Alright, I have a 2007 F150 5.4L 4x4 equipped with the factory tow package and 35" Cooper Discovery tires. I have medium duty Super Springs (adds another 2000lbs of spring to rear, a Reese WD hitch with anti-sway, Banks monster exhaust, edge Evo tuner, K&N FIPK, and Troyer e-fans, and a Prodigy break controller.

I just purchased a Keystone Tail-Gator 210RR (21' Toy Hauler) that weighs about 6400 lbs dry. I'm picking it up in LA on Monday and I haven't had time to install my 4.56 gears (wouldn't have had enough time to properly break them in), which means I'm still running 3.73s with my 35" tires. I will be towing it back bone dry with minimal weight onboard. My main question is will I be alright making a single 300 mile trip back to San Jose (south SF bay for those of you unfamiliar with CA) from LA, which includes one large mountain range that I have to cross while on I-5. I know I'll have to lock out OD with such high gears, but will I have tranny cooling issues?

I'm guessing I'll be okay given this is only a one time trip, but just wanted to make sure I'm thinking everything out right in my head. Thanks for any advice you guys might be able to give me.

 

you should be fine for a one time tow, we tow 2, 10,000+ lb trailers with our 1/2 ton dodge all the time(geared 4.10), its tow rating is only 8800... as far as locking out O/D, ANY TIME you tow anything whether its around town or on the highway, it should be OFF. i always drive O/D off in my lifted f150 unless im empty(not towing or hauling) and on a flat highway. you'll burn your O/D gear up in no time no matter what gear ratio you have in that thing, even quicker in the mountains. dont hot rod it. just take your time. no add-ons are gonna keep your tranny from burnning up, other than a larger cooler and a light foot. after you install your gears, see about puttin the largest tranny cooler you can fit in that thing, then you'd be set

 

If you still have your stock wheels and tires, put them back on for the trip.

 

I towed #6700 camping trailer for 2 years with 35s and 3.73 gears. But the farthest I went was about 120 miles. I took about 10 camping trips last year. It went Ok with the 3.73. Just take it easy,don't beat on the truck on hills. You will not be able to maintain speed limit on big hills so don't try. I ran with overdrive off because it constantly shifted with the overdrive on. It would shift to overdrive going downhill then downshifted on the smallest upgrade hill. So i towed with overdrive off.

 

Yah OD off untill you get your gears. At least you got 3:73. I pulled mine a few times at first with the 3:55's, lift and 35"s. I always tow now with OD if I can keep it there, and that's most of the time on the freeway.

 

Just made the trip. Went ok except for the main mountain pass the trans temp started getting real high. I'm assuming lower gears will help take some of the stress off of the tranny? The truck felt kind of gutless going up hills, which I know the 4.56s will help a lot with. Flat ground was ok but the rpms sat below the power band when I was cruising at 60mph (revs were right around 2100)

 

You need a bigger tranny cooler. Any time you are running with the converter unlocked, the fluid WILL heat up.

 

Who makes the best aftermarket tranny cooler? I checked out Troyer but it looked like theirs might be on the small side for long distance hauls up hills (the description says something about light towing, which I think I'm exceeding). Also, will a deep-dish fluid pan help with this? Thanks for all the help

 

Yes, a deeper finned pan will help. I also believe that there are tranny coolers that have small electric fans on them. I'd also do a tranny flush and replace the fluid with Amsoil.

 

I'm impressed that your F150 was able to haul that big load over the Grapevine.

Not surprised at all your transmission temps got elevated, especially if the weather was warm that day (we had a hot weekend in SoCal). The hot weather and altitude near the top probably cost your truck some horsepower.

That's a brutal climb, even going north. IMO it's worse (steeper) for towing going south.

Of course, the down hill going north might have got interesting with that much weight pushing you down the hill into the valley! Loaded big rigs cook their brakes all the time going northbound.

For those that don't know that road, the Summit is about 4,000', so the vertical gain out of LA is about 3,500', with little opportunity to cool down.

 

Yep too low, in 3rd at 60 I'm at 2800 rpms. Then I pull it up to about 3k hit OD and run 65 at 1900, that is untill a gust of wind or hill come my way

 

Ya it was about 98 degrees when I was towing. That's a brutal hill. I think any time you see run-away truck ramps it's a sign that you need to watch out. The tranny was running between 165 and 190 during the smaller hills and in the flatlands, towards the summit I lost all my momentum behind a very slow truck and had to hammer-down to keep moving. The trans temp peeked at about 225, which is right when the "oh sh*t" flashing lights started to come on on my Edge. I'm looking at a couple fluid coolers with 500ish cfm fans and aluminum radiators. Will this help keep my tranny temps down lower for longer? I'm hoping that fan/radiator for trans, 4.56s, and new higher grade synthetic ATF (not sure what brand is best, I use royal purple for everything else, is their max-atf compliant with merconV?) will keep me from cooking everything. The good news is that my troyer e-fans kicked a$$ and kept my engine sub-205 even when I was sitting at 3500 revs for a few minutes going up the summit.

 

Yes, RP Max-ATF is Mercon V compatible. Do a complete replacement with a machine.

How fast were you going and what gear was it in when the temp peaked?

 

Can't answer for the OP, but FWIW, northbound, I've seen loaded big rigs struggle to crest the summit at less than 20 mph. On a 100* day, it could be a lot less. The last couple hundred feet of the climb might be the steepest part.

If he got trapped in the slow lane I'll guess he had to drop to 1st gear.


Not fun in near 100* weather at 4,000' with 6,000+ lbs behind you, slow trucks in front of you, and cars blazing by in the fast lane at 70+ mph. Then the downhill starts.... I know I would have had white knuckles! That's a trip and tow that would have made PSD F250 or F350 work a bit.

 

My temp peaked when I had to downshift from 2nd to 1st to pass a truck creeping up the hill at about 15mph (I think that was the case, not 100% sure). I was making it up most of the hill in second at about 2800 rpm, which it sat real nicely at. The engine temp never got even close to overheating, which was nice. I'm going to install a troyer trans fluid fan and have the system flushed and filled with some RP max-atf to keep the temps safe for future tows.

It's hard for people to understand how long and steep that hill is until you drive it, it's about 15 miles at a very, very steep grade. It's not uncommon to see 50+ cars and dozens on semis pulled over to the side along the trip up letting their rigs cool off.

I have to admit my truck handled the weight much better than I was expecting with only having 3.73s pushing my 35's. I wasn't going to win any races but it made it up all the smaller grades with ease. I'm sure that once my 4.56s are put in and the trans cooler is running it will be a much less white-knuckle ride. The super-springs kept the tail end perfectly level even with a 700ish lb tongue weight. It would definitely be much easier in an SD but I can't complain.