Real world Off Roading Pros/Cons

Smithery

Well-Known Member
Joined
Oct 16, 2020
Messages
299
Reaction score
562
Location
California
Vehicles
Model X 100D, Volvo XC70, Mini Cooper JCW, R1T Max
But it has REGEN braking, way better than friction brakes in that circumstance, no?
Not if the battery is near full or cold.

Friction brakes have to be solely capable of stopping the load you need to stop.

The good news is that since you *usually* have high regeneration available you'll barely use those friction brakes in most circumstances. They'll probably never show up as a maintenance item.

Our Model X is 4 years/50k miles in and the original brake pads look like they could've been installed a month ago.
Advertisement

 

SANZC02

Well-Known Member
First Name
Bob
Joined
Feb 11, 2021
Messages
953
Reaction score
1,993
Location
California
First Name
Bob
Vehicles
Tesla Model S, Jeep Grand Cherokee; (LE - R1S)
Occupation
IT
Yes, but regen isn't always available. You need to be able to rely 100% on the friction breaks.
This is true for instance Tesla regen progressively reduces when over 90% charge and is non-existent above 98%.

I’ve also had some friends tell me in cold weather their regen breaking is spotty.

There is a readout on the dash giving you regen feedback on the Tesla.
 

hola29

Well-Known Member
Joined
Sep 15, 2019
Messages
177
Reaction score
210
Location
California
Vehicles
Nissan
I am not an offroader per se, but know a few people that do...They all run pretty large tires and modified rigs to fit them. Not sure I'd want to cut up a rivian and I wonder how the internal "computer" would handle huge tires. But they are rock crawling, which may be a subset of offroading...

I don't see a lot of off road specific pro / con discussions when it comes to EV trucks (specially Rivian and it's 4 motors system). From my experience with 4x4s, Prerunners, Rock Crawlers , Over-Landers I think the biggest Pros will be as follows:


-No need to purchase under body skid plates. The vehicles underside is a giant skid plate.
-No need to re-gears your differentials for bigger tires for more TQ or engine RPMs.
-No need to add lockers to the diffs.
-No worrying about a transfer case /4 high /4 low / all wheel drive modes. The T-case can get "stuck" in what ever mode you are in, which obviously sucks. Even manual shift T-cases can be hard to shift requiring you to rock back and forth. Also you need to come to a full stop + shift the transmission into neutral when going into 4 low and back out.
-On very steep inclines your engine might have trouble flowing oil and coolant through it, causing damage or stall.
-Engines can suck in dust or water. Might not be as bad with electric vehicles that don't need pure air for engine combustion.
-For auto transmission , no need for a bigger transmission cooler (can be a big issue for vehicles running big tires and running hard in the dirt)
-For manual trans , no worry about blowing up a clutch or exploding gear sets when abusing the vehicle.
-Overall no transmission headaches at all! A fully built up off road transmission can run 4k+ & require a lot of maintenance.


I think for the Cons

-Price
-Charging/Range


For the same issues:

Both can run IFS/IRS suspensions. You need to make sure control arms and spindles are strong enough from factory. I guess you can always go aftermarket or custom for stronger stock length arms or even run a wider long travel setup. I think the stock total wheel travel (fully drooped out to full bottom out) is around 6-8"? That's not a whole lot so better not drive too fast. I also think most parts will be cast aluminum parts? Might be good enough? Both will require CV upkeep or replacing the stock CVs with beefy CV joints (porsche 930 CV or RCV type) that wont explode. I don't know what hub assembly they will end up using but it should be strong enough for 35" tires minimum. I guess it's going to be a big unit bearing probably like most full size IFS trucks run. I doubt they will utilize hollow snouts / fully floated hubs. It would be great but probably not.

If you are into high speed off-roading (through desert trails and woops) I would think aftermarket is the only way to go for coil overs, bypass shocks and hydraulic air bumps. That air ride set up is probably good for 99% of normal people but I'm sure that poor shock and air spring will get very hot with such a heavy truck mashing through woops even at lower speeds over time. I would think, just based off similar trucks that run long travel or mid travel setups for desert trails you would want one coil over + one bypass shock per wheel (3' diameter for that heavy Rivian) . I don't even know if you can mount after-market shocks (Fox, King, Bilstein, Icon...) in the unibody setup. Maybe the big aftermarket shock companies that know how to build a real shock absorber will make a bolt in upgrade option that works with the factory mounting points. That auto rid height adjustment system is mostly a joke for serious abuse and has been around in luxury SUV for a long long time. It sounds great if your off road experience is = 0 .

Anyways, what else did I miss?
 

BillArnett

Well-Known Member
First Name
Bill
Joined
Nov 23, 2019
Messages
87
Reaction score
107
Location
Emerald Hills CA
First Name
Bill
Vehicles
Jeep Wrangler; Tesla Model S, Model 3 (& Cybertruck on order)
Yes, but regen isn't always available. You need to be able to rely 100% on the friction breaks.
When is regen not available? Two cases I can think of: 1) the battery is close to 100% full. But that will only be a problem if you charge up to 100% at the top of a hill which is kind of silly. Or 2) there’s some sort of failure but in that case you only need to stop once and it’s OK for the friction brakes to get a bit hot. Or I suppose the third case is where the driver has turned the regen off but that’s just stupid.
 

BillArnett

Well-Known Member
First Name
Bill
Joined
Nov 23, 2019
Messages
87
Reaction score
107
Location
Emerald Hills CA
First Name
Bill
Vehicles
Jeep Wrangler; Tesla Model S, Model 3 (& Cybertruck on order)
When is regen not available? Two cases I can think of: 1) the battery is close to 100% full. But that will only be a problem if you charge up to 100% at the top of a hill which is kind of silly. Or 2) there’s some sort of failure but in that case you only need to stop once and it’s OK for the friction brakes to get a bit hot. Or I suppose the third case is where the driver has turned the regen off but that’s just stupid.
Fourth case: your battery is cold at the top of the hill. But how did you get to the top without heating up the battery? You stopped at the top for an hour to enjoy the view? In cold weather? Maybe. Wouldn’t it be OK in that case to just go very slowly so that smaller brakes would be adequate? Or preheating the batter before starting down? Isn’t that better than foreclosing the possibility of larger tires?
 

cwoodcox

Well-Known Member
First Name
Corey
Joined
Mar 31, 2021
Messages
182
Reaction score
196
Location
Montreal, QC
First Name
Corey
Vehicles
2012 Ford Expedition
Occupation
Software Engineer
That should be easy enough. I'll be there with my R1T as soon as I can. The optional Hell's Gate obstacle will be fun but I wouldn't be surprised if I get some wheel rim rash. "Tip Over Challenge" should be easy with Rivian's low CG. Escalator: forget it.
Yeah. I’ve done it in side-by-side and in my old Tacoma. Lore says a local did it in a police-surplus Crown Vic once upon a time. It’s a pretty safe goal, imo. 😏
 

Babbuino

Well-Known Member
First Name
Manuel
Joined
Aug 1, 2020
Messages
1,193
Reaction score
2,386
Location
Florida
First Name
Manuel
Vehicles
Audi A3
Occupation
DESIGN engineer
Yeah. I’ve done it in side-by-side and in my old Tacoma. Lore says a local did it in a police-surplus Crown Vic once upon a time. It’s a pretty safe goal, imo. 😏
 

Blueassassin

Well-Known Member
First Name
Allen
Joined
Apr 5, 2021
Messages
480
Reaction score
1,078
Location
il
First Name
Allen
Vehicles
Hummer H1, Lotus Elise, Fusion Energi platinum
Occupation
Equipment Manager
pros,

  1. great visibility with the camera system
  2. low end torque of the electric motors and no gear changes
  3. individual motors on each wheel means the traction system puts power where it needs no "lockers" needed and tank turn torque vectoring
  4. solid skid pan means rocks wont get hung up underneath or take or exhaust drive shaft components
  5. four wheel independent suspension and adjustable ride if programed right can make a smoother ride off-road that can vary depending on weight on board along with helping keep the truck level in off camber situations
  6. space on board no need to have the huge rack in the back of the truck when overlanding cooler and alot of tools and such can be in the frunk balancing the truck better as well
  7. as stated low CGI

Cons,
  1. yes I'm not sure we will be able to just slap a lift kit on it and 44's the computer system will be too complex and probably not handle that well. Even my Tacoma was never happy shifting after changing tire size it was always searching for gear and downshifting at the wrong times what do you think that would do to this.
  2. yep cant just bring a gas can with you. This will be a fun one hopfully they will allow you to tie into another truck and get some range from them its possible.
  3. lots of things to break even today i noticed the little touch button area to open the charger door and the sensor very low in front of the driver tire smash that with a rock it could get expensive
 

BillArnett

Well-Known Member
First Name
Bill
Joined
Nov 23, 2019
Messages
87
Reaction score
107
Location
Emerald Hills CA
First Name
Bill
Vehicles
Jeep Wrangler; Tesla Model S, Model 3 (& Cybertruck on order)
...
  1. individual motors on each wheel means the traction system puts power where it needs no "lockers" needed and tank turn torque vectoring
  2. ...
Yeah but the video showing the truck climbing a rocky hill that was posted a few months ago is not too promising. It did get up the hill but it was kind of ugly with the wheels spinning briefly before the torque was transferred to the other side. The system needs to respond much more quickly. Or perhaps easier to implement, a "software locker" mode where all four motors are driven at the same speed.
 

Blueassassin

Well-Known Member
First Name
Allen
Joined
Apr 5, 2021
Messages
480
Reaction score
1,078
Location
il
First Name
Allen
Vehicles
Hummer H1, Lotus Elise, Fusion Energi platinum
Occupation
Equipment Manager
Yeah but the video showing the truck climbing a rocky hill that was posted a few months ago is not too promising. It did get up the hill but it was kind of ugly with the wheels spinning briefly before the torque was transferred to the other side. The system needs to respond much more quickly. Or perhaps easier to implement, a "software locker" mode where all four motors are driven at the same speed.
I'm with you there you can also tell they didn't have much off-road experience and was attacking that obstacle wrong with probably too much air in the tires. But they are working on getting the software there and it should be constant improvement IMO
 

Smithery

Well-Known Member
Joined
Oct 16, 2020
Messages
299
Reaction score
562
Location
California
Vehicles
Model X 100D, Volvo XC70, Mini Cooper JCW, R1T Max
Fourth case: your battery is cold at the top of the hill. But how did you get to the top without heating up the battery? You stopped at the top for an hour to enjoy the view? In cold weather? Maybe. Wouldn’t it be OK in that case to just go very slowly so that smaller brakes would be adequate? Or preheating the batter before starting down? Isn’t that better than foreclosing the possibility of larger tires?
Your battery can be near 100% at the top of the hill, or ice cold at the top of a hill, if you *live on the top of a hill*

I know lots' of people who live 3000' above where they work and commute down-mountain every day. They won't have regen *a lot* of the time. :)
 

BillArnett

Well-Known Member
First Name
Bill
Joined
Nov 23, 2019
Messages
87
Reaction score
107
Location
Emerald Hills CA
First Name
Bill
Vehicles
Jeep Wrangler; Tesla Model S, Model 3 (& Cybertruck on order)
Your battery can be near 100% at the top of the hill, or ice cold at the top of a hill, if you *live on the top of a hill*

I know lots' of people who live 3000' above where they work and commute down-mountain every day. They won't have regen *a lot* of the time. :)
Those people can simply charge to less than 100% before starting down. Otherwise they’re throwing away energy.
 

timesinks

Well-Known Member
Joined
Sep 20, 2020
Messages
233
Reaction score
512
Location
Seattle
Vehicles
ID.4, FJ, Sprinter
Those people can simply charge to less than 100% before starting down. Otherwise they’re throwing away energy.
Doesn't cover the cold case, which can happen not just because you live on top of the hill but because you parked on top of a hill without a power source for an extended period of time.

And no, a vehicle can't be designed such that you just "go slow" to account for that. We don't just engineer life safety systems to work 9 times out of 10, or even 999 times out of 1000. Regen won't always be available, and even when it is, won't always be operating at its peak potential. The within-an-acceptable-margin-of-100% life safety equipment is the friction brake. You're not going to find a manufacturer who does the calculation and comes up with a different answer here.
 

BillArnett

Well-Known Member
First Name
Bill
Joined
Nov 23, 2019
Messages
87
Reaction score
107
Location
Emerald Hills CA
First Name
Bill
Vehicles
Jeep Wrangler; Tesla Model S, Model 3 (& Cybertruck on order)
Doesn't cover the cold case, which can happen not just because you live on top of the hill but because you parked on top of a hill without a power source for an extended period of time.

And no, a vehicle can't be designed such that you just "go slow" to account for that. We don't just engineer life safety systems to work 9 times out of 10, or even 999 times out of 1000. Regen won't always be available, and even when it is, won't always be operating at its peak potential. The within-an-acceptable-margin-of-100% life safety equipment is the friction brake. You're not going to find a manufacturer who does the calculation and comes up with a different answer here.
You could pre-heat the battery in the cold case.

But I’m not really suggesting that Rivian eliminate the friction brakes. What I question is whether such large ones are really required. A Ford F-150, for example, can be had with 17” wheels (and brakes to match). If that’s good enough for Ford why can’t Rivian offer such an option? Those wanting to tow heavy loads might well opt for the bigger wheels and brakes but those of us more interested in off-reading would be much better served with smaller wheels and bigger tires.
 

Blueassassin

Well-Known Member
First Name
Allen
Joined
Apr 5, 2021
Messages
480
Reaction score
1,078
Location
il
First Name
Allen
Vehicles
Hummer H1, Lotus Elise, Fusion Energi platinum
Occupation
Equipment Manager
You could pre-heat the battery in the cold case.

But I’m not really suggesting that Rivian eliminate the friction brakes. What I question is whether such large ones are really required. A Ford F-150, for example, can be had with 17” wheels (and brakes to match). If that’s good enough for Ford why can’t Rivian offer such an option? Those wanting to tow heavy loads might well opt for the bigger wheels and brakes but those of us more interested in off-reading would be much better served with smaller wheels and bigger tires.
I would rather they keep the big brakes and give us an option to program in bigger tires I’m thinking 38”s would be a nice fit.
 
Advertisement

 
Advertisement
Top