Just posted in DIY thread-Rebuild of Hill Tensioners

If only it was as easy as that The bearings we use have to be made for us (painfully, on a 6 month lead time I might add...) and have a much longer part number that specifies the unique bearing precision, clearance, cage specification and grease code amongst other things. The full part number is never put on the bearing itself but always on the bearing packaging. Its quite a common mistake to presume that a standard off the shelf bearing with the same "short code" will do the same job. In a non critical application where a I would say its not a problem - this application is however a completely different kettle of fish!

 

Well this thread just got doubly interesting...

I have to side with Paul on this one.

I was the Logistics Manager (for 5 years) for a DS/GS (Direct Support/General Support) military maintenance facility, and know, specifically with NSK Bearings, the 'short' number, as Paul called it, is only part of the story.

M1A1/A2 Main Battle Tanks, M2 Bradley's, MLRS (Multiple Launch Rocket Systems) all use specialized, non-standard parts, but very often will use the frame, or basic pattern, of an off-the-shelf bearing, but have very specific internal tolerance specifications, speed specs, grease specs, etc.

Pretty standard, but not well-known, stuff in the world of specialty or military-specific parts.

Mike

 

Sometimes A Mil-Spec part number can be assigned to an 'off the shelf' part, that has been 'verified' under test or inspection to comply with all requirements of the Mil-Spec. Because this testing and verification costs money, the price of the part goes up.

However Mil-Spec parts can also be modified versions of an OTS part, it is generally made to more stringent tolerances. Manufacturers will test and measure all parts made and those that meet Mil-Spec are marked as such and those that do not pass but still meet the requirements of a commercial spec, will receive a different part number. So yes lead times can depend on the 'yield' of parts manufactured, that meet the Mil-Spec or a higher standard.

Then there are Part Designs or Mil-Spec parts made, that are never allowed to be used beyond the Military or commissioning party. Those that pass 'test or meet spec' are used and the rest are destroyed. This may not apply here but it can give one an idea of why Military expenses can be very high.

 

So as a side Paul, are your tensioner bearings rated to go 30,000 miles? I am planning to use them on my upcoming major. And thanks for providing us with a clearly superior product.

Henry

 

+1! I have a set that's currently being installed on my car. Now I have to decide if I should spring for the throwout bearing and flange...

 

Throw out bearinig emphatic YES. Flange probably not. Depends on which flange your car uses. Mine (a '93 Serie Speciale) did not need the flange.