In a message dated 7/22/2005 8:04:18 AM Pacific Standard Time, 13brv3@bellsouth.net writes:

Back in 2002, the attached pictures were distributed, showing what happens when the o-ring fills the groove too completely.  

 

Thanks for the amazing picture Bill!   I'm as guilty as anyone when it comes to trying to "improve" the design, but sometimes we need an example like this to remind us that Mazda has spent way more time and money getting this right, than all of us combined could ever imagine.   

 

Cheers,

Rusty (going to be hard to run a stock single rotor Mazda though)

Just for reference guys,

 Most fluid o-ring seals fill between 75-85% of the groove WHEN COMPRESSED. That means that the o-ring will be above the groove about 25-30% before assembly. The diameter of the o-ring will USUALLY leave about 30-40% of the width of the groove visible BEFORE ASSEMBLY. To my eye this has always looked like too much free space, but like many other engineering items has been established by breaking parts like in the picture. If you live in the USA you can get a phamplet circular from Parker which shows the gland (the o-ring groove) sizes for most standard size o-rings. usually available for free. They have a larger catalog that shows how to calculate the o-ring and groove sizes. This is avalable even from the cheapest sales shops for a few bucks. Highly recomended if you plant to size o-rings. There are signifigant differences between TYPES of groove seals as well; the rotor housings are a static face gland. Parts that move or rotate have different sized grooves and more importantly different surfaces finishes. (roughness or the lack of it!)

 

Bill Jepson