Rick Staples has made some very valid critcisms of my original post
regarding bearings-
> First, to say that Clevite 77, one of the largest manufacturers of
engine
> bearings in the world, makes bearings "not suited for passenger car use"
is
> just silly.
Well, I did go overboard with that, hehehe- lets say I intensely dislike the
characteristics of the CL77 family.
> Millions of vehicles with millions of miles attest otherwise.
> The tri-metal bearing is a tried and true design, used for decades in new
and
> rebuilt engines.
Yes, even GM has occasionally used them in low performance engines,
particularily with forged cranks. 'GM77' is stamped on the back of the
shells. Since the mid 1980's, theres been so many mergers and what not in
the engine parts business, most people will be using Clevite bearings just
because theres little else availible, particularily for older engines.
Clevite 77 is one of those ideas that to my mind is similar to Ford Twin I
Beam- Ford used a dumb front suspension for many years in thier trucks that
approximated the engineering of the competition but was a dumb design when
introduced and became a very well developed and completely dumb design when
they ultimately discarded it and put a properly designed suspension like the
competition had used for nearly forty years already. CL77 bearings are
availible in several varieties, but thier leadership in the bearing market
is largely due to the enourmous marketing resources availible thru the years
thru thier association with larger corporations, rather than the excellence
of this particular product.
> One of its features is, in fact, that it IS EXTREMELY "EMBEDIBLE",
> contrary to the above quote...
This SHOULD be true, but doesnt seem to be the case in service- Factoring
out rebuilt engines, which are real wild cards, I have to tell you, I've
never seen a GM assembled engine using a tri-metal bearing that hadn't
significantly damaged the journals thru abrasive wear. This is interesting
to me, as I have almost never seen damage to a journal using either real old
school tin/lead type bearings, or M100-M400-M500 types. A special horror is
discovering wear on journals on Tufftrided forged cranks out of many types
of sixties GM engines. Cranks like this quite often remain 'oversize'
(Tufftrided Cranks gain a thou or two from the hardening process) post
200,000 miles on M400's. I suspect the abrasive particles that damage cranks
in normal operation may be of some size/configuration that embeds into, or
is retained by M400 better. Certainly, you see much more evidence of
embedded contaminants in a aluminum bearings generally upon disassembly. It
seems the thin babbitt overlay wears off the tri-metal type bearing on the
first turn of the key virtually.
Your remarks about cleanliness and preperation are right on the money- I've
dissected a few engines that had bearing troubles that had evidence of the
abrasive material that had been used to polish the journals still sitting in
the oil journals more than occasionally. Most 'engine mill' machine shops
take very little care in assuring bearings have a proper environment and
that things are clean and correctly fitted.
Essentially, my experiences with CL77 is even with perfect assembly and
clearances, they will not adequately protect the crank journals, although my
expectation of adequate protection is ZERO wear and surface abrasion of the
journals. This is quite ordinarily possible with aluminum bearings, but so
rare with tri metal types, I've never seen an unmolested journal in tandem
with a tri metal type. That said, they seldom wear to a point that they
fail, either- but it is a real mess in there if you ever do subsequently
wish to rebuild/service it. Very few could be just polished, most needed
turning.
For reference, heres a couple pages
Clevite's page
http://www.engineparts.com/tech/brgselec.html
Moraine '400' type- the specs listed for the "A-400" are the spec for M400,
actually-
http://135.145.6.78/ProductsCombined/OEProducts/ProductsforAllOE/Powertrain_
Systems/Powertrain_Products/eb-mmp-alumb.html
Clevite 77 type bearings;
http://135.145.6.78/ProductsCombined/OEProducts/ProductsforAllOE/Powertrain_
Systems/Powertrain_Products/eb-mmp-copperc.html
If you click 'next' and 'previous' theres a few other types of beaing and
thrust washer styles discussed also, such as configurations for automatic
transmissions and other vehicluar applications.
Incidentally, the 'search' function on the FM site is pretty good, you can
look into many different products-
I will do some digging in coming weeks to see if in point of fact the
aluminum bearings ARE availible from FM. Up til now, I've just been using
NOS GM M400's, as they're still around in large numbers if you dont mind
digging a bit.
Much comes down to personal preference and experience, however, for what my
opinion is worth, I certainly feel M400 style aluminum bearings are better
for the vast majority of people. Enjoyed your post very much Rick!
Kind Regards,
Brent Covey
Vancouver BC
regarding bearings-
> First, to say that Clevite 77, one of the largest manufacturers of
engine
> bearings in the world, makes bearings "not suited for passenger car use"
is
> just silly.
Well, I did go overboard with that, hehehe- lets say I intensely dislike the
characteristics of the CL77 family.
> Millions of vehicles with millions of miles attest otherwise.
> The tri-metal bearing is a tried and true design, used for decades in new
and
> rebuilt engines.
Yes, even GM has occasionally used them in low performance engines,
particularily with forged cranks. 'GM77' is stamped on the back of the
shells. Since the mid 1980's, theres been so many mergers and what not in
the engine parts business, most people will be using Clevite bearings just
because theres little else availible, particularily for older engines.
Clevite 77 is one of those ideas that to my mind is similar to Ford Twin I
Beam- Ford used a dumb front suspension for many years in thier trucks that
approximated the engineering of the competition but was a dumb design when
introduced and became a very well developed and completely dumb design when
they ultimately discarded it and put a properly designed suspension like the
competition had used for nearly forty years already. CL77 bearings are
availible in several varieties, but thier leadership in the bearing market
is largely due to the enourmous marketing resources availible thru the years
thru thier association with larger corporations, rather than the excellence
of this particular product.
> One of its features is, in fact, that it IS EXTREMELY "EMBEDIBLE",
> contrary to the above quote...
This SHOULD be true, but doesnt seem to be the case in service- Factoring
out rebuilt engines, which are real wild cards, I have to tell you, I've
never seen a GM assembled engine using a tri-metal bearing that hadn't
significantly damaged the journals thru abrasive wear. This is interesting
to me, as I have almost never seen damage to a journal using either real old
school tin/lead type bearings, or M100-M400-M500 types. A special horror is
discovering wear on journals on Tufftrided forged cranks out of many types
of sixties GM engines. Cranks like this quite often remain 'oversize'
(Tufftrided Cranks gain a thou or two from the hardening process) post
200,000 miles on M400's. I suspect the abrasive particles that damage cranks
in normal operation may be of some size/configuration that embeds into, or
is retained by M400 better. Certainly, you see much more evidence of
embedded contaminants in a aluminum bearings generally upon disassembly. It
seems the thin babbitt overlay wears off the tri-metal type bearing on the
first turn of the key virtually.
Your remarks about cleanliness and preperation are right on the money- I've
dissected a few engines that had bearing troubles that had evidence of the
abrasive material that had been used to polish the journals still sitting in
the oil journals more than occasionally. Most 'engine mill' machine shops
take very little care in assuring bearings have a proper environment and
that things are clean and correctly fitted.
Essentially, my experiences with CL77 is even with perfect assembly and
clearances, they will not adequately protect the crank journals, although my
expectation of adequate protection is ZERO wear and surface abrasion of the
journals. This is quite ordinarily possible with aluminum bearings, but so
rare with tri metal types, I've never seen an unmolested journal in tandem
with a tri metal type. That said, they seldom wear to a point that they
fail, either- but it is a real mess in there if you ever do subsequently
wish to rebuild/service it. Very few could be just polished, most needed
turning.
For reference, heres a couple pages
Clevite's page
http://www.engineparts.com/tech/brgselec.html
Moraine '400' type- the specs listed for the "A-400" are the spec for M400,
actually-
http://135.145.6.78/ProductsCombined/OEProducts/ProductsforAllOE/Powertrain_
Systems/Powertrain_Products/eb-mmp-alumb.html
Clevite 77 type bearings;
http://135.145.6.78/ProductsCombined/OEProducts/ProductsforAllOE/Powertrain_
Systems/Powertrain_Products/eb-mmp-copperc.html
If you click 'next' and 'previous' theres a few other types of beaing and
thrust washer styles discussed also, such as configurations for automatic
transmissions and other vehicluar applications.
Incidentally, the 'search' function on the FM site is pretty good, you can
look into many different products-
I will do some digging in coming weeks to see if in point of fact the
aluminum bearings ARE availible from FM. Up til now, I've just been using
NOS GM M400's, as they're still around in large numbers if you dont mind
digging a bit.
Much comes down to personal preference and experience, however, for what my
opinion is worth, I certainly feel M400 style aluminum bearings are better
for the vast majority of people. Enjoyed your post very much Rick!
Kind Regards,
Brent Covey
Vancouver BC
