When at the scales

[SteveSueMac]

Ok - I've sent the pic to Sean. Lets see what he thinks (the guy is amazing - I feel awful bothering him on weekends but I work during the week and can only tweak this thing on weekends).

Any other thoughts on why the steer axle would LOSE 60 pounds with more WD applied? Pretty confusing! :-}

[SteveSueMac]

One other thought richinny - if the trailer nose looks down, should the stinger come UP one hole?

[richinny]

geometry is not my strong point so we'll wait for Sean.

[SteveSueMac]

Originally Posted by richinny

geometry is not my strong point so we'll wait for Sean.

Mine either!!! :-)

I've sent him the pic and a few questions.

I welcome other insights too - it's a big mystery to me as to how I'd lose an additional 60 lbs by adding an inch to the WD jacks! :huh?:

[Ridgerunner3]

SteveSueMac, is your truck a 2011 - 2013 2500HD? I changed from a 2010 2500HD to a 2012 2500HD and found that the rear spring loading had changed. The hitch on the 2012 truck sits higher than the 2010 when the truck is sitting unloaded. But, the rear springs on the 2012, with initial load, squat with less load than the 2010.

All of this is to say, when I bought the 2012 I adjusted my Propride stinger according to the unloaded truck new hitch height. I ended up with the nose of the AS sitting too low. It turned out the loaded height (with trailer attached) of the 2010 and 2012 were the same. I reset my PP stinger back to the setting I had for the 2010 and all was good.

I assume GM changed the spring loading for a softer ride in an unloaded 2500HD.

My PP stinger is set level when attached to the truck (no trailer attached) and three holes showing above the top bolt.

Hope this is helpful.

[SteveSueMac]

Ridgerunner3 - yes, it is a 2013 and my stinger is exactly the same as yours (3 holes on top).

[Ridgerunner3]

Originally Posted by SteveSueMac

Ridgerunner3 - yes, it is a 2013 and my stinger is exactly the same as yours (3 holes on top).

I set my bar jacks at 6" like you also. My truck is a crew cab.

Do you have any close profile pictures of the hitch with the trailer attached to the truck?

The picture I attached looks like I am sitting on a slope. Just poor photography. The trailer is sitting level with the hitch setup you see.

I am sure Sean will be able to work through this with you.

[ROBERT CROSS]

Am I rong, both sets of tickets look the same...

I would try.... shorten your jacks one hole. Adjust bars 'til rig looks level.
You would then have to re-weigh.

Other option....un-hitch. Measure the height of the TV thru the center of the front wheel to the edge of the fender wheel opening.(both sides should be within 1") Hitch-up measure again with no WD, then adjust your jacks 'til your back the the un-hitched measurement.
This procedure got us to within 80lbs of the CAT weights.

If you could get back to 4600lbs you should be good to go.

Bob

[SteveSueMac]

Originally Posted by Ridgerunner3

I set my bar jacks at 6" like you also. My truck is a crew cab.

Do you have any close profile pictures of the hitch with the trailer attached to the truck?

The picture I attached looks like I am sitting on a slope. Just poor photography. The trailer is sitting level with the hitch setup you see.

I am sure Sean will be able to work through this with you.

Just looked through all my pics - none like that. I measured front and back of trailer to the ground and only off by 1/2". Sean said going up one hole in that case wouldn't help much. Do you have scale tickets for yours, ridgerunnner3?

[SteveSueMac]

Originally Posted by ROBERT CROSS

Am I rong, both sets of tickets look the same...

Bob

You're right - same set of 3 tickets - only meant to include one...it's the same set...

[ROBERT CROSS]

Originally Posted by SteveSueMac

Just looked through all my pics - none like that. I measured front and back of trailer to the ground and only off by 1/2". Sean said going up one hole in that case wouldn't help much. Do you have scale tickets for yours, ridgerunnner3?

What about tow vehicle steering axle measurements?, get the weights/measurements right there, then you can work on getting the trailer back to level if needed.

Bob

[SteveSueMac]

Originally Posted by ROBERT CROSS

What about tow vehicle steering axle measurements?, get the weights/measurements right there, then you can work on getting the trailer back to level if needed.

Bob

Meaning wheel well height? It's within a half inch of unloaded. I'm a rookie - I'm sure I'm missing something. :-/

[Ridgerunner3]

Originally Posted by SteveSueMac

Just looked through all my pics - none like that. I measured front and back of trailer to the ground and only off by 1/2". Sean said going up one hole in that case wouldn't help much. Do you have scale tickets for yours, ridgerunnner3?

I'll need to go to my camper to get my weigh tickets.

Your truck must be a diesel with the front end weight you recorded.

Did you weigh all three times on the same scales during the same trip?

Did you setup the tilt on the stinger so that it was level to the ground with the truck parked on a level surface? I think your stinger tilt angle could be your problem. This is one item that is very easy to check. I believe the stinger tilting up (even slightly) would give you less weight distribution at 6" on the bar jacks than level to slightly pointing down.

[SteveSueMac]

Originally Posted by Ridgerunner3

I'll need to go to my camper to get my weigh tickets.

Your truck must be a diesel with the front end weight you recorded.

Did you weigh all three times on the same scales during the same trip?

Did you setup the tilt on the stinger so that it was level to the ground with the truck parked on a level surface? I think your stinger tilt angle could be your problem. This is one item that is very easy to check. I believe the stinger tilting up (even slightly) would give you less weight distribution at 6" on the bar jacks than level to slightly pointing down.

Yes, it's a Duramax 2500 and yes, all 3 tickets are on the same scale in the span of less than 2 hours.

I have zero washers behind the rivet on the hitch - long story, but that's something I worked out with Sean. It's level at zero washers but a washer or two would push it on a bit of a downward angle toward the trailer and I can see how that might improve the WD. Could that be the cause of my loss of an additional 60 lbs on the steer axle when I applied another inch on the jacks??

[ROBERT CROSS]

Any other thoughts on why the steer axle would LOSE 60 pounds with more WD applied? Pretty confusing! :-}

Only one answer...your not applying more lift on the bars.
Tilting the head down a bit and more WD.

FWIW....my first trip to the scales. First weight no WD, second max WD. That way I had a base I could work from.

We run a 2500 Burb, Hensley with 1000lb bars. Now the Burb is nowhere near as stiff as the D-max, but we still have to bend those bars to apply enough force.

Pic is with a 4" drop I now use 6" and trailer is level with the same WD settings.

Bob

[Ron Gratz]

Originally Posted by SteveSueMac

A couple additional notes. One one of these trips I sat in the truck (I'm pretty sure it was the 3rd one) while the other 2 I was standing on the steer axle scale outside the truck as the operator wasn't giving me any time to adjust....

If you were standing on the steer axle pad instead of sitting in the cab,
the steer axle load would be too heavy and the drive axle load would be too light.
But, the trailer axles load would be unaffected.

When going from 6" to 7", the trailer axle load increased by 40#.
In theory, the steer axle load should have increased by about 80# and the drive axle load should have decreased by about 120#.
The data show the steer axle decreased by 60# and the drive axle increased by 20#.

The data suggest that an extra load of approximately 140# was on the steer axle during the 6" weighing.
If we reduce the steer axle load for 6" from 4480# to 4340# and increase the drive axle load from 4260# to 4400#,
the steer axle load, when going from 6" to 7", increases by 4420-4340 = 80# and the drive axle load decreases by 4400-4280 = 120#.

Those results make much more sense to me.

This analysis assumes a TV wheelbase of 160", TV ball overhang of 64", and ball to TT axles midpoint of 242".
Other values will have a small effect on the results.

Using the assumed TV/TT dimensions and the "adjusted" scales values gives:
for 6" -- tongue weight = 938# with 18# transferred to trailer axles,
for 7" -- tongue weight = 940# with 61# transferred to trailer axles.

The indicated tongue weight might be less than actual if the TT was in a nose-down attitude when axle loads were measured.

Ron

[SteveSueMac]

Originally Posted by ROBERT CROSS

FWIW....my first trip to the scales. First weight no WD, second max WD. That way I had a base I could work from.

Since I have the empty truck weights, I can do a run over the scales hitched but without the WD applied and then another run w/7" or more applied to the jacks. I think I may also need to put in a washer to tilt the stinger down a tad.

Thanks

[SteveSueMac]

Originally Posted by Ron Gratz

If you were standing on the steer axle pad instead of sitting in the cab,
the steer axle load would be too heavy and the drive axle load would be too light.
But, the trailer axles load would be unaffected.

When going from 6" to 7", the trailer axle load increased by 40#.
In theory, the steer axle load should have increased by about 80# and the drive axle load should have decreased by about 120#.
The data show the steer axle decreased by 60# and the drive axle increased by 20#.

The data suggest that an extra load of approximately 140# was on the steer axle during the 6" weighing.
If we reduce the steer axle load for 6" from 4480# to 4340# and increase the drive axle load from 4260# to 4400#,
the steer axle load, when going from 6" to 7", increases by 4420-4340 = 80# and the drive axle load decreases by 4400-4280 = 120#.

Those results make much more sense to me.

This analysis assumes a TV wheelbase of 160", TV ball overhang of 64", and ball to TT axles midpoint of 242".
Other values will have a small effect on the results.

Using the assumed TV/TT dimensions and the "adjusted" scales values gives:
for 6" -- tongue weight = 938# with 18# transferred to trailer axles,
for 7" -- tongue weight = 940# with 61# transferred to trailer axles.

The indicated tongue weight might be less than actual if the TT was in a nose-down attitude when axle loads were measured.

Ron

Thanks Ron - I can't pretend to understand the math you're using but I'm really grateful for the analysis. I haven't weighed 140 lbs in a long time so I'm not sure how that figure is the extra load of standing on the platform vs. sitting in the driver's seat of the TV. Again I'm not quite sure how you got to the calculations but your recalculation suggests I was actually getting more on the steer axle with 7" than the scales suggest. That's of some comfort. I'm going to see about inserting a washer in the drawbar to angle it slightly downward and recheck level across the rig. Next time I will be 100% sure the weights will all be calculated with me in the drover's seat so there is no difference.

I'm curious - How did you calculate tongue weight?

Thanks again for the thoughtful, detailed insights.

[Ron Gratz]

Originally Posted by SteveSueMac

--- I haven't weighed 140 lbs in a long time so I'm not sure how that figure is the extra load of standing on the platform vs. sitting in the driver's seat of the TV.---

I don't want to offend, so please keep in mind that the analysis is based on scales data which are not 100% accurate and assumptions which also can be erroneous.

So, just for example, if a person weighs 280# and 50% of his weight is carried on the front axle when seated in the front seat, the front axle would carry 140#
If the person then moves from the cab to the steer axle pad, the load on the pad would increase by 280-140 = 140#.
If your weight is nowhere close to 280#, then I need to rework my analysis.

I'm curious - How did you calculate tongue weight?

The net load removed from the front axle is a function of three TV/TT dimensions and two unknowns: 1) the tongue weight, and 2) the load transferred to the TT axles by the WDH.

The net load added to the rear axle is a different function of the same TV/TT dimensions and the two unknowns.

This means we have two simultaneous equations from which the two unknowns can be calculated when we know three TV/TT dimensions and the net load changes for the front and rear axles.

Again, assumptions must be made and that leaves room for error.

Ron

[SteveSueMac]

Originally Posted by Ron Gratz

I don't want to offend, so please keep in mind that the analysis is based on scales data which are not 100% accurate and assumptions which also can be erroneous.

So, just for example, if a person weighs 280# and 50% of his weight is carried on the front axle when seated in the front seat, the front axle would carry 140#
If the person then moves from the cab to the steer axle pad, the load on the pad would increase by 280-140 = 140#.
If your weight is nowhere close to 280#, then I need to rework my analysis.

The net load removed from the front axle is a function of three TV/TT dimensions and two unknowns: 1) the tongue weight, and 2) the load transferred to the TT axles by the WDH.

The net load added to the rear axle is a different function of the same TV/TT dimensions and the two unknowns.

This means we have two simultaneous equations from which the two unknowns can be calculated when we know three TV/TT dimensions and the net load changes for the front and rear axles.

Again, assumptions must be made and that leaves room for error.

Ron

No offense taken. 271 on my bathroom scale this morning - thankfully this is just between you and me! Oh, and it's mostly muscle. :-)

Now that we have that out of the way, that makes sense - of course the driver's weight would be spread over 2 TV axles!

Is it also odd then that if the trailer weighs 6280 that the TW is 15% (940)?