ST-4 Modification Sprockets

[redsqwrl]

So I searched, and read up on the different attempts to make splines. Most recently Reddogs steering wheel adapter.

I busted out a file and said how hard can that be......

After 48 minutes of filing and sweat I wound up with this.

This is a pilot project for my personal use. I am hoping to report in mid to late next week with some data. if the run out is perfect I will consider making these by request.

They are the same tooth count as Louis' build.

Special thanks to Don for the layout parts. Thanks to kirk for taking my giggly phone calls about whether or not these will work.

• they are metric.
• the splines are indexed the same relative to the sprocket teeth.
• The seal surface is not the same RW hardness as OEM sprockets.

 

[300 H and H]

He is so excited he forgot to say what they are for!! These are drive sprockes for the variator out put shafts. They are 16 tooth count. These and enough HP to drive them will alow a Snow Trac to aproach 30 mph top speed. High speed gearing if you will....

Regards, Kirk

 

[Snowtrac Nome]

mike the way to get around the seal surface is called a speedy sleeve

 

[redsqwrl]

Ah Yes, great application. I saw those on the counter when I picked up the Sprockets.

hardening them should not be too costly.

Mike

 

[redsqwrl]

well, I can get the 11 tooth sprocket out, but I can't get the 16 tooth in....

I will have to loosen the motor and variator up in its mounts to slip the sprockets in.

That will be a while before I can find a pot in the schedule to tear into this....

Mike

 

[JimVT]

check those seals on that shaft when you "tear into it." They are a challenge to get to when they start leaking. I think someone here run with a bad one and lost oil in the case.

 

[Snowtrac Nome]

yes jim it was me they got hard over the years and shattered one winter on a 100mile round trip it smoked the transmission on the last leg of the trip

 

[JimVT]

I thought it was you.
I also am thinking that mike may have the one with big holes cut so you don't have to pull the transaxle.
jim

 

[Snowtrac Nome]

yes mikes have access doors cut he can slide the 11 tooth sprockets out, but the new larger sprockets wont fit in with out lifting the trans axle a bit.

 

[JimVT]

I looked at that one prior to buying mine. and took a few pictures.

 

[redsqwrl]

Woot Sprockets are in.

The Steps were pretty straight forward.

Read and review the manual.
Call Don to ask a couple questions about my approach.
Drain trans
Remove rear lower skid plate.
Remove long tension bolts.
Remove motor mount to frame bolts while supporting engine variator combo.
remove bolts that support rear most point of transmission (done from inside the cat)
Remove side covers.
Remove old sprockets and end caps.
replace seals.
Reverse order.

I recommend breaking the chains and moving the master to the front most postion.
Next time I will be installiing new chains rather than to add a few links.

I only drove around a hayfield on firm snow. I can still start out in 3rd but I anticepate that will not be the case should I find the right snow conditions her in the midwest that actually challenge this machine, I have yet to see it sink in more than 6-12 inches.

Taking it out to play this weekend hopefully I can get some video and photos.

Mike

 

[JimVT]

a seat restraint would be needed if achieving 30mpg in our hills

 

[redsqwrl]

Re: ST-4B Modification Sprockets

I am at the 2.5 or the 2.65 final drive ratio. (not sure if I have 40 teeth or 42.

I am hoping for a comfortable cruise speed not a land speed record.

I did this to a snow master.

 

[redsqwrl]

Well it happened,, I was able to get into the snow a bit.

On packed snow. I can still start out comfortably in each gear. Driving in the top (3-3.5K) of second or bottom of third gear puts me in perfect speed to keep pace with the folks in the photos.

We figured our cruising speed was about 8-10mph.

After lunch I got out front and let is snap to see what was there and fourth gear is now about 20 MPH at 3K. It can pull up speed when throttle is applied. but the machine is nice at that speed.

Lunch stop. thursday. is photo one.

Photo 2 is a morning run to find lake superior.

In the fluffy deeper snow, I found it took a bit of throttle as expected to keep the systems happy, (steering and cooling) Fourth gear is out unless going downhill or following someone. Third uses all the motor if I am breaking trail.

I am pretty sure my front sprockets are 40 tooth. My small or rear sprockets are 16. this ratio meets my needs. I am very happy with

P.M. me if you would like custom spockets for your ST.

Mike