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5th Gear Woes in a 91


CO_pathfinder
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So I'd just like to start by saying screw the old 55mph National Speed Law. Dumbest thing ever. Why? Because it ruins the 5th gear ratio (OD, if you dare to call it that... 400 rpm less than 4th)

 

In the 87-94, the gearing ratios, from 1st to 5th go like this: 4.061 || 2.357 || 1.490 || 1.000 || 0.862.

 

Now, in 95, the OD gear, 5th, had its ratio changed, as the National Speed Law was repealed by Congress (thank Jesús)

 

Does anybody know what this ratio actually is? I can't seem to find it anywhere on here or in the FSM, but then again, I suck at navigating the FSM. I'm considering removing the weak-sauce 5th thats in there now and replacing it with one from a 95 or later when I replace my clutch sometime next spring/summer.

 

Thanks,

 

Sean

 

EDIT: The above, of course, is true for the 5 speed manual, I don't know if the same can be said for the autotragic's ratios

Edited by CO_pathfinder
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Well, the 3.0 can't really pull much more than that ratio other than on the flats anyway, so it isn't a huge loss.

I can't recall if the gears are different for the 1995, much less how much, but IIRC the tranny for the R50 has some different gears in it not to mention the repositioned fill hole so that would be ideal.

 

B

 

For the 1996 R50:

3.580

2.077

1.360

1.000

0.811

Interestingly enough, the manual also states that there is no change in the gearing for a 1995 WD21, and a 2wd D21 with the VG30E will have the same gearing listed for the 1996 R50.

This info can easily be found in at the bottom of the MT section of the FSM, under Service Data and Specifications... ;)

 

Edited by Precise1
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Different final drive ratio's


As for your plan to swap gear boxes for what might or might not be an actual gearing change, Just my opinion, but I doubt that the rewards would be worth the cost and work involved :shrug: How often do you really drive at 55+ ...an honest % here :togo:


EPA ratings were the same for both 1991 http://www.fueleconomy.gov/feg/calculatorCompareSideBySidePopUp.jsp?column=1&id=8479
and 1995 http://www.fueleconomy.gov/feg/calculatorCompareSideBySidePopUp.jsp?column=1&id=12452

 

The old are what appeared on the window stickers and the new reflect the adjustments to all pre-2007 models due to EPA changes

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Oh and just a note here, I would refrain from specifically calling the top gear (in this case 5th) in a manual transmission "OD" as it will likely just cause confusion to those reading. OD is a term regularly reserved for Automatic transmissions.

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I drive almost exclusively highway miles, so my whole getting ~15 mpg highway, ~17 city thing is rather annoying (and bass ackwards) when you combine it with 200 mile trips 2-3 times a week.

 

I've got a lot of experience rebuilding old transmissions, but haven't really ever messed with the gearing, and wasn't sure if the rpm difference between the auto and the manual was because of the actual 5th ratio or the final drive. I wasn't going to swap the whole tranny, was just going to see if stealing the 5th from an autotragic would net me any useful gains :wiggle: From what you're saying, it doesn't seem like it

 

Manual must have 4.636 and the auto must have 4.363? Excuse my lack of Pathfinder knowledge, I'm still on the learning curve. Then again, who isn't?

 

Anyways, if I nabbed a LSD from an auto (AND the front diff), could I expect to see Pathfinder "hyper-milage"? :lol: Long final drive + early shifting = :treadmill: ?

Edited by CO_pathfinder
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I drive almost exclusively highway miles, so my whole getting ~15 mpg highway, ~17 city thing is rather annoying (and bass ackwards) when you combine it with 200 mile trips 2-3 times a week.

Short answer: Your using the wrong vehicle as your daily driver.

There is nothing backwards in the 15/17 that ratio is perfectly normal of full time dino burners, especially when considering the era. Todays reversal of those numbers, with the city milage being the higher one is mostly due to the wide adoption of hybrids, where the electric motors are used much more in the city.

As for the drive, I did 500-700+ (500-550 base commute + on the clock travel) per week and not including after work trips or weekends for years. It's fuel consumption and costs are just something you except or find an alternative too. When I decided to lift it, I understood that those costs would rise, never did I try to fool myself into thinking that I could make it a fuel efficient daily driver.

 

I've got a lot of experience rebuilding old transmissions, but haven't really ever messed with the gearing, and wasn't sure if the rpm difference between the auto and the manual was because of the actual 5th ratio or the final drive. I wasn't going to swap the whole tranny, was just going to see if stealing the 5th from an autotragic would net me any useful gains :wiggle: From what you're saying, it doesn't seem like it

Ok I am confused here, first swapping internals is going to be much more work that simply swapping transmissions... and are you talking about swapping some of the internals from an Auto into a Manual? I want that video documented please! Even more so if you are talking about swapping the 5th gear from a Pathy's auto... they are 4spds, that's 3+OD.

 

Manual must have 4.636 and the auto must have 4.363? Excuse my lack of Pathfinder knowledge, I'm still on the learning curve. Then again, who isn't?

According to 1994 FSM PD-98 the ring and pinion ratio's were 4.375 and those trucks factory equipped with the optional 31x10.5R15LT's and P235/75's received 4.625 gears... which does not really clarify what got what, given that those are the two sizes available anyway... unless I am missing something here :shrug:

 

The 1989 FSM is even LESS clear, because according to it, my truck came with 4.6's, which it did not. :rolleyes:

 

Anyways, if I nabbed a LSD from an auto (AND the front diff), could I expect to see Pathfinder "hyper-milage"? :lol: Long final drive + early shifting = :treadmill: ?

No
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Sorry 'bout the OD thing, I've always referred to the top gear as OD. Habit of owning auto's for most of my life.

The 5th gear in the manual is identified as "OD" in the ratio chart of the FSM's but I think most people associate OD with Auto's, that is the only reason I said that :aok:

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never did I try to fool myself into thinking that I could make it a fuel efficient daily driver.

Oh, I'm certainly not trying to convince myself that a 23 (almost 24 :) ) year old dino will ever be fuel efficient. I'm no Tungsten. Moreso just trying to get as much out of it as possible while at the same time learning about the vehicles by tearing JY vehicles apart in order to keep mine in top condition. In all truth, was just spitballing some ideas haha.

 

 

 

Ok I am confused here, first swapping internals is going to be much more work that simply swapping transmissions... and are you talking about swapping some of the internals from an Auto into a Manual? I want that video documented please! Even more so if you are talking about swapping the 5th gear from a Pathy's auto... they are 4spds, that's 3+OD.

Swapping internals isn't that hard :scratchhead: used to do it all the time in my buddies Firebird; we used to blow that trans up all the time at Bandimere (drag strip in Colorado). It was always 4th that we exploded, so we would just find the same ratio gear from some old JY Pontiac and swap it in. I don't know what possessed me enough to think that an auto was a 5-speed haha. But I think you got my point. I'd steal the (what I would hope to be) longer 4th and swap it for my 5th. This was before you guys reminded me that different trim levels, as well as manny vs. auto, had different rear gears. Whoops.

 

 

 

According to 1994 FSM PD-98 the ring and pinion ratio's were 4.375 and those trucks factory equipped with the optional 31x10.5R15LT's and P235/75's received 4.625 gears... which does not really clarify what got what, given that those are the two sizes available anyway... unless I am missing something here :shrug:

Figured this one out, I think: The top model trucks got the 31s and 4.3, because this was part of the "sport" package, IIRC. So, for WD21, this would be SE, since LE wasn't around yet. This would make sense,

Nevermind. I'm pretty sure that Manual transmissions were SUPPOSED to get the 4.625 gears. Unless they came with the 31's, in which case they got the 4.375 gears. Yes, this makes sense? Then, autos all got the 4.375, because a 4 speed with 4.625 would be disgusting.

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Nevermind. I'm pretty sure

Please do your self a favor and stop right there because the end of that sentence should be... "Nissan has shown to rhyme or reason as to what a Pathfinder was, or was not equipped with, no matter what trim badging was stuck on the hatch door or printed on the window sticker."

 

;)

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Manual Trans vehicles typically come with the 4.3 ratio front and rear diff gears. Automatics came with the 4.6 gears. This is not always the case but has been true in all of the pathfinders that I've ever seen. The 4.3 ratio in the manual trucks is used since the manual trucks inherently make more power to the ground through less drive train loss and can push a slightly taller gear set with the same effort. The autos were given 4.6 to help mask the effect of the power sucking automatic transmission.

 

The automatics Rev lower going down the freeway because of the much taller final drive ratio of the auto Trans' vs the manuals 5th gear.

 

My girls 1993 pathy came stock with 31" tires, manual Trans, and 4.3 gears. My 93 auto came with 4.6 gears and 235/75 tires. My 92 auto came with 4.6 gears and 31" tires.

Edited by Nefarious
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