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

What gear ratios did these Jeeps come with?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=80836		 Page 1 of 2
Author:  jrsavoie [ Tue Dec 09, 2014 4:32 pm ]
Post subject:  What gear ratios did these Jeeps come with?
I'm trying to figure out why it seems half the people I talk to get 30 mpg plus and half the people get about 25 mpg or below?

What gear ratios are stock in the CRD's?

How do you tell what you have?
Author:  gmctd [ Tue Dec 09, 2014 5:00 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
IIRC, All the US auto CRD's are right at 3.5:1, like the big Ram Cummins, which stupidly went to 3.73 for the CRD models, with appropriate reduction in fuel mileage across the board

Per FSM 3.55 and 3.73 - no indication of application, auto or manual trans - I'd think 3.55 would be us, 3.73 would be them (gassers)

Any export manual trans postings would serve to identify ratio and chassis

Maybe better question for more useful answer would be: post your rpms in o\d at 65mph................

Or each of -

30 -
45 -
55 -
60 -
65 -

for better info spread across istandard on-road scenarios
Author:  tjkj2002 [ Tue Dec 09, 2014 7:43 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
All CRD's sold in the US have 3.73 gears from the factory.
Author:  DOC4444 [ Wed Dec 10, 2014 12:41 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
Being on our third rear end, I think TJ has it right, 3.73s.

DOC
Author:  user113 [ Wed Dec 10, 2014 1:09 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
jrsavoie wrote:

How do you tell what you have?


If you have a CRD you have a 3.73. But if you want to confirm, order a copy of your build sheet. You can get it from moparownerconnect.com
Author:  DOC4444 [ Thu Dec 11, 2014 12:28 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
Or you can count the teeth when you have it apart.

DOC
Author:  gmctd [ Thu Dec 11, 2014 1:23 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
The numbers are stamped on the ring and pinion, as in 37:10
Author:  jrsavoie [ Thu Dec 11, 2014 10:01 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
Thanks for the info. I didn't know if the info was included in the VIN or like the GM's on a code in the glove compartment.

If there is no difference in gear ratios, that eliminates the gear ratio as being a possibility in the differing fuel mileages experienced with these vehicles.

If anybody has any ideas, I am wide open. I do not have a lot of time to spend on the Jeep right now. But I would like to get the fuel economy situation rectified.

I hate to do it, but sooner or later I might have to cut my losses and dump this thing. 25 mpg with this small a vehicle is not enough to put up with the doors hitting me in the shoulders every time I ride in it. And definitely not enough to recoup anything in fuel savings
Author:  ChesterCRD [ Thu Dec 11, 2014 10:58 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
My Jeep reports an average of 29-30 and on the highway at 70 it claims to be getting 32. However my calculations based on fuel put in and mileage driven (granted the mileage isn't perfect and I don't correct it) puts me at an average of 27ish. I drive around in FL mostly which is pretty flat.

My guesses on the reports:
1. Some people are going on what the EVIC reports.
2. Different driving styles, tire sizes, loads, and driving areas.
3. Optimism. Some people fudge a little up to convince themselves they are getting more out of the vehicle than they are.
4. Corrections -- I've seen descriptions of why the mileage should be adjusted up and down ~10% based on various factors.
5. Tunes -- The GDE tune improved my mileage slightly. When I first put it on, my EVIC reported some mpgs in the mid 40s at 65-70 mph. That settled down over a few weeks of driving, but may also impact what people report.

If you're seeing around 25, I think your vehicle is operating properly. You can impact that slightly up or down with your driving style and such, but I don't think you're going to see VW TDI type numbers with this vehicle.

My spreadsheet justifying my CRD purchase is an ongoing joke between the wife and I. :lol: I still like my Jeep though.
Author:  jrsavoie [ Thu Dec 11, 2014 11:24 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
I always base everything on the 6.5 diesels we have. BAsed on the fuel mileage we get with them, a tiny little thing like these Jeeps should be capable of far better mileage than 25 mpg. A Suburban is about 3 times the size and can still get 20 mpg with half of what I invested in extras for the Jeep.

I got 18 mpg regularly with our K3500 crew cab long bed single rear wheel truck, 4:10 gears with 5 speed NV4500, before I added the ladder rack and tool boxes. Now it gets about 16 mpg.

With the 1996 K1500 Suburban 3.42 gears we can load the whole family and still get 18 mpg.
Author:  thermorex [ Thu Dec 11, 2014 11:35 am ]
Post subject:  What gear ratios did these Jeeps come with?
25 vs 18 is still a big difference. If the 2.8 engine would be in another vehicle, more aerodynamic, I bet will get 30mpg. I mean honestly, it's a jeep, not a small Vw tdi.

I do get about the same mileage as you do when driving around the town. If I go hundreds of miles distance, I get 27-30+, depending on how hard I step on the pedal.
Author:  papaindigo [ Thu Dec 11, 2014 11:56 am ]
Post subject:  Re: What gear ratios did these Jeeps come with?
Real world mpg depends on so many factors that it's virtually impossible to compare mpg for the same type vehicle between owners. Factors include individual driving habits; climate vs. weather; terrain; winter vs. summer fuel; ambient temps; humidity; tire size/weight/pressue; brake condition; air filter; fuel filter; engine operating temp (e.g. thermostat condition); GDE tune; whether or not mpg is derived from the inaccurate EVIC and or odometer or derived from GPS corrected data; actual amount of fuel (e.g. unless tank is filled from the same pump to the same level readings can be wildly different) etc. I could go on almost forever.

From my personal experience with 2 different 05 KJ CRDs (1st purchased new off the lot and driven 16,400 miles until totaled by dump truck - 2n purchased with 26,400 on odometer). Both vehicles got (GPS corrected) right about 17-18 mpg in town (8 mile one way commute to work; generally flat roads; average speed 25mph with high of 45mph) pretty much regardless of AC use or ambient temps vs. 25-26 on the highway maybe 27-28 rarely (with/without AC at speeds of ca. 62mph/1,800rpm). On second vehicle post GDE EcoTune in town a pretty consistent 22mpg but can range from 20-24mpg vs. a pretty consistent highway 31mpg but can range from 29-34mpg. A known bad thermostat cut both by about 10%. On the other hand my son gets consistently about 5%+better mpg in his 06 in the same driving conditions with the same GDE tune. Interestingly when he drives my 05 he gets slightly better mpg than I do but not quite as good as his 06, go figure.
Author:  gmctd [ Thu Dec 11, 2014 2:07 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
My big '96 RAM 5.9L 12v 5-spd X-cab lwb drw would regularly get ~25mpg with 3.55 final drive - when the idiots at DCJ engineering (oxy-moron) plugged 3.73 gearset into the CRD 5.9L 24v, fuel mileage dropped to ~16-18mpg across the board - I'm talking my youngest son's ought-6 2500 4-dr short bed, and he drives like a blue-haired little ole lady - he got disgusted about my truck's mileage and dumped his truck for a VW CRD, some little hatch-back type go-cart - saved a lot of money over his 100mi each way commute to work, which also involved ~200mi each way overtime work - he's EMS

I prefer driving Big Dooley, so the KJ has been seldom driven, but I had wanted to shove a set of 3.55's into the 8-1/4" axles to see if that was the cure - avg 20mpg is good, but seems like the li'l puffer could do much better with reduced rpm across the board

I s'pect the 3.73 was chosen so the intended soccer-moms and soccer-dads wouldn't be constantly complaining about the drive-line vibrations, also known as lugging - symptoms are reasonably smooth in a Diesel V8, little harsher in a Diesel 6-cyl, absolutely worst in a Diesel 4-cyl
Author:  jrsavoie [ Thu Dec 11, 2014 3:29 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
gmctd wrote:
My big '96 RAM 5.9L 12v 5-spd X-cab lwb drw would regularly get ~25mpg with 3.55 final drive - when the idiots at DCJ engineering (oxy-moron) plugged 3.73 gearset into the CRD 5.9L 24v, fuel mileage dropped to ~16-18mpg across the board - I'm talking my youngest son's ought-6 2500 4-dr short bed, and he drives like a blue-haired little ole lady - he got disgusted about my truck's mileage and dumped his truck for a VW CRD, some little hatch-back type go-cart - saved a lot of money over his 100mi each way commute to work, which also involved ~200mi each way overtime work - he's EMS

I prefer driving Big Dooley, so the KJ has been seldom driven, but I had wanted to shove a set of 3.55's into the 8-1/4" axles to see if that was the cure - avg 20mpg is good, but seems like the li'l puffer could do much better with reduced rpm across the board

I s'pect the 3.73 was chosen so the intended soccer-moms and soccer-dads wouldn't be constantly complaining about the drive-line vibrations, also known as lugging - symptoms are reasonably smooth in a Diesel V8, little harsher in a Diesel 6-cyl, absolutely worst in a Diesel 4-cyl


So if I am going to drive a Chrysler product, I should go for a 96 5.9.

The wife keeps complaining that she wants a vehicle made in this century. Personally until they come out with something to make me happy, I will stick with stuff made in the last century.
Author:  gmctd [ Thu Dec 11, 2014 3:55 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
I wouldn't go that far, but pilot-injection makes the li'l puffer a lot more liveable than, say, the Cummins 4-cyl that was used in a lot of bread-truck vans, and such - as your significant other is accustomed to Diesel torsional vibrations (based on your other line-up), she likely would not complain about the KJ, butcept that it's smaller than a Suburban, less room and way more cramped

Ennyhoo, and dunno nuttin' 'bout the later V6 CRD KJ's, but they are larger than the '05-'06 versions, and IIRC the Grand Cherokee also gets the V6 CRD engine, with it's larger body

Far as the GM lineup, which you obviously like, some professional aftermarket D-max conversions were done on the late Suburbans (with full engine\drivetrain warranty), as well as some owner-conversion upgrades, and those should be showing up in the pre-owned vehicle markets, for another this-century Diesel option
Author:  rancherman [ Thu Dec 11, 2014 7:33 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
jrsavoie wrote:
gmctd wrote:
My big '96 RAM 5.9L 12v 5-spd X-cab lwb drw would regularly get ~25mpg with 3.55 final drive - when the idiots at DCJ engineering (oxy-moron) plugged 3.73 gearset into the CRD 5.9L 24v, fuel mileage dropped to ~16-18mpg across the board - I'm talking my youngest son's ought-6 2500 4-dr short bed, and he drives like a blue-haired little ole lady - he got disgusted about my truck's mileage and dumped his truck for a VW CRD, some little hatch-back type go-cart - saved a lot of money over his 100mi each way commute to work, which also involved ~200mi each way overtime work - he's EMS

I prefer driving Big Dooley, so the KJ has been seldom driven, but I had wanted to shove a set of 3.55's into the 8-1/4" axles to see if that was the cure - avg 20mpg is good, but seems like the li'l puffer could do much better with reduced rpm across the board

I s'pect the 3.73 was chosen so the intended soccer-moms and soccer-dads wouldn't be constantly complaining about the drive-line vibrations, also known as lugging - symptoms are reasonably smooth in a Diesel V8, little harsher in a Diesel 6-cyl, absolutely worst in a Diesel 4-cyl


So if I am going to drive a Chrysler product, I should go for a 96 5.9.

The wife keeps complaining that she wants a vehicle made in this century. Personally until they come out with something to make me happy, I will stick with stuff made in the last century.


a '96, 97 and up to a 98.5 All have P7100 inline IP's... The ULTIMATE 'hands off' combination ever stuffed into a pickup.

LOL, our '00 Ram 3500 was actually built in Sept of '99... so technically speaking.. my Lib is the first one for me to be built in the 21st.
Even though the engine was built in Italy... I'd say the Jeep is more 'home based' than any Ram!
Engines built in Brazil... Some trans (new manuals) built by MB in South America somewhere.. and the whole mess is screwed together in Mexico. (Ram)
Author:  gmctd [ Thu Dec 11, 2014 8:00 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
My '96 drw was built down there, and I upgraded the IP with TST stuff with 4" ss turbo-back exh for over 500hp - hadta install the late 13" clutch, pressure plate and flywheel to handle the upgraded power - has DANA80HD 3.55 limited-slip gears

My '01 drw was built here, and I EDGE'd it with 4" ss turbo-back exh and other stuff, upgraded the 48RE to '06 48RE specs to handle the upgraded power - has DANA80 3.55 limited-slip gears

Easy to tell where the RAMS were built:

Down there - frames and running gear were dipped in hot beeswax (yep, you read it right: beeswax) and are now very rusty

Up here - frames and running gear are painted black, showing very little rust at this late date

Late CRD's, dunno, but they have painted frames and DCJ Corporate 3.73 axles, not as easy to upgrade by simple swapping, tho I was willing to try B4 son#2 dumped the '06 RAM for a VW CRD
Author:  minisub [ Thu Dec 11, 2014 8:08 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
gmctd wrote:
....

but I had wanted to shove a set of 3.55's into the 8-1/4" axles to see if that was the cure - avg 20mpg is good, but seems like the li'l puffer could do much better with reduced rpm across the board.....


Interesting thought. But the math, oh the math. Assume R&P set at $600 and a 5% increase in MPG in direct proportion to ratio difference. Further assume $4 fuel and 25 mpg base and it would take 75k miles to break even! Even at a 20 MPG base it would take 60k miles....
Author:  gmctd [ Thu Dec 11, 2014 8:18 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
True - but the KJ FSM lists 3.55's as available, so I had tho't to search the boneyards for other late DCJ Corporate 8-1/4" axles, such as KJ's, GC's, Wranglers, RAM 1500's, etc - early KJ 3.55 would have been direct diff assembly-swap, the others would have been R&P swapout, all cheaper than across the parts-counter

It's still in the back of my mind to research and accomplish, but it's becoming more and more of a pipe-dream - sigh............
Author:  thermorex [ Thu Dec 11, 2014 8:41 pm ]
Post subject:  Re: What gear ratios did these Jeeps come with?
gmctd wrote:
True - but the KJ FSM lists 3.55's as available, so I had tho't to search the boneyards for other late DCJ Corporate 8-1/4" axles, such as KJ's, GC's, Wranglers, RAM 1500's, etc - early KJ 3.55 would have been direct diff assembly-swap, the others would have been R&P swapout, all cheaper than across the parts-counter

It's still in the back of my mind to research and accomplish, but it's becoming more and more of a pipe-dream - sigh............


Too bad you can't just throw some 31s on it just to see the mileage. I guess 31s with 3.73 would best simulate the 3.55 gear ratio with stock tires, this without calculating anything.
Page 1 of 2 All times are UTC - 5 hours [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/