At 10:07 AM 5/20/00 -0700, Scott Meyers wrote:
>A recently installed used 5 speed transmission (70,000 miles advertised)
>is a vast improvement over the original, but it scrapes a little going
>into third gear, up or downshifting.......sometimes. If I drive it like
>an old man and take a lot of time between gears, it rarely scrapes.
>1-2-4-5 are all fine (87 Nissan 200SX).
>I put 80/90 weight tranny good quality generic fluid in it upon
>installation last week. It also mentions having a posi additive - FYI in
>case it matters.
>I hear from some that ATF fluid is preferred. Hmmm. Maybe.
>Which will help this problem more - heavier fluid, a fluid 'additive',
>or the lighter ATF fluid? Please forget expensive synthetic fluids -
>outside budget here.
When I wore out the 2nd gear syncro in my Lotus Europa transaxle, it would
"scrap"/grind up or down with synthetic gear oil. Conventional oil "solved"
the problem . . . but only until the gearbox warmed up which only took a
few miles. New syncro solved the problem! I think that what is happening is
that there is not enough syncro "rubbing" material left to serve as the
"friction" surface which gets the two parts to match speed. Slow shifting
just gives the gears time to match speeds on the upshifts. Double clutching
will work for downshifting.
Pretend that you are driving a "dogring" gearbox like my current autocross
85 Van Diemen RF-85 Formula Ford