Towing and 4WD

Wobbly · **Posted:** Thu Feb 01, 2007 10:16 am

We'll be towing a travel trailer whose weight and dimensions are at the upper end of the CRD's tow rating. Under which conditions might 4WD be used to increase towing stability?
I'm concerned mostly with towing on pavement at highway speeds under adverse weather and road conditions. I'm not familiar with Selec-Trac and how to optimise its use.

Thanks.

Jeger · **Posted:** Thu Feb 01, 2007 10:56 am

With our transfercase you can use full time 4WD whenever you want, even if it is dry. Just dont use part time on the dry stuff. I wouldnt bother using it unless it is getting slick out as in snowy or icy, there is no need when it is dry or just wet. Braking is going to be the biggest issue anyhow. If you do happen to find yourself in such bad road conditions that full time 4WD is not quite cutting it then try part time. Part time will give equal torque split to the front and rear, full time will not.

Wobbly · **Posted:** Thu Feb 01, 2007 1:29 pm

Jeger wrote:

With our transfercase you can use full time 4WD whenever you want, even if it is dry. Just dont use part time on the dry stuff. I wouldnt bother using it unless it is getting slick out as in snowy or icy, there is no need when it is dry or just wet. Braking is going to be the biggest issue anyhow. If you do happen to find yourself in such bad road conditions that full time 4WD is not quite cutting it then try part time. Part time will give equal torque split to the front and rear, full time will not.

Say we're going down a long, steep, windy grade, does being in full time 4WD reduce front brake heating because of the engine braking effect? Has anyone fitted an exhaust brake to the CRD?
http://www.pplmotorhomes.com/parts/rv-t ... diesel.htm

Hmm, reading my own link, I see that diesels have no engine braking effect. Ouch, those exhaust brakes are expensive, too.

Jeger · **Posted:** Thu Feb 01, 2007 2:33 pm

Wobbly wrote:

Jeger wrote:

With our transfercase you can use full time 4WD whenever you want, even if it is dry. Just dont use part time on the dry stuff. I wouldnt bother using it unless it is getting slick out as in snowy or icy, there is no need when it is dry or just wet. Braking is going to be the biggest issue anyhow. If you do happen to find yourself in such bad road conditions that full time 4WD is not quite cutting it then try part time. Part time will give equal torque split to the front and rear, full time will not.

Say we're going down a long, steep, windy grade, does being in full time 4WD reduce front brake heating because of the engine braking effect? Has anyone fitted an exhaust brake to the CRD?
http://www.pplmotorhomes.com/parts/rv-t ... diesel.htm

Hmm, reading my own link, I see that diesels have no engine braking effect. Ouch, those exhaust brakes are expensive, too.

I would have to say no it wouldnt slow you down or save your brakes much at all. Essentially all of the parts that get power while in 4wd are already spinning even while in 2WD, putting it into 4WD just connects those parts to the power.

I have mentioned the exhaust brake before and people didnt seem to think it would be a good idea and may not work at all with our vehicles. Some said they think the CRD engine brakes pretty good, I dont really think it does, and I think the only reason it does at all may because of the EGR flow control valve shutting partially while off the throttle and restricting the intake. But thats just guessing on my part.

I would get the best rotors you can find and the best brake pads you can find, a good properly adjusted trailer braking system and call it good.

EDIT: What would be really slick would be to rig up a water mist system to cool your brakes if they get too hot, like they do on those racing semi's :twisted:

Wobbly · **Posted:** Thu Feb 01, 2007 2:53 pm

Jeger wrote:

Wobbly wrote:

Jeger wrote:

With our transfercase you can use full time 4WD whenever you want, even if it is dry. Just dont use part time on the dry stuff. I wouldnt bother using it unless it is getting slick out as in snowy or icy, there is no need when it is dry or just wet. Braking is going to be the biggest issue anyhow. If you do happen to find yourself in such bad road conditions that full time 4WD is not quite cutting it then try part time. Part time will give equal torque split to the front and rear, full time will not.

Say we're going down a long, steep, windy grade, does being in full time 4WD reduce front brake heating because of the engine braking effect? Has anyone fitted an exhaust brake to the CRD?
http://www.pplmotorhomes.com/parts/rv-t ... diesel.htm

Hmm, reading my own link, I see that diesels have no engine braking effect. Ouch, those exhaust brakes are expensive, too.

I would have to say no it wouldnt slow you down or save your brakes much at all. Essentially all of the parts that get power while in 4wd are already spinning even while in 2WD, putting it into 4WD just connects those parts to the power.

I have mentioned the exhaust brake before and people didnt seem to think it would be a good idea and may not work at all with our vehicles. Some said they think the CRD engine brakes pretty good, I dont really think it does, and I think the only reason it does at all may because of the EGR flow control valve shutting partially while off the throttle and restricting the intake. But thats just guessing on my part.

I would get the best rotors you can find and the best brake pads you can find, a good properly adjusted trailer braking system and call it good.

EDIT: What would be really slick would be to rig up a water mist system to cool your brakes if they get too hot, like they do on those racing semi's :twisted:

How about a chute? Or having my wife hold up one of those sun reflectors that say 'Call Police' through the sunroof? Should get some drag out of that.

Cowpie1 · **Posted:** Thu Feb 01, 2007 11:57 pm

[/quote]

How about a chute? Or having my wife hold up one of those sun reflectors that say 'Call Police' through the sunroof? Should get some drag out of that.[/quote]

Boy, did that bring back memories. I once drove a semi for a national carrier that didn't want to spec jake brakes on the trucks. For a joke, a few of us got some old Army parachute bags and stuffed them with rags and hung them on the back of the trailers. Labled it... CFI Jake Brake - Pull in case of emergency.

Wobbly · **Posted:** Fri Feb 02, 2007 12:37 am

Cowpie1 wrote:

How about a chute? Or having my wife hold up one of those sun reflectors that say 'Call Police' through the sunroof? Should get some drag out of that.[/quote]

Boy, did that bring back memories. I once drove a semi for a national carrier that didn't want to spec jake brakes on the trucks. For a joke, a few of us got some old Army parachute bags and stuffed them with rags and hung them on the back of the trailers. Labled it... CFI Jake Brake - Pull in case of emergency.

[/quote]

Corn Flakes, Jake brakes... could be a C&W song there, good buddy.

alljeep · **Posted:** Fri Feb 02, 2007 1:18 pm

Wobbly wrote:

We'll be towing a travel trailer whose weight and dimensions are at the upper end of the CRD's tow rating. Under which conditions might 4WD be used to increase towing stability?
I'm concerned mostly with towing on pavement at highway speeds under adverse weather and road conditions. I'm not familiar with Selec-Trac and how to optimise its use.

Thanks.

I'm not sure I'd do it. Our front differential housings are made of aluminum versus the heavy duty steel Corperate 8.25" rear diff which is designed to handle the heavy loads. Sure, the load is now split between front and back, but still, it seems like a big unknown to me.

Your stability will come from a good weight distribution hitch that forces some of the tongue weight back down onto the front axel/suspension.

BCool · **Posted:** Fri Feb 02, 2007 1:32 pm

I called the manufacturer and he said that the breaks should work just fine for the jeep and 5000 pounds, he wouldn't recommend it. So that settles the exhaust break issue i guess. I'm sure you could still try it and let us know if it helps enought in stopping to warrant the price. You could also get a few sets of pads for a grand.

Flying J · **Posted:** Fri Feb 02, 2007 11:51 pm

I'd be real concerned about the jeep (tranny in particular) holding up to a e-brake. I had to jump through lots of hoops to get a pac-brake to work with my 97 Dodge Ram diesel automatic. Basically if you don't find a way to keep the tranny locked up things will get really hot really quick. Might need stiffer exhaust valve springs too.

Might just invest in a good brake controller and see how that works for you. I'd be interested in hearing about your towing experiences.

Pete M · **Joined:** Mon Feb 05, 2007 12:37 am **Posts:** 89

I've flat-towed my Jeep Comanche with our CRD (30+ hours total driving) and after some experimenting I now will always shift it into full-time 4wd. It feels much more confidence-inspiring. Now, the physics involved with flat-towing are different that hauling a large trailer (front tires of my MJ like to follow the grooves in the pavement more than a trailer would) , but I'd probably do the same with a trailer.
Jeep on!
--Pete

Joe Romas · **Posted:** Mon Feb 05, 2007 7:57 am

[quote="Wobbly
Say we're going down a long, steep, windy grade, does being in full time 4WD reduce front brake heating because of the engine braking effect? Has anyone
Hmm, reading my own link, I see that diesels have no engine braking effect. [/quote]

In the above situation your biggest problem is going to be your "at the limit" trailer pushing your KJ down the hill and causing the rig to fishtail :shock:

Trailer brakes are the important thing here to stop the fish tailing. Years ago I towed a 15' Sprite English travel trailer, 2000 pounds, with a Bronco II and putting on the Bronco's brakes going down hill actually made the fish tailing worse. Once the trailer's surge brakes kicked in the rig strightened out but the feeling before that happened was not good

Also what figure are you using for your trailer? The empty trailer alone is not realistic because all your personal stuff along with water adds up fast. You'll want a load equalizing hitch with a anti sway device and electric brakes on your trailer with a easy to reach manual activation button.

Regarding 4x4, why put added ware on your transfer case :?:

Wobbly · **Posted:** Tue Feb 06, 2007 1:33 am

Joe Romas wrote:

[quote="Wobbly
Say we're going down a long, steep, windy grade, does being in full time 4WD reduce front brake heating because of the engine braking effect? Has anyone
Hmm, reading my own link, I see that diesels have no engine braking effect.

In the above situation your biggest problem is going to be your "at the limit" trailer pushing your KJ down the hill and causing the rig to fishtail :shock:

Trailer brakes are the important thing here to stop the fish tailing. Years ago I towed a 15' Sprite English travel trailer, 2000 pounds, with a Bronco II and putting on the Bronco's brakes going down hill actually made the fish tailing worse. Once the trailer's surge brakes kicked in the rig strightened out but the feeling before that happened was not good

Also what figure are you using for your trailer? The empty trailer alone is not realistic because all your personal stuff along with water adds up fast. You'll want a load equalizing hitch with a anti sway device and electric brakes on your trailer with a easy to reach manual activation button.

Regarding 4x4, why put added ware on your transfer case :?:

[/quote]

We're getting a proportional control electric brake controller with a "panic mouse" that is accessible on the dash. Trailer brake application will be proportional to pressure on the tow vehicle brake pedal. Pushing the the panic button when sway begins will apply 40% of trailer brake maximum effort for 3.5 seconds. We'll also have a weight distributing hitch and dual cam sway control. The trailer has electric brakes. Not sure if they are on both axles, or just one.

We'll also try to travel with near-empty water and waste tanks. As my wife collects interesting rock specimens, I'll be tossing them. She'll retaliate by jettisoning any treasures that I find.

Joe Romas · **Posted:** Tue Feb 06, 2007 9:35 am

[quote="WobblyWe'll also try to travel with near-empty water and waste tanks. As my wife collects interesting rock specimens, I'll be tossing them. She'll retaliate by jettisoning any treasures that I find.[/quote]

Sounds like you've done your homework on the brakes

My wife always took along everything including the kitchen sink even though the trailer had one of it's own :lol:

Good luck traveling. I'm looking for a 16" Casitia or Scamp trailer for behing our CRD

Wobbly · **Posted:** Tue Feb 06, 2007 10:11 am

Joe Romas wrote:

[quote="WobblyWe'll also try to travel with near-empty water and waste tanks. As my wife collects interesting rock specimens, I'll be tossing them. She'll retaliate by jettisoning any treasures that I find.

Sounds like you've done your homework on the brakes

My wife always took along everything including the kitchen sink even though the trailer had one of it's own :lol:

Good luck traveling. I'm looking for a 16" Casitia or Scamp trailer for behing our CRD

[/quote]

EBAY has frequent scam auctions for both of these trailers. The listers hijack real EBAY accounts that have good feedback ratings. They always ask to be contacted by direct email instead of through EBAY. Down payment by Western Union is requested. The trailer pictures are taken from real listings.

It's interesting to compare European trailers to North American ones. The former are much lighter, since they use lightweight materials. Unfortunately, they can't be imported without going through the same NHSTA process ($$$$) as a grey market car. The only mods they would require to be legal would be DOT-labeled brake lines and taillight lenses.

Joe Romas · **Posted:** Tue Feb 06, 2007 10:25 am

[quote="Wobbly
EBAY has frequent scam auctions for both of these trailers. The listers hijack real EBAY accounts that have good feedback ratings. They always ask to be contacted by direct email instead of through EBAY. Down payment by Western Union is requested. The trailer pictures are taken from real listings.

It's interesting to compare European trailers to North American ones. The former are much lighter, since they use lightweight materials. Unfortunately, they can't be imported without going through the same NHSTA process ($$$$) as a grey market car. The only mods they would require to be legal would be DOT-labeled brake lines and taillight lenses.[/quote]

We had a 13' Sprite in the late 1960's that was made in England we towed with our 1962 Land Rover. It was very roomy inside for the size. Then a later 15' version that was assembled in the US. I've seen the scams on ebay and there's a Scamp there now. I don't know i it's real or another scam.

chrispitude · **Posted:** Sat Jun 16, 2007 1:25 pm

I asked my local transmission shop about towing in full-time 4WD, and he said absolutely not. The transfer case is not designed for the kind of sustained power transmission that the drivetrain sees while pulling the load and fighting the extra wind resistance. Of course, this was for a 4400lbs travel trailer. For a small utility trailer, it might not make much difference.

- Chris

Metal Man · **Posted:** Sat Jun 16, 2007 6:31 pm

Quote:

I asked my local transmission shop about towing in full-time 4WD, and he said absolutely not. The transfer case is not designed for the kind of sustained power transmission that the drivetrain sees while pulling the load and fighting the extra wind resistance. Of course, this was for a 4400lbs travel trailer. For a small utility trailer, it might not make much difference.

Does the manual caution against this?
I always tow in 4WD.
The European Liberty is rated to tow 7400lbs.
http://www.jeep.co.uk/jeep/versions.aspx?ID=444,3,97

barnez224 · **Joined:** Fri Jan 19, 2007 11:28 am **Posts:** 130

Somewhat of a sidenote for this post:

I was just looking around on Edmunds.com and noticed that our CRD's will out-tow an H3 by 500 lbs. Hope I meet someone with an H3 soon so I can rub that in a little bit (along with our mileage, of course).

Bob V · **Posted:** Sun Jun 17, 2007 1:22 am

As far as the exhaust brake goes, our jeeps have a VGT turbo and they can be made to work as an exhaust brake, but you do need to keep the trany locked up or it can over heat (the trany). I have noticed that if I lock out the over drive on the trany going down hill I get some engine braking, I would like to know how this efficts the tranny temps.

Towing and 4WD

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