Why does axle ratio effect trailer GVWR?
08-20-2018, 10:28 AM
#21
Senior Member
Tell that to all the 1st gen ecoboosters who complain about overheating during the summer while towing far under GCWR, including me. I tow a 5500 lb trailer and have a 17100 lb GCWR and it still gets warm.
The J2807 requirements are that they have to maintain 45mph up Davis Dam in a minimum of 100F heat at max GCWR. Ecoboost clearly dont have a power issue, so what else is it?
The J2807 requirements are that they have to maintain 45mph up Davis Dam in a minimum of 100F heat at max GCWR. Ecoboost clearly dont have a power issue, so what else is it?
08-20-2018, 12:23 PM
#22
5.0 DOHC V8
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Two identical trucks. One with 3.31 gears, the other with 3.73. They're both pulling a trailer that is the max weight of the 3.73 truck. Do you really think the 3.31 won't be running hotter and probably overheat? It has to work harder to pull the same weight as the truck with the 3.73 gears...
The 3.31 may be in an 8.8" ring gear axle housing, whereas the 3.73 may be a 9.75"... the 9.75 housing is rated for a higher GAWR, which could influence the vehicle's GCWR.
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BlackBoost (08-20-2018)
08-20-2018, 01:19 PM
#23
Yes but again that's gearing which relates to how hard the engine is working. Towing over that weight, or even something larger than the max frontal area can be done, but it won't take long for the engine and transmission to be running too hot for the cooling systems to manage. Harder working engine = hotter engine and transmission. Too hard or too long = overheating. Simple.
08-20-2018, 02:21 PM
#24
5.0 DOHC V8
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Yes but again that's gearing which relates to how hard the engine is working.
I'm not talking about gearing... only used the ring and pinion examples to factor the two different axle housings into the discussion. The 9.75 axle housing assembly is a higher-weight-rated unit.
08-20-2018, 04:05 PM
#25
True, but that's only applicable to vehicles that can already tow a certain GCWR and why it is made available. Those configs that only have the 8.8 and don't have the option of a 9.75 is because other limits are already reached, so increasing the GAWR to increase the GVWR to increase the GCWR is not possible. The 3.5L NA, 3.3L and some configurations with other engines are in this limitation.
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Apples (08-20-2018)
08-20-2018, 05:53 PM
#26
Senior Member
So no, the RAWR does not affect the GCWR (I guess the housing itself could influence it if the 8.8 runs into cooling issues above a certain GCWR)
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Apples (08-20-2018)
08-21-2018, 07:51 PM
#27
Rear Axle Ratio doesn't have to effect GCWR.
J2807 Allows for the vehicle to be tested with the Tallest Axle and all rated the same. I have some suspicion this may have been done with the Non-Max Tow 3.5EB for 2018.
J2807 Allows for the vehicle to be tested with the Tallest Axle and all rated the same. I have some suspicion this may have been done with the Non-Max Tow 3.5EB for 2018.
08-22-2018, 01:39 PM
#29
Heating up to the point that the engine cuts power and warning signs come up on on the dash? Im not just talking about the needle moving slightly to the right.
08-22-2018, 01:59 PM
#30
There are several components to SAE J2807 (not just the one you mentioned..and it's 40mph): http://www.trucktrend.com/how-to/tow...-the-standard/
What other components would be effected by the rear axle ratio in a meaningful way? Acceleration tests? Doubt it. All new V8's and ecoboosts have more than enough power.
