The Stovebolt Site Forums The Shop Area The HiPo Shop what do lower gear numbers do for low end???

HI Stovebolters

I am currently debating on switching my current 1985 K5 Chevy Blazer rear end with 4.10 gears with a more modern Chevy Colorado rear end with 3.42 gears in it.

With the 4.10's hooked behind the current stock 4 speed (sm420 ?? I think) my first gear is a granny gear....second gear is like a normal 1 st gear and 3rd and 4th gears are like the normal 2nd and 3rd gear is in today vehicles. I know from a high end aspect the the lower the number in the rear end will result in a higher top end with lower rpm's in the end.

So will the 3.42's make the 1st and 2nd gear's a little more user friendly??? or will it make harder to use???

Any insight would be a wonderful thing.

MikeC

The taller gears (3.42 is "taller" than 4.10) will make it slower off the line. It might make it a little more user friendly, but I wouldn't think it would be a considerable difference. Why not just get 3.42's for your current rear end? If you change to the Colorado your brakes are different again, you have to worry about mounting and all that... Seems like not the best way to make the change.

Is there a reason you want to use the Colorado? The width of the rear end is also narrower than the K5.

I know that you've been having frustrations with your truck, I don't think this is the right way for you to get taller gears.

It will make a much better driver out of it. All gears will be higher ratio but you have the granny 1st gear for rock crawling.
If it is 4 wheel drive you will have to replace both axles.
The manual 4 speed in that will be a SM 465.

I had 3.42 gears in my 59 Suburban with a 350/SM465 and 31x10.10-15 tires. It was very driveable. I only used granny as a granny and could go down the road 90mph+ if I decided to. You will still only user granny every now and then.