BR100+ speed increase

[BAsh]

Looking to increase the top speed of a 1991(?) BR100+. Have read elsewhere that the 4.27 gear ratio works well. How much of an increase in speed would switching the gear ratio provide? Any pitfalls to watch out for?

 

[redsqwrl]

Welcome Bash. Its feet per minute and circumference. how fast do you want to go. anything over 19-22mph is fast for a snow cat and as attractive as 30 MPH thiokol model 601 sounds, it is not fun. I have been 26mph in a tucker waiting to die from flying angle iron, not fun.
I have rebuilt a Bombi with a 4.10 RP with a mercedes diesel over drive trans, it was less fun. lastly I created sprockets to make a snow trac go 30+, When the grousers started hitting the sub frame I smiled and shifted into 4th and laid on the throttle. it was a blast.
the 601 is scary fast and shape of the grouser makes it hard to handle on firm snow or ice.
seems the snow trac is designed for road speed.

Will you on firm snow, ?

 

[BAsh]

Currently my BR100+ will go 15 mph GPS with engine RPM at 4500. If I could get to approx 25 MPH at 4500 that would be great. Not that I need to go much faster at the top end; but I would like to travel at 15-20 MPH without maxing out the RPM's on motor. Conditions are primarily packed snow and some powder. I am on the prairies so the powder is only usually 1-2 feet deep. Thank-you.

 

[labradorshooter]

I put 4.27 gears in my br100+ , picked up a nice bit of speed. if I remember right i get around 30KPH or 18 MPH. if you lookup my threads youll find my build and pictures of the install. you'll need to trim the pinion gear.

 

[BAsh]

Thank-you, that post is excellent. Do you happen to know the diameter of your brake disc. One of the previous owners discarded the one on my br100+ and the calipers and I would like to get them re-installed.