Featured Toyota bZ4X Specifications Revealed

Reasons it could be harder than it sounds:

It could involve not only a replacement hub but also half-shafts and CV joints or different wheels.
That could require different packaging (fitting everything in).
Those changes could require re-testing, re-certification, etc.
Those changes also might require manufacturing capacity not available at the moment.

"Simple solutions" like Loctite might not be followed by consumers or technicians leaving Toyota liable.

Sometimes simple sounding failure have complex solutions. I'm reminded of a story of the early days of flight. Guy flew a plane, wing ripped off on takeoff. So he strengthened the spars. Wing ripped off again. Turns out, there were two spars - front and back. The problem was, the back spar was stiffer than the front spar leading the wing to pitch up when lift was applied (front spar moved more), causing more lift, causing more pitching...and boom! The solution was to *weaken* the back spar through making it less stiff. Is it obvious that when your wing rips off that the problem is that it's too strong?

 

You don't need to be an engineer, just have an open mind.

Does any other Toyota vehicle have lug bolt problems? The only other one with lug bolts is the supra and it does not have problems. The design was likely borrowed from bmw like the engine. BMW, Audi, and Porsche have been using them for decades. If there was an engineering challenge then they would have switched to studs long ago. So it is a solved engineering problem, that was probably solved 100 years ago.

Changing a tire is different, which makes me wonder why toyota did it on this car. I suspect there may be parts that need to be made to solve the issue, which in my mind is likely a poor design with inadequate testing. Somehow even though this car is late to market, toyota seems to have rushed some things. An interesting wrinkle is there was dealer gouging on the small number of these vehicles shipped and the refund offer did not appear yet to include this dealer mark up.

 

I'm thinking this is a repeat of the oil sludging issue. Toyota made a design decision to reduce production costs without proper testing. This time it is harder to blame the customer for the problem.

 

It's impossible that Toyota did something wrong. John says Toyota is slow & methodical into the EV market in order to make sure everything is right.

.

 

Good thing Tesla doesn't wait to make sure everything is right.

 

Supra is actually produced by BMW, and BZ4X is made by?

If I recall correctly, none of the Toyota design in the past involve wheel lug bolts and lug nuts only???

Also, I wonder if responsible party/parties have looked into the alignment design of the wheels in relation to hardware application? Will the movement of the wheels against the amount of load to the bolts/nuts with combination of toe/camber/caster can cause the bolts to spawn loose while driving?

It will be interesting to find out the resolution of this problem for sure...

Posted via the PriusChat mobile app.

 

He's busy in the comment sections of these articles, thus why he isn't here sharing the wisdom.

The Supra probably let someone in Toyota see how much BMW saves per unit using wheel bolts instead of the studs and nuts. Why try out the bolts on the bZ4x first? Maybe the slightly lower unsprung weight was seen as more beneficial to a BEV's efficiency, or because they were only going to be making low numbers to start, or that is just how timing and model development lined up.

 

Lose wheels is certainly unacceptable for any manufacturer but especially for Toyota that spoiled us with reliable and indestructible vehicles for decades.

I am sure some Toyota engineers lost their job over this lose wheels disaster. The problem with the latest designs is that Computer Assisted Design has been automated so much that engineers do not exercise much engineering judgement anymore.

 

It's a bit sad, really. I have lots of niggling issues with my Toyota cars, but the one thing they never do is fail to get me where I'm going. I've never had one need mechanical repairs that weren't normal wear and tear. They spent over a decade trying to ignore the EV phenomenon and now they're stumbling all over themselves to catch up, and they're making a lot of mistakes. Wheels falling off is like Keystone cops level of ineptitude.

I bet I'm not alone in biding my time waiting for a Toyota EV with the expectation of reliability like our Priuses. The lackluster charging performance and this issue really give me pause about whether Toyota is willing or able to maintain its reputation for reliability in the EV world.

My Volkswagen cars all had wheel bolts. Every single time I got new tires the shop monkeys would lift the car up to eye level and use the air ratchet and the wheel and tire would promptly fall off the car and bounce across the shop.

 

It was easier to make design mistakes before CAD. Either way poor assumptions will lead to poor design. Key is proper testing and it doesn't seem like they did that on this vehicle. Toyota did get the prius into production fast in 1997 but had a design problem that it would shut down in hot weather or high altitude, this car was only sold in Japan. This required a reduced power turtle mode. In less than 3 years they addressed that problem by modifying the engine, and changing the battery and electric motors. We never saw the problem outside japan because those first customers caught the problem before it was imported.

This bz4x has only gone to a tiny number of customers. Its better that they piss them off and fix the design, then simply having the dealers put in new bolts that may not solve the problem. I am not sure the only problem is bolts. The symptom is tight right turns or heavy braking to cause the problem. Brakes or steering may also have problems that need to be addressed. I'm sure we wouldn't be hearing about problems though if they had stuck with the stud design they use on almost all of their cars and trucks.

I am glad they caught this early and I am sure they will be able to fix it. It is just frustrating that toyota fought plug-ins so long that they can't make a decent volume of rav4 primes and get this flawed vehicle out late. If it was 2015 instead of 2022 I would just call it new tech pains.

 

I respectfully disagree - I had them on my smart fortwo cdi and far preferred working with them to studs. With studs, you risk damaging them every time you put a wheel on or off because the studs stick out further than the locating boss at the centre. With wheel bolts, the threads of the studs are nowhere near the wheel when you hoist it into place and rest it on the hub. Clocking in the threaded hole in the hub to the clearance hole in the rim takes a minor effort but once you've done it, it's a breeze.

 

I had them on a VW and hated the damn things, made a single person blowout a 2 person blowout , in the rain and mud drop a bolt and then you gotta clean the bastard as the threads are on the outside, wedge the wheel on the knee in the mud since I don’t have 3 hands and start fumbling with the top screw, even more fun it was recessed into the hub so it was hard to aim and maneuver.
worse they had a security pattern with a poorly designed lug wrench.

Definitely makes an emergency repair far more irritating than it ever needed to be.

 

When I got rid of the TDIs, I absolutely did not miss the wheel bolts.

 

You guys might appreciate this article from bestcarweb.jp. They just had an article about why Japanese cars use wheel nuts and European cars use wheel bolts.
なぜ日本車ホイールはボルト止めが少なかったのか？　ナット止めのほうがいい理由があるのか？？ - 自動車情報誌「ベストカー」

I'll provide a partial translation starting with the title:
Why were Japanese car wheels less bolted? Is there a reason why it's better to stop with a nut? ?

The majority of Japanese cars use the nut fixation method, while the bolt fixation method is the mainstream for European cars (excluding some British cars). Why do European cars use bolts instead of nuts, even though the basic structure of the car is the same?

　We will explain the advantages and disadvantages of bolt-fixed wheels and nut-fixed wheels, and explain why European cars use bolt-fixed wheels.

For European cars, which are frequently driven at high speeds, the rigidity is enhanced with a bolt-fixed type.
　In the bolt-fixed type adopted by European cars, a female thread is cut on the wheel hub side, and a bolt is fixed and tightened there. In this case, the connection surface of the screw is one point between the wheel hub thread and the bolt thread. On the other hand, the nut-fixed connection surface used by Japanese cars is a two-point connection: the part where the hub bolt is fixed to the wheel hub, and the part where the nut is fixed and tightened to the hub bolt.

European cars are routinely driven at high speeds exceeding 150km/h, as typified by German autobahns, so they need not only acceleration power but also powerful braking ( Brakes) force is required, and high rigidity is required for suspension parts that are subject to excessive loads.

　As for the assembly rigidity of the wheel, the bolt-fixed type with few connection points (screws), which tends to reduce rigidity, provides higher rigidity. This is the definitive reason why European cars have bolted wheels.

Japanese cars are nut-fixed, giving priority to workability.
　Compared to European cars, Japanese cars drive less frequently at high speeds, and their maximum speed is limited to around 120km/h. Therefore, the wheel fixing does not require as high rigidity as European cars, and the nut fixing type is adopted in order to prioritize the convenience of wheel removal work.


Me again: There, now you know. My only question, if the bZ4X is limited electronically to 99 mph (160 kph), why the wheel bolt?

Are Tesla's wheel bolted or Dodge Chargers or Chevy Corvettes or Ford Mustangs or even Toyota's GR series cars? NASCAR used to always used lug nuts until they moved to a single lug nut hub. Obviously they've never been on an American highway.

I also entered bZ4X VINs on Toyota's recall page and quite a few are no longer subject to the recall while the majority are so they obviously fixed some of them before they left the factory.

edited to make sure bZ4X VINs were entered and not any VIN.

 

Since the rigidity of the wheel-hub connection has absolutely nothing to do with the rigidity of the fasteners (they are not rigid, they are springs that apply clamping force - essentially all the rigidity comes from the face-to-face connection surfaces), I don't believe one word of this claim.

That's just not how bolted connections work. Bolt are clamps the keep the bearing surfaces together. Nothing more.

If you don't think studs can do the job in a heavy-load situation, realize that wind turbine blades are fastened to the hub with studs and nuts. Think about the loads on that connection - centrifugal force, out-of-plane bending loads from the wind and fully-reversing in-plane loads from gravity.

 

My Tesla as well as Corvettes use lug nuts. This is true for most american cars.
The reason stated in your links was probably older technology the lug bolts provided better stiffness and european makers stuck with the design. Either way the design rules are pretty simple and its surprising toyota had trouble. It shows a lack of adequate testing, as any design for automotive should be tested because design rules sometimes do not provide all the answers. Take today's cayman. It handles exquisitely well but there is some design magic that makes it so. The magic is really good designers and testing of alternative designs (it does have wheel bolts) but nuts or bolts aren't really important here.

Nascar primarily used lug nuts because they started with american cars.

 

For those curious about what happens when they idle a plant, like the same plant they make the bZ4X (Motomatchi plant).

Struggles Inside Toyota's Immobilized Plants

 

According to a Reuters report quoting two sources, Toyota will now submit a set of measures to fix the issue with Japan's transport ministry.

 

Thank you for posting that article I appreciated it. Having had a chance to visit and work in the Motomatchi Plant in 2011 I found the article very interesting.

This quote was interesting to me

"Although the production lines aren’t running, the plant workers who make things for a living refuse to stand still. Regardless of the situation, they keep doing what they can to improve their conditions."

Toyota will not lay off workers or let them go. In 30 years working for them in the United States Toyota, a non-union company, never once threatened a lay off or letting us go. Through some incredibly hard times -investigations into unintended acceleration, parts issues, weather natural disasters, Covid shutdowns- Toyota always provided work for those who wanted to work be it training, on the floor kaizen, painting sweeping the floors etc. until the storm was weathered, and regular production resumed. It was nice to have a job for 30 years and never once worry if you were going to have work during that time.

 

Toyota has resumed bZ4X production at the Motomatchi plant. Apparently the hub bolts weren't properly tightened at the factory causing them to prematurely fail. So the remedy is to replace all the wheel bolts and tighten them to spec in a filing to Japan's transport ministry. Probably took them awhile to get and replace 2700 sets of 4 wheel bolts since it's not just chips that are in short supply.

Toyota Resumes bZ4X Production After Fixing Wheel Hub Bolt Issue