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jordandvm · 11-26-2004, 05:23 PM

Before deciding to go with an AS, another trailer mfg'er shared with me a spreadsheet that could be used to calculate whether my tow vehicle would work with the trailer. I used it to compare several tow vehicles in combination with different sized trailers. I found it quite helpful in my initial search for the ideal tow vehicle to use with the trailer I wanted. Try it out and give me some feedback after you've used it!

I've posted it on the web but the link wouldn't work! Nick Crowhurst found it elsewhere and posted the link below in his post!

Jim

RichardT · 11-26-2004, 05:28 PM

Your link does not appear to work.

nickcrowhurst · 11-26-2004, 05:34 PM

Is it this one? http://www.popupexplorer.com/files/T...yWorksheet.xls

jordandvm · 11-26-2004, 05:37 PM

Quote:

Originally Posted by richardt

Your link does not appear to work.

Hmmm....it works on my computer......I've been trying to devise a way to get this on the forums...and since it's a spreadsheet...and since we cannot attach .xls format files to posts, I created a users site on msn to place the file. Maybe I'm the only one who can access the file!! I'm sorry, I thought this would work...any one have any suggestions?? I would prefer not to email this file to each person who wanted to use it...but have it accessible to all easily on the web. Now, maybe you all could help me out to solve this because I think it would be helpful to a lot of folks here on the forums.

Jim

jordandvm · 11-26-2004, 05:44 PM

Quote:

Originally Posted by nickcrowhurst

Is it this one? http://www.popupexplorer.com/files/T...yWorksheet.xls

That's it!! I could not find it after I downloaded it from the computer some time ago. Great! Well anyway it's accessible now thanks to you! Has this been on the forums before?? I sure haven't seen it. Evidently some of you have used it before...but I didn't think it was common knowledge on the forums! I guess I better edit my initial post to erase my errant hyperlink!!

Thanks!

Jim

Tinsel Loaf · 11-26-2004, 06:52 PM

Thank's, Looks good. Now I just need to find my weight numbers and plug them in.

Happycampers · 11-26-2004, 08:16 PM

This is another one that works real well.

Weight Calculator

Tinsel Loaf · 11-26-2004, 09:31 PM

It calculates that I might be at or about 100 pounds over gross with the 3.55 rear end. 16,000 pounds. With the same tow vehicle with a 4.10 rear end I could tow an additional 3000 plus pounds. 20,000 pounds. So am I really in a towing danger zone or am I just wearing the drive train / transmission out faster.

baldeagle · 11-27-2004, 06:05 AM

Thanks... great worksheet. Combined with the Interstate Scales actual weights data I obtained this is a useful bit of information.

Combine that with tire capacity tables from Goodyear and you can calculate the needed tire PSI's for both the trailer and tow vehicle.

I am able to run under the "suggested" inflation numbers I have frequently seen posted thereby softening the ride for the trailer contents. BTW - I DO check the tires for temperature EVERY time I stop during trips. Never had a tire I could not lay my hand on due to temperature.

Thanks again,

Dave

nickcrowhurst · 11-27-2004, 07:11 AM

Quote:

Originally Posted by Tinsel Loaf

So am I really in a towing danger zone or am I just wearing the drive train / transmission out faster.

Tinsel Loaf, changing your differential from 3.55 to 4.10 would not affect the safety of your rig, IMHO. Your transmission will just change gears at lower road speeds. With the 3.55, you need to be more careful not to "lug" the engine and transmission. That is, you need to be wary about using overdrive, if fitted, and you may occasionally need to use manual overide to select a lower gear to protect the systems. A higher gearing means lower RPM at a given road speed, which means lower fluid pressure in an automatic transmission, which means lower clamping forces on the internal clutches, which leads to slippage, which leads to heat, which destroys the fluid, and then the transmission. To deal with this, I use a BD pressure-loc, which raises tranny fluid pressure at low RPMs, and I keep a close eye on the tranny fluid temperature gauge. Nick

Tinsel Loaf · 11-27-2004, 10:25 AM

Thank Nick
I do take it out of overdirve when I'm not on level ground. The BD pressure loc looks like a good addition to keep the transmission running longer.

Happycampers · 11-27-2004, 03:25 PM

This is where I get really confused. How can you be overloaded at 16,000 pounds with a 3.55 and go to a 4.10 gear and be able to go up to 20,000 pounds. I understand the gears but the amount of weight that axles can carry hasn't changed nor has your stopping ability, the brakes are not bigger. Can anyone help me understand this. Thanks Marvin

nickcrowhurst · 11-27-2004, 03:42 PM

Quote:

Originally Posted by happy82301

This is where I get really confused. How can you be overloaded at 16,000 pounds with a 3.55 and go to a 4.10 gear and be able to go up to 20,000 pounds. I understand the gears but the amount of weight that axles can carry hasn't changed nor has your stopping ability, the brakes are not bigger. Can anyone help me understand this. Thanks Marvin

Marvin, imagine two trucks which are identical, apart from one having a 3.55 axle, and the other a 4.10. Take them to a very steep incline, and drive them up empty. Now repeat the process, adding one thousand pounds to each truck. Keep repeating the process, adding 1000 pounds each time. Eventually, the 3.55 axle truck will be unable to climb the hill in first gear, but the 4.10 axle truck will keep going, because it is in a lower gear. Carrying capacity will depend on braking, suspension, frame strength and steering, but designers have to ensure that their vehicles will be able to handle the steepest grades they are likely to meet, even when fully loaded. Thus the 4.10 will rate a higher capacity, even though the axles and brakes are identical. I hope this helps. Nick.

Happycampers · 11-27-2004, 04:30 PM

Hi Nick, I understand that. So what Jim is really saying is that he is underpowered not overloaded. Marvin

nickcrowhurst · 11-27-2004, 05:35 PM

Quote:

Originally Posted by happy82301

Hi Nick, I understand that. So what Jim is really saying is that he is underpowered not overloaded. Marvin

Marvin, no, not necessarily underpowered. It's a matter of gearing. A race car might develop twice the horsepower of my diesel truck, but it couldn't pull my Airstream over the Rockies. It develops the high horsepower at high revs, and because of its gearing, that is at high speed. Remember the two identical trucks going up the hill? They both develop the same horsepower, but the 3.55 fails first because of its higher first gear. The 4.10 can produce more ultimate "leverage" or torque, on the driving wheels, in first gear, in the efficient rev range of the engine. Think of two cyclists climbing side by side up a very steep hill, which gets steeper and steeper. Both riders are identically powerful, and both bicycles are identical, apart from one having a lower first gear ratio. You know that the other guy will stop first, and it's the same with trucks. Nick

Tinsel Loaf · 11-27-2004, 06:12 PM

It’s interesting that the Gross Vehicle Tow Rating Changes that much with less than one rev of the drive shaft to rear end gear ratio. Technically if my rig were weight by the Highway Patrol and I was over 16,000 pounds I would be in violation of the law. If I changed the differential to a 4.10 ratio I might be within the law being able to tow 20,000 pounds but because of the tow vehicle vin number which would identify me as having a 3.55 I still would be in violation by exceeding the 16,000 pound limit, if they wanted to get really picky.

jordandvm · 11-27-2004, 11:43 PM

Quote:

Originally Posted by Tinsel Loaf

It calculates that I might be at or about 100 pounds over gross with the 3.55 rear end. 16,000 pounds. With the same tow vehicle with a 4.10 rear end I could tow an additional 3000 plus pounds. 20,000 pounds. So am I really in a towing danger zone or am I just wearing the drive train / transmission out faster.

For all you "ArmStream Quarterbacks" waiting for spring to return, I thought you might enjoy crunching some numbers on your rigs while waiting for the travel season to return! Seriously.....I started this thread to give folks who have never towed before (like me before purchase) a simple reference to input information on different tow vehicles and trailers, so they could see "on paper" they were in the "safety range". The forums provide great help, but there are some diversities in opinions. This spreadsheet was the first "hard" evidence I could "hang my hat on" that I was in the "ballpark" when choosing my tow vechicle. The car dealers are not informed in these matters, and the AS dealers "may" tell you anything to sell you the "trailer of your dreams"!
"TinselLoaf", which spreadsheet did you use? I tried to post the "popupexplorer.com" spreadsheet. Did you use that one? I found the "weight calculator" from HAPPY to be confusing, and didn't understand all the information needed to input (I haven't been able to weigh my AS yet). I didn't see any input in either spreadsheet for different rear end axle ratios (did I miss something?) entered into the spreadsheets!
Where did you get the extra 4K lbs on the 4.10? The calculation of 16,000 is your Total Rig Weight (Actual wight tow vehicle + Actual weight Travel Trailer)?

Jim

Happycampers · 11-28-2004, 08:36 AM

Jim, Sorry if I made this more confusing, Just thought this would another option of calculation weight. Just noticed your tow vehicle. Very nice, I would think you could tow any trailer Airstream makes except for maybe a 34ft with a slide out. Marvin

jordandvm · 11-28-2004, 09:24 AM

Quote:

Originally Posted by happy82301

Jim, Sorry if I made this more confusing, Just thought this would another option of calculation weight. Just noticed your tow vehicle. Very nice, I would think you could tow any trailer Airstream makes except for maybe a 34ft with a slide out. Marvin

Marvin,

I think both spreadsheets are helpful....if you have all the information to input into them. I haven't weighed mine yet at a scale, so I couldn't complete yours. When I purchased my 22' AS, I had a Ford Ranger V6 4x4 with 4.10 rear end. I towed it one time with this on flat land, and quickly realized that if I wanted to do any serious hills, I'd better seek more power! That's where the spreadsheet helped. I chose to buy 3/4 ton because I was in the safety range (85% of GCWR) with water tank full. Also, I thought that "if" I wanted to, I could trade for larger AS, if the 22' didn't work out! One point stressed in discussions on these forums that the spreadsheet does'nt address specifically is that "braking ability" was extremely important, and bigger is better!

Jim

claudette · 11-28-2004, 06:56 PM

Thanks very much for posting the towing capacity worksheet. I had printed out a long explanation of how to do it from some website and had done it manually, but this was easier. FWIW, it confirmed that my manual calculations were pretty much on the money.

I'm debating between an F-250 PSD crew cab and the Silverado 2500HD crewcab w/ Duramax & allison tranny as the tow vehicle for an '05 CCD 28 ft. Using the Ford data, I'll be about 68% of GCVWR, and with the Chevy, about 65%.

I've learned so much by reading threads on these forums. Thanks again for the worksheet.
Claudette