Prototyping a Serviceable Charcoal Canister for the 40-Series

[procomsignathid]

Thank you Pighead (and huge thanks for the canister loan)!

Based on that pic, its looking to me that a replacement couldnt be much taller (like the ‘78 onwards model is). Now that Im moving away from a top-vent design, all the complexity is in the lid, so Ill just have two “can” sizes, one pre-78 and one 78+.

Anyone with an early 70s ‘40 have a pic of where the canister is installed?

 

[ranchdawg]

I don’t want to throw any wrenches into this, but i think you also find that with different years you will find different circumferences. I picked a free what I believe is a ‘73 bracket thinking it would fit my ‘75 canister and it wasn’t even close, the ‘73 was much bigger. (‘73 on the right)

 

[procomsignathid]

Interesting... And good to know. I think a universal fit is possible, but only insofar of where it mounts to the truck. I don't spose you still have the canisters for those? I'd love to know the part #s that match up to each bracket... So far I have dimensions for 77740-60010, 60011, and 60014. Looking for 12 and 13, and Im pretty sure that your '73 is one of those.

 

[procomsignathid]

Being a little less lazy about it... For the 40-series, here's what I know so far:

• 09/1971 - 02/1974: 77740-60010: 95mm diameter, 114mm height (this based off photos and converted to metric, if anyone has better measurements let me know)
• 02/1974 - 01/1975: 77740-60011: 98mm diameter, 117mm height (pigheads canister, although I forgot to grab height and based that off a photo)
• 01/1975 - 08/1976: 77740-60012: measurement TBD
• 08/1976 - 09/1977: 77740-60013: measurement TBD
• 09/1977 - 07/1983: 77740-60014: 116mm diameter, 170mm height. taller canister with third port for the carb bowl, similar design as FJ60

Up until 09/77, all canisters had two ports up top (purge/tank), and a vent port on the bottom. I believe they are similar in form factor, but clearly not all the same as @ranchdawg has shown. Those wider brackets do look like the ones I got from a 60014 model though. The more photos / dimensions, the better!

 

[ranchdawg]

I have cans 11 and 12 for my ‘75, and a bracket for a ‘73. Cans 11 and 12 I believe are the same size, except for the ports on the top, they look smaller to me on the 12. Date range for these two are 2/74 to 8/76 I think.

 

[procomsignathid]

Getting closer on a lid design... It's two-part now, so I'll have to have a gasket, but this follows the Toyota design, keeps it serviceable, and maximized the interior volume for charcoal granules. For CA-spec vehicles, the check-valve on the purge port (left) would be open (no ball or spring), but I may include it for belts-and-suspenders. All the metal parts are stainless steel.

 

[procomsignathid]

Purchased my first round of OTS parts (springs, ball bearings, filter fabric, o-rings, etc.) to begin prototyping! I have a digital manometer on its way as well, and this week I'll begin check valve prototypes. I'm targeting ~.4PSI cracking pressure for tank pressure -> canister, and .1-.2PSI cracking pressure for the purge check valve and makeup-air check valve (canister to tank).

Also, here's more pics from the design process. The copper-colored part shows reinforcement ribs for what will make up a honeycomb lattice, this supports/compresses the charcoal bed (and filter fabric) while allowing vapors to pass through:

Based on what I know at this point, I'll have two different sizes/designs, so that they fit in with existing brackets if the owner still has them:

• Pre 09/77: A "short" model approximately 100mm in diameter, somewhere between 120-140mm in height. This model would only have two ports on top (tank and purge).
• 09/77 / later: A "tall" model approximately 120mm in diameter, somewhere between 170-190mm in height. This model will have a larger, 3rd port up top (the carb port, shown in the pics above) to be a drop-in for folks that have their original carb / emissions equipment. Easily blocked-off for de-smogged builds that use carbs (such as the cityracer aftermarket replacement) that don't have fuel bowl vent ports on their carbs.

I'll be modifying the vertical sizing to achieve a similar charcoal bed volume as the OEM part #s.

Next up, modeling check-valve prototypes and bracketry. Im guessing that initial runs of brackets I sell will be glass-reinforced Nylon PA6, and if I can find a manufacturer I'll shoot for steel replacements in the long-run. The closest bracket I was able to find is from McMaster Carr for a sobering $130 per bracket. Yikes... Off-the-shelf doesn't look like a viable option, so manufacturing it is...

Lastly, I've been learning FreeCAD as part of this process. It's open-source and allows you to save your work locally as opposed to the cloud, which fits into my whole self-sufficiency philosophy, but boy howdy is there a cost to go with the principled route... It's about 300% harder than Fusion360 in my estimation. not sure if there's any 3D modelers out there, but thought I'd share. Keeping my recurring cost manageable is a big part of how I can make these parts affordable, but I seem to have chosen the path of pain, ha.