On Nov 12, 11:33am, banta@abingdon.eng.sun.com wrote:
} >>non-detergent oil in my xxx gearbox because of problems with the
syncro rings???
} >Rumor has it. Apparently some synchronizer rings are coated with
} >[something] that the detergent removes, which accelerates wear. I
} >seem to recall that Alfas are the main victims of this user error
} >and I don't know whether or not British cars succumb to it. I
The source we've had for this is Phil Either, and his mechanic's
comments on Spridget trannys. I haven't been able to verify
this yet, but it may be a good Idea to write to some places like the
SpriteMidget Centre, or Spridgbits, in England, or other places
that do extensive work on this stuff. How about John Twist, @University
Motors, probably the most published MG tech writer in this country?
It still sounds a little strange to me. these are wear surfaces,
and a coating/treatment may not last long anyhow.
} I've also heard that some synchros are sintered with some oil that
} the detergents leech out and "clean" away.
Uh, er, that's a little on the fuzzy side. This comment may have
origin in the nature of many bearings, commonly reffered to as
"Oilite" bearings. From Machinery's Handbook, 16th Edition (c) 1959:
"Pourous Bearings.- These are usually made from plain or leaded bronze,
... and are made from powdered metal that has been pressed into shape
and then sintered, [which means "to heat without melting" -rg]
producing a spounge-like structure capable of absorbing large amounts
of oil, usually about 25 per cent of the volume of the bearing
material. These bearings are used where lubercation supply is
difficult, inadequate, or infrequent. This type of bearing should be
flooded from time to time to resaturate the metal."
(goes on to list loading, temperature ranges, etc.)
A common example of oil-lite bearings:
Trans. shaft pilot bushing in the end of the crank.
(which explains why you don't want to use grease here, but oil.
Grease will plug the holes, the rest will get worked away.)
Some older cars would have used straight brass- grease is the
answer here. Modern cars use a sealed bearing.
Oilite may also be used for internal transmission bearings.
You can tell by looking closely- solid bushings are smooth, oilite
look duller, and close examination reveals their pourous nature.
You shouldn't machine the bearing surface of oilite- get the proper
ID bushing.
Keeping oilite happy: Most reccomendations were to use standard & light
weight oils. Now lets go one better:
10 years ago, I was working for NCR, (printer division) and we had/did
very extensive research on bearing lubrication. It was found that a
high shear oil performed much better. ATF was about the best thing
going. (Gear oil is too heavy here) So, to re-lube your oilite
bearings, use ATF. Immersing for a couple of days should be good.
Even better- use a vacum jar- first put your container of ATF
in and purge the air. Then drop in your bushing, and purge again.
When you let the pressure back in, oil will be forced into the bearing.
Let sit for a couple hours. Works real well.
On Nov 12, 11:10am, Dick Nyquist wrote:
} I have heard that once converted to 90wt it's best to stick with it.
} Going back to 30-50 after many miles on 90wt may not be a good idea
} unless you are rebuilding th box.
Ptooey. Use 90 wt Hypoid gear oil where reccommended, it is designed
to stand up under high shearing forces, as ATF. Reccommended for
most rear ends, and for most Big American Transmissions, but not
most British transmissions. It's so thick, that it slows your
syncro action, making shifts more difficult, and causing more
wear. The British transmissions don't require the high-shear oil.
The problem with detergent oils should have something to do with
their holding contaminents in suspension, which would make the
oil more abrasive, and may lead to more wear. They may also have
poorer film charistics.
Bearings subjected to high speed, and light pressure require fairly light oil.
Reccomendations: Straight 30 weight, or other non-detergent may be good.
Running a detergent for a *SHORT* time can help clean things out,
and free up sticky syncros. ATF, often used in todays manual
transmissions (And, may also have been used as the break in oil for
TR transmissions, to be replaced at the first change. I'll have to
confirm that.), can do wonders for a sluggish transmission.
You can run ATF in many manual boxes continously.
Disclaimer: there are exceptions! I'm not sure exactly what
the reasons, but ALFA's require a specific characterisitc, and therefore
type of oil.
________________________________________________________
Roger Garnett (garnett@BATCOMPUTER.TN.CORNELL.EDU)
The South Lansing Centre For Wayward Sports Cars
"All donations of stray, orphaned, odd, neglected, etc.
sports cars and bits in need of a good home accepted."
"The drop off bin is right there- behind the barn..."
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