Steel crush washers on aluminum cases?

[Ken_K]

Several discussions on this site regarding aluminum, copper, and coated steel drain plug washers, but very few on steel crush washers. I'm curious why Toyota uses steel crush washers on drain plugs for aluminum transfer cases and transmissions. For example, my Tundra and Highlander both use Toyota steel crush washer 12157-10010 for transfer cases.

I understand these washers are designed to compress, but if over torqued, wouldn't they damage the softer aluminum surface?

Edit: For comparison, Honda uses flat aluminum washers on their aluminum cases. I'm not claiming Toyota is wrong, just don't understand their logic.

 

[Soft Cars]

Not only that, but you have the potential for corrosion since they are dissimilar metals.

 

[joegreen]

I assume the steel is easier and cheaper to produce and they don’t have any issues in there application

 

[nthach]

Even weirder is Toyota uses copper washers on the front diff of the Lexus LX/GX and T4R/LC100/LC200. And the pumpkin is aluminum.

 

[Jetronic]

Not only that, but you have the potential for corrosion since they are dissimilar metals.

And the drain bolt is made from?

 

[FowVay]

These types of crush washers are flimsy rolled metal designed to collapse as you apply force to them. The aluminum washers that you buy are annealed, dead soft aluminum that slightly deforms each time you apply torque to them. Both designs are application specific in that you generally get the rolled steel gaskets on drive train components and annealed aluminum on oil pans. Other applications on the engine may use soft copper when it's a steel-on-steel application.

Note that all of these seals are designed as a one-time use item. People insist on reusing the aluminum drain plug washers until they look like they've been run over by a freight train but note that each time that annealed material is compressed it is being cold work and hardened. After a few compressions you have a completely non-compliant material which no longer conforms to the sealing surface. It's impossible to get a proper torque on these hardened gaskets and this leads to leaks and stripped pans.

If you're using a new steel crush gasket and applying the proper torque then you should not worry about stripping the threads. Just don't use it more than once for the collapsible steel or twice for the annealed aluminum.

 

[skyactiv]

I prefer the steel crush gaskets that crush well when the plugged is tightened.

 

[oggb]

The steel ones are cheaper.

 

[Rand]

The steel one is similar to the subaru style.. and are my favorite. you can tell when its fully crushed and super easy to get the torque right.

 

[Ken_K]

Even weirder is Toyota uses copper washers on the front diff of the Lexus LX/GX and T4R/LC100/LC200. And the pumpkin is aluminum.

Yes, interesting that Toyota specs copper, steel, and aluminum gaskets for aluminum cases on one vehicle. Yet, Honda specs aluminum gaskets on the CR-V and Pilot's transmissions and differentials.

I'm not a mechanical engineer, but logic tells me gaskets should be softer than surfaces they're meant to seal. Just curious why spec steel crush gaskets for aluminum.

 

[CR94]

... The aluminum washers that you buy are annealed, dead soft aluminum that slightly deforms each time you apply torque to them. ... People insist on reusing the aluminum drain plug washers until they look like they've been run over by a freight train but note that each time that annealed material is compressed it is being cold work and hardened. After a few compressions you have a completely non-compliant material which no longer conforms to the sealing surface. It's impossible to get a proper torque on these hardened gaskets and this leads to leaks and stripped pans. ...

My Mazda came with one of those. In dozens of re-uses over 600K miles, it never leaked. It did become thinner. Beyond a certain point, I didn't have to worry about it falling off the drain plug.

 

[PimTac]

I'm not a mechanical engineer, but logic tells me gaskets should be softer than surfaces they're meant to seal. Just curious why spec steel crush gaskets for aluminum.

I think many aluminum oil pans have a steel drain insert. That would make sense if the drain plug is steel.

 

[Ken_K]

I think many aluminum oil pans have a steel drain insert. That would make sense if the drain plug is steel.

I was wondering the same thing, but I cannot see any steel inserts on the transfer and differential cases

 

[2strokeNorthstar]

Even weirder is Toyota uses copper washers on the front diff of the Lexus LX/GX and T4R/LC100/LC200. And the pumpkin is aluminum.

That's not odd. Copper washers on aluminum is very common