Why is Mazda bell housing designed like this?

[NoahLKatz]

Mazda, and a lot of other makes, have a large. and unused as far as I can tell, area at the top of their bell housings.

What's it for?

I wouldn't think it's needed for MOI, which is already enormous.

And why the double walls at certain points around the periphery?

 

[gruntguru]

To feed "beaming" loads higher up on the engine block?

Consider that the bottom of the engine block is not far from the crankshaft CL (even coincident on older designs).

je suis charlie

 

[NoahLKatz]

Could be.

A guy on a Miata forum who seems knowledgeable said "Bending strength and stiffness of the engine/transmission assembly. The drivetrain is structural in the Miata, there are no transmission mounts."

Surprising if the entire trans is cantilevered from the engine.

 

[3DDave]

https://forum.miata.net/vb/showthread.php?t=398690

There's pictures.

 

[NoahLKatz]

Ah, thanks for the link.

So while the trans isn't cantilevered, its connection to that frame makes it part of a long beam in bending.

 

[GregLocock]

Yes, it is a very nice solution to various driveline woes, but it isn't especially light, at first glance. It's great because it eliminates two of the most difficult isolators in the car, the transmission rear mount and the diff nose mount, which always seem to require an awful lot of structure to get reasonable noise sensitivity figures.

Lotus SID was designed to be built in that configuration, as a possibility (every bush in the spine chassis and end subframes and driveline mounts had the same form factor, and we had a kit of parts so we could rebuild it in many different configs) , but I don't think they ever tested that one.


Cheers

Greg Locock


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