Fuel Pump Diaphragm Hardness?

[Dr. Frankenstein]

Does anybody happen to know the Shore hardness of the rubber OEM GL1000 fuel pump diaphragms? I was thinking about trying to rebuild one with some 1/32" Buna-N rubber sheeting, but don't want it to be too hard...maybe 40A? What would be a good hardness?

Here's comparison chart off the O-Ring Store website:

"Durometer Shore A scale is a type of measurement for rubber material hardness. The rubber durometer chart below gives you an idea of the rubber hardness that you want for your application. Generally, most rubber materials fall under the rubber durometer scale of Shore A. If you need a rubber or O-ring durometer that feels like a running shoe sole, review our rubber hardness chart below, then pick Shore 70A. A rubber durometer of Shore 70A is the most commonly chosen material hardness for all applications.
Duro 20A = Rubber Band
Duro 40A = Pencil Eraser
Duro 60A = Car Tire Tread
Duro 70A* = Running Shoe Sole
Duro 80A = Leather Belt
Duro 100A = Shopping Cart Wheel
*Most common durometer"

[gltriker]

Have you seen this Topic in NGW Club ShopTalk? https://www.ngwclub.com/forum/page/ST

https://www.ngwclub.com/forum/viewtopic.php?t=9967

[Dr. Frankenstein]

Yeah; easy IF you have a drill press and a lathe. I was just going to grind off the retainer rings and sketch out another one; maybe get a fine drill bit and run a pin or clip through the centering pin to keep it all in place. I want to replace the diaphragm, not the whole spring and lever. Has anybody else tried it?

[pidjones]

Important to use fabric reinforced nitrile (buna-n) rubber and NOT Viton. Many are enamored with Viton, but it is not as mechanically strong against multiple flex as nitrile. We investigated this at work on diaphragm pumps for helium. The manufacure strongly advised against Viton because of this. We had investigated Viton due to its ozone resistance only.

[Dr. Frankenstein]

I'm currently searching, but do you know anybody who offers fabric reinforced Buna-N sheets in 1/32" thick? That measurement also works out to .035", or .94 mm (the OEM measured diaphragm thickness), which is pretty close to 1mm, which I'll probably try - I just have to Find some first!

[gltriker]

I'm currently searching, but do you know anybody who offers fabric reinforced Buna-N sheets in 1/32" thick? That measurement also works out to .035", or .94 mm (the OEM measured diaphragm thickness), which is pretty close to 1mm, which I'll probably try - I just have to Find some first!

Did you notice this specific detail in the ShopTalk link I directed you to in post #2?

"6: Get a sheet of diaphragm material. I used "GOSS HANDI-GASKET GP12 Diaphragm sheet - Nitrile, Fabric reinforced" It's around 1mm thick. Trace the old shape onto the new sheet and cut it out."

[Explorer]

Or if your existing pump really is toast, you could always wire in an electric pump, there are places to mount it. A lot of people have had success going down that road.

[Sidecar Bob]

I figured using something that was made to be used as a fuel pump diaphragm would be the best bet so I did some online searching and found one that could be modified, then used Peteybug's method to rebuild it
viewtopic.php?p=269684#p269684
It was still working perfectly last summer, 9 years later so I guess it was successful. And the same part I used is still available for the same price.

[Dr. Frankenstein]

Sidecar Bob, that's an awesome write up! Thanks for pointing out that Marxparts gasket!

gltriker the same for your post as well! How much and size was a sheet of the Goss handigasket, and how thick is it? I measured the original at 1mm (1/32", or .99mm), and I *guessing a hardness of 70...? How important is that hardness, to let the pump rubber flex...? A durometer of 70 seems to 'industry standard.'


Amazon has a sheet of 1/32" (.99mm) Buna-N rubber for $6 - might that work too? Ideally I'd like to find a 12"X12" sheet of reinforced Buna-N rubber to play around with, but so far all I can find is the just 'Buna-N sheet." Is that the same stuff?