WillieA

I recently rebuilt my Topeak Joe Blow Sport Twinhead pump head. It was leaking badly and needed new o-rings. The reason for this post is to document the exact o-rings used. I know you can buy a replacement head (for $30+), but what fun is that? I like to repair stuff, and it is very satisfying to have my Twinhead now working like it was brand new.

The important thing to note is that Topeak used not one or two sizes of o-rings in this head, they used THREE DIFFERENT sizes of o-ring. Clearly this is a case of engineering with no intent to repair. But luckily, o-rings come in standard sizes and with a little detective work, I was able to deduce the correct sizes.

To rebuild, one has to remove both nipple adapters with rubber inserts, unscrew a slotted nut on one side of the head, remove the (yellow) lever, and push out a sliding plunger which enables the head to do its thing. The nut, the lever and the slider all have different size o-rings, to wit (note that all the o-ring designations below are per AS568B, an SAE aerospace standard):

• the nut uses a 011 o-ring (available from Danco as their #6 package, confusing, I know)
• the lever uses a 012 o-ring (Danco #7)
• the slider uses two 013 o-rings (Danco #41)

All of these Danco items are available at a certain USA orange home supply chain in 10x quantities. Ace Hardware in the US has them in single quantities at a reasonable price. I am affiliated with no hardware retailers. Please note that these are for the original Joe Blow Sport model - YMMV if you have a different pump head.

Reassembly is the reverse of disassembly, with lots of silicone grease and care reinserting the slider so that its o-rings are not pinched in the lever holes. If there is any interest in this, let me know below and I'll re-repair my Twinhead and take pictures. I simply wanted to document the o-ring sizes for the Greater Interweb.

Willie