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WTB: Rear diff. JDM 3.909

Nabeel

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Joined
Jul 14, 2006
Messages
260
Location
K.S.A
As above looking for Rear diff. JDM 3.909. I find that my tranny is JDM and need toreplace my Rear 3 bolt diff.to JDM one.

Thanks
 

ctm

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Joined
Dec 31, 2007
Messages
204
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SoCal
I have a rear diff ring & pinion assembly that came from a member in Europe. It's a direct swap with that from the 3.545 diff. I was planning to use it with an Evo 2 trans, but need to $ to get 16/2000 running again. If you have not already found out it's a rare item.
 

Nabeel

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K.S.A
I am not expert on tranny internal. But do I need to change the JDM transfer case if I swap the front diff and rear output shaft inside the transmission?
 

ctm

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Dec 31, 2007
Messages
204
Location
SoCal
pauleyman -- what you suggest has been the workaround option for most members with a JDM close ratio tranny. this is because the 3.909 rear diff is SO HARD to find. although changing the final drive of a usdm trans may be easier, it is not ideal and does not allow one to fully experience and appreciate the 3.909 rear diff mated to a JDM close ratio gearbox, which when used with an FP green, street strip 20g (like mine) or smaller turbo in a responsive gvr4/dsm, the result is a sweet set up for autocross, time trial and the street. I know at least two other local guys along with me who either run a JDM GVR4 RS/Evo1 or Evo3 trans with a 3.909 rear diff and these setups are a blast to drive.
 
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GSX_TC

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Apr 7, 2011
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3,722
Location
Houston, Texas
I'm Soo jealous now. But how are those setups on the track though?
 

ctm

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Dec 31, 2007
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204
Location
SoCal
Nabeel -- it is NOT necessary to replace your transfer case if you change the final drive of the trans or the rear diff ring & pinion. however, it would be good if you reply with the tranny code of the JDM gearbox you plan to use. in most cases it starts with "w5m33..." and is stamped at the top of the bell housing. knowing the type of tranny you have helps to be sure you are after the correct rear diff.
 
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ctm

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Dec 31, 2007
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204
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SoCal
GSX_TC - if by "track" you mean drag racing, then the Evo1/GVR4 RS, Evo2 or Evo3 close ratio trannies are not ideal because they require one additional shift to 5th gear (vs just to 4th for usdm trannies).
 

Nabeel

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Jul 14, 2006
Messages
260
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K.S.A
The code is WQWK. It is already in the car.
 

ctm

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Joined
Dec 31, 2007
Messages
204
Location
SoCal
More questions for you:
1) Have you used the tranny? What car did it come from?
2) What car is this tranny going in?
3) How far along is the tranny installed in the car -- ie, are the transfer case, starter, axles and wheels attached already?
4) What starter plate did or are you planning to use, 1g or 2g?
5) If the axles are not yet in, look through the holes from both sides where the axles would normally go. Can you see through to the other side or does a cross bar appear?

Your answers will help to determine if there are more considerations that need to be addressed -- ie, it may not just be the 3.909 rear diff that's needed to get the tranny to work in your car.
 
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cheekychimp

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Apr 19, 2004
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7,333
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East Sussex, U.K.
Quoting ctm:
pauleyman -- what you suggest has been the workaround option for most members with a JDM close ratio tranny. this is because the 3.909 rear diff is SO HARD to find. although changing the final drive of a usdm trans may be easier, it is not ideal and does not allow one to fully experience and appreciate the 3.909 rear diff mated to a JDM close ratio gearbox, which when used with an FP green, street strip 20g (like mine) or smaller turbo in a responsive gvr4/dsm, the result is a sweet set up for autocross, time trial and the street. I know at least two other local guys along with me who either run a JDM GVR4 RS/Evo1 or Evo3 trans with a 3.909 rear diff and these setups are a blast to drive.



If you think a 3.909 setup is a blast to drive, you should try the rally spec 4.3 ratio transmissions ... SSSWWWEEEEEETT!!!
 

ctm

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Joined
Dec 31, 2007
Messages
204
Location
SoCal
I have not and would jump at the opportunity to! How is it different from the "RalliArt spec" dog box trans, a couple of which (along with lots of spare parts) were being sold by Ramana (sp?) a while back?

Since the days when this forum was hosted in Yahoo groups, I can recall that there have only been a handful of true dog box trannies in the hands of forum members. I know of the two already mentioned above and two from a guy in TX who went incognito after bailing on a monster build on his BG GVR4. I recall it had a water cooled IC, Civic style radiator fitting within the upper and lower front supports so he had room for his huge turbo. It would be interesting to know what became of these? There were a couple of others who were close to one or both major US rally shops that built/campaigned Evo 1 - 3s.
 

Nabeel

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Joined
Jul 14, 2006
Messages
260
Location
K.S.A
ctm'

The JDM tranny & transfer case already installed & I am driving the car. The only problem I have is shifting issue at high RPM + the front wheels runs faster than the rears as I realized that when car was jacked & running.



Quoting ctm:
More questions for you:
1) Have you used the tranny? What car did it come from?
2) What car is this tranny going in?
3) How far along is the tranny installed in the car -- ie, are the transfer case, starter, axles and wheels attached already?
4) What starter plate did or are you planning to use, 1g or 2g?
5) If the axles are not yet in, look through the holes from both sides where the axles would normally go. Can you see through to the other side or does a cross bar appear?

Your answers will help to determine if there are more considerations that need to be addressed -- ie, it may not just be the 3.909 rear diff that's needed to get the tranny to work in your car.

 

ctm

Well-known member
Joined
Dec 31, 2007
Messages
204
Location
SoCal
Ok, what transfer case is installed with your WQWK tranny (ie, what car did it come from)?

Also, you never mentioned what kind of car you installed them in?

Your tranny came with a LSD right (at least that is what its code indicates)? Was the LSD replaced, modified, or still stock? If stock (and presuming it's installed in a USDM GVR4), can you explain how you got around the anticipated front passenger side axle issue?
 

Nabeel

Well-known member
Joined
Jul 14, 2006
Messages
260
Location
K.S.A
The tranny + transfer case from galant as at the last of the Cood is K from (WQWK) the rear diff is stock US Spec.(3.545)

web page

I did not understand the pass axle part? And I have no history about the tranny if has stock LSD. or welded. from the red color sealed it seems opened before.
 
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pauleyman

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Joined
Feb 27, 2011
Messages
91
Location
Oklahoma City, OK
You're driving it this way? Your VC on the center diff is likely already toast and possibly the center also.
 

cheekychimp

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Joined
Apr 19, 2004
Messages
7,333
Location
East Sussex, U.K.
Quoting ctm:
I have not and would jump at the opportunity to! How is it different from the "RalliArt spec" dog box trans, a couple of which (along with lots of spare parts) were being sold by Ramana (sp?) a while back?

Since the days when this forum was hosted in Yahoo groups, I can recall that there have only been a handful of true dog box trannies in the hands of forum members. I know of the two already mentioned above and two from a guy in TX who went incognito after bailing on a monster build on his BG GVR4. I recall it had a water cooled IC, Civic style radiator fitting within the upper and lower front supports so he had room for his huge turbo. It would be interesting to know what became of these? There were a couple of others who were close to one or both major US rally shops that built/campaigned Evo 1 - 3s.



I believe Alex at DSG had those two Ralliart dog boxes for a while but I have no idea if he still has them. I believe TRE also used to be able to build a short ratio box. Having never driven either, it is difficult to make a direct comparison. The most striking feature of this 4.3 transmission that I have is that it is only 1st through 4th that are close ratio with 5th being identical to the old 3.545 transmission so cruising on the highway is never a chore. I have heard the problem with the competition boxes was that they were limited to about 100 mph at 7000 rpms in 5th which meant cruising at highway speeds was annoying. That said 3.909 and 4.3 are only final ratios and are a product of primary and secondary ratios. Whilst this transmission is a blast the gears aren't as short as you might expect given that this is as big a jump again from 3.545 to 3.909. Consequently, I think the gear ratios themselves may be different to compensate. One day I will have to crack the thing open and see exactly what is inside and see if some even better ratios could be created. I could live with a bigger jump from 4th to 5th if I could make 1st through 4th even shorter.
 
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