What limits tow ratings for unibody vehicles?

[3930dave]

df - agreed, the game has changed, it is tough to find a stick in a full size truck now. Dodge may still be the exception.

Glancing at the Ford site, I can only see Automatics listed.

I was trying to pull up some older truck listings (like the ones I can afford !), but it appears somebody bought somebody and shut down this useful tool:

www.trailerboats.com/towrating

Maybe Chris or one of the other guys has found a replacement search engine.

I'm showing my age.... the Sell used to be (for a customer who cared about towing) the Automatic, but now a daze the point is mostly moot.

Good example on the Colorado though '52.

It was mostly older trucks that I had checked out tow rating wise. Today's small cars seem a bit too much like taking a pair of nail clippers to a gun fight for me.

But, as the judge said to the guy who was rustling calves in a Chevette, "Where there is a Will, there is a Way !". That one still gets me, or anybody else who's had to load calves in a truck.

I worked with a guy years ago, who was a Trials rider. He used to head out on rough roads with a buddy in an old Corolla, which probably had much less tow rating than yours. Towed a trailer with a couple of motorcycles, loaded the car with a couple of guys and gear. Going UP steep dirt roads, everybody except the driver had to get out - there was so little traction on the front wheels that they were just spinning. Got 'er done though.

Toyota has upgraded (upsized actually, more to the point) the Corolla over the years, it is now a more solid stable platform than the old ones were. Fine for homeowner occasional light towing.

JD - always cracks me up when I hear of a guy busted for trying to steal a car - spent 5 minutes attempting to drive 1.5 blocks, because he can't drive a standard.

As Dirty Harry said (Squint) "A man's just gotta know his limitations" (Close Squint).

I miss standards in big (light) trucks.

Rgds, D.

 

[dfkrug]

dfkrug posts about the 1500# towing capacity of his Corolla...and according to what I found online that car has a base weight of 2770 pounds...my '04 Lesabre has a base weight of 3570 pounds but the tow rating is only 1000#...makes little sense to me

Even closer to home is the tow rating for a Camry vs a Carolla. The former outweighs
the latter by more than 1000#, but the tow rating is only 1000#, vs 1500. And, the
Camry can be bought with a 270hp engine. Same manufacturer, so you would
assume same towing philosophy. Go figure.

To take us back to the OP's question, tow ratings make little sense.

What is also interesting is our friends in W Canada love their giant pickups as much
as they do here in California, despite much higher gas taxes. Despite that, you
see those different tow ratings for smaller cars. Europe has very few big pickups.

 

[dfkrug]

Not really an issue, just hang on a cooler.

This is very much an issue for the Manufacturer's tow rating, since they are
not likely to offer a "tow package" with a cooler in a common unibody sedan.
Clearly, you can mitigate for this by adding a cooler, but they sure don't know
about that.

The reason automatics have the better tow rating is because of the lack of a good starting gear in most of the manuals. It's an issue of gradeability, being able to get the load moving, especially if a grade is involved like a loading dock. If the automatic doesn't have enough gearing, then the torque converter makes up for it. Many of the recent manuals were also built for lighter duty than the old cast iron creeper gear transmissions.

Yes! That's what I was saying in post #46. With my Tacoma 4x4 MT, I can get started in 4L
with its granny gear, and switch to 2L or 4H after getting up a short grade (like a loading dock), but
I don't do that on the fly. But, that is not offered in unibody sedans either.

A slush-box, with its torque multiplication, is ideal for getting a big load started
without wear.

 

[toppop52]

The Colorado manual transmission has something like a 4.36 first gear vs 3.06 in the auto trans. but is still rated to tow 1000 lbs less.

 

[JDgreen227]

Was just thinking about the car we had before the '04 Lesabre...which was a '92 Olds 98 Regency, we were the second owners. It had the same 3800 V6 engine with about 30 less hp, weighed more that the Buick we have now and GM rated it to tow 3,000 pounds...the "tow package" from the factory was a slightly lower axle ratio and a heavy duty turn signal flasher. Same basic unibody. The former owner used it to tow a BMT combination that weighed about 2800 pounds all over Florida and he told me he never had any issues at all. I used the 98 to tow 1500 pounds several times, even though it had only rear drum brakes and smaller front discs than my Buick has now, it stopped the weight just fine.

 

[toppop52]

I towed my 19' jet boat with a 468 cubic inch big block Chevy back in the 80's with an '85 Grand Am that had the Buick 3000 (3.0 litre) V6 and something like 3.07 gears, of course the tires were only about 26" tall so overall gearing was good. I actually built my own hitch and welded it with many supports across the rear unibody and it was tough as heck, don't know what it did for crush zones and such, but it was strong.

 

[dfkrug]

I actually built my own hitch and welded it with many supports
across the rear unibody and it was tough as heck, don't know what it did for crush zones and
such, but it was strong.

Yeah, that's the way to do it. What kind of total weight do you suppose you were pulling?
As for crush zones, I suppose a boat would act like a pretty good crush zone in a rear-ender.

 

[toppop52]

Yeah, that's the way to do it. What kind of total weight do you suppose you were pulling?
As for crush zones, I suppose a boat would act like a pretty good crush zone in a rear-ender.

The boat was around 2800 lbs and the trailer was c-channel in 4" and was a single axle but fairly heavy, with fluids such as gas and beer I expect it was over 4000 lbs, car was an LE with sport suspension and air shocks. The rig easily outweighed the car but I never had an issue. The cr had factory heavy duty suspension NE cooling which included tranny and oil coolers.

 

[toppop52]

I understand gear ratios, believe me, I towed a 10,000 lb Donzi for many miles. The difference is with the manual in those trucks you get either 3.73 or 4.10 gears, the auto is 3.23- 3.42 and 3.73, so with best combo the auot still has a small advantage but not 1000 lbs worth.

 

[toppop52]

You really don't need to explain very much about automotive technology to me, not being asinine but I built and raced go karts, drag cars an SCCA sedan Firebird Formula, and several 80+ MPH offshore boats. I understand the concept. I've driven a 2.9 Colorado on a test before I bought my 3.7 Colorado and my best friend owns a dealership and drives 5.3 Colorado ZQ8. The 2.9 with manual tranny would absolutely pull 3500 lbs if the clutch were heavy enough but from the factory it isn't and with a so so driver it wouldn't hold up. Now personally I'd never tow with anything but an automatic. The problem with those trucks is not first gear ratio.