Need Uphill Advice, Please

HorsesInTow · 09-30-2007, 10:12 PM

I bought my used 04 SE with Big Tow, 4x4, Off-Road about 3 weeks ago. Has 32K miles and looks in new condition. I bought it to tow - I have two horses for a gross trailer weight of about 5,000 lbs. I live in the hills and this is where I tow, almost exclusively.
In the few outings so far, it has taken most of the grades fine, but I have one major concern about climbing a slow, steep hill. The last 1/4 mile home is up a very steep grade that I take in 4WD low, 1st gear. It is paved, but not smooth. The first time towing the horses up this grade went fine, but the second time and third time did not. After climbing most of the way up, the truck stopped moving forward (no wheel slipping) intermittently. It was a very bumpy and worrisome situation. When I drove up with an empty trailer (about 2600 lbs), it drove up fine (as it did the first time I drove up with it full).
The first time I had this problem, I stopped the truck, put it in neutral, then back into 1st and continued on. That seemed to work for the few more feet ascending the hill, but I sure need to find out what is going on. I take this hill slowly because it is so steep... could I be lugging it even in 1st with 4-Lo? Or what else should I be looking at? I'd really appreciate any insight. Thanks!

red_rider_elsinore · 09-30-2007, 10:29 PM

Have you tried to up in 4-hi? If you were lugging it in 4-lo you could've overheated the transmission. 5k lbs is not too heavy to try to make it 4-hi. I would try that. I friend of mine who was racing at some dunes in 4-lo overheated the transfer, and it wouldn't go back into 4-lo. Maybe the transfer overheated. Next time go into park and then back into drive. Sorry I can't help.

mtofell · 09-30-2007, 11:20 PM

Have you tried it in 2wd? If the wheels aren't slipping there is no reason for 4wd... that could be causing things to bind up. This truck has a lot of torque and should be able to handle the situation you describe.

Fox Delta · 09-30-2007, 11:39 PM

strange - remember that 4lo is supposed to be for non-paved roads or just straight ahead maneuvers (like pulling froward up a boat ramp) to avoid driveline bind. It will tolerate some light turning just be verrry careful.

is it so bumpy that you are starting and stopping alot? You could be building too much heat, what does your tranny gauge show? if so, try to set a rpm (like 1800) in 4lo, this is enough to keep you moving slowly but not working up as much heat as starting and stopping....

**loufish** · 10-01-2007, 05:12 AM

You should not be in 4wd on pavement, you'll put the driveline into a bind...
Try in first gear, but keep the rpm up around 3000 rpm...This must be one steep hill...

BigA · 10-01-2007, 05:26 AM

Yea, I wouldn't think you would need 4wd on pavement, maybe 4Hi if it is wet and you had to start from a stop.

HorsesInTow · 10-01-2007, 10:47 AM

Thanks for your input. The reason I'm choosing 4-Lo is for the torque boost. This road is at least 45 degrees uphill and I'm pulling 5,000 lbs. I'd use 2 wheel Lo if it were an option so the power stayed in the back where I need it most. I really need to go slow because I've just come around a curve and can only accelerate carefully for my horses' sake. I did check with a Nissan Svc rep about using 4-Lo on hard pavement, and he said it was no problem for the short duration I described. I will get a load of hay today in the trailer, which will get the trailer weight cloe to 4,000 lbs and "play" with speed up the hill without worrying about the horses becoming frightened or getting hurt. I'll also try straight 2WD, but I'd think(?) that I'd lug for sure without the extra torque.

HorsesInTow · 10-01-2007, 10:59 AM

Thanks for replying. The transmission gauge tells me I'm not overheating, but I will try 2WD with a load of hay and see how well it does. (I'd think power in the back wheels pulling a trailer uphill will give me better traction.) I do have to stay pretty slow for the sake of the horses, and have a hard time imagining that this steep grade wouldn't require the extra 4-Low torque, but it wouldn't hurt to try a few things differently with hay in the trailer... don't need to worry about the hay geting bounced around a bit!

HorsesInTow · 10-01-2007, 11:11 AM

That is the crux of the problem. Yes, it is one steep hill - at least 45 degrees and I'm coming out of a turn, climbing this hill and pulling horses, so I need to stay pretty slow and accelerate very easily. But if I am lugging, clearly I need to accelerate a bit more since I can't gear any lower. It's tricky with the horses back there; they really need a midas touch - any jolt or sudden speed change is hard on them (especially on a steep hill). Interestingly, I've towed them up this hill for the last 11 years with a T100 SR5 (manual trans) in 4-Lo without any problem. Needless to say, the V-6 T-100 was inadequate for long grades, but took this short, steep in stride!

Beach-TJ · 10-01-2007, 08:04 PM

This happens from time to time with the guys that run auto transmissions in rock crawling riggs. With an auto on an incline the transmission basically gets starved for fluid and will slip. Specifically, I think it's the tq converter that is getting starved. A solution to this problem is to replace the stock pan with a high capacity pan that allows you to hold extra fluid. The deeper pan and its extended fluid pickup allows the vehicle to operate at steeper angles without starving the transmission of ATF.
But I do not know if anyone makes a high capacity pan for the Tittan though. I know some of the crawling guys over fill there auto transmissions, but those are generally trail only rigs, I don't think that's a good idea for a street driven truck.
I agree that the 4 lo is a good idea for both extra power and extra control, and is much kinder to your transmission.
It could be a combination of ATF fluid starvation and the extra weight of the horse trailer that are causing you to stop moving on the incline, as every extra pound will make fluid starvation more obvious.
Maybe this will give you some insight into your issue.
I hope you can find a solution.

cneary812 · 10-02-2007, 06:03 AM

Quote:

Originally Posted by HorsesInTow

That is the crux of the problem. Yes, it is one steep hill - at least 45 degrees and I'm coming out of a turn, climbing this hill and pulling horses, so I need to stay pretty slow and accelerate very easily. But if I am lugging, clearly I need to accelerate a bit more since I can't gear any lower. It's tricky with the horses back there; they really need a midas touch - any jolt or sudden speed change is hard on them (especially on a steep hill). Interestingly, I've towed them up this hill for the last 11 years with a T100 SR5 (manual trans) in 4-Lo without any problem. Needless to say, the V-6 T-100 was inadequate for long grades, but took this short, steep in stride!

here is your problem right there... You are used to the low tq that the V6 T100 offered. You are now driving a V8 with alot more TQ than you had before. Have faith in your Titan, it will do the job just fine in 2wd as long as you take it easy. Your Titan should be able to tow that trailer up that hill in 2wd even if it weighed 7000 lbs.

Roco · 10-02-2007, 06:53 PM

Here's another answer: Cummins.

HorsesInTow · 10-03-2007, 09:40 PM

Quote:

Originally Posted by Beach-TJ

This happens from time to time with the guys that run auto transmissions in rock crawling riggs. With an auto on an incline the transmission basically gets starved for fluid and will slip. Specifically, I think it's the tq converter that is getting starved. A solution to this problem is to replace the stock pan with a high capacity pan that allows you to hold extra fluid. The deeper pan and its extended fluid pickup allows the vehicle to operate at steeper angles without starving the transmission of ATF.
But I do not know if anyone makes a high capacity pan for the Tittan though. I know some of the crawling guys over fill there auto transmissions, but those are generally trail only rigs, I don't think that's a good idea for a street driven truck.
I agree that the 4 lo is a good idea for both extra power and extra control, and is much kinder to your transmission.
It could be a combination of ATF fluid starvation and the extra weight of the horse trailer that are causing you to stop moving on the incline, as every extra pound will make fluid starvation more obvious.
Maybe this will give you some insight into your issue.
I hope you can find a solution.

That's something I'd never have thought of, but it makes sense. Don't know if I can increase fluid volume, but I'll start by checking the trans fluid level to make sure it is at max. Thanks!

Delta15 · 10-03-2007, 09:55 PM

Quote:

Originally Posted by HorsesInTow

I will get a load of hay today in the trailer, which will get the trailer weight cloe to 4,000 lbs and "play" with speed up the hill without worrying about the horses becoming frightened or getting hurt. I'll also try straight 2WD, but I'd think(?) that I'd lug for sure without the extra torque.

Did you ever try this?

HorsesInTow · 10-03-2007, 10:29 PM

Quote:

Originally Posted by Delta15

Did you ever try this?

Yes, it climbed the hill with a gross tow wt of about 3700 lbs in 2WD - at just under 2000 rpm. Came up just fine, and I think (now) that I can take all that good advice and drive up in 2WD when the road is dry, but the road will be wet and covered with redwood needles about 5 months out of the year, so 4WD has to be an option.
I'm going to check my transmission fluid level and, if it isn't at max, I'll add enough to get it there. What Beach TJ discussed makes a lot of sense to me - although I'd never had thought of it.
Thank you everyone for your time and ideas. I'll report back as soon as I make some progress.