Towing in the Mountains

[fredthedog]

I'm curious if anyone here has towed a trailer over the Sierras between Tahoe and Yosemite over Hwy 88, Hwy 4 or Hwy 108.  Monitor Pass, Ebbetts Pass and Sonora Pass are all over 8,000' and Ebbetts and Sonora have grades of 24% and 26% respectively.  I could take the easier route over 88 but would like to do Ebbetts w/o worrying about the tranny or the brakes.  I have a 2,500# Fleetwood Sante Fe w/ electric brakes, Prodigy controller and a Chevy Avalanche in good condition w/ a 5K+ towing capacity.  Can anyone share their experiences of a similar trip?  Thanks in advance.

[AustinBoston]

I'm curious if anyone here has towed a trailer over the Sierras between Tahoe and Yosemite over Hwy 88, Hwy 4 or Hwy 108.  Monitor Pass, Ebbetts Pass and Sonora Pass are all over 8,000' and Ebbetts and Sonora have grades of 24% and 26% respectively.  I could take the easier route over 88 but would like to do Ebbetts w/o worrying about the tranny or the brakes.  I have a 2,500# Fleetwood Sante Fe w/ electric brakes, Prodigy controller and a Chavy Avalance in good condition w/ a 5K+ towing capacity.  Can anyone share their experiences of a similar trip?  Thanks in advance.

Here's one way to think of a 26% grade.  My setup is 37 feet long.  On a 26% grade, the back of the pop-up is more than 9 feet 6 inches higher than my Astro's front bumper.  :yikes:

Here is what Mountain Directory West for Truckers, RV and Motorhome Drivers (R & R Publishing) says about them.  I have never driven any of these passes, but I have used this directory and I usually trust it, but read on...

[INDENT]EBBETTS PASS elev 8730
(on California Highway 4 southwest of Markleeville, CA-includes PACIFIC GRADE SUMMIT)

This pass is subject to winter closures. Between Markleeville and the junction of State highways 4 and 89 there are truck warning signs for westbound traffic-"Tractor-semis over 36' kingpin to rear axle not advised." A little farther down the road-"Tractor-semis over 30' kingpin to rear axle not advised next 55 miles" and "Trailers not advisable beyond this point." Just about 2 miles west of the junction of 4 and 89 is another sign-"Ebbetts Pass ahead-very steep, narrow, winding road-vehicles over 25' not advisable." This would, of course, apply to vehicles going over this pass from either direction.

The descent eastbound from the summit back towards Markleeville is about 6 miles of mostly 9-11% grade with 10 mph hairpin turns and many other sharp curves. There is little room to swing wide during the turns because of vertical rock on the shoulder or drop-offs. The road is so narrow the highway department doesn't even paint a center stripe.

The descent westbound from the summit is similar as far as road conditions. The first 5 miles west of the summit are mostly 6-10% grade. Then, after about 1/2 mile of fairly flat grade the climb up to Pacific Grade Summit begins. This climb is about 3 miles of 10-12% grade with sharp curves and narrow road. Large vehicles should avoid this route.

The descent from the Pacific Grade Summit to the west is a rolling and stairstepping descent for over 50 miles. The road widens and improves about 7 miles down from the summit. There are many sections of 5-7% grade during the descent but they are usually short.[/INDENT]

Emphasis is in the original text.  Note that it says nothing about a 24% grade anywhere.  But this site includes a photo of the sign indicating a 24% grade ahead.  One site on cycling called it the "official testing site for bionic knees."  :yikes:

[INDENT]MONITOR  PASS elev. 8314'
(on California Highway 89, between US 395 and State Highway 4, south of Lake Tahoe, CA)

This pass is posted with warnings-"Tractor-semis over 36' kingpin to rear axle not advised."

The eastbound descent from the summit of Monitor Pass begins with about 1 mile of 4-5% grade. At this point there is a sign--"8% grade next 8 miles." This grade is steady except for a one mile stretch near the bottom where the grade eases to about 5%. The last 1/2 mile to the stop sign at the junction with US 395 is back to 8%. There are 25 to 40 mph curves.

The westbound descent begins with a short drop and climb to a second summit about 3/4 mile to the west. There is a brake check area at this point and the truck speed limit is 20 mph all the way to the bottom of the hill 7 1/2 miles ahead. The grade is mostly in the 7-10% range for the 7 1/2 mile descent. There are a couple of short sections where the grade eases to about 5%. At the bottom of the hill is a stop sign and T intersection. This is the junction of State highways 89 and 4.[/INDENT]

I'd be spending 25 minutes at 20 MPH or less on this.

[INDENT]SONORA  PASS elev. 9626
(on California Highway 108 east of Sonora, CA)

This pass is subject to winter closure. There is a sign for westbound traffic at the junction of US 395 and State 108 that should get the attention of anyone thinking of driving this pass in a large vehicle-"26% grade 10 miles ahead." An employee of the California Department of Transportation indicated that this information is correct, although for a very short section of road on the east slope. However, there are 10 to 15% grades in a number of places on both sides of the pass. The DOT employee also indicated that a number of trucks try the pass every year and cannot successfully negotiate the hairpin turns and must be towed out. The road is very narrow with sharp and steep turns.

The westbound descent from the summit to Kennedy Meadows is about 10 miles of grades that vary from 6% to 14%. There are a few short stretches where the grade eases or even goes uphill but most of the descent is very steep downhill grade. West of Kennedy Meadows the grade rolls up and down, usually in short stretches of 6-7%. There is a 2 mile 6% stretch just east of Strawberry and much of the last 10 miles into Sonora are 6-7%. The last 6 miles into Sonora are steady 6% descent.

The eastbound descent from the summit is about 10 miles of grade that varies from 7% to 15% plus the short section of 26%. The road is very narrow and winding with very sharp curves. After reaching the valley floor, the road rolls up and down for 5 miles to the junction of US 395 and State 108.[/INDENT]

Now this is in a different league altogether.  Although I would love to drive this, I would only do it in a sportscar.  Because of the elevation, I'd want a turbocharger...

More general advice:

Most normally-aspirated (i.e. non-turbocharged) engines loose between 2% and 4% of their horsepower for every 1,000 feet of elevation above sea level.  At 8,000 feet, your truck would be off at least 16% of it's horespower, and may be missing as much as 32%.  If you want to try a steep pass with only 2/3 of your truck's engine, you're on your own.

Austin

[fredthedog]

I'm glad I asked for advice.  I'll skip Ebbetts and Sonora.  I've done the west side of Monitor before (up & down), albeit w/o the trailer.  The descent was somewhat more severe than it should have been as I wasn't using the tranny and was probably riding the brakes more than I should have.  I've always figured that brakes are cheaper than a transmission but I suppose I should quit babying the tranny.  That mountain towing guide is going in my camping library as soon as I get back.  If anyone is interested, I'll post an account of the trip over Monitor Pass.  Heading out in 2 days.  Thanks for the extremely useful comments.

[mspgray]

You must go over Sonora Pass in a sports car. It is beautiful and definitely not for towing a trailer. We went to the top from 395 south last weekend in an older Honda.  Coming back down, our brakes started getting pretty hot. I was getting ready to ralph, but it was the brakes that made my DH slow down.

[AustinBoston]

I've always figured that brakes are cheaper than a transmission but I suppose I should quit babying the tranny.

While I agree that brakes are cheaper than transmissions, transmissions (and engines) have mechanisms for dealing with the heat, enspecially with an aux tranny cooler.  You do have one of those, don't you?  You should towing there!

Another thing that can help save the tranny is to stop at the top and let the engine idle for 10-15 minutes (or turn off and enjoy the scenery for a half hour).  This lets the tranny cool after the main workout going up.  Using engine braking going down is a workout for the transmission, but the main load is going up.

"You can go down the hill a thousand times too slowly, but only once too fast."

Austin

[Landroverpup]

Here's one way to think of a 26% grade.  My setup is 37 feet long.  On a 26% grade, the back of the pop-up is more than 9 feet 6 inches higher than my Astro's front bumper.  :yikes:

Here is what Mountain Directory West for Truckers, RV and Motorhome Drivers (R & R Publishing) says about them.  I have never driven any of these passes, but I have used this directory and I usually trust it, but read on...

[INDENT]EBBETTS PASS elev 8730
(on California Highway 4 southwest of Markleeville, CA-includes PACIFIC GRADE SUMMIT)

This pass is subject to winter closures. Between Markleeville and the junction of State highways 4 and 89 there are truck warning signs for westbound traffic-"Tractor-semis over 36' kingpin to rear axle not advised." A little farther down the road-"Tractor-semis over 30' kingpin to rear axle not advised next 55 miles" and "Trailers not advisable beyond this point." Just about 2 miles west of the junction of 4 and 89 is another sign-"Ebbetts Pass ahead-very steep, narrow, winding road-vehicles over 25' not advisable." This would, of course, apply to vehicles going over this pass from either direction.

The descent eastbound from the summit back towards Markleeville is about 6 miles of mostly 9-11% grade with 10 mph hairpin turns and many other sharp curves. There is little room to swing wide during the turns because of vertical rock on the shoulder or drop-offs. The road is so narrow the highway department doesn't even paint a center stripe.

The descent westbound from the summit is similar as far as road conditions. The first 5 miles west of the summit are mostly 6-10% grade. Then, after about 1/2 mile of fairly flat grade the climb up to Pacific Grade Summit begins. This climb is about 3 miles of 10-12% grade with sharp curves and narrow road. Large vehicles should avoid this route.

The descent from the Pacific Grade Summit to the west is a rolling and stairstepping descent for over 50 miles. The road widens and improves about 7 miles down from the summit. There are many sections of 5-7% grade during the descent but they are usually short.[/INDENT]

Emphasis is in the original text.  Note that it says nothing about a 24% grade anywhere.  But this site includes a photo of the sign indicating a 24% grade ahead.  One site on cycling called it the "official testing site for bionic knees."  :yikes:

[INDENT]MONITOR  PASS elev. 8314'
(on California Highway 89, between US 395 and State Highway 4, south of Lake Tahoe, CA)

This pass is posted with warnings-"Tractor-semis over 36' kingpin to rear axle not advised."

The eastbound descent from the summit of Monitor Pass begins with about 1 mile of 4-5% grade. At this point there is a sign--"8% grade next 8 miles." This grade is steady except for a one mile stretch near the bottom where the grade eases to about 5%. The last 1/2 mile to the stop sign at the junction with US 395 is back to 8%. There are 25 to 40 mph curves.

The westbound descent begins with a short drop and climb to a second summit about 3/4 mile to the west. There is a brake check area at this point and the truck speed limit is 20 mph all the way to the bottom of the hill 7 1/2 miles ahead. The grade is mostly in the 7-10% range for the 7 1/2 mile descent. There are a couple of short sections where the grade eases to about 5%. At the bottom of the hill is a stop sign and T intersection. This is the junction of State highways 89 and 4.[/INDENT]

I'd be spending 25 minutes at 20 MPH or less on this.

[INDENT]SONORA  PASS elev. 9626
(on California Highway 108 east of Sonora, CA)

This pass is subject to winter closure. There is a sign for westbound traffic at the junction of US 395 and State 108 that should get the attention of anyone thinking of driving this pass in a large vehicle-"26% grade 10 miles ahead." An employee of the California Department of Transportation indicated that this information is correct, although for a very short section of road on the east slope. However, there are 10 to 15% grades in a number of places on both sides of the pass. The DOT employee also indicated that a number of trucks try the pass every year and cannot successfully negotiate the hairpin turns and must be towed out. The road is very narrow with sharp and steep turns.

The westbound descent from the summit to Kennedy Meadows is about 10 miles of grades that vary from 6% to 14%. There are a few short stretches where the grade eases or even goes uphill but most of the descent is very steep downhill grade. West of Kennedy Meadows the grade rolls up and down, usually in short stretches of 6-7%. There is a 2 mile 6% stretch just east of Strawberry and much of the last 10 miles into Sonora are 6-7%. The last 6 miles into Sonora are steady 6% descent.

The eastbound descent from the summit is about 10 miles of grade that varies from 7% to 15% plus the short section of 26%. The road is very narrow and winding with very sharp curves. After reaching the valley floor, the road rolls up and down for 5 miles to the junction of US 395 and State 108.[/INDENT]

Now this is in a different league altogether.  Although I would love to drive this, I would only do it in a sportscar.  Because of the elevation, I'd want a turbocharger...

More general advice:

Most normally-aspirated (i.e. non-turbocharged) engines loose between 2% and 4% of their horsepower for every 1,000 feet of elevation above sea level.  At 8,000 feet, your truck would be off at least 16% of it's horespower, and may be missing as much as 32%.  If you want to try a steep pass with only 2/3 of your truck's engine, you're on your own.

Austin

Hwy 108 - Sonora Pass. That 26% grade going down on the west side is "nuts"! I would never take a trailer on that road! I don't recall a steeper paved road without switchbacks.