Here piggy piggy (tow pig's)

codrus wrote:

Cotton wrote: My 2002 Dmax 3500 needed injectors when I purchased it. I replaced them all and the hard lines. It's enough of a pain in the ass that I really didn't want to bother with it again for a long time. I did use dash command with the extended GM PIDs to see which ones were weak, but in the end wanted the piece of mind of all fresh replacements.

So did you DIY it, or pay someone? Looking at the write-ups I've seen online it doesn't look that hard, but a bunch of people I've talked to say "it's a diesel, you don't want to mess with it", but then they don't specify why.

I did both. I did them on a buddies truck, well he helped by watching, then paid to have them done on mine (worked out great for the buddy lol). It's not that difficult, just very time consuming. There are good write-ups on duramax forum, which is what I used the first time. I just didn't have the time when mine needed them, so paid a shop. The going rate is around 1k in the US and that's with you providing the parts, so shop around if you keep getting high estimates. I bought my injectors and lines from Lincoln Diesel Specialists. I also bought the CAT filter and adapter...that is an easy install and the filters are cheaper and provide better filtration than stock.

Not long after I installed injectors in my 95 7.3 Powerstroke....MUCH easier job on that engine, but I still like the duramax better. I don't feel like diesels are terrible to work on though.....just messier in general.

alfadriver wrote: In reply to curtis73: The interesting point of your hauling measure of tow capacity and the manuf. tow rating- they are generally the responsibility of the same person/group. So if you don't trust the tow rating, how is it that you trust the hauling rating? And vise-versa.

I don't. At all. GVWRs are equally nebulous as tow ratings. Ever notice how the GVWR intervals are the same as DOT class ratings? There is nothing to suggest that an 11,800 lb Ford will perform exactly the same as its GM or Ram counterparts. Diesel Power magazine did a comparison a few years ago that measured that exact metric; They took 1-ton duallys from each of the big three, loaded them to their GVWR, and put them through skidpad tests, braking tests, undulating road tests, cooling tests... the differences were rather large.

My point is that the manufacturer tow rating is part liability, part warranty, and part marketing. One one hand, brand X makes a whopper of a tow rig, but they keep the rating conservative to prevent liability. Then brand Y comes along with a sub-standard product and says "well, we have to stay competitive with X, so we'll push that rating up a bit."

My other point is that the tow rating is a number based on what the vehicle can handle in terms of transmission, tongue weight, cooling, etc. So to say that a 9000-lb tow capacity is a hard and fast rule is ridiculous. The difference between a short flatbed gooseneck at 9000 lbs is vastly different from an ultralight 34' travel trailer at 9000 lbs. The weight is only a very small factor in towing capacity.

So first, to say that the manufacturer's rating is fact is foolish. Second, to discard the millions of other factors involved and cling to that rating is doubly foolish.

If you use the manufacturer tow rating, all it means is that you are less than x% likely to fry a tranny, overheat, or tear up axle bearings. Period. It has nothing to do with how you select a trailer or how you drive it. In some situations (like travel trailers or enclosed trailers) you may need to keep it lower than manufacturer recommendations. Delivering a 15,000 lb tractor two blocks away? I would use a Tacoma if I had to.

In reply to curtis73:

So, if the manufacturer ratings are 100% rubbish, what would you suggest people go by?

Tom_Spangler wrote: In reply to curtis73: So, if the manufacturer ratings are 100% rubbish, what would you suggest people go by?

Exactly what I'm wondering.

FWIW, they are not rubbish- as there are tests that are required. But I'm sure that won't convince you.

If you can't at all trust the tow rating, what can you trust?

i dont think ive ever looked at a tow rating. used to tow my 79 capri on an 1800lb trailer behind a 76 ford f100 3hrs roundtrip to go drag racing. My buddy has done alot of miles towing a car trailer behind his 93 dakota. The one disclaimer is that the land here is pretty much flat!

alfadriver wrote:

Tom_Spangler wrote: In reply to curtis73: So, if the manufacturer ratings are 100% rubbish, what would you suggest people go by?

Exactly what I'm wondering. FWIW, they are not rubbish- as there are tests that are required. But I'm sure that won't convince you. If you can't at all trust the tow rating, what can you trust?

I use experience and overkill. But when a manufacturer tells me that two vehicles have the same tow rating with D or E range tires, or when they tell me that a far better equipped vehicle can only tow 3000 instead of its 4800-rated little brother, I have zero faith in their numbers. ZERO.

But it doesn't take much common sense to know that a 3/4 ton truck should be fine with x amount of properly-equipped trailer. The rest of the world will continue using factory tow ratings; like my friend with the big travel trailer behind his Disco. I don't even consider factory tow ratings at all. None. Zip. Zero. At best, if I'm in new territory (like when I was towing with my friend's Disco) I looked it up... and promptly laughed out loud when it said 6800 lbs. I give him another 10,000 miles on his Jatco, tops, and that is only if he doesn't end up in a ditch coming down the mountains. At the very best, I would say that factory tow ratings are an (incredibly vague and nebulous) indicator of an extremely broad range of where someone might feel comfortable towing and not fry a transmission or end up dismembered. But I'm stretching to say that.

This is really not a debatable issue. Any browsing at any RV/towing forum you'll find this is common sense knowledge. It makes zero sense that one exact number could possibly apply to the wide range of trailers, circumstances, and road conditions. C'mon guys... do you really think that a 9000-lb 32' travel trailer in the desert is exactly the same level of safety as a 9000-lb triple axle gooseneck in Georgia? If you honestly think that, then there is honestly nothing more to say.

I will say this again (keeping in mind that I was an IC/designer for GM and Saab many moons ago and saw this all play out first hand). Factory tow ratings are marketing and liability. Period. Sure, engineers who actually put their brains into the project have a very good notion of how much it will likely be able to tow. R&D and testing show that it is probably good around X lbs. But if you want to believe that the actual final published number is real, and not a fantasy number debated and decided by suits, fine. Believe what you want. I have been in the meetings. I know that isn't the case. But if you actually believe that this one number applies to every single thing you could possibly tow and every driving condition there is, then your opinion is noted.

Done... back to your regularly scheduled programming.

Thank you! ^

curtis73 wrote: keeping in mind that I was an IC/designer for GM and Saab many moons ago

Right... maybe I'm getting my abbreviations mixed up, but you were a Integrated Circuits designer for GM without any formal education on the subject? And that somehow qualifies you to comment on the mechanical aspects of a vehicle?

Anywho, no, I do not believe that 9k lbs of this vs 9k lbs of that is the same, what I do believe is that the engineers went "if we have a properly loaded trailer of any sort, what is the maximum our truck is rated to tow with a variety of factors including cooling, wear and tear, and overall strain on the vehicle" and they came up with that number. Common sense isn't common, and especially your common sense I suppose. However, luckily for us, physics (for the most part) is pretty set in stone in the practical world.

I have found no info that shows a Disco 2's (98-04) being able to tow more than 5500lbs, which seems reasonable for them. LR3's and 4's saw lots of improvements and are rated to tow 7700lbs, which again seems reasonable. But I digress, for some reason your experience and RV forums trump our opinions and knowledge on the subject, as well as the engineers who get paid a lot of money to make sure this stuff is right.

I'm really just arguing for the sake of argument now

HiTempguy wrote:

curtis73 wrote: keeping in mind that I was an IC/designer for GM and Saab many moons ago

Right... maybe I'm getting my abbreviations mixed up, but you were a Integrated Circuits designer for GM without any formal education on the subject? And that somehow qualifies you to comment on the mechanical aspects of a vehicle? Anywho, no, I do not believe that 9k lbs of this vs 9k lbs of that is the same, what I do believe is that the engineers went "if we have a properly loaded trailer of any sort, what is the maximum our truck is rated to tow with a variety of factors including cooling, wear and tear, and overall strain on the vehicle" and they came up with that number. Common sense isn't common, and especially your common sense I suppose. However, luckily for us, physics (for the most part) is pretty set in stone in the practical world. I'm really just arguing for the sake of argument now

I am also arguing for the sake of argument

I will try to answer this more fully tomorrow, but there are so many complex things to understand here.

First of all, IC/designer means Independent Contractor in Design.

We agree on many things, but the whole story boils down to this: Yes, incredibly talented and underpaid engineers come up with heavily researched numbers. Then corporate suits crunch those numbers against trailering liability, established legal precedent (including the number of GM vehicles sold in areas where precedent is unfavorable), standard deviations, incurred warranty costs, and a hundred other factors and spit out their own numbers.

Engineers don't have absolute numbers, they have a bell curve. They see that a worst-case scenario shows a transmission failure within warranty when not towing anything all the way up to a 300k-mile zero-failure vehicle while towing twice the engineering limit.

So, to assume that one single number is the golden rule is (as we all know) a complete farce, the actual published numbers are only about 1/10th based on the actual engineering of the vehicle. Max tow ratings are 1) a number generated by a bunch of suits with MBAs, not engineers, and 2) a vague stabbing guess at a number that can be off by as much as 7000 lbs in either direction and still be true.

Its a numbers game, and the engineers' numbers are useless in the eyes of the suits. Being an engineer for a car company is like being a cashier at WalMart and telling the CEO how to improve the business.

Your premise is correct; there are heavily educated engineers that make valid recommendations, but it is naive to assume that those are the numbers that actually get published.

Hence why you have a Caprice rated at 60% more tow capacity than its far more competent twin brother Impala SS.

Physics has nothing to do with tow ratings other than a starting point. Engineers put years of effort into coming up with a bell curve of numbers... and then stuffed suits with MBAs change it at will.

We are arguing the same thing; its just that I have personal experience with the actual process. Your faith in the ratings is simply misguided by the mistaken impression that engineers actually have any say in the published numbers, and further mistaken by the impression that the number represents a small range of safe deviation. It doesn't. It represents a swing of +/- 7000 lbs in some cases.

So attacking my common sense isn't the avenue I was expecting, but we'll roll with it. You are saying that engineers are paid to come up with these numbers. I agree. They are. But the numbers you see are not the engineers' numbers. Not at all. The numbers you see are a fraction of engineers' efforts shoved through an algorithm of legal mumbo-jumbo, probability, and statistics.

Saying a vehicle can tow 9000 lbs safely is so absurd. The truth is, the vehicle can tow 9000 lbs while providing a low probability of hurting stockholders' wallets or reducing corporate profits.

So the conclusion is that rules of thumbs, generalities, common sense, and experience is better than engineering and physics.

Ok.

Good luck with that.

I will agree that the engineers are underpaid. But other than that, I'll stick to my suggestion method.

Did all the manufacturers finally start using J2807 for tow ratings?

In reply to logdog:

No, but that does not mean that tests are not done.

But I wish everyone would just do it.

curtis73 wrote: I use experience and overkill. But when a manufacturer tells me that two vehicles have the same tow rating with D or E range tires, or when they tell me that a far better equipped vehicle can only tow 3000 instead of its 4800-rated little brother, I have zero faith in their numbers. ZERO.

I'll grant you the Caprice example (though it's from 20 years ago), but to me the change in tire load range doesn't mean anything if the tires were not the weak point in the system. Maybe the "E" tires were overkill in relation to the cooling system, trans, rear end, springs, or whatever else on the truck was the limiting factor for the tow rating, in which case changing them wouldn't make a difference.

And your assertion that this is accepted truth on RV forums is not correct at all. I've spent quite a lot of time on them, and people DO trust factory ratings. The one thing that they keep coming back to is GCWR rather than tow rating. In other words, the total weight of the tow vehicle, trailer, and all passengers and cargo. But it's still a number from the manufacturer.

I will agree that nothing gets published by a major corporation until the lawyers have had a look at it, and that includes tow ratings. But I interpret that differently than you. Based on MY experience of working in and around the auto industry for 22+ years, my feeling is that tow ratings are probably pretty conservative.

I generally go by GCWR as well and I make sure my axle weights are in check. More for legal reasons than anything else. I've had the GCWR maxed out on my 02 K3500 and it wasn't breaking a sweat...what a beast. Now on the flip side the actual tow rating on my 99 Cherokee is 5k....I would not tow 5k with it ever.

alfadriver wrote: So the conclusion is that rules of thumbs, generalities, common sense, and experience is better than engineering and physics. Ok. Good luck with that.

That's not what I'm saying at all. Physics is king. But the numbers you see published are NOT ultimately based on the physics.

So, in the absence of physics being part of those published numbers, one has to choose: a) blindly believe what a suit says is safe, or b) temper those numbers with logic, experience, and common sense. I choose B.

Its really easy, if you want to tow about 7,000lbs or more, down the highway and through the mountains safely, get a 3/4 ton. Thats my rule of thumb and it has never failed me.

curtis73 wrote: Physics has nothing to do with tow ratings other than a starting point. Engineers put years of effort into coming up with a bell curve of numbers... and then stuffed suits with MBAs change it at will.

Uh, you did say that.

And you are so very sure that the numbers that are generated are not based on physics. Which is really interesting. As there are actual tests that are run and have to be passed. So I'm not sure where you get that position. As Tom points out, the tow rating is based on the weakest link. Be it the chassis, brakes, power, cooling, whatever. Although, most ratings of the last 15 years (when I started paying attention) is based on cooling. There's a test for that.

While you seem to be sure that MBA's run the show, I can tell you, again, that it's not the case. All MBA's do is constrain what engineers can do, that's it. They don't make up numbers after the car is developed. You choose not to believe that, which is fine. But that choice means that your position can summarily be dismissed as well. As a representative of the group that you dismiss so quickly, I'll choose not to go with your position.

One more thing- nobody wears suits anymore.

Tom_Spangler wrote:

curtis73 wrote: I use experience and overkill. But when a manufacturer tells me that two vehicles have the same tow rating with D or E range tires, or when they tell me that a far better equipped vehicle can only tow 3000 instead of its 4800-rated little brother, I have zero faith in their numbers. ZERO.

I'll grant you the Caprice example (though it's from 20 years ago), but to me the change in tire load range doesn't mean anything if the tires were not the weak point in the system. Maybe the "E" tires were overkill in relation to the cooling system, trans, rear end, springs, or whatever else on the truck was the limiting factor for the tow rating, in which case changing them wouldn't make a difference.

Fair, but I used that truck example because the D-range tires were an inadequate engineering/physics choice and entirely based on people complaining about the ride. The truck in question has a GVWR of 9000 and a tow capacity of 10,000.

Based on MY experience of working in and around the auto industry for 22+ years, my feeling is that tow ratings are probably pretty conservative.

Agreed, but there are plenty of examples in trucks where the tow rating is inflated to match market perception.

alfadriver wrote: So the conclusion is that rules of thumbs, generalities, common sense, and experience is better than engineering and physics. Ok. Good luck with that. I will agree that the engineers are underpaid. But other than that, I'll stick to my suggestion method.

Man, its pretty bad when alfadriver says something that I 100% agree with AND can't word any better

alfadriver wrote:

curtis73 wrote: Physics has nothing to do with tow ratings other than a starting point. Engineers put years of effort into coming up with a bell curve of numbers... and then stuffed suits with MBAs change it at will.

Uh, you did say that.

Let me rephrase.

the Physics that the engineers so carefully used to determine the vehicles operating parameters has nothing to do with published tow ratings other than being a starting point from which the numbers are altered.

But I can see how my phrasing was confusing.

One more thing- nobody wears suits anymore.

Maybe its just been too long since I was in the business. Yes, there is a ton of engineering and physics involved. Tons of testing. But at GM in the late 90s, there was absolutely nothing that was sacred. They gave us parameters, we worked miracles, they said "thanks for the suggestion, but we're going this way with it." and all we could do was watch them make up completely bogus numbers. When the sales brohure came out for the vehicle we all just laughed.

So when a manufacturer gives me a number and says "this vehicle is rated to tow X lbs," I take it with more than a few grains of salt.

We are all really arguing the same exact thing. Physics + engineering + testing = tow rating. That is not the debate. Its just that I believe that the published number is based on a lot of other considerations and the physics and engineering part gets all but nullified.

alfadriver wrote: And you are so very sure that the numbers that are generated are not based on physics. Which is really interesting. As there are actual tests that are run and have to be passed. So I'm not sure where you get that position. As Tom points out, the tow rating is based on the weakest link. Be it the chassis, brakes, power, cooling, whatever. Although, most ratings of the last 15 years (when I started paying attention) is based on cooling. There's a test for that.

I'm really starting to get frustrated that you aren't reading what I'm writing.

Yes, there is engineering and physics involved in how the developers make the vehicle.

Yes there are weakest links that are discovered.

I never argued that. You just believe that those tests are the last word. They tested it, it must be 100% fact and truth. I believe (because I was actually there and saw the process) that the numbers are changed after the tests and numbers and physics and engineering and therefore are no longer representative of a vehicle's actual towing capacity. There were entire teams of mathematicians and statisticians who's exclusive job was precedent establishment, risk assessment, legal incursion, and market research. There was an entire team of people whose sole job description was to take the test data and come up with what was to be published based on those parameters. So, yes, when a corporation hires teams of people to look at test data and (usually, not always) alter the final numbers before release, I believe it.

While you seem to be sure that MBA's run the show, I can tell you, again, that it's not the case. All MBA's do is constrain what engineers can do, that's it. They don't make up numbers after the car is developed. You choose not to believe that, which is fine. But that choice means that your position can summarily be dismissed as well. As a representative of the group that you dismiss so quickly, I'll choose not to go with your position.

Were you working as an exec for GM in the late 90s? It is possible that in your place of work these things are not the case and that they are true in my experience. Simply choosing to dismiss my argument based on the fact that you are an MBA is a generalization that is a false positive.

I'm not saying its some crazy conspiracy. I'm not saying its even a bad thing. I'm saying it happens; with tow ratings, GVWRs, GCWRs... the physical limitations of the vehicle don't always match up with the numbers in the brochure. The same can be said for EPA MPG testing. They tested it, it must be true, right? Of course you can't expect that exact MPG and you don't.

I'm just confused as to why you guys are so insistent that those numbers are ironclad fact. All I'm saying is that the numbers are generalized, altered to meet acceptable risk and market perception. Why is that so hard to grasp?

Ooo... It's been a few months since we've have a good towing-related bitch-thread...

Personally, having also owned a 12V Cummins, I agree on the "No diesels" criteria. Especially if it's a occasional use vehicle. Due to various reasons, I rarely drove my truck unless it was needed for something and it suffered greatly from that sitting. In my experience, US gas motors are more tolerant of that. My Cummins was second only to my E30 in needing to be towed.

I'd go with a van. Probably a Ford, but mainly because that's what I'm familiar with.

curtis73 wrote: I'm just confused as to why you guys are so insistent that those numbers are ironclad fact. All I'm saying is that the numbers are generalized, altered to meet acceptable risk and market perception. Why is that so hard to grasp?

But you went further than that. You said that the tow ratings are "a fantasy number debated and decided by suits" and that you put ZERO credibility in them. I'm all for skepticism, and I admitted that the lawyers have their say before the numbers get published, but I think it's ridiculous to say they mean nothing. If a manufacturer rates one vehicle to tow 6000 lb and one to tow 10000 lb, I'm gong to bet there's a pretty big difference in their capability.

To me, the tow rating is a starting point. You do have to use common sense. My travel trailer weighs 6000lbs empty, so theoretically it could be towed by most midsize SUVs. But I wouldn't. My general rule of thumb is to stay under 80% or so of the factory rating to have something of a safety margin.

logdog wrote: Did all the manufacturers finally start using J2807 for tow ratings?

I've driven the road they use to test SAE J2807 many times. I don't want to tow anything up it, using anything! Not even a 500lb. tire trailer using a semi!

Yup.. this test. http://www.trucktrend.com/how-to/towing/1502-sae-j2807-tow-tests-the-standard/

Horrible. I'd rather load myself up with some Natty light and hitch up my pinto to a 5ther full of John Deere loveliness... I know better than engineers.