Dual Motor R1T on a steep slippery boat ramp?

[R.I.P.]

You will be fine. With DM you get advantages of a system that can selectively and automatically anchor certain tires to provide better traction to others; as explained many times by retired automotive engineer R.I.P.. You'll also get a drivetrain that is more efficient overall. Should the front wheels start to spin on the ramp, the rear axle will engage automatically to provide additional traction. If that particular ramp is so slippery that all four wheels would spin, despite traction management... then chances are nothing else would find traction on said ramp and someone coated the entire ramp with Crisco as a prank.

Actually, the rear will already be engaged on the ramp. The rear axle only disconnects over 20 mph when the vehicle is under light throttle. This way, all wheels are driving it forward to get the vehicle moving, or when throttle action is moderate or above... Getting rid of that nasty front tire wear from the front-only drive.

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[R.I.P.]

And that all brings up another interesting question---what puts more torque to the ground, a QM or a DM Rivian, considering that the DM makes less power/torque, but has differentials.

The QM will get more torque to the ground; IF all four wheels have maximum traction.

 

[UnsungZero_OldTimeAdMan]

Actually, the rear will already be engaged on the ramp. The rear axle only disconnects over 20 mph when the vehicle is under light throttle. This way, all wheels are driving it forward to get the vehicle moving, or when throttle action is moderate or above... Getting rid of that nasty front tire wear from the front-only drive.

With the QM, is it at all possible through software to utilize the braking system (in similar but not identical fashion as DM) to increase traction to the tires that have it and further improve off-road capability? especially at low speeds? The current strategy of just the right amount of send-it doesn't make a whole lot of sense.

 

[mpfurnari]

Yes, I would expect the dual motor Rivian to be quite a step up from the frontier. I'm not sure how advanced the traction control is in the frontier, but Rivian's is quite good. It is also a heavier vehicle which often results in better traction, although that is not a hard and fast rule.

Yes, I actually recommend the dual motor Rivian over the quad for just about anything except drag racing. It is Rivian's latest design, and has improvements over their first one (the quad). It is a very capable off-roader, and the more predictable handling on-roader. Oh, and it has better range too.

Except for heavy off-road stuff, I have had very good experience with the stock 21 inch road tires and wheels, even in snowy/icy conditions.

For off-roading and overlanding I throw on a set of 20-in toyos, which make this rig one of the better pick ups in the fleet for serious overlanding.

Thank you @R.I.P. Your input is far better than the sales folks at Rivian. They should hand you a commission for the sale .

 

[R.I.P.]

With the QM, is it at all possible through software to utilize the braking system (in similar but not identical fashion as DM) to increase traction to the tires that have it and further improve off-road capability? especially at low speeds? The current strategy of just the right amount of send-it doesn't make a whole lot of sense.

No, because it has no "other side" to work off of. Each wheel is working blindly by itself.

 

[R1TruKaLa]

I am pretty sure if a QM loses all traction on one side it will spontaneously flip over on that side.

 

[downranger12]

Good questions. I'm hoping to hear from someone who has tried it. I've asked all the Rivian folks who have contacted me to complete my sale, and none can answer it, so I want to hear from someone with experience. Good question on tires; My truck has Michelin LTX M/S. I wonder how the stock 21" road tires would do in comparison. I'd hate to have to shorten range with a more aggressive tire.

Early on, I had to call for a tow due to a non working L3 charger in Western IA. The tow arrived in due time, driven by a nice farm kid. He tilted the bed to about 40 degrees and hooked me up. His winch failed to bring the truck along prompting him to ask how heavy the vehicle was? The flatbed was covered with used/spilled oil from his towing wrecks and junkers.
I hopped in and put it in gear, taking it right to the top. All of the 21s were alternately taking turns straight up the incline.
Have a little faith. The vehicles, in your case too, are so heavy, the tires, when they slip will quickly work their way down to dry concrete and do the job. The torque vectoring is phenominally effective.

 

[Adamn]

The extra weight of the Rivian should give you more traction. Especially with more weight in the rear where it's going to be more slick. If you can arrange a test ride before hand see if they'll meet you at your lake to do a test launch or make friends with a local owner and take them out for a day on the lake to test it out. I'd be pretty surprised if the DM Rivian wouldn't be able to pull the boat up the ramp even with the 21" wheel/tire setup.

 

[JoelD]

FWIW, my quad motor R1T (June 2022 vin 7xxx) has no problem with my 24 foot Boston Whaler on ramps in Emerald Isle (where I live) or at the Radio island ramp, or the Beaufort Town Creek ramp. All they can get pretty nasty. The R1T says it weighs 7,000, and that’s about right.

 

[HaveBlue]

Since you have boat ramp experience, you know how slippery they are and I've only launched and retrieved boats a few times.
From driving my R1S DM offroad and in the snow, I can say the the torque delivery is super smooth with very little motor stall over tough obstacles. The traction control excells in snow as well as in crossed up situations. It's better than Toyota's Atrac system.
I don't think locking diffs will provide a lot of benefit (despite how much I like them) on a flat boat ramp over most traction control systems. Everything is traction limited so tires if anything might help.

In any case, a Rivian will perfom at least as well as your frontier in a boat ramp situation.
A Frontier has between a 34x-42x crawl ratio in low range. With 175 ftlb at 2000rpm provides 6K-7K ftlb of torque. A Rivian has a 12x crawl ratio and 600-900ftlb motor torque so 8K-10K ftlb usable. Of course in High range the frontier will only muster about 2K ftlb, which is why a Rivian accelerates so hard and can carry that pull. It doesn't need to shift and the frontier won't be winning any races in low range.

There is one really big hazard with a Rivian. It could slide into the water as soon as you put it in park. This is because only the rear wheels are braked in park is my understanding. On your frontier, applying the parking brake or shifting to park locks all four wheels in 4wd. There is no way to have the Rivian stay in hold mode and apply any reasonable amount of brake force. You will have to stay in the car and apply brakes with your foot.

 

[mpfurnari]

Picked up my truck 2 weeks ago.... Dual motor, max pack. Took the boat to the ramp today and took it up and down the steep slippery ramp about 20 times to get the ramp very wet. Zero issues! I stopped the boat at lots of places on the ramp. I did get maybe a second or two of slip on the way down but quickly stopped. Full disclosure: I had the brakes on the trailer modified to EoH. It's nice being able to dial in the trailer braking with the integrated brake controller.

If you read my original post, I was worried both about descending the ramp and getting back out. Coming back out was flawless. The truck just casually came up the ramp with no strain and no slip at all. Way better experience than my old tow vehicle.

I want to thank everyone and especially @R.I.P. for getting me past my concerns. You were right!

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