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I was hoping you might have some input on the gentleman above that has an 88 with FT4WD D/R and a 3.90 rear diff...

yikes, guys, like i said, my dad fab-ed the motor, it hardly is even an RX under the hood. we had nothing to start out with. as in no original motor in vehicle at time of aquisition. exhale, corky. i am not a diff expert, although my father is a gearing genius. ask him about racing ministocks. leave him alone, we have 20k mi on this rig, no problems yet. i don't know the condition, but the thing just says 3.9 and this is what i am told. Oh, and i'm a 17 year old girl. no gentleman.

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So is low range on all these RX models 1.2 ratio?

 

1.196 to be exact.

 

I was hoping you might have some input on the gentleman above that has an 88 with FT4WD D/R and a 3.90 rear diff...

 

XT6 FT4WD trans are 3.90. I know, I had one and the diff. It could be possible that there is a trans from it in that RX....there is mention of many parts from other subies going into this single RX....could have happend that its got a 3.90 XT6...but then again, how could it be D/R???? Could be possible that the gearing guiness pulled the trans apart to install the 3.90 ring/pinion from something else and also match that with the rear diff's 3.90.

 

If not...its simply got a 3.90 in the rear. No harm in doing this with a 3.70 FT4WD trans or PT4WD trans...the only problem is when the 4WD is engaged or when the diff is locked...on a hard surface. Otherwise...on something loose...not that much noticable...but the rear end WILL drag...I know...ive done it. I also drove for about 12k miles with a 3.90 in place of where a 3.70 should have been...never locked the diff tho...and everything was peachy. Trans workes great...only reason I swapped was beacuse I wanted the DUAL RANGE and the clutch was toast from too much HP and autocross launches being dealt to it.

 

Why is there no harm to the EA82/ER27 FT4WD trans? The center diff is open until closed. Its NOT an EJxx/EGxx/EZxx trans with a viscous center or clutch pack. If it WAS an auto FT4WD...then there would be a problem...but its not.

 

:headbang:

 

Ok, back to surfing...

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Calebz, for some reason I thought you agreed with the guy about the S/R tanny in the RX, I re-read it again and see that you didn't. Not sure what you are talking about with the guy and the 3.90, he told us it was a 'hillbillied' car and wasn't original. About teh auto, look at the link I posted on the 89 options, you see an auto as an option for the RX in 89.

 

4RnrRick, here is a link to an 86 tranny data page and an 88 tranny data page, they should answer all your questions.

http://www.corkysrocks.net/86transdata.jpg

http://www.corkysrocks.net/88transdata.jpg

Just remember, the 86 is an On-demad 4WD and the 88 is a FT4WD.

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The beauty of the RX trans is the low range nearly perfectly splits each gear. For example, the RPM gaps between each gear is about 1000RPM (5th is a little more, I think), the difference in the low range is 500 RPM. So you can split any gear in half if needed to keep the EA82 in it's power range. It's also nice for getting of the line...

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The beauty of the RX trans is the low range nearly perfectly splits each gear. For example, the RPM gaps between each gear is about 1000RPM (5th is a little more, I think), the difference in the low range is 500 RPM. So you can split any gear in half if needed to keep the EA82 in it's power range. It's also nice for getting of the line...

 

hehehehehe.....which is why I love it so much.... :banana::burnout:

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Not sure what you are talking about with the guy and the 3.90, he told us it was a 'hillbillied' car and wasn't original..

What I was talking about is that he says he is using a FT4WD D/R trans in combination with a 3.90 rear diff.......

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This reminds me of the rarity of this car. The guy I bought my RX from didn't even know what he had, aside from being the sporty model in the subaru line of the time, he didn't know anthing about the car. Didn't know what a turbo did, aside from making it faster, didn't know it had an LSD (or what one was), or that it was even a farily rare car. Guess I can't complain, though, I got it for $675!

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I looked.. and then I looked at my own FSMs.. don't see anything that suggests FT4WD D/R with a 3.90

 

I looked over it....and I still cannot say for sure that the FT4WD D/R was offered as 3.90....I know the S/R was for XT6.

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I looked over it....and I still cannot say for sure that the FT4WD D/R was offered as 3.90....I know the S/R was for XT6.

Yep, I'll have to agree, I scoured the books trying to find where I thought I saw the 3.90 D/R FT4WD tranny info and can't find it, I did find that the XT6 does have a S/R FT4WD tranny with a 3.90. so that may be where the S/R FT4WD center lock diff tranny that I have came from. So, after much review of all my technical data, I'm going to have to agree (and it hurts to do this :lol: jk) with Calebz, there isn't a FT4WD D/R 5 speed tranny with a 3.90 ratio.

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Yep, I'll have to agree, I scoured the books trying to find where I thought I saw the 3.90 D/R FT4WD tranny info and can't find it, I did find that the XT6 does have a S/R FT4WD tranny with a 3.90. so that may be where the S/R FT4WD center lock diff tranny that I have came from. So, after much review of all my technical data, I'm going to have to agree (and it hurts to do this :lol: jk) with Calebz, there isn't a FT4WD D/R 5 speed tranny with a 3.90 ratio.

 

Off Topic sort of.... the JDM EA81 RX had a D/R and LSD.....

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I looked over it....and I still cannot say for sure that the FT4WD D/R was offered as 3.90....I know the S/R was for XT6.
Section 3-1, page 10 of 1987 Factory Service manual for 4-Door Sedan, Station Wagon, and 3-Door.

 

4WD, 5-speed, Dual-Range

 

Rear reduction gear: Final 3.900, *3.700

* = Turbo model

 

So there is a 4WD, Dual-Range 5-speed non-turbo 1987 model that has the 3.900 final drive gear ratio. Turbo's have the 3.700 final drive. ;)

 

Man, my FSM's have been becoming useful. :grin:

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Section 3-1, page 10 of 1987 Factory Service manual for 4-Door Sedan, Station Wagon, and 3-Door.

 

4WD, 5-speed, Dual-Range

 

Rear reduction gear: Final 3.900, *3.700

* = Turbo model

 

So there is a 4WD, Dual-Range 5-speed non-turbo 1987 model that has the 3.900 final drive gear ratio. Turbo's have the 3.700 final drive. ;)

 

Man, my FSM's have been becoming useful. :grin:

While true, it doesn't quite meet the requirements of the conversation.

 

The trans we were speaking of is not just the plain old D/R, we were actually talking about a FT4WD D/R (such as is found in the RX) as far as anyone has been able to show thus far, they are all 3.70

 

The Part time D/R (as you have found in your FSM) is a 3.90

 

Those FSMs sure are fun aren't they? I have gotten tons of use out of mine :)

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Ok, enough tech stuff and back to topic :grin:

The reason I bought my RX is because its the rarest of all.

They only made a black RX in the last half of 89.

If it wasnt for this, I would still own my 84 T-Coupe. And embarrasing alot of RallyX's with newer/faster rigs.

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Good info now I know why my 85 DR tranny doesn't seem as low as my 81 DR tranny, the low gear ratios are different, my 81 is way more torquey and tacks out way earlier than my 85 DR turbo wagon whilist rallying. Awww never mind they are totally different ratios, 3.90--3.70 Awsome info!!

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