LOST JEEPS :: View topic - Could 3.21 gears work with CRD?

Could 3.21 or lower numerical ratio gears work with CRD? What options are in the computer for tire sizes and gear ratios? How would this effect shift points? What front differential does the '08 Liberty use? Those questions asked The CRD seems to be cruising at an RPM higher than a diesel should for optimum fuel economy. I am open to all thoughts, even the negative ones.
Lewis

The cool kids dig a high reving engine.

Dude...UR so uncool!

My 4.10 gears plus my Edge EZ module smoke it up yo!

But seriously....no 3.21 gears for you. And Ford does not impact our lives.

Some of us run bigger tires and go off road and tow lots so the 4.10 gears are pretty sexual compared to the stock 3.73. The stockers could not keep up with The Rockies and 32" tires

Would those be the cool kids that enjoy selling engines that they have designed to be out-of-spec to the engine manufacturers' original design limits?

I also would like to let it run a lower rpms, but it's probably like the vw's, when I had a tdi asked about lower gearing for mileage, was told that the tdi had to run at the higher rpm for emission reasons, so I figure the crd is the same.
A two speed rear end would be just neat. :lol:

tulsa wrote:

No, but you could go with 3.55s

For Jeep to have given the CRD the same gears as the 3.7 gasser(patooie!, with cudos to gmctd) shows a real lack of understanding of the diesel torque range.
Lewis

The people who make those decisions have either had lobotomies, or been completely bought off. There isn't any other LOGICAL conclusion.

geordi wrote:

The people who make those decisions have either had lobotomies, or been completely bought off. There isn't any other LOGICAL conclusion.

A lot of the people who make these decisions have slowly risen through the ranks in the automotive companies. They've had free cars, gas, and service for so long they've completely forgotten the cost and time of maintaining a vehicle. And the problems that rise from poor design / maintenance (walking).

3.55 gears are not only available, but they are factory in some KJ's. I think that's the axle ratio in the manual transmissioned gas and CRD.

3.21 gears are available in the 08 Liberty. I know the front diff in the 08 is a Dana 30/186mm the rear is a 8.25 Chrysler. The question is will they bolt up in a CRD and can they be interagrated into the computer?

tulsa wrote:

Rear axle shouldn't be a problem, ours is a 8.25 Corporate as well. Can't remember exactly what we have for a front axle, but given their drive for cost savings the last few years, I'd be willing to bet it's the same.

As for the computer, given the availability of aftermarket reprogrammers for those that like to bolt on lifts and large tires, shouldn't be much of a problem. At that, should be a simple matter for the gents at Inmotion to come up with a tweak to their programming to cover it.

retmil46 wrote:

tulsa wrote:

Great input. I am pretty sure the '08 Liberty is a Dana 30a and should be able to bolt up OK. I will check with Inmotion about gearing options. I have gotten tired of asking questions of service reps. Now to watch the junkyards for '08 Libbys.

Author:	tulsa [ Fri Sep 19, 2008 9:25 am ]
Post subject:	Could 3.21 gears work with CRD?
Could 3.21 or lower numerical ratio gears work with CRD? What options are in the computer for tire sizes and gear ratios? How would this effect shift points? What front differential does the '08 Liberty use? Those questions asked The CRD seems to be cruising at an RPM higher than a diesel should for optimum fuel economy. I am open to all thoughts, even the negative ones. Lewis

Author:	JL Rockies [ Fri Sep 19, 2008 10:01 am ]
Post subject:
As of right now, you're limitied to the stock 3.73 or you can change them to 4.10 like the cool kids.

Author:	geordi [ Fri Sep 19, 2008 5:04 pm ]
Post subject:
That is going the wrong way. I know exactly what he is asking, and I FULLY believe the CRD can support a LOT lower RPM usage than the design fools at Mopar have chosen for us.

Author:	JL Rockies [ Fri Sep 19, 2008 5:09 pm ]
Post subject:
The cool kids dig a high reving engine.

Author:	Sir Sam [ Fri Sep 19, 2008 5:33 pm ]
Post subject:	Re: Could 3.21 gears work with CRD?
tulsa wrote: Could 3.21 or lower numerical ratio gears work with CRD? What options are in the computer for tire sizes and gear ratios? How would this effect shift points? What front differential does the '08 Liberty use? Those questions asked The CRD seems to be cruising at an RPM higher than a diesel should for optimum fuel economy. I am open to all thoughts, even the negative ones. Lewis No, but you could go with 3.55s

LOST JEEPS http://www.lostjeeps.com/forum/phpBB3/

Could 3.21 gears work with CRD? http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=36053	Page 1 of 2

Author:	geordi [ Fri Sep 19, 2008 6:12 pm ]
Post subject:
JL Rockies wrote: The cool kids dig a high reving engine. Would those be the cool kids that enjoy selling engines that they have designed to be out-of-spec to the engine manufacturers' original design limits? Because that would be Ford. International told them "Don't spin this faster than 3500 rpm" which would have meant that Ford would have gotten bone crushing torque, but would have needed to pony up for more and better gears. Instead, they decided to stick with ~3.73 rear ends and only 4 gears... And BARELY any overdrive to speak of. Spin it faster, it's cheaper for Ford, and who gives two rips about that economy thing. "But but but they now have big HP numbers! That makes our willys bigger!" says the morons at Ford. Big surprise, International told them to go fook themselves when the engines started failing right and left from being over-revved. Obviously, Mopar and GM behave the same way. It's the same lack of logic that allowed everyone (EXCEPT the Asians) to sell cars without a transmission drain pan, and GM to ask the question "Why do they need more than two gears anyway?" Translation: we build stinky poo, they'll buy it anyway.

Author:	JL Rockies [ Fri Sep 19, 2008 6:45 pm ]
Post subject:
Dude...UR so uncool! My 4.10 gears plus my Edge EZ module smoke it up yo! But seriously....no 3.21 gears for you. And Ford does not impact our lives. Some of us run bigger tires and go off road and tow lots so the 4.10 gears are pretty sexual compared to the stock 3.73. The stockers could not keep up with The Rockies and 32" tires

Author:	geordi [ Fri Sep 19, 2008 7:20 pm ]
Post subject:
JL Rockies wrote: Dude...UR so uncool! My 4.10 gears plus my Edge EZ module smoke it up yo! But seriously....no 3.21 gears for you. And Ford does not impact our lives. Some of us run bigger tires and go off road and tow lots so the 4.10 gears are pretty sexual compared to the stock 3.73. The stockers could not keep up with The Rockies and 32" tires That may be true... But what mountain ranges are you finding in Ft Lauderdale, FLORIDA? My house is in Boca. Don't think I don't know that the ONLY hill worth talking about is Mt Trashmore. hehehehehe

Author:	ATXKJ [ Fri Sep 19, 2008 7:41 pm ]
Post subject:
Yeah - didn't the 4:10's get put in after moving to Florida? -- have they seen the Rockies yet?

Author:	tjkj2002 [ Fri Sep 19, 2008 7:42 pm ]
Post subject:
geordi wrote: Would those be the cool kids that enjoy selling engines that they have designed to be out-of-spec to the engine manufacturers' original design limits? That would be the same thing if you went to 3.55's or 3.21's,out of specs for a auto tranny. Hey a Detroit 8V92TA turning 8500rpms sounds cool ,handled that rpm with ease for over 45min,40 of them running just on it's own engine oil(fuel lines cut) till it started on fire(valve covers where off,replaced injectors and some dumb idiot messed with the buffer switch)till the fire department force fed it water through the turbo for 5 min before it hydrolocked and cracked the block in 4 pieces.

Author:	journeyjim [ Fri Sep 19, 2008 9:04 pm ]
Post subject:
I also would like to let it run a lower rpms, but it's probably like the vw's, when I had a tdi asked about lower gearing for mileage, was told that the tdi had to run at the higher rpm for emission reasons, so I figure the crd is the same. A two speed rear end would be just neat.

Author:	geordi [ Fri Sep 19, 2008 9:54 pm ]
Post subject:
journeyjim wrote: I also would like to let it run a lower rpms, but it's probably like the vw's, when I had a tdi asked about lower gearing for mileage, was told that the tdi had to run at the higher rpm for emission reasons, so I figure the crd is the same. A two speed rear end would be just neat. That sounds about right, considering the stupidity of the newest emission "reduction" ideas. Hmm, let's reduce emissions by burning even MORE of the stuff that produces the emissions in the first place. The regeneration systems inject raw fuel on the EXHAUST stroke (TOTALLY wasting all that fuel) as a means of raising the EGT. Does this seem stupid to anyone else? What that VW answer proves is not that the engine or transmission can't handle the lower RPM (which it OBVIOUSLY can, it does it from every single stoplight) but that the EPA doesn't WANT less fuel burned. Burning less fuel will INSTANTLY reduce the emissions by that same percentage, all the time and forever. I'm hearing similar arguments from even the ultra-greenie crowd that wants to build electric vehicles. People have asked the question: "Why not power an electric car with a small or medium size generator, instead of dead-weight batteries?" "Because generators don't have any of the emissions control equipment of larger car engines" is the answer. What I see as the hidden answer: "Because a generator that burns ONE gallon per HOUR all the time would mean a car getting 80 mpg at 80mph, 60mpg at 60mph... And it is completely impossible to develop ANY emission controls for a small engine that burns so little fuel. It really needs to burn 10 gallons per hour or more." The fallacy there is that is is OF COURSE possible to develop emission controls for a small engine. I'm sure that a tiny catalytic converter could be developed with an ELECTRIC heater (instead of a raw fuel heater) just like have been used for 20 years on cars. But the emissions output of such a small engine... Do they REALLY compare with the likes of a Hummer or an Excursion? The people who make those decisions have either had lobotomies, or been completely bought off. There isn't any other LOGICAL conclusion.

Author:	tulsa [ Sat Sep 20, 2008 8:48 am ]
Post subject:	Re: Could 3.21 gears work with CRD?
Sir Sam wrote: tulsa wrote: Could 3.21 or lower numerical ratio gears work with CRD? What options are in the computer for tire sizes and gear ratios? How would this effect shift points? What front differential does the '08 Liberty use? Those questions asked The CRD seems to be cruising at an RPM higher than a diesel should for optimum fuel economy. I am open to all thoughts, even the negative ones. Lewis No, but you could go with 3.55s I think 3.55's should be an option in the computer(I do not know what options are available), but only 5% change in rpm. For Jeep to have given the CRD the same gears as the 3.7 gasser(patooie!, with cudos to gmctd) shows a real lack of understanding of the diesel torque range. I would like to be able to shift out of OD on a long hill pulling a load and keep the rpms down at 65 or 70 mph. How would changing the gearing change the shift point speeds? Lewis

Author:	ATXKJ [ Sat Sep 20, 2008 9:14 am ]
Post subject:	Re: Could 3.21 gears work with CRD?
tulsa wrote: For Jeep to have given the CRD the same gears as the 3.7 gasser(patooie!, with cudos to gmctd) shows a real lack of understanding of the diesel torque range. Lewis Everything about CRD's indicates this was a 'quick and dirty' project to test feasibility - with as many off the shelf parts as possible - with minimal design resources - minimal disruptions to standard production i.e. plug in a diesel and see if people will buy it. There was no attempt to understand or optimize for the diesel. That said, the 3.55's were an option on some Libertys - so they should fit (although not common, so probably not easy to find) - you can get some of the effect by taller tires - however that increases the rotating mass and makes bad aerodynamics worse so depending on your driving - it could easily make things worse.

Page 1 of 2	All times are UTC - 5 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/

Author:	danoid [ Sat Sep 20, 2008 9:21 am ]
Post subject:
geordi wrote: The people who make those decisions have either had lobotomies, or been completely bought off. There isn't any other LOGICAL conclusion. A lot of the people who make these decisions have slowly risen through the ranks in the automotive companies. They've had free cars, gas, and service for so long they've completely forgotten the cost and time of maintaining a vehicle. And the problems that rise from poor design / maintenance (walking). 3.55 gears are not only available, but they are factory in some KJ's. I think that's the axle ratio in the manual transmissioned gas and CRD.

Author:	tulsa [ Sat Sep 20, 2008 9:36 am ]
Post subject:
danoid wrote: geordi wrote: The people who make those decisions have either had lobotomies, or been completely bought off. There isn't any other LOGICAL conclusion. A lot of the people who make these decisions have slowly risen through the ranks in the automotive companies. They've had free cars, gas, and service for so long they've completely forgotten the cost and time of maintaining a vehicle. And the problems that rise from poor design / maintenance (walking). 3.55 gears are not only available, but they are factory in some KJ's. I think that's the axle ratio in the manual transmissioned gas and CRD. 3.21 gears are available in the 08 Liberty. I know the front diff in the 08 is a Dana 30/186mm the rear is a 8.25 Chrysler. The question is will they bolt up in a CRD and can they be interagrated into the computer?

Author:	retmil46 [ Sat Sep 20, 2008 10:09 am ]
Post subject:
Not just on our CRD's - go to a Dodge Cummins forum and read some of the gripes about the available gear choices. They used to have choices available down into the 3.40's and 3.20's, and the complaints have been many since Chrysler eliminated those choices. Basically, numerically lower (ie, taller) gearing is better for unloaded fuel mileage and high speed driving, while numerically higher (ie, lower) gearing is preferred for towing heavy loads - even a diesel can be ran too low in the rpm range depending on conditions. For our one-off U.S. market experiment CRD, 3.73's seems to have been a compromise between fuel economy and towing ability, saving Chrysler the time and expense of offering more than one gear ratio. A few months back, Ranger1 informed me that Chrysler was actually offering 3.21 gearing in the '08 Liberty and Patriot as well if I remember correctly. I did a search of the aftermarket options available at the time. Going by memory, you can get replacement gear sets for both the front and rear axles in 3.55. And if you were willing to convert the beast into strictly a 2WD unit, you could go as low as 3.08 for the rear axle. My old '87 MB has a 2.65 rear end, but only 1:1 in 4th with the old-fashioned auto tranny in it. I'd give my eye teeth for a 5th gear OD in it, it'd be able to push close to 40 mpg on the interstate. Driving to work and keeping it at 55 mph and a little over 2000 rpm, it regularly exceeds 35 mpg. I went from 195/65R15's to 205/70R15's on it, 5% difference in diameter - speedo low by 1 mph for every 20, and odometer low by 1 mile for every 20. For doing 55 mph, I split the difference between 50 and 55 on the speedo, engine turning a couple hundred rpm slower - as long as I remember to do this, it does make a noticeable difference in fuel economy.

Author:	retmil46 [ Sat Sep 20, 2008 11:15 am ]
Post subject:
tulsa wrote: 3.21 gears are available in the 08 Liberty. I know the front diff in the 08 is a Dana 30/186mm the rear is a 8.25 Chrysler. The question is will they bolt up in a CRD and can they be interagrated into the computer? Rear axle shouldn't be a problem, ours is a 8.25 Corporate as well. Can't remember exactly what we have for a front axle, but given their drive for cost savings the last few years, I'd be willing to bet it's the same. As for the computer, given the availability of aftermarket reprogrammers for those that like to bolt on lifts and large tires, shouldn't be much of a problem. At that, should be a simple matter for the gents at Inmotion to come up with a tweak to their programming to cover it.

Author:	tulsa [ Sat Sep 20, 2008 12:53 pm ]
Post subject:
retmil46 wrote: tulsa wrote: 3.21 gears are available in the 08 Liberty. I know the front diff in the 08 is a Dana 30/186mm the rear is a 8.25 Chrysler. The question is will they bolt up in a CRD and can they be interagrated into the computer? Rear axle shouldn't be a problem, ours is a 8.25 Corporate as well. Can't remember exactly what we have for a front axle, but given their drive for cost savings the last few years, I'd be willing to bet it's the same. As for the computer, given the availability of aftermarket reprogrammers for those that like to bolt on lifts and large tires, shouldn't be much of a problem. At that, should be a simple matter for the gents at Inmotion to come up with a tweak to their programming to cover it. Great input. I am pretty sure the '08 Liberty is a Dana 30a and should be able to bolt up OK. I will check with Inmotion about gearing options. I have gotten tired of asking questions of service reps. Now to watch the junkyards for '08 Libbys.

Author:	Sir Sam [ Sat Sep 20, 2008 1:23 pm ]
Post subject:
tulsa wrote: retmil46 wrote: tulsa wrote: 3.21 gears are available in the 08 Liberty. I know the front diff in the 08 is a Dana 30/186mm the rear is a 8.25 Chrysler. The question is will they bolt up in a CRD and can they be interagrated into the computer? Rear axle shouldn't be a problem, ours is a 8.25 Corporate as well. Can't remember exactly what we have for a front axle, but given their drive for cost savings the last few years, I'd be willing to bet it's the same. As for the computer, given the availability of aftermarket reprogrammers for those that like to bolt on lifts and large tires, shouldn't be much of a problem. At that, should be a simple matter for the gents at Inmotion to come up with a tweak to their programming to cover it. Great input. I am pretty sure the '08 Liberty is a Dana 30a and should be able to bolt up OK. I will check with Inmotion about gearing options. I have gotten tired of asking questions of service reps. Now to watch the junkyards for '08 Libbys. Inmotion can't help you. The speedometer input goes into the BCM, the BCM broadcasts the data on the PCI bus. To re-calibrate the speedo someone with a DRBII needs to connect to the PCI bus, and change the configuration for revs in BOTH the BCM and ABS modules, doing only one will not work, both need to be changed. The ECU has nothing to do with the speedo - it is merely a slave to the master(s).