Talk to me about SUV tow rigs

[YotaAtieToo]

I imagine it has to be dramatically better. There’s a guy on a ford forum that is in the process of doing an Allison 1000 6 speed swap. That trans has such a deep 2nd overdrive it’s probably useless unless you’re unloaded but you still gain an extra gear between 1st and 5th you didn’t have before. Smaller RPM drops would be nice so your not lugging or screaming

Your 550 would make perfect use of that 2nd od. My works 550 has 4.88s and the stock 6 speed with what I'm assuming is a similar 6th gear to the Allison. Even grossing 38k, it could use a taller gear for anything over about 65. 95% of the highways I run are 60mph and it's perfect, even will pull slight grades in 6th. Them also doesn't have that waaa, WAAAAA down shift like 4 and 5 speed autos.

 

[06h3]

Your 550 would make perfect use of that 2nd od. My works 550 has 4.88s and the stock 6 speed with what I'm assuming is a similar 6th gear to the Allison. Even grossing 38k, it could use a taller gear for anything over about 65. 95% of the highways I run are 60mph and it's perfect, even will pull slight grades in 6th. Them also doesn't have that waaa, WAAAAA down shift like 4 and 5 speed autos.

4r100 is .71
6r140 is .67
Allison 1000 is .60

So the 6r140 isn’t much deeper then a 4r100 but is much better between 0 and 60.

 

[arse_sidewards]

So the 6r140 isn’t much deeper then a 4r100 but is much better between 0 and 60.

You won't see transmissions much deeper than .6-7 for the same reason you don't see diff gears much taller than 2.75-3.

The gear set design starts becoming enough of a compromise with heat/friction and torque on upstream components you're just better off changing something else to get the same effect.

 

[YotaAtieToo]

4r100 is .71
6r140 is .67
Allison 1000 is .60

So the 6r140 isn’t much deeper then a 4r100 but is much better between 0 and 60.

Im not super impressed with the allison in our 2015 3500 at work.

With a tall 1st gear, it really struggles to get a load moving, and ya 6th is about useless. Almost needs 4.30s even in a pickup.

Google say 0.62 6th, but that is tall, 200 rpm at 70.

What's this thread about again?

 

[arse_sidewards]

Im not super impressed with the allison in our 2015 3500 at work.

With a tall 1st gear, it really struggles to get a load moving, and ya 6th is about useless. Almost needs 4.30s even in a pickup.

Google say 0.62 6th, but that is tall, 200 rpm at 70.

What's this thread about again?

What's the actual numerical ratio for first though?

It doesn't really matter whether your range of trans gears is on the numerically high side or the numerically low side so long as the splits aren't asinine and the overall spread is good because then you just spec the axle gear ratio to match what you're trying to do with the vehicle which apparently failed to happen in your case.

 

[Cameronswmp9]

Another question: is there a way to SAFELY raise towing capacity? I understand it's a complete system that handles everything, suspension, brakes, power train, etc, and upgrading one doesn't carry over to all.

Reason for asking is to obviously check all boxes, but to handle everything. For the trail rig, I can build it how I want it, but going to be in the 8K range based on my math, and the shortest would be a crew cab short bed, so still a long truck. Have no problem with building it as a driver, but have plans for cross country trips and driving out and back with a beating in the middle does add in a bit of a scare factor. Or add another truck for towing, but this is the type of trip where the SUV would shine, no matter how it's sliced. And as a driver is almost a requirement for me, honestly.

Have a 2nd project I want to build, which will happen based on space, but either rig can tow no worries (street, autocross truck deal) which doesn't require a different truck for towing.

Just having some other thoughts running around my head, and I think I know the answer (yes it can be somewhat, but not enough to really matter or make enough of a difference) and my end goal is a driver and use the SUV for towing the other, or the trail rig for towing that (trail rig as a do all truck, think DMansBlueFreak I think is his name here, just more streetable)

 

[arse_sidewards]

Another question: is there a way to SAFELY raise towing capacity? I understand it's a complete system that handles everything, suspension, brakes, power train, etc, and upgrading one doesn't carry over to all.

Practically? Tons.

For the purposes of weight ratings and legality? No.

 

[Gbkeith]

Another question: is there a way to SAFELY raise towing capacity? I understand it's a complete system that handles everything, suspension, brakes, power train, etc, and upgrading one doesn't carry over to all.

Reason for asking is to obviously check all boxes, but to handle everything. For the trail rig, I can build it how I want it, but going to be in the 8K range based on my math, and the shortest would be a crew cab short bed, so still a long truck. Have no problem with building it as a driver, but have plans for cross country trips and driving out and back with a beating in the middle does add in a bit of a scare factor. Or add another truck for towing, but this is the type of trip where the SUV would shine, no matter how it's sliced. And as a driver is almost a requirement for me, honestly.

Have a 2nd project I want to build, which will happen based on space, but either rig can tow no worries (street, autocross truck deal) which doesn't require a different truck for towing.

Just having some other thoughts running around my head, and I think I know the answer (yes it can be somewhat, but not enough to really matter or make enough of a difference) and my end goal is a driver and use the SUV for towing the other, or the trail rig for towing that (trail rig as a do all truck, think DMansBlueFreak I think is his name here, just more streetable)

It depends on what you’re starting with. If you swap a set of 4.30 superduty axles and hydroboost into something from the 80’s that had small disc/drums and 3.33’s you’re better off for towing. But how much better is going to depend on what else is going on.

And it’s not going to change your axle weights. Upfitters can do it but generally won’t because of what all is involved.

 

[Cameronswmp9]

It depends on what you’re starting with. If you swap a set of 4.30 superduty axles and hydroboost into something from the 80’s that had small disc/drums and 3.33’s you’re better off for towing. But how much better is going to depend on what else is going on.

And it’s not going to change your axle weights. Upfitters can do it but generally won’t because of what all is involved.

That was my thought. Axle swaps with better brakes can, not exactly legally change them, but to what degree in a modern truck/SUV? In an older K30, aeronose F350, etc then a Bigger difference, for sure.