results of CAT Scales and WD hitch adjustments

[funkill]

Okay – I finally started working on improving my hitch set-up today. Last month I spent a couple hours trying to configure the hitch with my new 2000 Yukon XL (1/2 ton) and never got it quite right per the DrawTite WD setup instructions. The main problem was that the rig rode high at the hitch ---- with the trailer several inches higher at the tongue than rear bumper.

Cutting to the chase: My review of the data is as follows. I didn’t see any significant differences based on measurements at TV wheel wells alone. Scale differences are more obvious. Weigh master suggested I use the setup from my second pass (at 6 links). After calculating the percent load capacity of the axles, I’m inclined to agree. Adds a bit more to the TV Drive Axle, but I read that it is more capable of handling the extra load (vs the Steering axle).
5 links
added 130 lbs to TV Front (98% max GAWR)
added 280 lbs to TV Rear (80% max GAWR)
removed 380 lbs from TT axles (86% max wt)
6 links
added 60 lbs to TV Front (96% max GAWR)
added 400 lbs to TV Rear (84% max GAWR)
removed 420 lbs from TT axles (85% max wt)

Here’s the full scenario: Today I loaded some ballast to my TV and TT in my best effort to mimic actual weight of additional equipment that I’d have stowed during a regular trip.

I lowered the head assembly on the shank to the lowest position (essentially, lowering the ball as far as possible – which was only one hole lower than started with). I measured the TV Front/Rear wheel well heights and then hitched to the trailer. I re-measured (finding a gain at the Front and substantial loss in the Rear). I then towed the trailer about 5 miles without the spring bars engages as detailed in my Tahoe Owners Manual – for my Premium Smooth Ride option: “Level Control – Self-Adjusting”. I’m told this is, essentially, gas shocks – mechanically driven. Not Auto-leveling, not Auto-ride, not controlled by any compressor or electrical connection. (Details on this system at post # 28 at http://www.airforums.com/forums/f464/auto-leveling-on-tow-vehicle-40012-2.html .) After this short tow, I measured Front/Rear heights again and it did change. Then I engaged the spring bars so that the rig (TV/TT coupled) appeared most level and with the Front/Rear heights adequate (6 links) The 800 lb spring bars definitely moved the load and I did notice them flex/bend some.

TV uncoupled: Front 34-7/8" , Rear 36-3/16"
TV with TT (no spring bars, no travel): Front 35-9/16" , Rear 34-3/4"
TV with TT (no spring bars + 5 miles): Front 36", Rear 35-3/8"
TV with TT (spring bars at 6 links): Front 35", Rear 35-7/8"
TV with TT (spring bars at 5 links): Front 34-1/2", Rear 36'
TV with TT (spring bars at 5 + 15 miles): Front 34-5/8", Rear 36"

I left the spring bars with 5 links engaged and preceded to the CAT Scales. Below are the weights. NOTE: my front passenger (200 lbs) had to leave so I annotated in the results as pass/no pass! This accounts for the changes you may notice (esp. in ross weight). The weigh master said that he believed the second run was my best setting (at 6 links engaged).

TV Uncoupled (no pass): TV Front 2840, TV Rear 2900, Gross 5740
TT uncoupled (no pass): Tongue 700, Rear 5160, Gross 5860
max bars (5 links) (pass): TV Front 3140 , TV Rear 3220, TT 5480, Gross 11860
adj bars (6 links) (pass): TV Front 3060, TV Rear 3340, TT 5440, Gross 11840
no bars (no pass): TV Front 2580, TV Rear 3740, TT 5260, Gross 11580

Some additional info.
2000 Yukon XL, 5.3 Vortec V-8, ½ ton, 2-WD, 3.73 axle ratio, factory tow package – my giant
Bridgestone Revo, E-rated 65 psi verified (80 max)
Curb Weight 4769
GVWR 7000
Front GAWR 3200
Rear GAWR 4000
Payload 1905
Front axle capacity 3400
Rear axle capacity 5500
Front spring rating 3150
Rear spring rating 4000
Towing capacity 8000
Wheelbase 130”
Length 219”
1973 Airstream, 27’ Overlander, rear bath double – cute as a button
Henschen axles (new 2009) 3200 lbs each
Gabriel shocks (new 2007)
Marathon, D-rated tires, 60 psi max 60 psi verified
Tekonsha Voyager brake controller – pain in the ass
DrawTite WD hitch: 800 lb spring bars (rated as 800 lb max tongue weight, 12,000 max gross trailer weight) - no issues

So, do any of you have any comments, suggestions or witty comments? This has been a challenging day for me --- intimidated by the scales (and having to back off for each successive pass) and then solid rain on my way home. Thankfully my dad helped me through this!!! When I say "I" in the post, I really mean "we".
Laura