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marcusgl10z28

retrofitting a dual range for center diff lock possible?

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Ive serched and cant seen to find anthing but i have a fulltime 4wd single range 5mt w difflock and a 5 mt dual range... my question isis there a way to merge the two... the rxctrans gear ratios arent low enough and the dual range is but i wanted the best of both worlds

 

Am i reaching to far? Is this possible to do? What is needed to do it? Any opinion or input would be greatly apritiated.

Edited by marcusgl10z28

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Ive serched and cant seen to find anthing but i have a fulltime 4wd single range 5mt w difflock and a 5 mt dual range... my question isis there a way to merge the two... the rxctrans gear ratios arent low enough and the dual range is but i wanted the best of both worlds

 

Am i reaching to far? Is this possible to do? What is needed to do it? Any opinion or input would be greatly apritiated.

 

Nope....can't be done....unless you also had a D/R turbo trans....(either PT or FT4wd only in RX models)

 

But what you need is an upper shaft with the D/R gears and a Turbo 2nd-4th gear set......that's the key.

 

Regular D/Rs use a taller 2nd-4th gears (5th too but 5th can be swapped between them)

 

1st and second, the small gear is part of the Upper shaft......so if you are gonna keep the FT4wd locking diff  (on the lower shaft)....you need an upper shaft with a gearset that matches.......1st is the same on all.....but 2nd......second is the crux of the biscuit.  So you need a turbo upper shaft and gears.

Edited by Gloyale

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Hi  This is Jerry, i have a 88 rx 5 speed dual range with center diff lock  it could be yours make me an offer call me 509-952-2855 Thanks Jerry

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Hi  This is Jerry, i have a 88 rx 5 speed dual range with center diff lock  it could be yours make me an offer call me 509-952-2855 Thanks Jerry

 

Bingo!

 

Stuff a regular D/R lo range set into that and you'r in business

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I need lower gears for the freeway... @70 mph im just above idle running a ft 5mt 3.7 final and 235 75 15 mt's there just isnt enough power in that low rpm to even attempt a slight incline on pavement gotta take 4th and a steep grade in 3rd to keep the speed up 4th & 3rd are my freeway gears... the 3.9 final d/r can handle it but i really enjoyed the capability of the f/t 5mt w the ej22

 

Ok so i can swap 3rd & 4th gear sets? Still 3.7 final?

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IIRC the EA turbo manual transmissions that have the 3.7 ratio final have a .87 overdrive in 5th and the non-turbo 3.9 units have a .78 overdrive. The 3.9 with the higher (lower numerically) od ratio is actually higher geared. I don't know if that answered any of your question but I thought I would let you know.

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IIRC the EA turbo manual transmissions that have the 3.7 ratio final have a .87 overdrive in 5th and the non-turbo 3.9 units have a .78 overdrive. The 3.9 with the higher (lower numerically) od ratio is actually higher geared. I don't know if that answered any of your question but I thought I would let you know.

 

Yeah....5th in the 3.7 box is actually a lower gear.....but 5th is the one gear where both upper and lower gear can be swapped around to different shafts.

 

Ok so i can swap 3rd & 4th gear sets? Still 3.7 final?

 

No....you have to keep the gears that match the type of pinion shaft you have.....the PT boxes have narrower diameter pinion shaft (at least at the part the 3rd and 4th spindle presses on).

 

 

 

You could MAYBE swap gears from an EJ AWD box....they have the large diameter pinion shaft like the FT4wd...

 

but as mentioned....you'd end up with taller gears using the PT D/R gears....

 

 

 

Pintonut......the stock GL D/R non turbo 5spd has the lowest first gear of any 3.9 box.  They pretty much all have the same 1st..... (3.545:1)  ............it's 2nd-5th that are different.

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Ok well dont think i will ever use 4 or 5. Whats 2&3 should i look for

 

 

(3.545:1)??? That to the r&p right or is. That to the splitter shaft so to axel?

Seems high geared? For 1st low range

Edited by apintonut

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Sweet link to numbchux's build! Lsd up front is sweet.. but im not quit willing to go that deep in custom work to a trans.. i mean im capable i just dont wanna...lol

 

Thanks for all these answers but maybe my question got a little mixed. What i want is to be able to selectivley lock the center diff for max power to the rear.. i just drove in soggy grass after hooking up the newly aquired d/r and i know ill miss the ft 4 wd i had... 2 wd just sucks especially with open diffs.

 

Does this just mean ill need an rx trans? And specifically im running 30" tires so the tall gears put me out of power range in the rpms i need lower standard drive gears.. i know i will get this with the d/r trans but the downfall of street performance having lost awd and the ability to lock up the center diff is a huge loss to me.

 

How bad does running pavement with 4wd high on hurt the trans?

 

So there is no way to frankenstien a 3.9 na d/r trans with my old fulltime trans to keep the best of both worlds?

 

Ive been told the dual range is more sturdy to higher hp than the rx trans and and it simply isnt an option due to the tall freeway gears in it has. Simply put any turbo trans just isnt gonna turn tires good enough or as iv been told wont hold up to a franken turning 30's.

 

Gloyal what are you showing when multplying the all the gear numbers is this the ratio at the stubs?. Im unsure of what you mean.

 

Thank you for all this awsome input and knowlege

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Ive been told the dual range is more sturdy to higher hp than the rx trans and and it simply isnt an option due to the tall freeway gears in it has. Simply put any turbo trans just isnt gonna turn tires good enough or as iv been told wont hold up to a franken turning 30's.

 

Gloyal what are you showing when multplying the all the gear numbers is this the ratio at the stubs?. Im unsure of what you mean.

 

 

 

Yeah the math is final drive = Engine RPM:wheel rotation

 

Turbo trans should be fine to turn 30's

 

Final drive is taller (3.7) but the 2nd -5th ratios are lower......If my math is right, you shold be actually lower freeway geared with the Turbo trans.

 

 

5th gear N/A = 0.780:1

5th gear Turbo= 0.871:1

 

N/A  3.9 x 0.780= 3.042

 

Turbo  3.7 x 0.871= 3.2227

 

So you would actually be looking at taller freeway gears with the N/A trans.

 

1st is the only gear where the Turbo trans is taller gears at the stub.

 

My 2.2 powers my wheeler w/30's thru a D/R......and its fine on the freeway.  65mph @ 2100rpms  .......4th for hills but what's wrong with that?

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Ive been running an ej matched to a 3.7 turbo trans and im looking at 1500rpm or less at 65 in 5th with the 30s real world mph is an estimate..lol

 

Same tires with a dr in my sedan

And im at 2500 rpm at 65 like you were saying with yours. And i havr to take 3rd on hills with the fulltime turbo trans at 60 or so. My old sedan w d/r powrred 30s uphill in 4th like u said.

 

In my head this means taller 5TH than the na d/r trans but according to your math im incorrect??.. im confused.lol.. i apologizr if im reprtative but then i just swapped out for a trans i cannot modify to fulltime and has taller gears than my old one?. So this means even less crusing power?? Thank you for yur time dan

Edited by marcusgl10z28

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