9 or 10 speed trans on an xj

Old 05-20-2018, 01:13 PM
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Default 9 or 10 speed trans on an xj

So i know this is an odd question but would any of you think an xj would get better mpg, acceleration and maybe reliability with a new 9 or 10 speed transmission thats now being made or would it be pointless? Take multiple things out of the equation like electronics and programming. Just pretend everything worked lol would it be better or worse? doesnt have to be the new cherokees transmission it can be from other companies. I hear shift points suck and reliability is horrible on most. Also would be interested in a cvt on an xj and keep it in the power band for longer at low rpms. Boring i know but possibilities lol
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Old 05-20-2018, 02:28 PM
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Originally Posted by EEVEE View Post
So i know this is an odd question but would any of you think an xj would get better mpg, acceleration and maybe reliability with a new 9 or 10 speed transmission thats now being made or would it be pointless? Take multiple things out of the equation like electronics and programming. Just pretend everything worked lol would it be better or worse? doesnt have to be the new cherokees transmission it can be from other companies. I hear shift points suck and reliability is horrible on most. Also would be interested in a cvt on an xj and keep it in the power band for longer at low rpms. Boring i know but possibilities lol
just buy a Yaris dude. You can leave your man card at the door.

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Old 05-20-2018, 07:14 PM
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Nah, 9 levels of slow? That just seems... slower.
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Old 05-20-2018, 09:26 PM
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No, transmissions of that type are used to make up of a lack of torque and keep the engine within it's power band. A 4.0 doesn't have a lack of torque problem. So, in other words, it's pointless.
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Old 05-20-2018, 09:29 PM
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The only way those transmissions work is if they are electronic and tuned to the engines torque curve and accelerator position. So unless you have that type of situation, they would be of no benefit
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Old 05-20-2018, 10:27 PM
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you guys think so? i would think if youre in constant stop and go traffic the where you get to 30 mph then stop and repeat for miles more gears would help it not work as hard and maybe get more city mpg or on the highways lower rpms.
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Old 05-21-2018, 04:54 AM
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My opinion is the only way you're going to get better mileage with a 4.0 XJ is with 2wd and a manual trans, meaning no front axle gears to turn.
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Old 05-21-2018, 06:31 AM
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Might as well just debate the real, and, more important question...



Leprechaun ****, or unicorn farts?

Discuss.


LOL
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Old 05-21-2018, 09:44 PM
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Originally Posted by EEVEE View Post
you guys think so? i would think if youre in constant stop and go traffic the where you get to 30 mph then stop and repeat for miles more gears would help it not work as hard and maybe get more city mpg or on the highways lower rpms.
If this is your traffic situation, with all due respect, why in God's name are you driving an XJ? They were economical back in the 80's when they were first produced, but more fuel efficient vehicles have been being made ever since.

Nothing wrong with out of the box thinking, but you're trying to re-invent the wheel, here.
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Old 05-22-2018, 08:49 AM
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A few points to ponder on this one:


A trans with more gears could possibly provide a lower 1st gear, nice for off road, and maybe a taller top gear for more optimum RPM at higher road speed- which means 4.56s with 33s at moderate rpm on the freeway. Win!


Every engine, whether our 4.0s or eco-mizer 3cyl, will have an optimum area in the rpm range for a specific task e.g. towing, cruising, economy etc. A trans with more gears has better chance of choosing an optimal gear for the task at hand.


Now, where do we get this tranny and how fast can I bolt it in?
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Old 05-22-2018, 10:55 AM
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Dreamer
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Old 05-22-2018, 11:08 AM
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You can buy enough gas to put your XJ in a junkyard 10 times over for the price/benefit of a conversion like that.

Originally Posted by dave1123 View Post
My opinion is the only way you're going to get better mileage with a 4.0 XJ is with 2wd and a manual trans, meaning no front axle gears to turn.
Truth! With my 4.0 SE 4x4 manual I get 20 MPG in combined driving during a 30 mile commute. You won't get better than that with any other transmission.
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Old 05-22-2018, 12:14 PM
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Originally Posted by Basslicks View Post
If this is your traffic situation, with all due respect, why in God's name are you driving an XJ? They were economical back in the 80's when they were first produced, but more fuel efficient vehicles have been being made ever since.

Nothing wrong with out of the box thinking, but you're trying to re-invent the wheel, here.
nothing wrong with some sanding down on rough edges and greasing of the wood bearings lol

And yes the price is a huge factor but hey i cant complain for a free jeep!
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Old 05-22-2018, 08:09 PM
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Originally Posted by TimV View Post
A few points to ponder on this one:


A trans with more gears could possibly provide a lower 1st gear, nice for off road, and maybe a taller top gear for more optimum RPM at higher road speed- which means 4.56s with 33s at moderate rpm on the freeway. Win!


Every engine, whether our 4.0s or eco-mizer 3cyl, will have an optimum area in the rpm range for a specific task e.g. towing, cruising, economy etc. A trans with more gears has better chance of choosing an optimal gear for the task at hand.


Now, where do we get this tranny and how fast can I bolt it in?
You're not wrong... only problem is
vvvv

Originally Posted by 4.3L XJ View Post
The only way those transmissions work is if they are electronic and tuned to the engines torque curve and accelerator position. So unless you have that type of situation, they would be of no benefit
This.

It's not a bolt-in scenario. Has to be programmed. The ECU has to be programmed (good luck figuring out how to do that), can't use a TCU from a 4.0 so you have to use the TCU for whatever vehicle the transmission is design for, then you have to figure out how to get the flashed TCU to talk to the flashed ECU. THEN you have to make adapters just to get the thing to bolt UP to a 4.0.

By then, you may as well have just done an OM617 swap with a 6 speed manual and get absolutely bullet-proof reliability, torque, fuel economy, and super simple electronics (cause there are none) and fuel delivery.

Originally Posted by EEVEE View Post
nothing wrong with some sanding down on rough edges and greasing of the wood bearings lol

And yes the price is a huge factor but hey i cant complain for a free jeep!
This is a truth fact.
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Old 05-22-2018, 09:22 PM
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Its a dream lol. Thats why i said pretend everything worked. In real life this would be very difficult to achieve. but it just got me curious on more gears thats all.
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