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 > A Little Help With Weights

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Grit dog

Black Diamond, WA

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Posted: 06/11/22 10:32pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

JIMNLIN wrote:

Quote:

I think it depends on where you will be driving for how much overweight you can be "safely". Eg, braking going down a long steep mountain road at highway speed is different from in town on a flat road. I don't know how they "rate" brakes.

Bad braking is a thing of past years with the later gen model LDT size trucks.
Brake on a LDT are the function of the axle ratings ...at a minimum.
A 3500 drw GM may have a 9375 rawr and a 6000 fawr for 15375 lbs of braking performance. I haven't seen the OP cert placard gawrs and may look like these numbers.
At some point GM uprated the 3500 drw rawr to 10500 lbs = which would give this model drw a 16500 lbs of braking performance.....at a minimum.

Hooked up with a 24000 gvwr GN flatdeck or a stock trailer with three 8000 lb axles = 40500 lb of combined braking performance. This is how commercial haulers/ car haulers/cattle haulers can legally/safely operate at these gross combined weights and still carry up to max axle loads.


Not clear. If the duallies have the brakes on only one wheel (AFAIK), then how can the braking stopping distance be different from a single rear wheel 1-ton? Rubber on the road more but only one braking.

A single 1-ton has less RGAWR than a dually, but if it has the same stopping distance, how can that be related to the "axle" weight rate ratings?


Not sure what you mean by “1 wheel”. Rear axle is just like a srw once you pop the wheels off. Aside from unrelated differences like different width. Afaik, most 2500/3500/duallies if they have the same axle, they have the same brakes.
If you reach the threshold of traction when braking (panic stop scenario), the dually “could” brake better based solely on more tire width in the rear (and less in front, so go figure) IF apples to apples, load, tire pressure, surface, tire tread/compound.
Real world, not really a difference, unless the stars align. It’s whatever tire combo breaks traction first. Certainly no difference in “normal” braking.


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JIMNLIN

Oklahoma

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Posted: 06/12/22 03:41pm Link  |  Quote  |  Print  |  Notify Moderator

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Not clear. If the duallies have the brakes on only one wheel (AFAIK), then how can the braking stopping distance be different from a single rear wheel 1-ton? Rubber on the road more but only one braking.

A single 1-ton has less RGAWR than a dually, but if it has the same stopping distance, how can that be related to the "axle" weight rate ratings?

I'm using Fleet Ford specs....shows the F350 drw truck has a 1.50" diameter master cylinder vs a 1.315 diameter for the F250/F350 srw trucks.

And the F350 drw diesel uses the Dana 300 vs a Ford Sterling for the F350 srw.

Stopping distance ??
Fords brake system specs/axle system specs for vehicle brakes says nothing about required stopping distances.
Lots of variables in stopping distances between a fully loaded (full gawrs) one ton srw and drw.

* This post was edited 06/12/22 03:56pm by JIMNLIN *


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BFL13

Victoria, BC

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Posted: 06/12/22 04:08pm Link  |  Quote  |  Print  |  Notify Moderator

Interesting. Thanks for looking that up.


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JIMNLIN

Oklahoma

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Posted: 06/12/22 08:47pm Link  |  Quote  |  Print  |  Notify Moderator

That was from Fords 2022 models.

Yeah ....I would like to see Dodge/Ram and GM give us a website like Fleet Fords spec pages that has so much more component tech dimensions and sizes.
Separates lots myth/assumptions/opinions that gets posted as fact.

mkirsch

Rochester, NY

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Posted: 06/13/22 07:29am Link  |  Quote  |  Print  |  Notify Moderator

Grit dog wrote:

Not sure what you mean by “1 wheel”. Rear axle is just like a srw once you pop the wheels off. Aside from unrelated differences like different width. Afaik, most 2500/3500/duallies if they have the same axle, they have the same brakes.


Wheel = tire and rim.

Dually has 4 tires and rims on the rear, so it seems like BFL13 seems to think there should be 4 rotors and calipers on the rear.

Also, BFL13, you don't "stomp" the brakes going down hill. You "brake firmly" which can be achieved without "stomping."

ABS should not have a thing to do with normal braking even on grades. You might activate it if you do "stomp" the pedal and it's the least bit slippery.


Putting 10-ply tires on half ton trucks since aught-four.

BFL13

Victoria, BC

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Posted: 06/13/22 09:43am Link  |  Quote  |  Print  |  Notify Moderator

Some confusion developing here. I am just curious how things work with trucks, but the OP wants to know if he is "safe" with his set-up. He will get weighed and then more will be known about that.

It turns out that a DRW has stronger brakes than a SRW. Eg the bigger master cylinder mentioned above. Parts manuals could give more specs for the rest of the braking systems. I did find this too:

"With four back wheels instead of two, and a stronger rear axle, a dually truck can handle a larger amount of payload weight and offer more .....Most dually trucks are also equipped with bigger, stronger brakes for additional stopping power, as well as heavy-duty shocks and springs for greater capability to tread uneven terrain and rough driving surfaces"

I still don't see why braking specs have anything to do with axle weight ratings. I see that they would make the brakes stronger if the truck is expected to carry more weight. I would think they would use the GVWR for that. Whatever, the OP has a DRW so all he wants to know is how much "margin" does he have when overweight for braking while going down a mountain.

On "stopping distance", they have these roller things in brake garage floors that measure "braking" and perhaps that is how they decide how much braking a DRW needs based on the weight it is expected to be plus some margin.

I disagree with telling the OP he can ignore GVWR and just worry about RAWR, but nobody is going to change anybody's mind about that, so let's all just agree to disagree.

To me, it is all about the straw that broke the camel's back. The OP wants to know how many more straws will it take with his set-up. GM won't tell him!

On the question of using cab weight if you go over cargo weight rating, it is strange that the same exact cargo box and frame has different CWR if the truck is Diesel or gas. The Diesel engine weighs more so the truck has less payload out of its same GVWR. But the gas version has more CWR. So there they use front end weight to add to cargo weight. Using the little bit of cab weight (750 bs eg) for some extra cargo weight does not seem so bad then. So why do they even have a CWR instead of just a total payload rating?

Another confusion I started is about ABS. I thought it was different from "traction control". I should not have said "stomping" when I meant "brake hard". My question is whether you need to release or not to prevent overheating if you have ABS, and whether the ABS still does that (if it does) if you are overweight. I thought the OP would be interested in that too. He has had trucks for years so might already know how that works. I don't.

link to above quote

https://www.jdpower.com/cars/shopping-guides/what-is-a-dually-truck

Also "Wheel = tire and rim." Not to me. The "wheel" is the metal thing and the "rim" is part of that. The "tire" is the rubber thing that goes on the wheel. However, in casual talk, people often say "rim" when they mean "wheel" and "tire" when they mean the whole "tire assembly", so you have to figure out what they are really saying, which is usually not hard. [emoticon]

* This post was edited 06/13/22 11:16am by BFL13 *

mkirsch

Rochester, NY

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Posted: 06/13/22 01:45pm Link  |  Quote  |  Print  |  Notify Moderator

ABS is anti-lock braking system. It only applies when it senses wheel lockup, aka skid.

Otherwise the brakes work like brakes. IF you are holding the brakes while descending a long grade, they will get hot and fade, just like non-ABS brakes.

DRW trucks still don't have 4 rotors and calipers on the rear axles.

BFL13

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Posted: 06/13/22 02:17pm Link  |  Quote  |  Print  |  Notify Moderator

Here is what I find confusing. It says leave your foot down and do not pump the brakes and the ABS will grab and release as required, but that is for coming to a stop. It does not seem to cover what happens on a long steep downhill run for keeping the brakes from overheating. Or does it?

https://www.icbc.com/partners/driver-training/Documents/ts274w.pdf

Bedlam

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Posted: 06/13/22 02:53pm Link  |  Quote  |  Print  |  Notify Moderator

The ABS instructions you posted are for rapid/emergency stops and not for any other braking operation. You would not follow this every time you need to slow nor when descending a grade.


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Grit dog

Black Diamond, WA

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Posted: 06/13/22 03:03pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

Here is what I find confusing. It says leave your foot down and do not pump the brakes and the ABS will grab and release as required, but that is for coming to a stop. It does not seem to cover what happens on a long steep downhill run for keeping the brakes from overheating. Or does it?

https://www.icbc.com/partners/driver-training/Documents/ts274w.pdf


It's statements and questions like this that sometimes make me want to support those who just blatantly recommend more vehicle than needed for the job.
In other words, it's 2022 and if you don't even conceptually understand how ABS works and could somehow conceive that it will help a person who is riding their brakes down a hill, then you're grossly uninformed. Which is scary considering you drive a RV in the mountains!

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