. Too much weight and you'll lose RPM.
If, however, your engine can pull the weights in it's optimal RPM, your clutches take longer to shift up (low ratio to high ratio) so when you immediately jump from the trail into the soft snow (high load) your engine loses the battle with the load on the track thus allowing your clutches to BACKSHIFT, returning the clutches to a lower ratio thus maintaining the optimal RPM on the engine but reducing the speed of the track. This is downshifting of the variable transmission that is your snowmobile clutches.
I hope this makes sense to you
In essence, your clutches are constantly changing drive ratio from primary to secondary clutches. When there is a small load on the track, as in going down a flat trail, it's not hard to run a high ratio (primary fully shifted out, belt pulled down deep in the secondary)
When there is high load in the track, as in climbing a hill in deep, heavy snow your clutches need to react in order for the power of the engine to maintain it's optimal power RPM.
Snowmobile clutches are completely load sensitive so in the above instance when climbing the hill, your snowmobile engine does not have enough power to swing the weights that collapse the spring in the primary in conjunction with collapsing the spring and rolling down the helix thus closing the secondary. This is backshift.
Your clutches are always fighting to return to a lower ratio. It is a load from one side of the clutches or the other that inhibits this; the track or the engine.
When adjusting weights, primary or secondary springs, helix etc. you are simply adjusting when clutches react under differing loads.
For instance, If your sled is upshifting too fast (soft springs, high degree helix) it may pull like a freight train on flat ground. Upshifting, meaning, clutches are shifting to a high ratio. However if you take this same setup and put it on the mountain, you are adding another degree of load to the equation. The engine does not have the power to power through this thus resulting in belt heat due to the belt slipping and low RPMS due to the engine not having the power to pull such a load.
On the other end of the spectrum, if your clutches are running stiff springs and lower degree helix, your engine has to fight harder to upshift into a higher ratio. The engine can easily maintain optimal RPM but can also overrev. It also may have a problem not being able to shift all the way up due to such stiff springs. In order to shift out a heavy spring, you must run heavier weights. In order to due this, again, your engine must have enough power to stay in it's RPM range while doing this. Too much weight and you'll lose RPM.
If, however, your engine can pull the weights in it's optimal RPM, your clutches take longer to shift up (low ratio to high ratio) so when you immediately jump from the trail into the soft snow (high load) your engine loses the battle with the load on the track thus allowing your clutches to BACKSHIFT, returning the clutches to a lower ratio thus maintaining the optimal RPM on the engine but reducing the speed of the track. This is downshifting of the variable transmission that is your snowmobile clutches.
I hope this makes sense to you
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