TrailManor Owner's Forum - View Single Post

06-16-2010, 04:17 PM

Not sure where to put all this. The admin may want to move it.

Anyway, here is some weight info, calculations and speculation about our Tacoma + Elkmont combo.

We found a CAT scale on our current trip that measures 3 axles simultaneously. I ran across it three times for only $15; well worth it. Each time I tried to line up the truck at the same position, but the operator didn't think that was really necessary.

The first time was truck+trailer with WDH 800# spring bars cinched up to the max:
Steer Axle: 2760#
Drive Axle: 2940#
Trailer Axle: 3240#
Total: 8940#

Then I removed the WDH spring bars and got this:
Steer Axle: 2400#
Drive Axle: 3500#
Trailer Axle: 3040#
Total: 8940#

Finally we dropped the trailer:
Steer Axle: 2700#
Drive Axle: 2580#
Trailer Axle: 0#
Total: 5280#

So the loaded trailer weight is only 3660# (8940-5280), well below it's rated GVWR of 4230# and below the Tacoma's trailer hauling capacity of 6500#. The trailer was reasonably well loaded for these measurements: maybe 12gal freshwater, 40# propane, packed frig, all our other food, clothes, cookware, bicycle. I've also replaced the original battery with two golf cart types and add a 2gal water pressure tank. The trailer's dry weight with all the factory options, and before my mods, is declared to be 2980#, so we added about 680#.

At the WDH's max setting, an additional 200# (3240-3040) is put on the trailer axle. But that 3240# is still below the trailer's GAWR of 3619#, with 379# available.

The trailer's tongue weight, without the WDH spring bars, is 620# (3660-3040). That's 17% of the trailer's weight, pretty high. With the WDH, the tongue weight is reduced 200# to 11.5% of the trailer weight.

At the truck, the WDH removes 560# from the drive axle and adds 360# to the steer axle (the other 200# going to the trailer axle). The drive axle weight with WDH (2940#) is below its GAWR of 3110#, but the steer axle is 5# over its GAWR of 2755#. Without the WDH, the drive axle would be over-loaded by 390#.

The measured combined weight of 8940# is well below the Tacoma's GCWR of 11100#. But the Tacoma's GVWR of 5450# is exceeded by 250# (5700 = 2760+2940).

The truck was loaded with a cap, two kayaks, two people, 5gal water, bicycle, computer gear, outdoor rug&chairs, misc. boards and tools. Since taking these weights, we've moved the water, computers and some tools back to the trailer as it has more available capacity. This should put our steer axle weight under its GAWR.

My interpretation of all these #'s and ratings is that the Tacoma's axles, suspension, engine, transmission and drive train are capable of handling our Elkmont+load. And even though we are not close to exceeding the Tacoma's GCWR and trailer hauling capacity, we are close on the GAWRs, so we have to be careful.

But by exceeding the GVWR, I suspect that we are exceeding the truck's braking capacity (the GCWR assumes your trailer has brakes and can stop itself). I'm not sure whether this rating has more to do with long, down-hill braking or emergency braking. I can (and do) use the transmission to brake on long hills as the rear brakes are the old-fashioned drum type, not disk, and probably prone to over-heating.

As for emergency braking, I'm not sure what to do. By setting the Prodigy brake controller higher (7), I can use the trailer brakes to help stop the truck, but they get very hot and grabby in stop/go city traffic, so I've dialed them lower (5). But maybe dialing them back up would provide shorter stopping distances? Even when dialed high, I've never had the trailer brakes lock up, so maybe I'm being too cautious.

Two more things:
There is link posted on this board somewhere that explains how to calculate the weight your WDH will shift to the trailer axle. Because I've got my 800# spring bars cinched up to their max with only 5 links between the spring bar to frame hook, I made the calculation assuming each bar levered 800#. The result was a 210# weight shift, pretty darn close to that 200# measured. You can also calculate the weight taken off the drive axle and put on the steer axle and these calculations were reasonable too, though not quite as close to the measured.

I've gone to the full cinched up position on this 800# WDH because all lesser tensions allow the front end to rise slightly, and in this position the truck+trailer has the most solid, "planted" feel. Also, sway becomes negligible, and sway bars unnecessary.

06-16-2010, 04:17 PM	#1
brulaz Guest Posts: n/a	Tacoma+Elkmont weights Not sure where to put all this. The admin may want to move it. Anyway, here is some weight info, calculations and speculation about our Tacoma + Elkmont combo. We found a CAT scale on our current trip that measures 3 axles simultaneously. I ran across it three times for only $15; well worth it. Each time I tried to line up the truck at the same position, but the operator didn't think that was really necessary. The first time was truck+trailer with WDH 800# spring bars cinched up to the max: Steer Axle: 2760# Drive Axle: 2940# Trailer Axle: 3240# Total: 8940# Then I removed the WDH spring bars and got this: Steer Axle: 2400# Drive Axle: 3500# Trailer Axle: 3040# Total: 8940# Finally we dropped the trailer: Steer Axle: 2700# Drive Axle: 2580# Trailer Axle: 0# Total: 5280# So the loaded trailer weight is only 3660# (8940-5280), well below it's rated GVWR of 4230# and below the Tacoma's trailer hauling capacity of 6500#. The trailer was reasonably well loaded for these measurements: maybe 12gal freshwater, 40# propane, packed frig, all our other food, clothes, cookware, bicycle. I've also replaced the original battery with two golf cart types and add a 2gal water pressure tank. The trailer's dry weight with all the factory options, and before my mods, is declared to be 2980#, so we added about 680#. At the WDH's max setting, an additional 200# (3240-3040) is put on the trailer axle. But that 3240# is still below the trailer's GAWR of 3619#, with 379# available. The trailer's tongue weight, without the WDH spring bars, is 620# (3660-3040). That's 17% of the trailer's weight, pretty high. With the WDH, the tongue weight is reduced 200# to 11.5% of the trailer weight. At the truck, the WDH removes 560# from the drive axle and adds 360# to the steer axle (the other 200# going to the trailer axle). The drive axle weight with WDH (2940#) is below its GAWR of 3110#, but the steer axle is 5# over its GAWR of 2755#. Without the WDH, the drive axle would be over-loaded by 390#. The measured combined weight of 8940# is well below the Tacoma's GCWR of 11100#. But the Tacoma's GVWR of 5450# is exceeded by 250# (5700 = 2760+2940). The truck was loaded with a cap, two kayaks, two people, 5gal water, bicycle, computer gear, outdoor rug&chairs, misc. boards and tools. Since taking these weights, we've moved the water, computers and some tools back to the trailer as it has more available capacity. This should put our steer axle weight under its GAWR. My interpretation of all these #'s and ratings is that the Tacoma's axles, suspension, engine, transmission and drive train are capable of handling our Elkmont+load. And even though we are not close to exceeding the Tacoma's GCWR and trailer hauling capacity, we are close on the GAWRs, so we have to be careful. But by exceeding the GVWR, I suspect that we are exceeding the truck's braking capacity (the GCWR assumes your trailer has brakes and can stop itself). I'm not sure whether this rating has more to do with long, down-hill braking or emergency braking. I can (and do) use the transmission to brake on long hills as the rear brakes are the old-fashioned drum type, not disk, and probably prone to over-heating. As for emergency braking, I'm not sure what to do. By setting the Prodigy brake controller higher (7), I can use the trailer brakes to help stop the truck, but they get very hot and grabby in stop/go city traffic, so I've dialed them lower (5). But maybe dialing them back up would provide shorter stopping distances? Even when dialed high, I've never had the trailer brakes lock up, so maybe I'm being too cautious. Two more things: There is link posted on this board somewhere that explains how to calculate the weight your WDH will shift to the trailer axle. Because I've got my 800# spring bars cinched up to their max with only 5 links between the spring bar to frame hook, I made the calculation assuming each bar levered 800#. The result was a 210# weight shift, pretty darn close to that 200# measured. You can also calculate the weight taken off the drive axle and put on the steer axle and these calculations were reasonable too, though not quite as close to the measured. I've gone to the full cinched up position on this 800# WDH because all lesser tensions allow the front end to rise slightly, and in this position the truck+trailer has the most solid, "planted" feel. Also, sway becomes negligible, and sway bars unnecessary.