Coil Springs ride quality vs. Air Suspension - no compromise at all (says Cybertruck lead engineer)

[mongo]

It is likely a handling/trailer sway issue. Understeer with a trailer is how the handling rated and then a trailer can only sway so much. Both of these are counteracted by suspension changes in all trucks, regardless of their setup. Typically it means stiffer suspension, especially with sway (which is likely the primary issue). Tesla choosing a softer suspension, as they have stated for ride quality, would most likely cause the issues.

Agree it's softer, but is it soft enough to cause the towing reduction while the other numbers support it?
As to handling/ stability, this version has rear wheel steering (which may impact rear axle capacity) and front drive unit. Both of which would improve the situation yet, as you call out, carry over numbers.

A solid axle matters… the contact patch doesn’t change nearly as much under load as an independent suspension. Basically a solid axle will just have the patch get bigger from the tires deflecting. Independent suspension will have a camber change putting more weight to the contact patch and at extreme enough angles less.

Solid axles do keep the tires flat to the ground regardless of ride height, but they are worse for handling. In a turn/ side load, the truck will tip to the outside. That unloads the inner tire which raises the axle on that side while pushing down the axle on the outside. That lifts the inner edge of the outside tire which is the opposite direction of camber you want.
Independent suspensions do camber when loaded, but in the direction that improves the tire contact patch during turns. Critical to the setup is the height at which the tire has neutral camber.

(Anybody feel like making popcorn and watching My Cousin Vinny? )

The takeaway is the suspension that met the ride quality that Tesla wanted couldn’t test out at more towing capacity. They have an incentive to have it rated as well as it can be. Sure they may want a jump to more capable models, but that jump exists at 9k to 11k too. Or 8k or 10k. 7500 is there because that is what it is rated for and the compromises made in the design equate to. It’s a carryover from the RWD because it’s simply the same suspension. They could design it for more and maybe in future iterations, they will… as of now it’s 7500.

Very much a carryover from RWD (2,006 payload for both? ). But is it accurate? Maybe they will test with the new version or get new shocks to boost towing. Or leave it as a differentiator. Will be interesting to see 3rd party testing and the final GAWR and curb weight numbers.

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[henchman24]

Agree it's softer, but is it soft enough to cause the towing reduction while the other numbers support it?
As to handling/ stability, this version has rear wheel steering (which may impact rear axle capacity) and front drive unit. Both of which would improve the situation yet, as you call out, carry over numbers.


Solid axles do keep the tires flat to the ground regardless of ride height, but they are worse for handling. In a turn/ side load, the truck will tip to the outside. That unloads the inner tire which raises the axle on that side while pushing down the axle on the outside. That lifts the inner edge of the outside tire which is the opposite direction of camber you want.
Independent suspensions do camber when loaded, but in the direction that improves the tire contact patch during turns. Critical to the setup is the height at which the tire has neutral camber.

(Anybody feel like making popcorn and watching My Cousin Vinny? )



Very much a carryover from RWD (2,006 payload for both? ). But is it accurate? Maybe they will test with the new version or get new shocks to boost towing. Or leave it as a differentiator. Will be interesting to see 3rd party testing and the final GAWR and curb weight numbers.

Given the difference in most half ton trucks with towing packages vs not is typically stiffer rear springs, bigger front sway bar and cooling improvements, a relatively small amount of difference in the suspension causes some large differences in towing rating. IMO it is perfectly plausible and likely. Especially given the brakes are the same and even the RWD would have enough power to do the acceleration tests. With this new AWD, the only differences are wheels, tires, and suspension. Both the AS 20" and 18" tires have a 116 load rating. So odds are that difference doesn't change things. Which simply leaves the suspension as a difference. When that is the major difference and the rating is different, seems very likely that is the reason.

You're right that independent will keep a better contact patch in cornering, but that is not what the rating is concerned with. It is control and predictability when loaded. There are two big reasons that any major towing vehicle has solid axles. Strength and load distribution stability. The latter is predictability of the contact patch under load, something solid axles are better at. One of the few really.

I really doubt any SAE testing facility will be publishing numbers on it... basically nobody does that and there won't be any real demand for the cost. I could see when Tesla runs out of excess RWD parts inventory that they redesign the suspension to offer a bit of an upgrade (if this model sticks around). It would likely be new rear springs and different sway bars (namely front).

 

[Gigahorse]

Yeah. Almost every car in the world uses springs. I don’t even think it’s the reason for the lower towing capacity. I think the lower towing capacity is not really lower just listed as lower, to help push the sale to the premium model, also less warranty claims. But I bet there is no difference in actually what you can tow. Unless they added some software limit.

Less warranty claims might be it considering the press with people ripping the bumpers off.

 

[CYBERTRUCKco]

i've driven the coil sprung LR Cybertruck, and I wouldn't have noticed the difference at all between air suspension on the road.

 

[RM Rilke]

For what it is worth, the Cybertruck doesn’t have shocks. It has struts. The strut body on the coil model is different, but I imagine the damper is the same. The goal was cost cutting and the damper has an adjustable range. No doubt it has a different map. The kinematics of the suspension are designed around a progressive spring curve. Both volume and pressure on an air spring change the progressivity of the curve. That is all engineered into the suspension design. A coil spring, in contrast, has a linear curve.

In order to optimize the suspension travel and static position with the existing kinematics, the preload on a linear spring has a more limited range. Hence the lower payload rating. The kinematics also determine dynamic weight distribution. The leverage curve is designed around a progressive spring. So the numbers will be different with a linear curve.

Placing a coil with a higher rate into the Cybertruck would not quite be the same thing as with a truck that has more progressive suspension kinematics designed to accept different linear rates. Those vehicles also have shocks where it is easy and inexpensive to change the range of the damper. In contrast, the CT damper is an expensive piece of kit. It has to be with such a complex rate from multiple variable curves in a large range air spring. Just my opinion.

 

[HaulingAss]

Well to be clear, he said specifically ride quality wasn't compromised. Obviously air suspension still has the benefits of lowering for more travel efficiency, ingress/egress, raising to level the truck, deep snow/mud/off-roading.

Yes, and the ride quality of the air suspension will be better when the truck is loaded to near it's max. GVWR because steel springs can't compensate for the additional weight and will ride in the lower range. If the load isn't balanced front-to-rear the truck will no longer be perfectly level and highway range will take a small but noticeable hit.

That said, this satisfies those who wanted a simpler truck and complained about the risk of air suspension service/replacement as the truck ages.

 

[HaulingAss]

Those vehicles also have shocks where it is easy and inexpensive to change the range of the damper. In contrast, the CT damper is an expensive piece of kit. It has to be with such a complex rate from multiple variable curves in a large range air spring. Just my opinion.

I'm not following you when you say "it is easy and inexpensive to change the range of the damper". Why would you want to do that when the damper is already set up for the Cybertruck and can fine-tune the amount of compression and rebound damping on the fly to accommodate different loads, different road surfaces and different travel speeds?

 

[mongo]

I'm not following you when you say "it is easy and inexpensive to change the range of the damper". Why would you want to do that when the damper is already set up for the Cybertruck and can fine-tune the amount of compression and rebound damping on the fly to accommodate different loads, different road surfaces and different travel speeds?

He's saying you wouldn't do that on Cybertruck, but there are other vehicles when you can/ would .

Placing a coil with a higher rate into the Cybertruck would not quite be the same thing as with a truck that has more progressive suspension kinematics designed to accept different linear rates. Those vehicles also have shocks where it is easy and inexpensive to change the range of the damper. In contrast, the CT damper is an expensive piece of kit. It has to be with such a complex rate from multiple variable curves in a large range air spring. Just my opinion.

 

[CyberGus]

(Anybody feel like making popcorn and watching My Cousin Vinny? )

 

[VAF84]

Don't think I've seen this answered, but say Tesla is doing this deal to get rid of extra parts. Are the is the non-air suspension used on this truck shared with any other vehicle or manufacturers? There weren't a lot of RWD CT's sold, and if this is a parts bin fire sale, wondering how easy it would be to replace them in the future.

 

[CallsignVega]

The new AWD is the perfect scenario for me. I had air suspension on a GL550 fail on me in the middle of a 600mi road trip. Ruined a couple of tires and was a very expensive fix and I sold it soon after 6k repair. Mechanic told me they all fail, just some last longer than others.

I avoid air suspension any chance I get. They will eventually fail without warning and it's something I don't like hanging over my head post warranty.

I don't listen to the radio, I don't haul trailers, and im indifferent to pleather vs cloth. Although visually, the CT cloth buckets look nicer to me.

Even if my preferences were different, 20k is way more discount than the slim difference between the 2 AWDs

Struts needs replacing too over time. So it's not like comparing something that lasts forever to something that doesn't. Actually' you'll typically need new struts before you need new air suspension components.

 

[FrostyCT]

Yeah. Almost every car in the world uses springs. I don’t even think it’s the reason for the lower towing capacity. I think the lower towing capacity is not really lower just listed as lower, to help push the sale to the premium model, also less warranty claims. But I bet there is no difference in actually what you can tow. Unless they added some software limit.

TOWING LIMIT IS LESS, BED PAYLOAD IS LESS.
YOU CAN'T ADJUST HEIGHT OF SUSPENSION.
NO WAY SPRINGS ARE GOING TO RIDE AS SMOOTH AS AIR, IMHO.
If you want to off-road at all this will not do well.

 

[Strykerwsu]

TOWING LIMIT IS LESS, BED PAYLOAD IS LESS.
YOU CAN'T ADJUST HEIGHT OF SUSPENSION.
NO WAY SPRINGS ARE GOING TO RIDE AS SMOOTH AS AIR, IMHO.
If you want to off-road at all this will not do well.

It will open the CT to many great offroad options, like Fox, Icon, Bilstein, etc. Definitely feel more comfortable taking more agressive offroad approach with those and more robust UCA.

 

[Gaximus]

TOWING LIMIT IS LESS, BED PAYLOAD IS LESS.
YOU CAN'T ADJUST HEIGHT OF SUSPENSION.
NO WAY SPRINGS ARE GOING TO RIDE AS SMOOTH AS AIR, IMHO.
If you want to off-road at all this will not do well.

The CT is capable off road, but is not a good off-road vehicle, people do not buy it to go off-roading. it’s too long too wide, too heavy and has horrible visibility.

I have a $10,000 jeep I use for off roading, that puts the CT in the dust.

 

[HaulingAss]

The CT is capable off road, but is not a good off-road vehicle, people do not buy it to go off-roading. it’s too long too wide, too heavy and has horrible visibility.

I have a $10,000 jeep I use for off roading, that puts the CT in the dust.

The term 'Off-Road' encompasses a lot of variety. Obviously, no stock pickup is a rock crawler (even though the Cybertruck can handle quite a bit for a pickup), but even on the tight PNW Cascades mountain trails I find the Cybertruck superior to a Jeep primarily because the longer wheelbase makes the ride quality difference on bumpy trails a night/day difference. And the active dampers kick in and greatly reduce the side-to-side motion which can become quite violent in a short-wheelbase Jeep. And when the trail gets narrow and overgrown I'm glad I'm not in a painted vehicle. That tough-ass body is a superpower of the Cybertruck off-road.

I'm not in bad shape for my age but a short-wheelbase Jeep or Toyota will beat me up pretty good on a trail that the Cybertruck handles without any problem. It's tiring and reduces enjoyment unless perhaps you are a lit 18 year old who revels in the bucking bronco nature of the ride.

The long wheelbase of the Cybertruck isn't as much of a disadvantage as it is in legacy pickups with similar wheelbases due to the 16" of available ground clearance, when needed. The long wheelbase smooths out both the front to back pitching of the vehicle, as well as the side-to-side. And the steer by wire is still shocking me, two years later, with the kinds of narrow treacherous places I can turn around in. Just last weekend I was in 4-inches of heavy wet snow with an ice layer underneath that was particularly slippery when I hit the snowpack line on a narrow road that would normally be closed by snow this time of year at a much lower elevation. It was too narrow to turn around and I had already progressed through some very tricky side slopes that threatened to put me over the unprotected edge of the mountain due to the slipperiness. I saw one slightly wider spot in the road that had a large tree that would prevent me from backing off the mountain if I tried to do a multi-point turn there and the tires lost traction in the snow/ice. But it didn't look wide enough between the vertical mountain on the uphill and the drop-off on the downhill. But I judged backing down to be higher risk so I gave it a go. My confidence was low because the wide spot looked the same length as the Cybertruck. But I did about a 9 point turn without even scaring myself, easy as pie. I was surprised again, even though I've been turning around on these narrow trails well over a hundred times in the Cybertruck. It's amazingly nimble for it's length.

Yes, a Jeep can out-wheel it if the rock-crawling gets severe enough, but that's not why I have an off-road capable vehicle. I can't think of one time I was turned back where I would have continued on in a Jeep. Don't get me wrong, those places definitely exist, it's just that I haven't encountered that situation yet (that I can remember). I've definitely done some Jeep trails that were near the limits for a Cybertruck, and that would have been relatively easy in a proper Jeep, but they were just little dead-ends to nowhere in particular.

The Cybertruck is a fine off-road vehicle, as long as your idea of off-roading isn't a dick-swinging contest. And people do buy the Cybertruck to go off-roading, especially if they need more carrying capacity than a short-wheelbase Jeep. Off-roading is how many people go camping. And the Jeep crowd can't bring half the stuff a Cybertruck can bring if you're into creature comforts (which I am more and more as I get older).

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