Flapper Box 356 vs 912

[Dennis Vogel]

Am I correct in understanding that all 356 double-flapper boxes are the same, regardless of S90, SC, or Normal? What distinguishes a 356 double-flapper box from a 912 flapper box?

I notice the 356 (616.106.042.00) and 912 (616.106.042.03) are different part numbers. When I look at photos, I'm not able to tell them apart. I need to obtain these for my 1960 S90, and don't want to get 912 by mistake. I'd like to trust descriptions, but verify by photo.

• Stoddard 912
• Sierra 356

On a related note, have people had good luck refurbishing used sets? How has the quality of new OEM been? It seems like NOS on these is gone (i.e. Stoddard no longer has them).

As always, thanks for sharing your wit and wisdom.

[Sebastian Gaeta]

The actuating arm is the only real difference between the 356 double flapper and the 912 IIRC. The 356 actuating arm is forked and uses barrell nuts/bolts to hold the cables in place while the 912 I believe has just a single arm.

They are pretty easy to restore as most parts are available from the usual suspects, but if you decide to buy the repro sets the vendors will ship you the correct ones as they will certainly know the difference.

[Dennis Vogel]

The 356 actuating arm is forked and uses barrell nuts/bolts to hold the cables in place while the 912 I believe has just a single arm.

Hi Sebastian. Have I correctly circled what you're referring to as the actuating arm in this photo? According to Aase, this is a 356 Super 90/SC Right Hand Flapper Box photo. I think maybe I am looking at the wrong thing, or the Aase part description is incorrect. Thanks for clarifying.

[Sebastian Gaeta]

I am probably just calling it the wrong thing. It is the rotating arm on the outside of the box that the rods connect to. In your picture above it would be outside of the box to the left.

[Dennis Vogel]

It is the rotating arm on the outside of the box that the rods connect to.

Let me try again. Is this it?

[Sebastian Gaeta]

Yup. See how it is split, or "forked"? The 912 boxes have a solid, single arm if that makes sense.

[Dennis Vogel]

Yup. See how it is split, or "forked"? The 912 boxes have a solid, single arm if that makes sense.

Got it. Thanks so much! I would not have figured that out on my own.

[Sebastian Gaeta]

Happy to help, and yes, you would have figured it out eventually!

[Mike Wilson]

Are the openings for the heater hoses larger on the 912 boxes?

Mike

[Ron LaDow]

Are the openings for the heater hoses larger on the 912 boxes?
Mike

Mike, I'm pretty sure no hoses connect to the 'air channels'.

[Sebastian Gaeta]

Are the openings for the heater hoses larger on the 912 boxes?
Mike

Mike, I'm pretty sure no hoses connect to the 'air channels'.

Right, they just connect directly to the heat exchangers.

[Greg Carter]

You can also modify a 912 box (normally easier to find in good condition) to be used on a 356 by replacing the 912 actuating arms with 356 replacement arms made by Precision Matters (PreMat). I just used a set of PreMat arms to repair my original 356 heater boxes which had badly damaged arms. The PreMat parts work well and are easy to install after carefully removing the original arms with a Dremel tool cut off wheel and grinding die then spot welding on the new replacement arms.

Greg

[Dick Weiss]

The 912 "flapper box" can be used on a 356--just connect the pull cable to the upper hole of the
double hole actuating arm.

[Mike Wilson]

Thanks for the clarification Ron and Sebastian.

Mikr

[Ron LaDow]

The 912 "flapper box" can be used on a 356--just connect the pull cable to the upper hole of the
double hole actuating arm.

Dick, there is no 'double hole actuating arm' on 912 air channels; that's the reason I had that part made.