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Does transmission ratio matter?


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13 replies to this topic

#1 Uberoo

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Posted 20 September 2013 - 10:58 PM

I didn't know where else to put this some I am putting it here. Does the transmission final drive ratio affect the output speed of the rear driveshaft?IE would a 4.11 transmission have more torque at the rear output than say a 3.90?



#2 bonvo

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Posted 20 September 2013 - 11:19 PM

if your asking about the output for the front wheels being related to the output for the rear wheels the answer is no you do however want to match the gearing in both the front diff (in this case the trans) and the rear diff



#3 Uberoo

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Posted 20 September 2013 - 11:25 PM

I had a feeling but damn.I was hoping to run a 4.11 subaru legacy transmission to get a slight reduction with an ej22 in front of a divorced transfer case.



#4 monstaru

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Posted 21 September 2013 - 01:29 PM

Your first gear ratio x diff ratio x t-case =crawl ratio

 

That trans would be like, 3.59x 4.11 x 2.7(just an example)=39.83

The final drive ratio in our world correlates to the entire system, where as in a Toyota world it is simply from the diffs.

 

The lower your first gear is , the better. Hence as to why you may have heard "Granny gear".



#5 Uberoo

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Posted 21 September 2013 - 02:02 PM

but with a divorced transfercase its exactly like a toyota or any other 4x4 truck.



#6 Uberoo

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Posted 21 September 2013 - 02:47 PM

I am thinking with the next incarnation of my offroader I should run a EJ22+5 speed AWD box running into a suzuki T case.With the high range reduction it is almost like having the subaru transmission in low which it more or less was anytime I was offroad or below 45 MPH.That way I don't need an adapter plate or flywheel work, and I get rid of an extra lever.With the high range reduction that limits my top speed to 77 MPH but the speed limit is 55-60 on the roads around here.

 

I will have to weld up the center clutch and find a suzuki box but overall it seems simpler...

 

On the other hand I loose a bit of low range.

stock subaru low range is 3.545x1.59X3.9=21.98

suzuki low range is 3.545x2.23x4.11=32.49

nissan+subaru low range is 3.545x1.59x2x4.11=46.33

 

suzuki low range with no other gearing gets me slightly lower than stock sized tires with 31" tires

If I run the same setup as what I running before with the nissan+subaru its about 2.1x slower with 31" than it was with stock tires.

 

In low gear at idle:

stock with 23" tires= 2.35 MPH

stock with 27" tires = 2.74 MPH

stock with 31" tires= 3.14 MPH(MMM pie)

suzuki/31" tires/4.11 gears = 2.12 MPH

Nissan+subaru/31" tires/4.11 gears =1.48 MPH

 

is less hassle worth less crawling?


Edited by Uberoo, 21 September 2013 - 03:48 PM.


#7 86hatchback

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Posted 21 September 2013 - 07:48 PM

Keep in mind all the aftermarket low range ratios for the Suzuki case. I've seen them used on Craigslist when guys go for an even lower set.

#8 Uberoo

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Posted 22 September 2013 - 01:43 AM

I haven't paid more than 800 for an ENTIRE CAR,I'm not about to spend that on a set of gears for a transfercase that just makes the Tcase weaker..



#9 ivans imports

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Posted 22 September 2013 - 11:07 AM

All the mud boggers use a simple chain and gear drive setup even up to 3000hp cars the more hp the stronger the chain the big hp guys use a dubble chain and 4 sprocets. But very few use a T case. Makes for quwick gear ratio changes and sprockets and chains are cheap at princess auto and endless ratios to pick from. Of the 100 drag cars iv'e seen with thiss setup have never seen on fail or come apart.



#10 monstaru

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Posted 22 September 2013 - 01:56 PM

The Suzuki transfercase is ridiculously stout.

I have seen a guy on 40's spin his tires and beat on one for over a year before it broke in half. It was geared at 6.5:1. Trust me, they are HIGHLY underrated by people.

 

The hard part is, finding one for sale. lol

If they are mounted right, they can last for a long long time.

Oh, and FYI, the gears are about 500 a set. At least the last time I bought a set they were.

cheers

 

Oh, and you are over thinking it. Until you reach like 50:1 and below(numbers going up), it really is all the same.

tens and thousands here are irrelevant......


Edited by monstaru, 22 September 2013 - 02:00 PM.


#11 Uberoo

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Posted 22 September 2013 - 02:04 PM

I found one for sale for $125, and the guy said he would take 100.Is that a good price?


Edited by Uberoo, 22 September 2013 - 02:05 PM.


#12 monstaru

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Posted 22 September 2013 - 02:24 PM

yes, buy it.And If you don't end up using it, I'll buy it. I need another one.

 

yes

I found one for sale for $125, and the guy said he would take 100.Is that a good price?



#13 Gloyale

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Posted 23 September 2013 - 03:45 PM

4.11 or 3.9 or any other ratio final drive will not matter in your case for rear output.  Purely a function of the lower shaft speed.  The lower shaft DRIVES the pinion in the final drive.......so it's "upstream" so to speak in the whole crawl ratio equation.

 

Use whatever subaru trans you can find with the lowest first gear ratio....which actually might be a 3.9  or even like a 3.7 turbo single range. (Best I can find in my research is 3.545 in the old and newer 3.9 and 4.11 boxes. 2wd EAs have a 3.633?  The 3.7turbo boxes have lower 2nd-5th  )

 

The 1st gear ratio, not the final drive is what matters here.  Using just the rear output, you can even remove the front diff and ring gear entirely, and put freeze plugs in the front outputs.



#14 Uberoo

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Posted 23 September 2013 - 11:31 PM

From the info I have found all 5 speed transmission had a 3.545 1st gear ratio .2wd is out of the question because there there no rear output.The turbo transmission sounds promising but needs an adapter or take the internals from a turbo box and put them in a legacy box..






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