Grinding when shifting down to 4th

[SRDarkcyde]

I was just wondering what kind of diagnosis you guys would have on this current problem I've be having. What has been basically happening is that when I shift down to 4th from neutal and my speed is above 45mph, I hear this grinding sound when I try to stick it in 4th, as if I'm grinding my gears. This only happens though, if I am at 45mph or above, if I'm at 40, then this doesn't happen. And I know it doesnt have anything to do with a mis-shift or not pushing the clutch all the way, because it is extremely consistent. What is your feedback guys?

[TokyoNights]

it could be that your 4th gear synchro is bad..what happens if youre going over 45 then push the clutch in and rev it up then down shift to 4th? if you match the revs is wount grind then youll know its the synchros.....

[DMC]

it is most likely your synchros i have the same problem with my fifth, is it hard to fix?

[Hikarispeed]

I have similar problems with 2nd and 3rd. Upshifts to 2nd and 3rd take a very long time. Downshifting from 4->3 and 3->2 at respective higher speeds require blipping the throttle with no problems.

[sykikchimp]

some redline tranny fluid helped my synchros a lot. gear box shifted much smoother.