C20 for towing

[Grit dog]

I'd look into adding a Gearvendors to a th400. 8 gears with 7 you can tow with including an od for increased mpg.

I won't correct you on the math, but will add my opinion that the cost of a GV will never recoup itself.
Not to mention, the worst part about old 3 speed auto transmissions (and others) is the high first gear, which a GV doesn't help with.
And the practicality of manual sifting and manually splitting the GV to split ratios every time you accelerate from a stop would be somewhere between frustrating and insanity.
And the GV won't do anything for maintaining highway speeds, practically, as it won't pull in OD with anything even close to stock power and a 6klb + trailer on the back.

Also, one can to ALOT to an old 2wd Chebby to make it tow much better (talking power to the wheels) with the $ just a GV costs.

 

[Z28 Guy]

If towing is your primary goal with the truck you are going to purchase, then as much as it pains me to say it, I'd dump the idea of a square and pick yourself a modern 1/2 ton of your favorite flavor. It will be a much better platform for you to start out with, especially if your plan is to tow 400 miles away on a regular basis. And the weight of your trailer and car needs nothing more than even the most basic modern platform.

With that said, if you are set on a square as your tow vehicle, anything from the 454 mentioned above to an LS Swap truck will do fine. Just be prepared for the maintenance required on these older vehicles to keep them running cool and towing reliably.

Im a LS guy at heart. The camaro in the picture on my first post is my car. Its a built LS2 with some goodies from Brian Tooley Racing. Car run low 11s with a 6 speed on motor.

Anyway, have you taken a look at marketplace on (modern) 01 to 08 so models?

Take a quick look and youll notice they all will have something in common. Tranny is slipping , tranny is trash, tranny is recently replaced. My conclusion tells that the 4l60E is garbage.

5.3 motors are good but at some point the lifters will tick really hard. The LS7 lifters is what everyone replace them with and they is garbage as well. I rather have a square body thats solid and not go leave me stranded on side the road with a burned out tranny towing my car.

 

[Big Chip]

I have a 454/TH400 with a 3.73 gear and I can tell you that speed is not your friend. It will pull your car no problem but it was definitely not designed for today's speeds. If you don't mind 70mph it would work ok except it would be thirsty. I drove 1900 miles with an average of 8-10mpg unloaded. I've pulled one of my enclosed trailers that weighs about 5500-6000lbs with no problem but it was just on 60mph roads.

If you want to really tow comfortably at a little higher speeds I'd suggest a 4L80e or gear vendors.

 

[Bennyt]

I’m confused how you get 8 gears and an OD with a GV on a th400. You mean 6 forward gears, right?

I won't correct you on the math, but

Sorry guys, brain fart. Even though I wrote t400, I was thinking of my own truck, that has a 700r4 swapped in it and I am planning on adding a GV for towing.

 

[Bennyt]

Not to mention, the worst part about old 3 speed auto transmissions (and others) is the high first gear, which a GV doesn't help with.
And the practicality of manual sifting and manually splitting the GV to split ratios every time you accelerate from a stop would be somewhere between frustrating and insanity.
And the GV won't do anything for maintaining highway speeds, practically, as it won't pull in OD with anything even close to stock power and a 6klb + trailer on the back.

Also, one can to ALOT to an old 2wd Chebby to make it tow much better (talking power to the wheels) with the $ just a GV costs.

No, you won't save enough on gas to justify the expense alone, but the ability to split a gear and keep the motor in the rpm range that is best might make the motor live longer and allow you to maintain speeds on hills.

I always found 1st gear to be acceptable with the proper rear gear. It's the 1-2 shift the the GV helps by giving you 1, 1.5, and then 2.

I haven't purchased a unit for myself yet nor used one, but most everyone I know that has one, loves it.

In my own situation, on my '90 DRW, 454 w/ 700r4, I frequently tow/haul from Phoenix to Flagstaff and am constantly hunting for gears. I used to have an '06 Suburban with the 4 speed and my uncle had the '07 with the 6 speed. He was able to maintain speed on hills where I was not.

 

[Midnightmoon]

Im a LS guy at heart. The camaro in the picture on my first post is my car. Its a built LS2 with some goodies from Brian Tooley Racing. Car run low 11s with a 6 speed on motor.

Anyway, have you taken a look at marketplace on (modern) 01 to 08 so models?

Take a quick look and youll notice they all will have something in common. Tranny is slipping , tranny is trash, tranny is recently replaced. My conclusion tells that the 4l60E is garbage.

5.3 motors are good but at some point the lifters will tick really hard. The LS7 lifters is what everyone replace them with and they is garbage as well. I rather have a square body thats solid and not go leave me stranded on side the road with a burned out tranny towing my car.

Very familiar with them. Actually bought a 2005 extended cab brand new. Solid truck other than the ongoing issues with the intermediate steering shaft.

There's nothing inherently bad or good with the 4l60E. It's simply an electronically controlled automatic transmission that needs to run cool on fresh, clean fluid to live a long life. I'm not doubting that the examples that you are seeing online have trans issues. But I would argue that almost any manufacturer's automatic trans from the same vintage would suffer the same problems if not properly maintained. And, even though this is a GM forum, many of us here own other brands. They all have positives and negatives and all can be very reliable with the proper care and maintenance.

Getting back to my previous statement. Coming from the perspective of someone that tows a lot of miles annually, the only thing that I was trying to point out is that there are much better options out there for strictly towing at this point. Not saying that you can't accomplish the same task with a Square Body. But, as mentioned above, the newest one of these trucks is now over 30 years old. It's going to be a project all in itself to find one, get it in to condition to be able to tow reliably, and then maintain it over the long term. Certainly go for it if it is something that you will enjoy as a project. I personally love to see the old trucks still working.

 

[Catbox]

I would say look for a Camper Special as they are built to haul and tow.
I have a 1979 C20 and it is a Camper Special, it did not care what-so-ever when I put 2,000lbs of scrap in the bed. It was perhaps just softer to go over bumps in the rear.

They come with all the big brakes and doo dads to make them live while doing what you want to do.

Mine has the 454 engine and SM465 transmission in it.
While the engine is not a racecar engine, it makes loads of power down low.

I do not like the transmission, but that just may be me.
It is a super slow shifting transmission, but I can pull 20mph lumping along in 4th all the way past the numbers on the speedo. So with the 454 in front of it, you don't need to shift a lot when not in town.

I will be replacing the manual with a 4L80 that I have one of these days.
That will get me some more MPG's on the road and be plenty tough enough for what a BBC can dish out.

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[Grit dog]

I have a 454/TH400 with a 3.73 gear and I can tell you that speed is not your friend. It will pull your car no problem but it was definitely not designed for today's speeds. If you don't mind 70mph it would work ok except it would be thirsty. I drove 1900 miles with an average of 8-10mpg unloaded. I've pulled one of my enclosed trailers that weighs about 5500-6000lbs with no problem but it was just on 60mph roads.

If you want to really tow comfortably at a little higher speeds I'd suggest a 4L80e or gear vendors.

OP's car on a flatbed is about equivalent to towing our boat. 'Bout 6klbs and not a ton of wind resistance. Less than the boat with a tower.
Best guess is the 454 in the '86 is about 300hp (stock Mark VI with headers and an Edelbroke intake and 750 on it), 4.10s with big tires = approx. 3.73 on stock tires.
It will tug the boat at 70mph at 3000rpms no problem.
I don't think OD is of much use towing, only on the return trip if it's a one way tow. Wouldn't want to leave an old 4 speed 700 or 4l60 in overdrive except in just the right conditions.
So yes, keeping the speed down is key. It will be non negotiable with any flavor of stock small block from the squarebody era.

 

[SirRobyn0]

And then look at me. 1984 C20 3.41 305 700R4. And I tow with it. Mostly feed for the farm on a flatbed trailer. Other times it's a heavy load in the bed only, but with the trailer I can get 5K of weight plus whatever the trailer weighs. Because of the low 1st gear in the 700R4 the 305 with 3.41 can get it moving, but it's less than ideal. The rear end gearing is my biggest issue. I need 4.10 or 4.56 so I can spin the engine at higher RPMs on the road.

IF I was looking for a truck to tow and haul with I'd want the SM465, but also do not feel that converting is worthwhile, so very shortly I'll be getting my 700R4 rebuilt, it'll get upgrades and reinforcements for towing and hauling. So that is something to think about. In the end whatever combination, you get will have benefits and limitations. TH400 has close gear ratio spacing and is from the factory very heavy duty, but not a very low first gear, and no overdrive. The 700R4 has to be built to be heavy duty, has a nice low first gear and overdrive, but relatively wide gear spacing. The SM465 is the most heavy duty, has a great VERY low first gear, ratio spacing is ok, but has no overdrive and is a VERY slow shifting transmission so much so that it can be a disadvantage in a situation where you are towing up a grade, by the time you made the shift you've lost a good bit of speed. All have pros and cons you just need to weigh out what you'd like best.

If you want a GV go for it, but don't kid yourself into thinking that you'll ever make back the cost in fuel savings or anything like that. Myself I would not put a GV on an automatic, but I would absolutely put the advanced adaptor's Ranger overdrive on an SM465.

 

[Bennyt]

Hopefully, within the next year I install a GV on my 700r4 and I'll update this thread and either be a hero or a fool.

 

[SirRobyn0]

Hopefully, within the next year I install a GV on my 700r4 and I'll update this thread and either be a hero or a fool.

I will be very interested in hearing your experience both with install and then use after install.

To clarify what I said earlier. Don't get me wrong if my truck had one I'd use it, it is just my opinion that the relatively large up front cost, followed by an installation that requires driveline shortening I don't think that it's worthwhile, but I could be wrong. Will be interested in hearing your results.

 

[Grit dog]

Hopefully, within the next year I install a GV on my 700r4 and I'll update this thread and either be a hero or a fool.

It’s all good.
I’m half talking out my ____ as I’ve never really used one. Not for towing and splitting gears anyway.

 

[Big Chip]

OP's car on a flatbed is about equivalent to towing our boat. 'Bout 6klbs and not a ton of wind resistance. Less than the boat with a tower.
Best guess is the 454 in the '86 is about 300hp (stock Mark VI with headers and an Edelbroke intake and 750 on it), 4.10s with big tires = approx. 3.73 on stock tires.
It will tug the boat at 70mph at 3000rpms no problem.
I don't think OD is of much use towing, only on the return trip if it's a one way tow. Wouldn't want to leave an old 4 speed 700 or 4l60 in overdrive except in just the right conditions.
So yes, keeping the speed down is key. It will be non negotiable with any flavor of stock small block from the squarebody era.

Good point about the o/d and towing, big no-no. I'm changing my vote to the Gear Vendors.

 

[ebodell08]

I have had very good luck with TH400s which is why I mentioned that combination. Yes, I will admit that combo is not really up to running 70mph+ all day. My "tow" vehicle is my 1993 K3500 with a 454/4L80E, 4.10 gearing. However, I rarely run over 65mph when towing. The truck will return ~13mpg on non ethanol at 55-57mph unloaded. Loaded or towing probably 10 mpg. I don't even check it anymore, it's not a commuter, I don't even put 700 miles on it most years. I have pulled the farm's big dump trailer with the K20, my primary concern there is brakes. Lord only knows what the K20 gets loaded/unloaded, whatever. It's bad, probably 8-10. The K20 is a 350/TH350 with 4.10 gears. It really does not matter, it's a chore truck and paid for. Not having a payment buys a lot of fuel even at $5/gallon. Older vehicles are more maintenance but I am not sure they are more than the stuff put out from 2019 to date. With the shortages there is a lot of material/parts substitution going on. I would be very concerned buying a newer truck knowing it sat for months waiting on parts.
Again all of this is my opinion. Add that to about $1.25 and you get a cup of marginal coffee at the Co-Op and a lot more opinions on everything from crop yields to drivetrains to tractor colors.....

 

[bucket]

Primary use is towing with not much day to day use and looking for an average available truck... 454, hands down. TH400 or SM465 are both fine choices. Try to stick with 3.73 or 4.10 gear. Use trailer brakes and a proper wheel/tire combo, then driving fast enough to keep up with traffic is no big deal. A healthy engine won't mind the RPM. A tired engine won't care for it, but a tired engine won't like towing 400 miles on a regular basis either.

If unloaded economy is a concern, both the TH400 and SM465 have options. Besides the previously mentioned Gear Vendors, you can install a Ranger gear splitter in front of the 465. Even if you don't feel like shifting two sticks to use all the gearing, it's still useful as an overdrive for high speed use.