Arcticmack Posted November 28, 2008 Share Posted November 28, 2008 (edited) Hey guys got my info from Mack and was wondering how to decifer the gvw rating of the rear axles,I know the front is 12000 lbs, its a FA522 but Im not sure on the rears.. they are,, SWD57's...?? whats the rating on them also there ratios are 5.77 and according to my booklet information on my build sheet, the lo-lo 1st gear ratio is get this!! 18.96!!?? theres some stump pullin gears in this thing LOLmy 5th hi-split is .85 guess that would be the overdrive..?it has the Quadraplex.. just wondering how to tell what the final drive gearing would be and about what speed it should have at engine gov, 2100...or cruising ,,round here thats 60mph. with 1100x20 tires. thankx guys I know someone will be able to help me out or where to look. thanks Robert. Edited November 28, 2008 by Arcticmack Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/ Share on other sites More sharing options...
steve s. Posted November 28, 2008 Share Posted November 28, 2008 Robert, SWD57 is a 38,000 lb bogie. It sounds like you have a transmission that is direct in 5th. The build sheet should tell you what model you have. There are some good road speed calculators on the web that will answer all your gear/ rpm/ tire size questions, do a search and find one you like. Steve Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25444 Share on other sites More sharing options...
ThaddeusW Posted November 29, 2008 Share Posted November 29, 2008 I came up with a formula where you plug in the engine RPM, trans gear ratio and rear ratio along with the tire diameter and it will give you the vehicle speed. I even wrote a simple program to compute it for you but never got around to polishing it up. I cant look now as I am going out but when I find the formula I will post it. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25455 Share on other sites More sharing options...
David Posted November 29, 2008 Share Posted November 29, 2008 Final dtive ratio is 4.90 (5.77 X .85). Check out this road speed caculator.http://www.roadranger.com/ecm/groups/publi...t/ct_062746.swf Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25459 Share on other sites More sharing options...
Arcticmack Posted November 29, 2008 Author Share Posted November 29, 2008 Robert, SWD57 is a 38,000 lb bogie. It sounds like you have a transmission that is direct in 5th. The build sheet should tell you what model you have. There are some good road speed calculators on the web that will answer all your gear/ rpm/ tire size questions, do a search and find one you like. SteveWell there not as strong as I was Hoping. but that'll do. there 5.77 ratios, and far as the tranny, it says Its DIRECT in 5th Direct, but in 5th Hi-split its .85 final. so guessing its an overdrive tranny. Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25471 Share on other sites More sharing options...
sdthoren Posted November 29, 2008 Share Posted November 29, 2008 .. just wondering how to tell what the final drive gearing would be and about what speed it should have at engine gov, 2100...or cruising ,,round here thats 60mph. with 1100x20 tires. thankx guys I know someone will be able to help me out or where to look. thanks Robert.Robert,I'll see if I can put my excel spreadsheet into words... If you want to get speed in miles per hour, MPH;1. start with this: rpm (revs per minute) * 60 (minutes per hour) gives engine revolutions per hour2. then this: tire diameter (inches) *3.14159 => this gives the tire circumference3. divide the tire circumference by: 12 (inches per foot) * 5280 (feet per mile) => gives the tire circumference in miles instead of inches!4. now multiply the transmission ratio by the differential ratio (engine rev / driveline rev * driveline rev / wheel rev)multiply items 1 and 2 together, then divide by items 3 & 4;For your truck, this becomes: MPH=(2100rpm*60)*(43.1*3.14159) / (12*5280*5.77*0.85) = 55mph.Not your 60mph quite cruising speed, but pretty respectable. I know I don't want to hit 70mph in my old dumptruck! Just for grins, I looked at gearing and torque. Assuming an ENDT673 puts out 600 ft-lbs, your low end gearing of 18.96, your tire size (I assumed 43.1"), and good traction, you can put 6334 pounds of force to the ground! That's almost 800 pounds of force per tire from 1422ft-lbs of torque applied to each tire! OK, enough is enough, the geek engineer in me is starting to come out!Hope you have fun with your truck!Scott Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25510 Share on other sites More sharing options...
Arcticmack Posted November 29, 2008 Author Share Posted November 29, 2008 Robert,I'll see if I can put my excel spreadsheet into words... If you want to get speed in miles per hour, MPH;1. start with this: rpm (revs per minute) * 60 (minutes per hour) gives engine revolutions per hour2. then this: tire diameter (inches) *3.14159 => this gives the tire circumference3. divide the tire circumference by: 12 (inches per foot) * 5280 (feet per mile) => gives the tire circumference in miles instead of inches!4. now multiply the transmission ratio by the differential ratio (engine rev / driveline rev * driveline rev / wheel rev)multiply items 1 and 2 together, then divide by items 3 & 4;For your truck, this becomes: MPH=(2100rpm*60)*(43.1*3.14159) / (12*5280*5.77*0.85) = 55mph.Not your 60mph quite cruising speed, but pretty respectable. I know I don't want to hit 70mph in my old dumptruck! Just for grins, I looked at gearing and torque. Assuming an ENDT673 puts out 600 ft-lbs, your low end gearing of 18.96, your tire size (I assumed 43.1"), and good traction, you can put 6334 pounds of force to the ground! That's almost 800 pounds of force per tire from 1422ft-lbs of torque applied to each tire! OK, enough is enough, the geek engineer in me is starting to come out!Hope you have fun with your truck!Scottyour a genius.. keep the geekyness coming, thank you for the help. Im sure that the 55 is good enough at least I know it will do that much all day long and never miss a beat, Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25523 Share on other sites More sharing options...
dak49 Posted November 30, 2008 Share Posted November 30, 2008 Anything less than 1 is over drive, therefore a .85 is an over drive gear. Just take your gear ratio times the top gear ratio will give you your fineal gear ratio. 5:77 X .85 =4.90I used another formula to figure your speed but it came out the same, 55@2100RPM.Good luckDak49 Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25556 Share on other sites More sharing options...
steve s. Posted November 30, 2008 Share Posted November 30, 2008 Well there not as strong as I was Hoping. but that'll do. there 5.77 ratios, and far as the tranny, it says Its DIRECT in 5th Direct, but in 5th Hi-split its .85 final. so guessing its an overdrive tranny.. Robert, All of the compound boxes have an overdrive gear, but the main box could also have an overdrive in fifth, which yours does not. So technically you have a direct transmission. Steve Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25593 Share on other sites More sharing options...
HK Trucking Posted November 30, 2008 Share Posted November 30, 2008 it says Its DIRECT in 5th Direct, but in 5th Hi-split its .85 final. so guessing its an overdrive tranny.It's a TRQ72. Single overdrive quad box.The TRQ 720, 7210, and 7220 would be the double overdrive versions of the quad box, with main direct in 4th. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25634 Share on other sites More sharing options...
Arcticmack Posted December 1, 2008 Author Share Posted December 1, 2008 It's a TRQ72. Single overdrive quad box.The TRQ 720, 7210, and 7220 would be the double overdrive versions of the quad box, with main direct in 4th. Thats right it is a TRQ72 as it says in my build sheet. so 55 is it Ive done some other figuring but thats what I come out with to9Thanx to those that pointes me in the right direction, and thats with 1100x24.5 tires.cause the 1100x20 is the same height right? 43.3 or so inches in dia. thats what it says it came with 1100x20s. when I bought it has 1000x20s so there going bye bye anyways, in favor of new Budd disk steels with new tubless highway traction radials. anyways thank you for all your guys input well taken and appreciated..Robert Quote Link to comment https://www.bigmacktrucks.com/topic/6024-found-my-ratios-i-think/#findComment-25655 Share on other sites More sharing options...
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