Honda steering recall 1

[GregLocock]

So here's Honda's explanation, I've bolded the bit that sounds like BS

The steering gear contains a unit that includes a worm gear and a worm wheel. Honda stated this condition
of momentary increase in steering effort occurs due to two factors within this unit. During manufacturing, the
worm wheel goes through annealing and component conditioning processes. These processes caused
internal stress and strain within the worm wheel. This strain was slowly released over the first few months of
the vehicle life. Over time, the released strain caused the deformation of the teeth on the worm wheel,
causing the worm gear to catch on the worm wheel. This results in the consumer’s momentary increased in
steering effort. Also, the manufacturing process did not guarantee consistent grease application and
therefore, some vehicles within the scope received too little grease which contributes to the momentary
increase in steering effort

So they are claiming the worm distorted enough in a few months due to internal stress relief that all the clearance between the two gears was used up. I'm no tribology expert, but the missing grease sounds far less unlikely.

Awesome in depth report (not) here

https://static.nhtsa.gov/odi/inv/2023/INOA-EA23003-12662.pdf

I'd add 2.4 lb of effort at the rim is roughly 5 Nm of steering wheel torque, which is almost the maximum you see in daily driving (6 or so). Perhaps that is not where they measured it, but the whole thing reeks of sanitisation.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[3DDave]

I would expect the gears and housing aren't identical materials and that differential thermal expansion and thermal transients were also a part of the problem - something that grabbing returned units from the box and making a test would not reveal. It's possible that "consistent grease application" means that sometimes they used no grease at all.

A buddy of mine was messing with people. We used some tungsten counterweights that were about 1 pound. He'd ask the victim of the prank to help restack the boxed weights from one area to another, handing them over one at a time. Move about 10-15 of them. Then toss an empty box. The empty box would usually get rocketed to the ceiling due to the changed mass vs the expected mass.

I can see where a smooth steering experience interrupted by a sticky spot would cause a large amount of concern.

 

[TugboatEng]

Annealing is not typically a finishing step for gears. Tempering or normalizing, maybe.

Creep is the process where metals slowly deform over time at stresses below their yield strength. Do any metals undergo creep at ambient temperature?

Do the know the deformation won't continue until the clearance becomes interference and binds the box up?

The grease and clearance pairing is unlikely. Grease doesn't fix insufficient clearance.

It's possible that the yield strength of the gear is being exceeded during certain driving conditions. Possibly due to the gear being annealed. This would be really bad.

 

[GregLocock]

I think they are using techie sounding metal problem to cover for actual lack of grease problem.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[Pud]

I'm surprised there's a worm and gear! Thought they went out in the 50's!
I'm with Greg. Blame the robot who was supposed to add grease.

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[MintJulep]

Awesome in depth report (not) here

https://static.nhtsa.gov/odi/inv/2023/INOA-EA23003...

To be fair, the purpose of an "ODI Resume" doesn't appear to be comprehensive root cause assessment.

The purpose seems to be to "have something on file", and it's fully suitable for that purpose.

 

[BrianPetersen]

I'm surprised there's a worm and gear! Thought they went out in the 50's!

It isn't in the rack-and-pinion part of the mechanism that you are thinking of. It's above that, in line with the shaft between the base of the steering column and the pinion that you're thinking of. It's the power steering gear-reduction mechanism that has the worm gear in it.

I know who builds these and I've seen the assembly line for those steering racks destined for a local Honda assembly plant. Don't know if it's the one affected.

(No, I didn't design the parts, or the greasing station, or the specs for them, or spot anything out of the ordinary ...)

 

[DrZoidberWoop]

OP better not be my wife, making excuses for hitting the stone mailbox with her Civic.