Quote:
Originally Posted by Sunline1
In both cases there is zero wt added to the front axle of the TV.
Is that the ideal wt transfer "ratio's" (TV wt./TTwt.),if you will for optimum towing/Balance/Bouncing ?
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Hi Sunline1
“Thesteigers” Tom has given us a lot of good details to work with here. And from this we can see where the weight is actually transferring from and why WD is so important with TT towing, even on a small camper like Tom’s T2199 and his TV.
Tom’s Tundra lost 420# from the front axle and gained 1,200# on the rear axle when he hitched up a loaded 800# tongue weight camper with no WD. Those weight shifts are a lot and are for sure in the range where a WD hitch is needed. The only real way to know this is either calculate it out or better, go weigh the truck and camper like Tom did. Scales tell all.
Now comes the question: What is the proper way to adjust WD on a TV? What “target” or “goal” are you trying to end up with?
Some say, you should get equal squat front and rear on the truck.
Some say the truck must be level when done adjusting WD.
Some say, you should get equal axle loading.
Some say you should transfer extra weight on the front end of the truck to try and help out the rear axle be able to carry more camper tongue weight or more bed weight.
Some say, read the hitch instructions and go by that. Many brands use different wording and different meanings come out of the wording. And then there are conflicts between the manufactures as which way is right.
When I first started learning about WD hitches those statements above where given out as almost gospel. And the folks stating them where very passionate that they have done it that way for years and that is the right way to adjust a WD hitch. There are a lot of opinions out there on what the right way is. So I set out and tried to actually obtain several of them. To make a long story short, I found many of them to be myths and when pressed the question, what is the right way to adjust WD, I could not get a lot of actual answers that added up. So I set off on a research mission to help educate myself. This is what I came up with.
There is no one size fits all WD setup concept that fits every TV out there in modern day TV’s. When WD hitches first came out, I think around the 50’s or earlier, TV’s where different then they are today and a lot simpler. Today we have, SUV’s, PU’s, Cars, Mini Vans, to name a few. Then we have, ½ ton, ¾ ton, 1 ton and heavier and lighter TV suspensions. Then we have Twin axle I beam, solid axle, Torsion bar, leaf spring, coil spring, MacPherson strut etc TV front suspensions. Then there is standard cab, short bed, long bed, extended cab, crew cab and the wheel base lengths etc. The combinations now a days are many. The myths setting about WD have some value but are for sure not gospel and are not even right in some cases. There is no one size fits all with all the combinations in TV’s out that can be set as gospel.
Then there is: Well what does the actual TV manufacture recommend for there vehicle when using a WD hitch? What do they say about what is the proper way to adjust a WD hitch for that TV? And then there is conflict between the hitch manufacture and the TV manufactures on what is the proper way. Who do you trust, the company that sells a $500 hitch or the company who sold you the ~ $25 to $55K TV that designed the front end suspension?
To make this worse, many TV makers do not even put instructions in there owners manual on what the right way is. I use to have a 2003 K2500 Suburban and at the time GM had nothing in the owners manuals up thru 2003 about setting up WD. I learned a lot because of that too..... In 2004 they actually started adding a page in the manual on what the proper why for that vehicle was. Ford then soon followed and Dodge also mentioned some.
Trying to make sense out of all that with actual technical details behind them, I came to these conclusions. These are my opinions and follow many of the TV manufactures recommendations. If you read the hitch manufactures wording just right, you can actually get the TV and hitch manufactures wording to agree.
PU trucks and SUV’s set up similar in nature. Mini vans and cars setup similar but different the PU’s and SUV’s. Full size vans sort of fall in with the PU’s and SUV’s. A ¾ ton suspension can set up different then a ½ ton but may also come out to be the same. A 1 ton can set up slightly different then a ¾ ton and still be very acceptable or can be the same.
So we really need to talk about what specific hitch and what specific TV you have on what is declared as the right way.
Let’s take Toms case here since we have a lot of info on it. First lets look at his truck
Look at his manufactures ratings.
GVWR - 6300 LB
Front GAWR - 3500 LB
Rear GAWR - 3650 LB
Now look at his truck unhitched weights
Truck without the trailer:
TV Front Axle - 2940 LB
TV Back Axle - 2920 LB
Tom has a PU truck, and a light duty one, I do not know for sure but I will put it in the class of a ½ ton truck. It is something lighter then that but it depends on what one calls a ½ ton truck any more….
Tom’s truck manufacture put a heavier axle rating on the rear axle then the front on purpose. And then they also caped the entire truck with a GVWR to not exceed. In Toms case he has a truck cap and gear loaded in the back of his truck that make the rear axle and front axle comes close to the same value before he ever added the TT. If we found the actual unloaded truck curb rear axle weight, the rear axle would be a lot less. A PU truck is built to carry weight on the rear axle of the truck. The front axle gains some weight by just having bed weight added but it is also holding up the engine all the time.
The front end steering components are designed to work thru the entire weight range, however they are optimal the way the truck rides around normally. Which is slightly over empty front end weight and expected passengers in side. The front end is very happy riding around and not wearing tires and not straining the suspension at the unhitched and unloaded bed weight. Note: Not every TV is like this, but we are talking a PU right now.
The main purpose of WD is to return the front end of the truck back to unhitched weight in the PU truck world so the steering geometry is more normal and the front end is held down to the road well in slippery conditions . It puts the proper balance back into the truck that dead weight on teh tow ball caused in an inbalance.
Some PU/SUV TV’s do not want any over drive or weight added by WD to the front, (GM) some can tolerate a little (Ford) and some say you can use all of the front axle ratings (Dodge use to say that, unless they changed there tune recently.)
We also want the rear axle to be heavy enough to not skid in wet conditions with the TT pushing us. If the rear axle is too light a heavy tongue TT can push it around easier.
Sometimes WD is set that the front end is returned to unhitched weight area and both front and rear are close to being equal. This is good as the truck is very balanced but is very conditional on the TT and truck. It occured but was not the exact goal you started with.
A side benefit of adjusting WD is that the rear axle is unloading some of that heavy weight added by the mechanical advantage lever effect of the tow ball being 5 feet behind the rear axle. In the process, some weight off the rear axle is transferred to the TT axles because the tires act as a support to the ground.
So the goal or target, again on a PU/SUV, is to set the WD hitch to return the TV front axle back very close to unhitched weight. On a ½ ton suspension or lighter you can get back to zero or unhitched weight pretty easy. On a ¾ ton there are other things that come into play that make the front end maybe be 50 or 75 pounds lighter as an average and still be OK. Crew cab long bed is harder then standard cab short bed. A 1 ton TV with helper springs on the back axle add yet another variation in here.
The rear axle then ends up holding the rest of the weight. It is designed to handle more weight on purpose. Pending the truck, the stance of the TV “might” be level, It might be the rear fenders are higher then the front (still a slight down angle like unhitched) and it might be if the bed weight was high enough, the truck rear is slightly less then the front. The goal was met to satisfy the front end. I have not found any TV manufacture that states that retuning the front end to unhitched weight when using a WD hitch to be unacceptable. Many declare that is the right way. I have not read every TV manual out there… if some one has a TV that it states to on purpose overdrive the front end with weight is the proper way to set up WD on that TV, please post so we can discuss and learn there is yet another combo out there.
And then there is the TV receiver. Many receivers that come from the OEM are built with a design intent to work on WD. If there intent is that the front end is to be returned to unhitched weight, then the strain the receiver tube can handle will be to that target. They may not have designed in a lot of extra cushion to over drive the front end and actually compress the front suspension by using the receiver. Many OEM receivers are now light weighted to the point they have a real hard time actually getting back to unhitched weight on the front end. As the requirement for better fuel mileage is mandated, extra steel has to go somewhere and the receiver is fair game. It only has to meet the spec they declare is the limit of the truck.
I know this is more then you thought, and I was on a roll so I just kept typing…. But it explains where I came up with my opinion from. And I am very open to anyone questioning it as I know I do not know every TV out there and can always learn more.
Hope this helps
John
PS you asked about ratio of weight percentage. Each TT and TV will come out with different weight % shifted. The TV wheel base, tow ball over hang and tow ball to TT axles all affect what the weight % changes on rear axle, front axle and TT axle gain is. A Que if it had a 800# tongue will have more weight shifted to the TT axle then a 32 foot T310SR with a 800# tongue as the distance to the TT axle is so different. And a standard cab short bed PU will have different % weight shifts then a Crew cab long bed with the same TT hitched to the back. There is no rule of thumb exact ratio that declares how much weight will be transferred where. If some one says it is a 33/33/33% split ask them exactly how that got that and does it work on all TV and TT's.
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