Hi There, from Mountain Pass Performance

[UnsungZero_OldTimeAdMan]

You know, it's interesting that GM was able to put 18" wheels on the Hummer EV then. GVCW is a little lower, but not by much.

And GM is now gold standard for engineering or doing right? /s

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[Epicloop]

How about a front brake 'downsize' kit so 18" wheels can fit?

You are ok with reduced braking performance?

You know, it's interesting that GM was able to put 18" wheels on the Hummer EV then. GVCW is a little lower, but not by much.

"In the braking distance test, the R1S was considerably better in the 60 to 0 mph braking test, beating its rival by 10 meters"
I like the Hummer but its braking is not stellar, looks like it could use 20" wheels & larger brakes.
GVCW? Did you mean GCWR and if so why are you factoring in trailer weight?
Curb weight is a ton + on the Hummer.

 

[Dark-Fx]

You are ok with reduced braking performance?

"In the braking distance test, the R1S was considerably better in the 60 to 0 mph braking test, beating its rival by 10 meters"
I like the Hummer but its braking is not stellar, looks like it could use 20" wheels & larger brakes.

A lot of braking effort is a function of tires as well. The Hummer EV shipped with MT tires vs the Rivian's AT tires. Stopping distance on my R1T is dramatically worse with the K02 tires versus the 22" sport tires it came with. I have been giving more space.

 

[JeremyP]

I'm not looking to have a huge debate about possibly a marginal difference in brake performance on a vehicle where you hardly use the brakes; I was giving a suggestion for a product targeted for people looking to improve their vehicle for trail use, not track use. 1 ton trucks have huge gcwr numbers and somehow can run 18" wheels.

 

[R1Thor]

I'm not looking to have a huge debate about possibly a marginal difference in brake performance on a vehicle where you hardly use the brakes; I was giving a suggestion for a product targeted for people looking to improve their vehicle for trail use, not track use. 1 ton trucks have huge gcwr numbers and somehow can run 18" wheels.

The thing that...non-Engineers and super car enthusiasts don't realize about brakes is, you think of them as "friction" components.

Whereas, more accurately, friction is only a byproduct of THERMAL TRANSFER.
If you reduce the area by which you can impart braking, you reduce the overall thermal load that can ever be transfered. This is how you develop brake fade.

I BET, with the right brake booster, I could find an old Dodge Neon's brake setup and can outfit it to work on a Rivian. BUT, I'm also betting that after I stop ...oh say...1, or 2 times at a rapid deceleration, the brakes will glaze an I'll no longer be able to transfer any more heat into the rotors.

Then I'm going to run headfirst into something.

The brakes are going to be spec'd in such a way so that, AT WORST CASE, you can stop over and over and over repeatably and reliably and not create a heat soak scenario that will then prevent you from being able to stop anymore. At which point, the wall, the tree, the ditch, or another vehicle will become your only stopping power.

That's...not a risk I'd ever be willing to take, even for 'off-roading.' I'm not an off-road enthusiast, though I'd like to learn. But...wouldn't you be using mechanical brakes a whole lot if you're driving over obstacles?

 

[JeremyP]

Yes I'm an engineer and understand the principles of brakes, and I do use my brakes going over trail obstacles, at 2 mph. I'll probably just get some 20" wheels that I don't mind scratching up on rocks.

 

[Chewy734]

We could have adopted the metric system for weights and measures, but pirates stole the 1 kg standard and imprisoned the scientist bringing it to the US.

https://www.snopes.com/fact-check/metric-system-pirates/

Thanks for sharing… it shows that was a False claim, but it was still an interesting read about history that I knew nothing about.

 

[mike813]

@MountainPassPerformance

What are your plans for performance parts?

a couple that I think make sense and you probably will have 1st mover advantage!!

1. Performance Tie Rods. Although I have not experienced one breaking some in the community have experienced this. It would be nice to have opitons for beefed up Tie Rods to upgrade or to carry when going offorad

2. A coilover kit to replace the stock air suspension. Similar cars with air suspension like the Land Rover Range Rover and Mercedes GLS become very expensive to maintain as they age and usually it's the air systems that go bad first before any other fancy stuff. If I want to keep my R1S after warranty I would love to have options similar to what Arnott offers for Mercedes air suspension.

I second this. I'm not really sure what a tie rod is, but I feel like I should have a few spare ones to carry around with me to share with friends after reading about the occasional failures.

Oh, and maybe some grab handles on the a-pillar. That's not really performance, but that sure would be nice.

 

[KimBrennan]

In your graph of efficiency, you stated before what most of the parameters were. I know with my previous electric vehicle I turned off climate control for max range, but I've got so much more range with my R1T that I'm lazy and leave it on. Still, a useful graph.

 

[UnsungZero_OldTimeAdMan]

I second this. I'm not really sure what a tie rod is, but I feel like I should have a few spare ones to carry around with me to share with friends after reading about the occasional failures.

Oh, and maybe some grab handles on the a-pillar. That's not really performance, but that sure would be nice.

The tie rod is an adjustable-length link in the steering. Without it, you can't turn the wheel. With incorrect length set, you can't track straight while steering wheel is dead center. It's an intentionally weak link in the system, like an electrical fuse. A tie rod that is too strong, could transfer force to and cause failure in other less accessible and/or more expensive components.

 

[Mark_AZR1T]

The tie rod is an adjustable-length link in the steering. Without it, you can't turn the wheel. With incorrect length set, you can't track straight while steering wheel is dead center. It's an intentionally weak link in the system, like an electrical fuse. A tie rod that is too strong, could transfer force to and cause failure in other less accessible and/or more expensive components.

This guy has nailed it....you don't need a beefier TRE, you may very well like to have access to a lower cost (than OEM) TRE for an on-the-trail replacement though...


And....Welcome Sasha! Excellent operation you have...!!

 

[MountainPassPerformance]

Thanks so much for the warm welcome everyone! It means a lot to us and I have to say the feeling of this forum is reminiscent of the early days of the Tesla forums.

As for the metric/imperial comments - I don't think Canada is much better! We do "human" height in feet and inches, weight in pounds, weight for very large objects are sometimes in metric tons and sometimes imperial tons, fluids are measured in mL or ounces depending on what you're talking about, we measure outside temperature in degC and indoor temperature or temperature of water in degF... pressure in psi and kpa depending on industry, it's a total mess!

 

[Tango45]

Asking for a friend, but can the top speed of ~110 mph (I can't remember the exact number) be removed? There was some outcry a while ago for a 1/4 mile mode or a track mode that removes it for a certain amount of time or something... again, asking for a friend; I drive sedately around my suburban neighborhood and local malls.

 

[MountainPassPerformance]

Asking for a friend, but can the top speed of ~110 mph (I can't remember the exact number) be removed? There was some outcry a while ago for a 1/4 mile mode or a track mode that removes it for a certain amount of time or something... again, asking for a friend; I drive sedately around my suburban neighborhood and local malls.

These types of software modifications are the hardest modifications to achieve and are basically impossible without some level of OEM cooperation or "unintended" cooperation ?

I would imagine the inverters are hard-coded with an RPM limit, so there's really no way around that without being able to reprogram the inverters - which would also then need to be reprogrammed after every software update.

 

[NDIrish]

The tie rod is an adjustable-length link in the steering. Without it, you can't turn the wheel. With incorrect length set, you can't track straight while steering wheel is dead center. It's an intentionally weak link in the system, like an electrical fuse. A tie rod that is too strong, could transfer force to and cause failure in other less accessible and/or more expensive components.

I am NOT a mechanical engineer (or better yet not a Mechanic) but couldn't you design the long straight "rod" that is the "weak point" to be detachable at BOTH ends so the week link is easily field servicable? I understand for alignment you probably only want adjustment on one end of it, but could instead of the interior side being a bigger piece with more parts, just "unpin/unscrew" long straight "rod" replace and be on your way. For an offroad vehicle the weak link should be cheap and easy to replace in the mud. Not a $500 part that is less than simple (not saying exactly difficult, just involved)

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