Need serious help with hardbody rear differential

[chadsig]

I own a 1997 hardbody, 4x4, 2.4 4cyl. Nissan. At about 60mph i am running around 3,000 rpm and at about 50mph i am running aroung 2,500rpm. I went to the nissan dealer and was told i had around a 4.62 gearing. I have a gear chart calculator from superior axle and gear and it says from my understanding that i am way high in the rpms. Is there any way to reduce the rpms? either by getting a different rear end i.e. (pathfinder?) or is their any other options at all?? From this chart it says that a 3.73-3.91 or even a 4.11 would lower the rpms. I dont mind losing a little performance.

[Desert Rat]

You'll lose a ton of performance going to taller gears, as your engine is not in its peak powerband at lower RPMs.

What size tires are you running? One thing you could do is run a bit larger tire. Your speedo will be off - It'll read slower than actual speed, but that's one way to get back to where you need to be.

Other options are sourcing axles out of an older 4 banger truck. 4.10s were available in the late 80s 4 banger HBs, and 4.375s were also relatively common. Look for CA41 (4.10) or CA43 (4.375) axle codes on the build sticker in a donor truck.

V6 truck axle swaps would be a good option for the rear, but the front has to come out of a 4 banger truck - your truck has an R180A front diff. V6 trucks had a larger R200A front diff that will not clear your oil pan.

[D21shoka]

Well here is a question for you. i got the same truck a 96 nissan hardbody 4x4 4.625 axles and i want to switch them out to a 3.73 gear axles both front and rear because obviously you cannot drive 4 wheel drive with 2 different differentials!! my thing was i had 2 choices, one was to change the 2 axles which i am resorting to now and the other was to find a 6 speed 4 wheel drive transmission which would cost a lot more and need more work!! also i am trying to find the right gears and pinions from a junk yard off older trucks for front and rear and also add that LSD to the rear!! any help is much appreciated!! thanks.

[Desert Rat]

Your truck wouldn't get out of its own way with 3.73 gears. 4.375:1 is the tallest gearing domestically available for an H233B rear axle, and you'd need to swap in an R200A front diff from a 4.375:1 geared truck along with some sort of differential drop kit to match the front. (see the "what axle do I have" thread stickied at the top of the forum for info on what was available in different trucks).

The 96-97 H233b rear is a 2 pinion axle. Earlier units were 4 pinion. An LSD should still have been a factory option for your truck, or you could swap in an older 3rd member from a WD21 pathfinder with an automatic trans for the same gear ration and axle spline count and factory LSD.

Bottom line: The KA motor is underpowered for a 4000 lb truck and it was geared low to compensate, and to put the engine in its peak power band at cruising speed. The taller gears will bring those rpms down, but you'll have no power without downshifting a couple times. Is it flat where you live? If so, you can get away with it, but if you live in moutainous country like I do, you want as deep a gear as you can get in the axles. I'm running 5.14 gears in mine with 33" tires and it's still a slug on the hills.

[D21shoka]

Well hears another question for you. i'm trying to get that engine up to 200+ hp then can i decrease the axle without having any problems taking off??

[codeman]

Hey Desert Rat, have a question for ya. I have a 1989 Nissan hardbody 4x4 with a 327 chevy motor and a 350 turbo transmission. At 55, I am turning 2700 rpms and it seems to need another gear. What I was wondering was does Nissan have something around 3.73 gears for their axles? It has 4.375 in there now. Thanks for your time.

[dvdswan]

D21 to get 200+ HP you will spend some green for sure to get that. you're not hurting the engine running at 3k at 60. codeman, get a 700R4 and you will have your lower rpm, around 2200. keep the gears for wheeling. just my $.02.

[longtooth]

Hey Desert Rat, have a question for ya. I have a 1989 Nissan hardbody 4x4 with a 327 chevy motor and a 350 turbo transmission. At 55, I am turning 2700 rpms and it seems to need another gear. What I was wondering was does Nissan have something around 3.73 gears for their axles? It has 4.375 in there now. Thanks for your time.

I would be more worried about snapping the axles from the torque from that v8

[chibinissan]

O justo whant to know if the LSD differential will fit on a non LSD housing I whant to make my truck LSD fast so I can start hooking up the egine