Is selec track (or full time 4WD) inherently bad or weaker?

[Sting-Gray Neutral Pres.]

I'll add that I recently drove up a long paved mountain road with many switchbacks, mostly two dry tire tracks surrounded by snow, but also sometimes full coverage, sometimes all dry pavement. Needed 4WD traction most of the snowy climb, but the long wheelbase locked transfer case of the part time 4WD would bind badly turning through the dry hairpins. I had to shift in and out of 4WD like 20 times in 10 miles and it sucked. Also the manual T-case gets harder to shift into 4WD in single digit temperatures. Full Time 4WD would have been perfect.
Sadly, just like the manuals Jeep doesn't offer Selec-Trac with the diesel, which was more important to me.

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[NachoRuby]

Sadly, just like the manuals Jeep doesn't offer Selec-Trac with the diesel, which was more important to me.

I want a manual diesel with selec-trac. That would be happiness for me.

 

[ShadowsPapa]

Wish I had it. Yeah, you can shift in and out but then you are taking your thoughts off the road and around here we have a lot of cases of black ice, or snow, dry, snow, dry and so on. I counted no less than 20 shifts just driving about that many miles. It's stupid. That's one thing I'd change about mine if I could.
If I could have it added, I would.
I've had a number of vehicles with and without similar systems - my Silverado had "automatic" mode which was basically the same thing and there was nothing weak or wimpy about that truck.

 

[Sting-Gray Neutral Pres.]

I want a manual diesel with selec-trac. That would be happiness for me.

That makes two of us.

 

[JRobes]

Hmm. I might be wrong. I was thinking it was an NV unit. Whatever it is, it’s what they used in the V6 Grand Cherokees of that year.

My 2004 GC overland WJ has the NV247 t-case (shifter has full time 4WD and 4WD low options) , and it along with the varilock front and rear axles is an absolute beast in winter conditions. I figured I'd sell the WJ after I got my JT, but after driving the JT in winter conditions it's no where near as good as the WJ so I kept it as a beater/winter vehicle. My only complaint about it was no part time 4WD option (like the JT's Selec-Trac), but after 150k miles she still hasn't worn out.

My 2¢, get the Selec-Trac if you live in colder climates.

 

[ShadowsPapa]

My 2004 GC overland WJ has the NV247 t-case (shifter has full time 4WD and 4WD low options) , and it along with the varilock front and rear axles is an absolute beast in winter conditions. I figured I'd sell the WJ after I got my JT, but after driving the JT in winter conditions it's no where near as good as the WJ so I kept it as a beater/winter vehicle. My only complaint about it was no part time 4WD option (like the JT's Selec-Trac), but after 150k miles she still hasn't worn out.

My 2¢, get the Selec-Trac if you live in colder climates.

Wish I'd kept my WJ - superior on our roads with the weather we have. Stable as heck.

 

[JET_83]

You still have full control. It has all the options we have, plus one extra. It still has 2HI, 4HI, and 4LO, but it also has a 4AUTO. There's no loss of control, just more options. If I were to buy an auto, I'd get it. There's no reason not to.

oh I thought it was all just auto

 

[jsalbre]

Is it a clutch pack or a viscous coupling?

Clutch pack.

 

[NC_Overland]

My 2004 GC overland WJ has the NV247 t-case (shifter has full time 4WD and 4WD low options) , and it along with the varilock front and rear axles is an absolute beast in winter conditions. I figured I'd sell the WJ after I got my JT, but after driving the JT in winter conditions it's no where near as good as the WJ so I kept it as a beater/winter vehicle. My only complaint about it was no part time 4WD option (like the JT's Selec-Trac), but after 150k miles she still hasn't worn out.

My 2¢, get the Selec-Trac if you live in colder climates.

Yeah, I had an 04 4.7l WJ with the 247 transfer case and that’s probably why I was thinking NV. However, in what you quoted, I was talking about 2017 model year.

I loved that grand Cherokee. I should have kept it longer.

 

[brianinca]

196K on my '98 Explorer with the clutch type BW4405 AWD system. I added a switch on the dash to disable the full time AWD functionality, 5% torque to the front wheels at all times.

I replaced the whole TC at about 115K due to chain stretch, but the overall reliability was fine. I wouldn't hesitate to take the wear & tear maintenance of CV axles for the benefit of effective AWD.

I noticed zero difference in gas mileage while in 2WD, but it reduced the (significant) understeer dialed into the suspension tuning. Between 2WD and an aggressive TrueTrac that replaced the factory clutch LSD, the handling was more to my taste at 120K than at 1K.

I'd have gotten the AWD in a heartbeat if it was available in 2020, but having driven a lot of pickups and always feeling that they would benefit MOST from AWD given the light load over the rear axle, I think the Gladiator is a pickup that would show the LEAST benefit in dry pavement handling.

I didn't realize until I went and looked it up, the JT is surprisingly balanced F/R on axle loads, which explains the strangely effective snow performance!

I traded my MY2020 for a MY2021 JTR specifically to get this feature (along with LED lighting); I did find (1!) apart of dealer stock on the lot in the 2 months I was actively looking for Rubicons/Mojaves, actually identified this one as it was in transit, and when it landed at the dealer I worked fast to get a deal done

Agree with the others, it's a great option to must-have if you live in inclemate winter weather; I used it 3 times the first week I owned the truck as many roads up here go from (crappily) plowed snow to bare pavement and back to snow again.

 

[dcmdon]

Is it a clutch pack or a viscous coupling?

Its a computer controlled clutch pack.

Its interesting. Back when I worked as a tech at a Subaru dealer, Subaru was using a viscous coupling on their manual transmission cars to bring power to the back wheels when necessary.

And they were using an electronically controlled clutch pack on their Automatic Transmission cars.

I played around a lot with the cars trying to feel a difference but could not. They both worked seamlessly with no sensation of the rear axle engaging or disengaging.

The Subaru was the opposite of the Jeep, with a permanent drive to the front wheels and the clutch pack/viscous coupling engaging to transfer torque to the rear as needed.

My Audi A3 3.2 Quattro also had a system like this and it was seamless. One strange thing about the Audi was that it had a Haldex system with a "torque tube" that was always driven. The clutch pack was actually in the back. They did this to try to improve the very nose heavy F:R weight distribution.

My Subaru STi had a true center differential. It always sent 33% of the power to the front and 67% to the rear. Unless you locked it or it sensed slippage and could shift more power to the front. That AWD system was truly magical.

 

[ShadowsPapa]

You won't feel the viscous coupling effect at all. It acts more solid with shear effect. With very little difference in speed it's a liquid, more difference it slowly acts "thicker" or "more solid".

I've had several cars with such a coupling in the transfer case. The one in this car was a NOS one I landed when my original blew the coupling. The reason for the failure was that the thrust washers inside were just that, washers, things wore, allowed movement. A Jeep dealer friend in MN said they used to take the brand new transfer cases, take them apart, machine the inside of the case to allow a thrust bearing to be put in place and the couplings lasted almost forever. This was in the 80s.

 

[jsalbre]

Its a computer controlled clutch pack.

Its interesting. Back when I worked as a tech at a Subaru dealer, Subaru was using a viscous coupling on their manual transmission cars to bring power to the back wheels when necessary.

And they were using an electronically controlled clutch pack on their Automatic Transmission cars.

I played around a lot with the cars trying to feel a difference but could not. They both worked seamlessly with no sensation of the rear axle engaging or disengaging.

The Subaru was the opposite of the Jeep, with a permanent drive to the front wheels and the clutch pack/viscous coupling engaging to transfer torque to the rear as needed.

My Audi A3 3.2 Quattro also had a system like this and it was seamless. One strange thing about the Audi was that it had a "torque tube" that was always driven. The clutch pack was actually in the back. They did this to try to improve the very nose heavy F:R weight distribution.

We had a 2010 Subaru Outback with the clutch pack AWD and it was great. Never managed to get it stuck in the snow and it’d hang the tail out in fast corners on dirt. The fact it was controllable sideways at 60 MPH showed how well they designed that system.

We’ve also had a 2014 VW Tiguan, 2018 VW Golf Alltrack, 2019 VW Tiguan, and currently have a 2021 VW Tiguan, all with clutch pack (Haldex specifically) AWD. They’ve all been phenomenal in the snow and the Alltrack had no trouble getting sideways in the dirt when we wanted it to. They all have the same constantly driven “torque tube” that your Audi did, with the clutch built into the rear diff.

 

[Dadiator21]

Great post… And great response from everyone. I think the question comes down to what type of climate are you driving in. I’m a new JT owner, but I can tell you that if you live in a snow country, you experience many situations where you go from icy/snowy conditions when pulling into traffic and then instantly on a road that is clear from the plow, salt/calcium chloride and that could be an issue for all time four-wheel-drive.

So far, I probably have averaged using it 4 to 5 times a week. The “manual experience“ does add to the experience… but I can’t imagine the added concern of when am I doing damage to my drivetrain by being in 4H, and stopping/slowing down to disengage. Anyone who lives in a climate that needs it, knows that you constantly switching from bad/good/to ideal conditions constantly.

Last thing I will say… It is a real safety issue to have to pull out from an icy/snowy surface and then deal with the middle section that may be full of ice before passing onto a well-maintained roads as traffic is coming both ways.

Reality is, I should probably just leave it in for auto all the time; but I Try to stay in 2WD for the majority of my trips.

 

[ilovebikes99]

Having a dedicated winter tire set will defeat any AWD or 4WD system. I used to drive a RWD BMW in a hilly city but I had real winter tires. No issues at all.
The Willys with the LSD is nice in snow. Only issue sometimes is starting from a dead stop on an incline when in 2WD but it will go even then. If I had real winters on instead of MT tires, there would be very little need for 4WD for urban/sub-urban driving

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