diff gears

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launchsquid

10 Year 15 Year
Joined
Jan 21, 2008
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5
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8
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I live in Greymouth, New Zealand.
I'm curious about what diff ratio's are in the standard diff's.

Mine seem very tall (or is that short?). When i'm driving on the black top at 100k's (60mph) it feels like i'm reving the motor pretty hard.

I would like to put different ratio's in, so i'm wondering if anyone has done this, and what ratio would do the best job?

also, if i got auto lockers at the same time do they generally provide all the gears at my selected ratio (meaning i don't have to source the chosen ratio) or am i supposed to have that already?

I'm only new to all this, so any advice would be appreciated thanks.
 
It all depends on what you want the vehicle to do. The main things you need to consider is if you want Fuel Economy, Towing Power, or a happy medium.

The 4.11 is a happy medium, if you want more fuel economy either switch to 3.73 or a larger tire. If you want more Towing Power go to a 4.56.

This all depends on how you plan on using it.
 
down here on the west coast of the south island in new zealand there isn't much in the way of rock crawling, so those 5.85's are just not going to cut it, sorry.
sadly fuel costs $1.75/l and that big petrol motor is drinking more then i would like. also i have found that most of my driving can be done in third gear, I can almost get started in 2nd gear, almost. but would 3.73 make a big difference? doesn't seem like a big change.:confused: btw my cruiser is of 1974 vintage

thanks
 
launchsquid said:
down here on the west coast of the south island in new zealand there isn't much in the way of rock crawling, so those 5.85's are just not going to cut it, sorry.
sadly fuel costs $1.75/l and that big petrol motor is drinking more then i would like. also i have found that most of my driving can be done in third gear, I can almost get started in 2nd gear, almost. but would 3.73 make a big difference? doesn't seem like a big change.:confused: btw my cruiser is of 1974 vintage

thanks
Click to expand...

holy s*** batman.....$6.65 per gallon. :eek: that's fxxxing insane. dude just walk!!!
 
might try rubber overdrive....tall tires.... but you'll end up in 4LOW alot when 4 wheeling

what size tires are you running?
 
http://lib.store.yahoo.net/lib/protopaccessories/gear-ratio.pdf

Take a look at this chart I have attached it shows the tire diameter in inches versus diff gear and rpm at 55 mph. Looking at a 30 inch tire which is pretty close to stock for a 55 you lose 200rpm going from a 4.11 to 3.73. Then if you wanted a little more you could drop another 300 rpm at 55 mph by going up to a 33 inch diameter tire.

So as you can see by making these simple changes you could save money on gas by dropping 500 rpm at 55 mph. Below I list the explanation for using the chart above.

The rpm highlighted in black are optimum for the tire size and ratio combination. These will most closely give you the best overall drivability. If you're looking for a ratio that will give better fuel economy for highway driving at the expense of some acceleration and overall performance, choose a ratio in the yellow shaded area. If you're looking for a ratio that will improve acceleration and towing power at the expense of some fuel economy, choose a ratio in the blue shaded area.

James:cheers:
 
I'm running 3.73 in my '55 with 33x9.5x15 MT's and driven by a 3B with a turbo and the H41 tranny. Seems good to me.
 
Diesels don't count, thats cheating. I ran my 6BT with 3.54's and 33's and she ran like a dream.
 
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