the same! Order the correct part number!
 For those of you who must replace rubber parts that are no longer available, see the rudimentary fluid compatibility chart below. Please don’t use this information to replace critical parts. If you do, you’re a “test pilot”. When selecting a replacement rubber part, note that rubber compounds are available in different hardnesses, usually on a “durometer” or “shore A” scale. Industrial suppliers such as McMaster-Carr Supply are a good source for rubber because they actually tell you what kind of rubber you’re buying (as opposed to your local hardware or auto parts store).
Mechanical Rubber Seals
Mechanical rubber seals are usually categorized as “static” or “dynamic”. Dynamic seals, such as o-rings, are those that are trapped into a cavity while another part slides across the seal. Dynamic seals are usually engineered precisely and are intolerant of incompatible fluids, poor metal surface finishes, and incorrect squeeze (the amount that the seal is compressed when installed). An example of a dynamic seal is the o-ring for a brake caliper piston. Static seals are usually trapped between two parts ( i.e. a valve cover gasket) and cannot move. Static seals are usually more forgiving and cause less problems.
Temperature
The rubber compounds listed in the chart will tolerate the temperature range of –40oF. to +225oF. Generally, rubber will become very stiff and possibly brittle at the lower end of the range and soften considerably at the high end.
Pressure
For rubber seals such as brake system o-rings that will be subjected to high pressure, use only correct replacement parts from a reputable supplier. The rubber parts are frequently manufactured to close tolerances and an incorrect replacement can fail under pressure.
-- Dave Evans
Fluid Compatibility Chart
| Fluid |
Compatible Rubber
Compound |
| Auto Brake Fluid |
Ethylene Propylene (EPR or EPDM) |
| Gasoline (with or without Ethanol) |
Buna-N (Nitrile) |
| Antifreeze (Ethylene Glycol) |
Buna-N (Nitrile)
Ethylene Propylene (EPR or EPDM)
Neoprene
Butyl |
| Automotive Oil, Petroleum Base) |
Buna-N (Nitrile) |
| Grease, Petroleum Base |
Buna-N (Nitrile) |
|
|
Reflections on a Trip to Grand Rapids
 I drove over to University Motors Ltd last weekend (Nov. 20). I have made this trip many times in the past 25 years. So have others in the club. UML Summer Party weekends, tech sessions at the shops on 614 Eastern Ave. and on Fulton St, UML anniversary parties…..many have attended and enjoyed these events. But this time it was different.
John Twists’ University Motors had become a victim of the recession climate affecting the entire country, and Michigan in particular. It had been announced on the University Motors Ltd. Website that fulltime business would cease on July 1, 2009, after 34+ years of service to the MG community. Service indeed. And now John was liquidating his business with an auction of tools, parts, shop equipment, and MG memorabilia. There were 252 lots to be auctioned, including a 1977 MGB you could have driven home.
I went to the shop on Friday afternoon to see John, and to preview the auction items. There were 3 or 4 others there as well, and John seemed to be in good spirits despite the circumstances. Many of the items were familiar, having been in the shops at Eastern Ave. and Fulton St. But this just wasn’t any fun for me.
The auction was held at 10:00 on Saturday. I arrived around 8:00 and John, always the gracious host, had a pot of coffee brewing. The auction company people arrived soon after. I would estimate around 150 people were there at the auction start, the Long Distance Award going to a guy from Nebraska. Several other CMGC members were there as well. John said a few words to the crowd, even referring to the event as being something like a Summer Party. Now that’s class.
The bidding was fast paced, the auction guys did their job well. There were great buys on shop equipment. You could have had a 2-post car hoist for about a third the cost of a new one. And that 1977 MGB went for a little over two thousand dollars. Well bought, as they say in the auction business. Everything went to a good home, I’m sure, which is just what John wanted. I brought back a Castrol University Motors Ltd. sign that had hung in the Fulton St. shop. It will have Pride of Place in my garage. There are tons of parts (literally) in the storage building, I’m not sure what will happen with these. Need anything for your MGB, call John.
With this event behind us now, I’m not sure what to predict for the future. I feel however, that we have not seen nor heard the end from John Twist. He indicated that he would try to be at the CMGC swap meet in February. Its hard for me to put a positive spin on all this, but in John’s own words when announcing the End of the Road….”All good things must come to an end. It’s been a simply wonderful run!”
-- George Goeppner
From all of the MG contingent…
Thank you John
Cover photo courtesy of George from his trip.
|
December 2009
