Rb20Det 4Th-3Rd Crunch

[mrsr32]

whenever i shift from 4th to 3rd, it crunches, going from 2nd to 3rd is no where near as bad.

any ideas on what is goign to break?

i think i might try some heavy weight shock proof in it?

[GTSBoy]

It's worn synchro(s). It's normal. It's not right, but it's normal.

Lightweight Shockproof will help. Learn to slow down your downshift or learn to rev match your downshifts.

[Seano350GT]

give redline shockproof a shot, might do your box some good. If you leave it unactioned it will get very bad over time

[mrsr32]

should i go lightweight over heavyweight?

[niZmO_Man]

lightweight I believe. Thinner oil = easier for synchros to spin? (I got that from the apparent used car yard trick of putting auto trans oil into worn manual boxes).

[Seano350GT]

lightweight I believe. Thinner oil = easier for synchros to spin? (I got that from the apparent used car yard trick of putting auto trans oil into worn manual boxes).

my mech thinks the heavier grade the better. If it's too light it causes problems. That's why i'm switching from Amsoil gear oil to genuine Nissan supposedly some of the guys that run aftermarket oils on my gearbox have problems.