Forum Discussion
184 Replies
Huntindog wrote:
Cummins12V98 wrote:
You have stated this repeatdly.
" I wish they would spec the trucks to their capability, for whatever reason, they don't."
They simply don't have the transmission that can pass the SAE test. You may be towing 30k and no doubt it tows just fine BUT it would not pass the SAE test.
New transmission will no doubt significantly increase the tow rating. Anxious to hear why now with the new transmission they have a higher rating since they said basically there is no need for a higher rating than 22,300#.
Just what is this test?
If it is the "J" towing standard, the only parameter in that test I recall that relates to the tranny is the fluid temp. Since I own one of these, I am well aware of what the tranny temps run, and am very confident that would not be an issue.
If there is some other SAE test that I am unaware of, or I have missed something, please enlighten me.
Look it up, it's the repeated launch on grade forward and reverse. I am sure that is the one it can't pass. SAE J2807
If this is NOT the reason for the LOW tow rating then please explain what is. The engine has plenty of power to do the job.
Remember the Allison is NOT the same in the pickups as it is in the MD applications.
AISIN is the same whether it's in a RAM or another Manufacturers Medium Duty vehicle.- looks like the side mirrors have running lights on them, not just the turn signals
Cummins12V98 wrote:
" I wish they would spec the trucks to their capability, for whatever reason, they don't."
They simply don't have the transmission that can pass the SAE test. You may be towing 30k and no doubt it tows just fine BUT it would not pass the SAE test.
New transmission will no doubt significantly increase the tow rating. Anxious to hear why now with the new transmission they have a higher rating since they said basically there is no need for a higher rating than 22,300#.
Like we have said before, I am also anxious to hear what they say about their "new found" tow ratings. My guess is they wont acknowledge the flip flop. I am a GM fan but this irks me big time. The trucks are capable of towing over 30K as they are with little effort. I agree that it might be the Tranny holding them back, it is not the rear end as someone suggested (but lack of 4.10's could be), nor the brakes, frame strength or the power of the engine. My 05-5500 4X4 had 5.19's. I also wonder if they don't want the added liability and warranty claims of their trucks running that heavy. Regardless of how good they are, lugging 30K plus around will accelerate wear. That is why the class 4-5 trucks don't make the same power as the 350/3500's do. They all back off the power with a longer duty cycle. If I apply GM's logic to the lower ratings, if only 2% utilize this kind capacity, so what if you increase the warranty claims on those 2%? You will sell a lot more trucks at the end of the month. I imagine you would have to go deep into a smoke filled room to find the true answer. The reality is, just as we discuss here, it gives the impression that the truck isn't as capable as the others. Based on my experience, I know that not to be true. But if your just looking at the spec sheet with no experience with the truck, it is a logical conclusion to draw. If they want to sell more HD's this has to change. They have zero issue wading into the hp and torque war, but for some reason draw the line on the towing capacity war. I will step off the soap box now.4x4ord wrote:
When GM wants to increase tow rating numbers they will add a 4:10 axle to their list of options.
I second that the transmission has been the issue. My motorhome also uses the Allison 1000 transmission and is limited to 30,000lb GCW. Freightliner has told me that the transmission is the weak link. I have looked at the Allison website and they confirm that rating without specifically mentioning the GM version of it.
It seems like I have heard that the 2020 GM HD trucks will come with the new transmission co-developed with Ford that seems to be working well with much heavier loads.- When GM wants to increase tow rating numbers they will add a 4:10 axle to their list of options.
Cummins12V98 wrote:
You have stated this repeatdly.
" I wish they would spec the trucks to their capability, for whatever reason, they don't."
They simply don't have the transmission that can pass the SAE test. You may be towing 30k and no doubt it tows just fine BUT it would not pass the SAE test.
New transmission will no doubt significantly increase the tow rating. Anxious to hear why now with the new transmission they have a higher rating since they said basically there is no need for a higher rating than 22,300#.
Just what is this test?
If it is the "J" towing standard, the only parameter in that test I recall that relates to the tranny is the fluid temp. Since I own one of these, I am well aware of what the tranny temps run, and am very confident that would not be an issue.
If there is some other SAE test that I am unaware of, or I have missed something, please enlighten me.- The new engines sound great but I am surprised that the Aisen transmission isn't getting more attention for only having 6 gears. I have a Cummins/6spd Allison combo in my motorhome and when that thing changes from 3rd to 4th and again from 4th to 5th it feels like it just dies due to wide gear spacing. I feel like a couple of more gears in that rig would be as good as 20% more torque.
RoyJ wrote:
There ARE other changes to the engine than just "dial up the boost" - that's not how OEMs do it, nor would it pass their durability / warranty testing.
The new engine has a different head, stronger / lighter pistons, stronger connecting rods, and altered turbo geometry. All that just to gain 15 hp and 75 lb-ft of torque.
How many of us would change that much just to gain 15/75? Shows the much higher standards of OEM power validation compared to "tuners".
Nope, I worked at Cummins and can honestly tell you that while reliability is high on the list, it is not the most important thing, passing emissions is. In fact, reliability is even decreased in the way of EGR's, unproven fuel pumps, and less reliable VGT for the sole purpose of meeting emissions.
The OE's have to pass a dyno certification in order to sell their engines so they have to tune it to pass these tests as well as providing a safe generic fuel mapping for many users in many applications and many scenarios. The aftermarket does not have to pass a dyno certification. Well..... they have to, but most don't.
They can also custom tune a truck for different applications instead of the one size fits all generic tune from the factory. When you are not towing, you don't need to reduce fueling to keep the EGT's low and you are not putting that much strain on your trans so you can safely add more power(to a point) when unloaded and dial it back when towing. All I have to do is turn a 4 way switch and I can go from a tune that is safe for towing to a higher power tune when i am not. OE's can't do that with emissions regulations.
Also, Cummins does add power to many of their engines via tuning without changing any of the hard parts all the time. They did it with the 6.7L, ISX, ISL, and many other engines. In fact, they even offer different power ratings on the same engine and you have to pay higher cost for the added power depending on how the truck is used. Almost all of the diesel manufacturers do this in the medium and heavy duty industry. Heck, my customers used to be able to pay a nominal fee for the licence from CAT to have their engines turned up by one of my 120 dealers. All that was involved was loading a tune that came from CAT.- " I wish they would spec the trucks to their capability, for whatever reason, they don't."
They simply don't have the transmission that can pass the SAE test. You may be towing 30k and no doubt it tows just fine BUT it would not pass the SAE test.
New transmission will no doubt significantly increase the tow rating. Anxious to hear why now with the new transmission they have a higher rating since they said basically there is no need for a higher rating than 22,300#. RoyJ wrote:
ksss wrote:
Back to the drawing board for what? I think I would wait and see what the Ram does going up Ike. If the Ram embarrasses GM and Ford, I would be inclined to agree. That has yet to happen on any run I have seen since they started the test, typically the Ram is number 2 or 3, but who knows maybe this is Ram's year. I think it will be interesting to see what the Ram fan boys say about the CP4 pump. Only Idaho has stuck to his guns. I bet there will be a rethinking about what a POS it is, now that Ram is using it.
There's a lot more to towing capability than the fastest up the hill - by that standard, every heavy spec Kenworth, Western Star, Volvo, etc., would be miserable tow trucks. At GCWR, they'll get embarrassed by a Ranger or CR-V also towing at GCWR...
If GM truly wants to compete (and perhaps they don't), they need to upgrade their chassis and axles to match Ram / Ford.
But, realistically, how many owners have CDLs to take advantage of Ford/Ram's tow ratings?
There is more to winning the pull off contest then speed up the hill, number of brake applications on the way down and the subjective points. You might want to check it out. I do have a CDL and do tow 30K plus routinely with my Duramax trucks up and down passes, including Teton pass. I wish they would spec the trucks to their capability, for whatever reason, they don't. However speaking of speed and controllability of a load, the Duramax typically wins the IKE test. It may not be a perfect test but it is pretty comprehensive.
