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Originally Posted by charlie
Next month want to go east from Salt Lake City over to Colorado Springs to have our tm worked on at the dealer located there.
There are two (2) highway possibilities I am contemplating; Interstates 70 and 80. Having never gone either one, and pulling a tm with a Liberty 6 cylinder, automatic, open for suggestions of the better of the 2.
I am concerned about high passes; so the one with the less steep grades will be preferable. The Liberty is just not that much of a beast on the higher and steeper roads.
Thanks
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Eastbound I-70 in Colorado has 3 grades that will bring your Liberty to a painfully long and slow crawl. The first is the climb over Vail pass...you start in Vail at about 8000 feet, after 10 miles of nearly continuous 7% grades you will reach the summit at 10,600 feet. Then comes a stairstepping descent down to Silverthorne/Dillon where you "bottom out" at 8700 feet. Then you get to climb a very steady (no breaks whatsoever) 7% grade for 8 straight miles until you reach 11,115 feet of elevation at the western entrance of the Eisenhower tunnel under the Continental Divide. Then comes another stairstepping descent (sometimes in the 6% range) until you get to the bottom of Floyd Hill east of Idaho Springs. Then you get to do another climb...this time around a 6% grade for about 2.5 miles...and if it's a warm day the elevation here is low enough (around 7000 feet) that you can encounter 80 degree temperatures and overheating is a definite possibility. A few miles later you get to do a long and plummeting descent into Denver.
Westbound I-70 is bad but not nearly as bad as going eastbound...first you do a 7 mile, 6% grade (usually in very warm temperatures) climbing out of Denver. Just west of Georgetown is "Georgetown Hill"...about 2 miles of 6 to 7 percent grade where you climb from 8000 to nearly 9000 feet. Then you have 12 more miles of 5 and 6 percent grades...at elevations of 10000 to 11000 feet...with a left lane minimum speed of 55 so you
will be stuck in the right lane at 25 mph behind the semis/RVs. Then you plummet down to Silverthorne and start all over again for the climb up to Vail pass...typical grades in the 5 and occasionally 6 percent range.
I used to tow my 2720SL with a Jeep Cherokee...the Liberty's predecessor...who's 4.0L I6 actually produced more torque at a lower RPM than the 3.7L V6 in the Liberty. I made exactly one trip on I70 with that rig and said never again...I was down to 25 mph for so long (watching the engine on the verge of overheating the entire time) that I swore I'd never do that again. I-70 across Colorado is
not a road you want to take with a marginally powered tow vehicle...which the Liberty (as you note) pretty much is.
By comparison, I-80 east out of the Salt Lake area is seemingly almost level...yeah there's the moderately challenging (but still fairly low altitude) climb over the Wasatch but after that it's basically just rolling terrain across Wyoming and the maximum altitude is just a little over 8000 feet. Crossing the Continental Divide in Wyoming is a total non-event...almost a laugh.
Because of these exceptionally long, very steep, and
exceedingly high altitude grades on I-70 in Colorado, long distance truckers regularly drive hundreds of miles extra to be able to cross the Rockies via I-80 and avoid I-70 through Colorado. I-80 has huge numbers of trans-continental semis whereas the truck traffic on I-70 is almost entirely the semis who are delivering goods within Colorado.
I might add that even traveling across the prairies/suburbs on I25 between Denver and Colorado Springs you will encounter several sections of 5% grades and will top out at 7300 feet (about 2000 feet higher than Denver) at the summit of Monument Hill. Several of these grades along I25 will also give your poor Liberty a real workout.
I should also add that after two unhappy towing seasons with the poor little underpowered Cherokee, I traded it for a Toyota Tundra truck with 4.7L 32 valve V8 that produced 315 ft-lbs of torque and had a 3.91 axle. I soon found that even that was still really not enough power so I spent roughly another $3000 modifying the truck to get even more torque (see the list of mods in my signature). I now think I'm close to having enough torque for pleasant towing in Colorado.
Any questions?