I read the "lugging" thread and thought of this. A friend with an 85 Toyota Celica 4-cylinder & 5-spd trans said he "oversped the trans". I assume this means he overcame the clutches ability to keep the engine engaged to the driveline, but I don't want to make an "a--" out of "u" and "me"

 

I don't think you could overcome a clutch unless it was slipping already, and at least in my experience, in those little 4-banger 5-speeds, the transmission is tougher than the engine.

 

When your friend says he oversped the trans, it means whatever he meant. Probably either a slipping clutch or bragging, or too high RPM in low gear.

Usually over speeding the trans means you are over reving it like staying in first gear at 60 mph or something like that. Or with an automatic, winding it up to maybe 8,000RPM in neutral.

There is a an overspeed where an automatic transmission does not have sufficient lubricating capacity to keep the tranny alive past a certain sustained road speed.

From other web site reading, some of the chebby trannies(4L60 in that case) will fail if you sustain over 120mph for long periods. The tranny will easily handle something like 150mph for short runs, but prolonged runs above 120 cause the tranny to overheat and fail. I suspect this is true of most typical auto trannies, and maybe manuals.

The fellow who discovered this got to pay lots and lots of money to get his tranny to live at sustained 150+ speeds on the Autobahn.

Most of us never see this kind of sustained speed so it never becomes an issue. However, winding it up in low gear or neutral has killed many a young boy's tranny, speaking from experience long ago.

Just my opinion,

Jim Henderson