mkvacik Posted October 24, 2016 Report Share Posted October 24, 2016 I have a Pete 387 I am trying to decide on how I want it set up. The main question, how far behind the axle is too far as far as the hitch goes? I looked at several at the rally, but didn't really think to measure. Pretty sure I have measured one that is about 7' behind the rear axle. I don't have a distinct single purpose for the bed at this point for sure. Ideally I would like room for my 4 seat rzr back there, keep the wheelbase as short as I can for maneuverability. Link to comment Share on other sites More sharing options...
RickW Posted October 24, 2016 Report Share Posted October 24, 2016 I added 6' of frame before building my bed. I doubt i would want to go any further. 2017 Entegra Anthem 44A SOLD - 2004 Volvo 780. 465hp and 10sp Auto Shift (from 2010~2017) SOLD - 2009 Montana 3400RL Link to comment Share on other sites More sharing options...
Steve from SoCal Posted October 24, 2016 Report Share Posted October 24, 2016 If the truck is singled think of the rear axle a the fulcrum point of a teeter totter, the farther away you place the load the more you unload the front axle. To keep the front suspension from becoming too bouncy it is best to have 65~70% of the capacity on the springs. Steve 2005 Peterbilt 387-112 Baby Cat 9 speed U-shift 1996/2016 remod Teton Royal Atlanta 1996 Kentucky 48 single drop stacker garage project Pulls like a train, sounds like a plane....faster than a Cheetah sniffin cocaine. Link to comment Share on other sites More sharing options...
mkvacik Posted October 24, 2016 Author Report Share Posted October 24, 2016 I added 6' of frame before building my bed. I doubt i would want to go any further. I took some pics of yours at the rally, I liked a lot of things about it! I still think I want to single though. Link to comment Share on other sites More sharing options...
mkvacik Posted October 24, 2016 Author Report Share Posted October 24, 2016 If the truck is singled think of the rear axle a the fulcrum point of a teeter totter, the farther away you place the load the more you unload the front axle. To keep the front suspension from becoming too bouncy it is best to have 65~70% of the capacity on the springs. Steve So your saying I almost need to make up my mind on how much junk I want to haul on the bed and ahead of the axle before I decide on that totally. Link to comment Share on other sites More sharing options...
mkvacik Posted October 24, 2016 Author Report Share Posted October 24, 2016 I took some pics of yours at the rally, I liked a lot of things about it! I still think I want to single though. You are 6' behind your rear axle or behind the original frame? If the frame do you know how far it was to the rear axle? Link to comment Share on other sites More sharing options...
Steve from SoCal Posted October 24, 2016 Report Share Posted October 24, 2016 So your saying I almost need to make up my mind on how much junk I want to haul on the bed and ahead of the axle before I decide on that totally. You should have at least a rough idea of fixed weight and moveable weight ie fuel, people toys etc. The most significant issue is, with a long moment arm the additional force in a bump for example, could unload the front axle. Best guess is factor in 1.4G acceleration for the pin weight. Steve 2005 Peterbilt 387-112 Baby Cat 9 speed U-shift 1996/2016 remod Teton Royal Atlanta 1996 Kentucky 48 single drop stacker garage project Pulls like a train, sounds like a plane....faster than a Cheetah sniffin cocaine. Link to comment Share on other sites More sharing options...
peety3 Posted October 24, 2016 Report Share Posted October 24, 2016 If the truck is singled think of the rear axle a the fulcrum point of a teeter totter, the farther away you place the load the more you unload the front axle. To keep the front suspension from becoming too bouncy it is best to have 65~70% of the capacity on the springs. Steve And think about how much it will load the rear axle. Think of your truck's frame as a simple lever, so for every pound of pin weight you apply to the fifth wheel, you'll end up with [front axle to pin distance]/[wheelbase] pounds on the rear axle.A 6k pin weight can easily translate to a 9k bonus on the rear axle (which also means 3k unload on the front axle). If you single the truck, you likely end up with a 20k rear axle, but probably had 8-9k on it empty. 9k of apparent trailer weight only leaves you ~2k for bed plus other cargo. Link to comment Share on other sites More sharing options...
phoenix2013 Posted October 24, 2016 Report Share Posted October 24, 2016 A primer on extensions: Link to comment Share on other sites More sharing options...
mkvacik Posted October 25, 2016 Author Report Share Posted October 25, 2016 Thanks for all the good info!I just went out and measured my class A because I like the way it handles with my 30' trailer behind it. 11 ft from center of rear axle to the reviever hitch, holy cow! Link to comment Share on other sites More sharing options...
DIESELSUBMARINER Posted October 25, 2016 Report Share Posted October 25, 2016 I don't want to hi-jack this thread, but I have a stupid here: what is the reason to move the hitch past the rear axle ? Isn't the weight preferred to be above the rear axle? or do you move it back for more cargo space on the truck? just trying to prepare my self for a future conversion :-) Link to comment Share on other sites More sharing options...
NoDirectionHome Posted October 25, 2016 Report Share Posted October 25, 2016 http://www.hhrvresource.com/truckbeds Yes http://www.hhrvresource.com/truckbeds "There are No Experts, Do the Math!" 2014 Freightliner Cascadia DD16 600hp 1850ft-lb 18spd 3.31 260"wb SpaceCraft S-470 SKP #131740 Link to comment Share on other sites More sharing options...
Dollytrolley Posted October 25, 2016 Report Share Posted October 25, 2016 Some folks have been using my live data weight & balance spreadsheet to do "what-if-loadings" to determine the actual axle loadings for both truck and trailer axles......... Like Trey says .......actual wheel positions loading needs to be considered...... If you would like to use the live-data-spreadsheet just send me a email at mmcdan3189@aol.com and I will email you the spreadsheet. The spreadsheet lets you move loads, hitch locations, axle locations and see the effects live. Drive on..........(lets see where are my axles and hitch and trailer loads ......today) 97 Freightshaker Century Cummins M11-370 / 1350 /10 spd / 3:08 /tandem/ 20ft Garage/ 30 ft Curtis Dune toybox with a removable horse-haul-module to transport Dolly-The-Painthorse to horse camps and trail heads all over the Western U S Link to comment Share on other sites More sharing options...
Alie&Jim's Carrilite Posted October 25, 2016 Report Share Posted October 25, 2016 I don't want to hi-jack this thread, but I have a stupid here: what is the reason to move the hitch past the rear axle ? Isn't the weight preferred to be above the rear axle? or do you move it back for more cargo space on the truck? just trying to prepare my self for a future conversion :-) Using the HDT, there is so much weight capacity even singled that the pin weight doesn't have to be centered over the axle like you would on a normal 3500 light duty truck. Moving the hitch towards the rear also makes the trailer react faster when backing, and track better around turns. A fifth wheel hitched 5-6 feet behind the axle acts like a bumper pull when towing, but no sway. Alie & Jim + 8 paws 2017 DRV Memphis BART- 1998 Volvo 610 Lil'ole 6cyl Cummins Link to comment Share on other sites More sharing options...
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