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Dakaty
GenIII
12/14/2001
19:18:52
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 Subject: Klc - Tell us about your rear end!
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Message:
(I know, its sounds bad..)
Klc - now that the weather has cleared up, can you give us a testimonial about going from 3.55 to 4.10 gears?
Your previous post stated that you are turning 2500 RPM at 70 MPH, with the new 4.10 gears. I checked my 5.9 Auto 3.55 and I am turning just under 2000 at 70 MPH.
Going from 2000 RPM to 2500 RPM is a 25% increase in RPMs which seems like a lot considering the gear ratio increased only about 15% (4.1 - 3.55 = .55 then .55 divided by 3.55 = 15.49%).
Do you know what RPMs you were turning at 70 MPH before the gear change?
Would others please post their RPMs at 70 MPH along with a trans and rear end gear description.
Thanks
Bill
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Duner
Dodge Dakota
12/14/2001
19:30:46
| RE: Klc - Tell us about your rear end!
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NV3500 5-speed with 3.92 gears & 28" tall tires.....
4th gear 3000 rpm = 65 mph
5th gear 3000 rpm = 90 mph
or very close to these speeds anyway.
Not absolutely sure that 255x55x17s are exactly 28" tall.
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Blckdak
GenIII
12/14/2001
20:49:20
| RE: Klc - Tell us about your rear end!
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Message:
Thats a loaded question if I've ever heard one!
Erin
2000 CC 4x4 Sport
Magnaflow Exhaust, Z-Tube, Runnin AMSOIL
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Klc
Dodge Dakota
12/14/2001
22:43:24
| RE: Klc - Tell us about your rear end!
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Message:
your right, it doesnt make sense, you wanna know why? BECAUSE I HAD 3.90 GEARS TO BEGIN WITH. i am such a dumba$$. i was going by the window sticker and the sticker in the glove box. both said 3.55. i just counted my old ring and pinion and it is as follows: ring: 39 teeth/ pinion:10 teeth.........this is a 3.90 ratio, correct? also i DO have a LSD in my truck, but it does not mention it on the window sticker, or in the glove box......strange isnt it? DC obviously made a mistake. oh well, thats what i get for being nieve and not taking the time to pop the cover and count the teeth. well, i can tell a difference with the 4.10 gears, (if they really are 4.10's, i guess i better take the cover off and make sure...lol) i havent really put my foot into it yet, because i need to break them in for a little while longer.
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Dakaty
GenIII
12/15/2001
22:21:32
| RE: Klc - Tell us about your rear end!
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Klc
I don't think that counting the teeth in your ring gear and pinion gear is the way to determine the rear end ratio.
If your window sticker and the sticker in your glove box said 3.55s, then that's what you had. (Unless someone before you could have changed the gears.)
Your window sticker should clearly state if you have the LSD option.
Are you sure you are turning 2500 RPMs at 70 MPH?
Wait a minute..I'm going out to my truck to check my glove box sticker - I'll be right back....
OK - My glove box sticker says
Code DMD - Axle ratio - 3.55.
Code DRB - Axle Rear, Corporate 9
Code DSA - Anti - spin differential
How does this compare to yours??
Bill
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Klc
Dodge Dakota
12/16/2001
11:10:43
| RE: Klc - Tell us about your rear end!
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i was alway taught to count the ring gear teeth and pinion gear teeth and divide the ring gear and pinion gear, and that is your ratio. i will double check on the internet but i am very positive that i saw that same gear/ratio formula somewhere else too.
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Hersbird
Dodge Dakota
12/16/2001
15:51:06
| RE: Klc - Tell us about your rear end!
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Message:
I'd have to trust counting the teath over what a piece of paper says. The teath of both the ring and pinion are the only things that make up the final drive ratio, what was ordered, or typed on a peice of paper don't affect final drive ratio. If this were the case I'd just go out to the garage right now with some white-out and get some 4.30's in there, then I could swap to 3.35 for highway mileage on the fly!
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