Gear ratio calculators vs. real life - Page 2 - JeepForum.com
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post #16 of 32 Old 09-13-2013, 12:04 PM Thread Starter
fourbtgait
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Quote:
Originally Posted by Renegade82
Just as a point of reference. With worn 33's, which are probably closer to 32"; a 258, T-4, and 3:73 gears, mine is begging for a 5th gear at top end highway speeds. I can't give you any rpm's, or even accurate mph, but cars be passin'!
Hence theoretically with a gear calculator, your set up in 4th gear at 60 mph is at 2350 rpm, 32" tire.
Mine with 31.5", 3.73, at 60 in 4th is 2387 rpm and in 5th is 2053.

The tire/gear chart at morris for 65 mph gives same rpm as the reaper chart and goes on to say with color coding its perfect for economy.
A lot of people might say theoretically yours is great but in practical usage you say its not.

Hence my original question before spending money. It seems the calculators are only so good....

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post #17 of 32 Old 09-13-2013, 01:00 PM
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If you want to make them more accurate, take a measurement from the ground to the centerline of the wheel/tire and multiply it by two.

The bottom half of the tire is loaded, the top isn't, so a measurement of the height isn't 100% accurate.
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post #18 of 32 Old 09-13-2013, 01:01 PM
Matt1981CJ7
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Russell,

With the OD, I think 3:73 will be your best choice for the type driving you do.

Or, as suggested, just keep the 3:54s and forget about using 5th gear in most situations.

Or, get the 4:10s and run a larger tire.

Good luck,

Matt
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post #19 of 32 Old 09-13-2013, 01:21 PM Thread Starter
fourbtgait
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Quote:
Originally Posted by Matt1981CJ7
Russell,

With the OD, I think 3:73 will be your best choice for the type driving you do.

Or, as suggested, just keep the 3:54s and forget about using 5th gear in most situations.

Or, get the 4:10s and run a larger tire.

Good luck,

Matt
Matt-

It is not an issue with 5th gear per say. It's fine on the highway with the 3.54, just a little boggy which means downshift. I do only get 15 mpg with the setup, 3.73 might give me a little more.

The aspect ive been looking at more is 1st gear. Taking off from dead stop on hills in high range, slow driving having to brake at water bars, large pot holes and such. That was one reason for the off hand comment about putting a twin stick in. 2 wheel low, run in 2nd or 3rd in the woods.

I am used to a granny gear in the woods or traffic to creep in. Pity there isnt a 5 speed with od.

Russell
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post #20 of 32 Old 09-13-2013, 01:48 PM
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Hmm, I'm wondering why your 1st gear is too fast for you. How high is your idle? What's the ratio of a T5's 1st gear?

With a 700 RPM idle, my 5:1 1st gear creeps along pretty dang slow, and that's with 2:73 diffs. I never find myself wishing I could go slower.

Anyway, I gotta run. Good luck, and let us know what you decide on.

Matt
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post #21 of 32 Old 09-13-2013, 02:10 PM
gmakra
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T-5 Low is 4.31 second 2.37 third 1.50 and fourth is 1.0
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post #22 of 32 Old 09-13-2013, 02:16 PM
Spieg8
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Quote:
Originally Posted by fourbtgait View Post
I am used to a granny gear in the woods or traffic to creep in. Pity there isnt a 5 speed with od.
You might look into a NV4500. That may be more to your liking than the T5 (and a lot stronger too).
Make: New Venture Gear
Length: 18.9"
Weight: 195 lbs.
Case: Cast Iron
Top Cover: Aluminum
PTO Ports: Both Sides
Gearing: 6.34, 3.44, 1.71, 1, .73, R 6.34 or,
5.61, 3.04, 1.67, 1, .74, R 5.61

http://www.novak-adapt.com/knowledge/nv4500.htm
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post #23 of 32 Old 09-13-2013, 02:17 PM
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Quote:
Originally Posted by fourbtgait View Post
That was one reason for the off hand comment about putting a twin stick in. 2 wheel low, run in 2nd or 3rd in the woods.
Install the twin stick on the D300 and be done.

My childhood was typical. Summers in Rangoon, luge lessons. In the spring we'd make meat helmets.
When I was insolent, I was placed in a burlap bag and beaten with reeds. Pretty standard, really.
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post #24 of 32 Old 09-13-2013, 03:05 PM Thread Starter
fourbtgait
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Idle is 700 rpm.

Speed is relative to a person.

A different tranny? Ummmm not at the moment.

Twin sticks and a hand throttle.....
Can i shift twin stick 2lo to 2 hi or vice versa without stopping?
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post #25 of 32 Old 09-13-2013, 03:39 PM
deadeye
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I can shift from 2low to 2 high on the move but not the other way.
I also have an auto trans so yours might be different.
I use 2 low in the woods most of the time.

83 CJ7, 350 TBI, TH350, Dana 300 twin stick, Dana 44 E-locker, Ford 8.8, Detroit, 4:10 gears, 35x13.5x15s
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post #26 of 32 Old 09-13-2013, 04:38 PM Thread Starter
fourbtgait
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Quote:
Originally Posted by deadeye
I can shift from 2low to 2 high on the move but not the other way.
I also have an auto trans so yours might be different.
I use 2 low in the woods most of the time.
Kind of what I thought, had to ask.
2lo in 3rd would be a bit higher than normal 1st, but 2lo in 2nd gear would be about right speed i think, 21.90 ratio vs 14.27 in 2hi and 1st.
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post #27 of 32 Old 09-13-2013, 04:57 PM
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I was wondering if my twin stick can switch between 2 h and 2 L or can it even go into 2 l i dont jave it in my jeep yet but its a t18 w a dana 20 and the po installed a twin stick kit
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post #28 of 32 Old 09-13-2013, 11:11 PM
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I have a set of 3.73 that were in for 9 month w/a 70yr old driver that went to 4.56's. He is a friend of mine and the D-30 gear set is cut for an OX locker so it will fit the carrier.

I have been wanting to use the 3.73's in my axles but I have 2.73's and I think my carrier break is 3.54 (maybe someone can confirm) for my D-30/D-44 setup.

These are Dana gear sets if memory serves (been sitting on my shelf for a few years).

Would like to get a set of 3.54's or even 3.31's as I am running a 360/TF-999 3spd.

P.S. When I needed to (when I had a stick-or use Peaches Jeep 3.31's/31") I just use 4 low and shifted gears when needed off road.

I also twin sticked my D-300 and love it.

Twin stick link - http://street2mud.com/forum/index.php?showtopic=198
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post #29 of 32 Old 09-14-2013, 01:02 AM
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Quote:
Originally Posted by Rollbar View Post
I have a set of 3.73 that were in for 9 month w/a 70yr old driver that went to 4.56's. He is a friend of mine and the D-30 gear set is cut for an OX locker so it will fit the carrier.

I have been wanting to use the 3.73's in my axles but I have 2.73's and I think my carrier break is 3.54 (maybe someone can confirm) for my D-30/D-44 setup.

These are Dana gear sets if memory serves (been sitting on my shelf for a few years).

Would like to get a set of 3.54's or even 3.31's as I am running a 360/TF-999 3spd.

P.S. When I needed to (when I had a stick-or use Peaches Jeep 3.31's/31") I just use 4 low and shifted gears when needed off road.

I also twin sticked my D-300 and love it.

Twin stick link - http://street2mud.com/forum/index.php?showtopic=198
Carrier break for the d30 is 3.54/3.73 the d44 is 3.73/3.92

77 CJ-7- AMC 360, Edelbrock cam, MC2100, Fenderwells, CJ T18/D20, Chevy D44/EB 9" rear, Trutrac f/r, 4.11, SOA, 1.25 lift shackles, 35x12.50 BFG KM2s, Shackle Reversal
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post #30 of 32 Old 09-14-2013, 06:16 AM
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Quote:
Originally Posted by fourbtgait View Post
Yes, I've read some of Keiths posts. If I remember, he Installed 4.10, then the T5 for the overdrive, finally I thought he did go to 3.73, to even it out.
Hence my curiosity of calculators vs real life. The calculators make it "appear" perfect, but...
Something like that, but not quite accurate.

My original intentions were to have 33x12.50 tires mated to the axles with 4.10 gears as this seemed to be the perfect setup according to gear ratio calculators and a couple drives in my friends Jeep who had the same setup. I liked the acceleration too.

My choice of tire size changed AFTER the gearing was done so we now had 32", actual 31" as they fit better in the wheel wells and looked proportional right for the CJ. So now we have 32x11.50 with 4.10 gears and a T4, 4 speed tranny. Great around town but once we inch up to 55mph, I caught myself looking for another gear to shift into. Shifting from 1st to 2nd is pretty quick work but not enough to eliminate 1st gear altogether and start out in 2nd instead. That lugs the engine a little to much and would probably burn the clutch disc.

So, out came the T4 and in went a T5 w/overdrive. Perfect setup now with the 32x11.50 tires and I shift into 5th at 55-60mph for nice cruising on the highway. If I'm feeling that fuel economics is in order for the day, I can shift into 5th at 45mph but no lower and it still accelerates on level roads while in overdrive. With the 4.10 gears, we have a lot of hills around where I live and acceleration going up hills is splendid. Shell 89 octane gas really makes a difference too.

IMHO, if I kept the 4 speed, then 3.73 gears with 32" tires would be a good choice. 4 speed with 4.10 gears, 33" tires. 4 speed with 4.56 gears, 35" tires. But with a 4 speed and 31" tires, then 3.54 gears.

The above would be for the I6 engine and not for a 4 cylinder or V8. For a 4 cylinder all the gear ratio's would move up one or two.
Example: 4 cylinder with 4 speed and 32" tires I would have 4.56 or 4.88 with a 5 speed.
8 cylinder with 4 speed and 32" tires I would have 3.54 or 3.73's with a 5 speed.

Even the new JK Jeeps from the factory with the 6 speed overdrive transmissions, true 32" tires will have 4.10 gears.

.
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