To full time all the time or not?

tjkj2002 · **Posted:** Thu Oct 02, 2014 1:13 am

mass-hole wrote:

[
Since literally every CRD owner discussing in this thread has at least an ECO Tune(except for maybe 1 person) if not a Hot Tune or stage 2 Turbo:

Stg 2 Turbo CRD - 400 ft-lbs X 3:1 1st gear x 3.73:1 FD = 4476 ft-lbs.
Hot Tune CRD - 370 ft-lbs X 3:1 1st gear x 3.73:1 FD = 4140.3 ft-lbs.
EcoTune CRD - 335 ft-lbs X 3:1 1st gear x 3.73:1 FD = 3748.7 ft-lbs.

All of these trq numbers are peaking @ 2000rpm with only slightly less at 1600rpm. That's recipe for wheel spin and why full-time 4wd does help us CRDers out substantially.

Got actual dyno #'s to back those up? Not a chassis dyno either but a actual engine dyno.

flman · **Posted:** Thu Oct 02, 2014 6:33 am

tjkj2002 wrote:

mass-hole wrote:

[
Since literally every CRD owner discussing in this thread has at least an ECO Tune(except for maybe 1 person) if not a Hot Tune or stage 2 Turbo:

Stg 2 Turbo CRD - 400 ft-lbs X 3:1 1st gear x 3.73:1 FD = 4476 ft-lbs.
Hot Tune CRD - 370 ft-lbs X 3:1 1st gear x 3.73:1 FD = 4140.3 ft-lbs.
EcoTune CRD - 335 ft-lbs X 3:1 1st gear x 3.73:1 FD = 3748.7 ft-lbs.

All of these trq numbers are peaking @ 2000rpm with only slightly less at 1600rpm. That's recipe for wheel spin and why full-time 4wd does help us CRDers out substantially.

Got actual dyno #'s to back those up? Not a chassis dyno either but a actual engine dyno.

I do not need a dyno, both of my CRDs spin and wear out the rear tires with out trying, it is a fact that every CRD owner knows, even stock. I can bet no one has ever complained in the gasser section about this problem.

thermorex · **Posted:** Thu Oct 02, 2014 10:51 am

The thing is that the loss of torque in the drivetrain that occurs between a gasser 4wd and a crd should be similar, provided it's the same transmission and rear axle/gearing. I am not sure how the math would work at wheel in tj's case, with his huge 35s and 5.13 ratio, but provided both Jeeps have the same Diff ratio, I think they should have the same torque loss, so in this case, whatever engine puts out more torque would win the torque "war".

flman · **Posted:** Thu Oct 02, 2014 5:26 pm

thermorex wrote:

The thing is that the loss of torque in the drivetrain that occurs between a gasser 4wd and a crd should be similar, provided it's the same transmission and rear axle/gearing. I am not sure how the math would work at wheel in tj's case, with his huge 35s and 5.13 ratio, but provided both Jeeps have the same Diff ratio, I think they should have the same torque loss, so in this case, whatever engine puts out more torque would win the torque war.

This did not even start as a war, it was in the CRD section, it is a problem we have with low end torque and normal driving, if we had gassers we would not even be discussing this.

I am just trying to decide if rear tire wear vs drivetrain wear, lots of vehicles are AWD now a days.

Dennis MacGyver · **Posted:** Thu Oct 02, 2014 11:07 pm

While in 4x4, don't you guys notice the drive-line bind when you make a "K" style (3 point) turn such as backing out of a parking place and turning the opposite direction ?

flash7210 · **Posted:** Fri Oct 03, 2014 7:21 am

Yes but only in part-time 4wd.
Full-time 4wd is like all-wheel-drive and doesn't have that binding in sharp turns.

thermorex · **Posted:** Fri Oct 03, 2014 8:17 am

flman wrote:

thermorex wrote:

The thing is that the loss of torque in the drivetrain that occurs between a gasser 4wd and a crd should be similar, provided it's the same transmission and rear axle/gearing. I am not sure how the math would work at wheel in tj's case, with his huge 35s and 5.13 ratio, but provided both Jeeps have the same Diff ratio, I think they should have the same torque loss, so in this case, whatever engine puts out more torque would win the torque war.

This did not even start as a war, it was in the CRD section, it is a problem we have with low end torque and normal driving, if we had gassers we would not even be discussing this.

I am just trying to decide if rear tire wear vs drivetrain wear, lots of vehicles are AWD now a days.

I went back to the previous post and changed to "war". I know this is meant to be a discussion and not a war or hot debate.

I one use 4wd full time only when I can't make it without struggle in winter conditions, and that's another reason I love the crd, it's a very good all wheel drive vehicle for all seasons, it handles light offroad as stock, it's a diesel with huge torque for the engine size, something a jetta tdi won't ever have even if it would come as an all wheel drive.

Personal opinion: I think the 4wd full time vs rear axle only (2wd) won't add so much wear and tear and extra fuel to justify not using it regularly. Obviously cruising on highway for extended periods of time on dry pavement should be done in 2wd, since it won't normally warrant the need of 4wd.

mass-hole · **Posted:** Fri Oct 03, 2014 10:19 am

Dennis MacGyver wrote:

While in 4x4, don't you guys notice the drive-line bind when you make a "K" style (3 point) turn such as backing out of a parking place and turning the opposite direction ?

I have noticed at full steering lock in full-time that it seems to drag a little. Not full-out bind like in part-time but I do feel it.

mass-hole · **Posted:** Fri Oct 03, 2014 10:25 am

thermorex wrote:

The thing is that the loss of torque in the drivetrain that occurs between a gasser 4wd and a crd should be similar, provided it's the same transmission and rear axle/gearing. I am not sure how the math would work at wheel in tj's case, with his huge 35s and 5.13 ratio, but provided both Jeeps have the same Diff ratio, I think they should have the same torque loss, so in this case, whatever engine puts out more torque would win the torque "war".

I think thats why were were talking wheel torque. Regardless of tire size you will apply the same twisting force to the wheel. The size of the tire determines what the force against the ground will be. A bigger tire is like having a short handle on your wrench and reduces the force applied to the road which is why he has to gear down to a 5.13. Now his tire applies the same force(actually a little more) for every foot-lb his engine make compared to a stock tired KJ with a 3.73 FD.

flman · **Posted:** Fri Oct 03, 2014 4:23 pm

thermorex wrote:

Personal opinion: I think the 4wd full time vs rear axle only (2wd) won't add so much wear and tear and extra fuel to justify not using it regularly. Obviously cruising on highway for extended periods of time on dry pavement should be done in 2wd, since it won't normally warrant the need of 4wd.

Agreed in the city or on the highway where the streets are clean, no need, but in the country with the gritty intersections, dirt roads etc. it comes in handy.

thermorex · **Posted:** Fri Oct 03, 2014 11:12 pm

mass-hole wrote:

thermorex wrote:

The thing is that the loss of torque in the drivetrain that occurs between a gasser 4wd and a crd should be similar, provided it's the same transmission and rear axle/gearing. I am not sure how the math would work at wheel in tj's case, with his huge 35s and 5.13 ratio, but provided both Jeeps have the same Diff ratio, I think they should have the same torque loss, so in this case, whatever engine puts out more torque would win the torque "war".

I think thats why were were talking wheel torque. Regardless of tire size you will apply the same twisting force to the wheel. The size of the tire determines what the force against the ground will be. A bigger tire is like having a short handle on your wrench and reduces the force applied to the road which is why he has to gear down to a 5.13. Now his tire applies the same force(actually a little more) for every foot-lb his engine make compared to a stock tired KJ with a 3.73 FD.

Correct, I was more talking about the force on the ground, since tj presented the math using his wheels and gearing.

To full time all the time or not?

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