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Open Roads Forum  >  Towing

 > 3/4 Ton Suburban WD setup - Which set up is right?

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JBarca

Radnor, Ohio, USA

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Posted: 08/21/05 06:46pm Link  |  Print  |  Notify Moderator

Edit: 10-25-05

To future fellow forum members who have come upon this post. What I started out asking is clarification on the correct way to adjust my WD hitch on a 3/4 ton NBS Suburban has turned into a complete hitch setup, receiver mounting and TV suspension investigation.

If you happen to have a Reese High Performance Dual Cam hitch with trunnion style spring bars, this post will help you set up the hitch properly even if you do not have a 3/4 ton truck.

Also found are good details on 3/4 ton GM suspension systems, why you want proper WD to the front axle and even some deflection issues on the TV frame.

This post is packed with all types of good technical data in the event you are doing your own investigation.

Hopefully the good work done by all the replies along with pictures, diagrams and data will help you some day as it has helped me immensely fully understand the way my WD hitch and TV suspension interact with each other along with proper setup of the hitch.

I know I now have a much better setup and a safer rig. Hopefully this helps you in your investigation.

Happy camping

John

End of Edit.


Need some input from those that have 3/4 ton TV and are WD hitch fluent. Ideally Suburban's or Yukon XL's as the truck dynamics are going to be close to the same as mine. I do not know if you will see what I have ended up with on a 1/2 ton or a longer wheel base pickup.

OK here goes. I have weighed my TV and TT fully loaded ready to go camping on each axle one at a time with the WD bars engaged. I know where each axle is in regards to GAWR. I have 880# extra capacity on the front TV axle and 380# extra capacity on my rear TV axle. The TT has at least 860# extra capacity each axle and I know my tongue weight static is 1,250#. So all my weights check out and are in line.

The weekend I have measured the weight distribution between the front axle and the rear when; empty, with full tongue dead weight and with the bars engaged. I feel I have my rig set up as optimal but it goes against the general rules of what is said about how to adjust a WD setup. I know I'm real analytical on things so what is said literally in conversation may not always be exactly what is meant.

I have a Carver Laboratory press that I use to measure weights with. Basically a big hydraulic jack with a fancy pressure gage on it to measure force. I use it for tongue weight. Works good. Well I took it to the TV to measure axle loads. Unfortunately I can only lift 1 wheel at a time as the OAH is too high to get under the diff. housing but I can see the weight shifts under various setups.

Here is the data. Again remember the weight readings are per 1 wheel lifting off the ground when measured.

(I hope this chart formats right on your screen.)

TV Front
________________TV Empty_____Full Tongue wgt.______WD Engaged
Fender well =_______35 1/4"___________36"_________________35 13/16"
Weight =___________2600#__________2400#________________2700#

TV Rear
Fender well =______37 7/16"__________35 5/8"________________36"
Weight =__________2400#___________3400#_________________3200#

Hitch dim to ground as ref. point to see movement. By chain loops on receiver.
________________18 3/16"____________15"________________15 7/8"

Notes:
1. 3/4 Ton Burb can almost the take full 1,250# tongue on it's own without WD.
2. Rear of TV is 2 3/16" higher than front when empty. Stiff back end in truck.

When WD is engaged:
3. Front axle at 1 tire is 100# heavier than when started.
4. Front wheel wells are 9/16" higher than empty.
5. Rear axle at 1 tire is 800# heavier than when started.
6. Rear axle is 1 7/16" lower than empty. (Rear Squat.)
7. Rear hitch is 2 5/16" lower than empty.

8. Truck is level front to rear tire wells within 3/16" with front being lower than rear.

What I have is a level TV and a level TT to within a tolerance as if I drive around the block the springs move around and the numbers change within an 1/8".

The TV and TT are level BUT my front axle is higher than when I started but yet 100# heavier as measured at 1 tire. If I take up any more on the WD bars to get the front closer to empty the rear end of the TV will rise and I will no longer be level.

So when folks say the front axle is suppose to be at least at the same height or lower fender height than when empty OR to have equal fender well drop front and rear... there is no way I can get there from what I see.

I do not have a truck that is level to start with. Rear is 2 3/16" higher to start with. The 3/4 ton springs will almost take the whole thing. I am heavier on the front axle than when I started even though the front of the truck fender well is 9/16" higher than when I started but level to the rear fender well.

So I have broke the rules of how to get proper WD setup but believe I have what was meant in having a proper WD setup.

Any one else have this sort of result with their 3/4 ton? OR help point me in the direction of what I can adjust to make it any better that does not affect the other rules.

Thanks

* This post was edited 10/25/05 08:02pm by JBarca *


John & Cindy

2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver

2004 Sunline Solaris T310SR
(I wish we were camping!)


skills4lou

Dillon, MT

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Posted: 08/21/05 07:06pm Link  |  Print  |  Notify Moderator

John,
Wow, that's a lot of tech! You're fine, now stop worrying and go camping!
[emoticon] [emoticon]


I'm not an expert, but I play one on the internet ">
"Never drive faster than your guardian angel can fly"

98 Chevy 3500 CC 4X4
'76 Kit TC
'99 Prowler 5th wheel

TURK2500

SE Michigan

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Posted: 08/21/05 07:20pm Link  |  Print  |  Notify Moderator

What you are describing is the same outcome I get with my 2500HD and my TT combination. The only problem I was experiencing was to much bounce, so I tilted my receiver hitch back toward the TT one notch (from ball axis vertical) so that I could transfer a little more weight to the front of my TV. I run with two links hanging for the best results (1200lb bars). In doing this I reduced my bounce dramatically, but my front fender height still remained a little (1/4 inch) above the normal TV height without the TT. My rear fender height drops about 1 inch.

I've heard the same thing about that the front should drop a little, so the question still remains....?

Mine pulls great, so I'm leaving well enough alone.


02 Chevy, 2500HD/4x4, 6.0L/4:10, GVWR 9,200lbs., GCWR 16,000lbs.
05 Jayco Eagle, 278FBS, GVWR 9,000lbs.
TV/TT loaded: 14,700lbs.
Loaded Tongue Weight: 1,300lbs.
Loaded TT weight: 8,500
Putnam XDR Class V, Reese HP Dual Cam.


BarneyS

S.E. Lower Michigan

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Posted: 08/21/05 07:26pm Link  |  Print  |  Notify Moderator

In my opinion, you are NOT fine!

The first thing that I see wrong with your set up is this statement.
"Notes:
1. 3/4 Ton Burb can almost the take full 1,250# tongue on it's own without WD.
2. Rear of TV is 2 3/16" higher than front when empty. Stiff back end in truck."


The 3/4 ton anything cannot take a full 1,250# on it's own! You are dangerously overloading your hitch receiver. The only way a receiver can take that kind of load is with the weight distributing bars engaged and tensioned properly.

If the rear of your truck is higher than the front when empty, it should still be higher than the front when you have the WD bars hooked up and tensioned. The only thing is that now, both the front and the rear should be somewhat lower than they were originally. They should still be in the same relative positions to each other though.

In looking at your numbers, you definitely do not have enough tension on your WD spring bars. You need to take up some more links to transfer more weight to the front of your truck and back to the TT axles. If you do not have enough chain links left, then you need to tilt your hitch head rearward to give you move room to take up links.

Do you have strong enough spring bars? With that kind of weight on the tongue, I would be wanting 1200# bars at the minimum and preferably 1400 or 1700# bars.

I think if you will spend some more time with your hitch, you will be able to get the weight distributed much better. Your truck is not so stiff that it will not settle. Even if it does not, you are still changing the steering geometry, braking ability and possibly increasing the wear of your rear axle and front axle components.

Hope this helps out a bit.

On edit: I just noticed another statement that you made which is an error in your understanding.
"If I take up any more on the WD bars to get the front closer to empty the rear end of the TV will rise and I will no longer be level."
As I mentioned above, the truck is NOT supposed to be "level" if it was not level before you started. It should still be in the same "attitude" as when you started - just lower to the ground. That rear end should still be 2 3/16 higher than the front after you hook up. [emoticon]
Barney

* This post was last edited 08/21/05 07:42pm by BarneyS *   View edit history


2004 Sunnybrook Titan 30FKS TT
Hensley "Arrow" 1400# hitch
2016 Ram Laramie 2500, 6.7L CTD, 4x4, SB


JBarca

Radnor, Ohio, USA

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Posted: 08/21/05 07:56pm Link  |  Print  |  Notify Moderator

BarnyS

Thanks, this is what I was looking for. First a few things.

What I mean by the 3/4 ton could almost take it was on the GAWR-RR. Sorry I did not intend to run it that way as the front is way too unloaded. My fault for not clarifying. Sorry [emoticon]

My Putnam XDR receiver is tongue rated at 1500# weight carrying and 1700# WD. So while I do not like getting that close to the limits I want to make sure I had more receiver than I needed.

I am using 1,200# bars and have the Reese HP WD hitch which has click (teeth) for finer ball tilt to help preload the bars slightly less than 1 whole chain link.

And I had already did 1 ball mount angle click to preload the bars a little and yes the rear end of the truck went up and the front went down slightly. However the entire talk on having a level truck just went out the window. This may be the myth here that I was confused on.

However I do know this, if I go 1 ball mount click to do more preload my TT will now be tongue high and not level. And a 1 hole drop on the hitch shank is big deal,they are not so fine an adjustment. They are on like 1 1/4 centers.

I know dropping 1 hole on the hitch shank if going to affect everything. I'll have to try it as I do not know of any other tricks to shift it.

I think I get where you are going with this. So correct me where I go wrong. Are we looking for close to equal axle weight drop and skip the level TV deal? If I understand this right then why have cargo load capacity in the back of your TV? There must be some ratio as the front is usually always heavier with the engine up there and the payload goes in the back of the empty truck. What am I missing here? It is probably the ratio but if so, what is it?

Thanks, I think I'm gaining.

John

Jim&Peg

Central Ohio

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Posted: 08/21/05 07:57pm Link  |  Print  |  Notify Moderator

I know most WD directions say front and rear should lower about the same;however, Drawtite directions are much more detailed and say the front may stay about the same. If the front lowers any, then the rear must lower at least one inch more. You can find their directions on the Drawtite website.

BarneyS

S.E. Lower Michigan

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Posted: 08/21/05 08:08pm Link  |  Print  |  Notify Moderator

"So correct me where I go wrong. Are we looking for close to equal axle weight drop and skip the level TV deal? If I understand this right then why have cargo load capacity in the back of your TV?"

Yes, you are looking for equal drop on both the front and rear and you can skip the level TV deal. [emoticon] HOWEVER, when you load both the front and rear axles as you are going to do, you now have LESS cargo capacity in the back of you TV. You still have to abide by the manufacturers gross axle ratings. This is why it is best to set up your truck/trailer/hitch with everything loaded as you would when you are ready to go camping. Then go to a scale and get it weighed so you know you are within your axle limits and your GVWR. I would not worry about the "ratio".
Barney

TURK2500

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Posted: 08/21/05 08:10pm Link  |  Print  |  Notify Moderator

BarneyS: You have raised my curiosity on this subject; I would think that not all TV and TT combinations are created equal. Unless one load's the TV and TT the same every time, I would think that there would be some some minor variations in "set-up heights". With the best "set-up heights" that I have been able to create (with my existing and other TV/TT's) my rear TV dimension always drops just a "little".

Would you think the ability to maintain the "levelness" of the TT plays into the adjustments being made at the hitch? This can be a challenge sometimes as well.

I have played with my link tension (3, 4 hanging), and the results were pretty much the same. I have never been able to get the front and rear of my TV's to drop the same dimension.

In order to go to the 1400lb or 1700lb bars, would you have to upgrade to a Class V hitch so the receiver will accept the bars?

BarneyS

S.E. Lower Michigan

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Posted: 08/21/05 08:14pm Link  |  Print  |  Notify Moderator

Turk,
You are correct that all tow vehicles will not be the same. The statements I have made above are the "ideal" and are not always exactly obtainable BUT most can be made very close to that ideal with some careful work and time. I have done this many times with my friends even though they were sure they had it set up right. I live VERY close to you. Send me a PM if interested and we'll set up a meeting place and go over you hitch.

Yes, I believe you would need to go to a class V receiver to use the 1700# bars but I am not entirely sure.
Barney

TURK2500

SE Michigan

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Posted: 08/21/05 08:24pm Link  |  Print  |  Notify Moderator

BarneyS: I'm dropping my TT off at the dealer tomorrow morning for some minor warranty work, when I get it back I will PM you and set-up a meeting. I'm planning a cross country trip in mid March 06, so it would be great to know that I'm as close to "ideal" as possible.

[emoticon]

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