By Jeff House
“I race a PMFR Pro Mod Suzuki. It’s peppered front to back with many quality PMFR parts, but I recently had an experience that caused me to want to focus on one part that people don’t give a lot of thought about…Sprockets” said Jeff House
Recently I decided I needed to try a gear change. After digging through the wasteland that is my shop, and flipping my trailer upside down I couldn’t locate the PMFR rear sprocket I knew I owned.
Call it Transitory amnesia… or impatience… But I ordered a psrocket from another source, even though I knew better.
I’ve run nothing but PMFR sprockets for years, so when the other brand arrived knew straight away that it was not of the same quality. The bolt holes and the sprocket teeth had sharp, rough edges and the whole finish of the product was not very nice. I convinced myself I was just being picky and that looks don’t matter, so I continued on installing it… covering up my beautiful PMFR rear wheel.
Once installed I adjusted the chain with my normal amount of slack and gave the rear wheel a quick hand spin, it turned about 1/2 of a turn and stopped.
A quick check found the chain I just adjusted was now tighter than the high “E” string on my Stratocaster. Rolling the rear wheel backward a bit saw the chain loosen back up.
For fun I pulled the chain, Mounted a dial indicator to the rear and checked the sprocket. It had a small amount of lateral run out… no real problem… But it had tens thousandths of an inch of radial runout. This caused the chain to be tight when it rolls on one side of the sprocket and loose when it rolls around to the other side.
It’s just a sprocket, but can you imagine what kind of load would be put on things like chains, transmission shafts and bearings (among other things) had I run this ‘out of round Pizza pan’ looking thing?
I found my PMFR sprocket.
It was in the drawer where I usually keep sprockets. Imagine that…
never again… only PMFR for me.
Thanks PMFR for making beautiful and acurate pieces.
– Jeff House
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