Datsun Roadster Forum-311s.org

They revisited my gearbox last year with all new bearings, b.t.w. I talk about a Sr20, CA18 gearbox with a 5 speed. Type FS5W71C, on the bell-house is CA71B or C written. After I build it in it was really quiet for a month, after that he starts slowly makes more noise, When I press on the clutch the gearbox is completely quiet, when I place the gearbox in neutral he starts whining, also when I drive in the 1st, 2th and 3th gear, in 4 he is quit as well.
I know that there are much more of these tranny's are used by you, so please let me hear what you think of this. B.t.w. the bush-pilot and clutch bearing are also new.

First thing I would try is to change the oil.

Sounds like a pilot bushing.. It only makes noise when that is slipping..

I heard a theory where they say that it must be the (front) countershaft bearing because the sound is in al the gears exept the 4th, that is because the countershaft than not works. Why it's wining in the neutral, I don't know, but then also the countershaft turns.
I don't know if Spriso found thes problem as well, because it happens often with these tranny's.

I've had many of these trannys in several 240sx's. Yes, the counter shaft bearing is a common failure point.

Bearing wear is usually a roar, gear wear a whine, just like a rear end. Gear wear is also common especially with turbos as you would expect.

In neutral, ALL the gears are turning. The only thing that isn't turning is the main shaft, so yep neutral noise is common even though there is minimal load. (Hearing gear lash and bearing noise)

It makes no noise with the clutch pushed in because it isn't turning then, the clutch is disengaged, the input shaft is stopped- the whole transmission is stopped.

You might try heavier lube 80-140. You could also add one quart of Redline ShockProof, if that doesn't save the gears, nothing will.

The heavier lube might affect shifting, lightweight shockproof would not. May not matter though, if the gears or bearings fail, shifting is somewhat irrelevent, so not much to lose by trying it.

I also found that they replace that counter-bearing by a closed one, even Nissan oem you can buy in a closed version, an other thing I found was that they filled instead of 3,5l, 5 liter oil in the tranny, because they starving of oil in the front part. (they do this with the Nissan Pathfinder)
And a third option I found was closing the holes in the middle section so that the oil can't go backwards.

If you just replaced the bearings, chances are it isnt the bearings. They usually go for 10's/100's of thousands of miles.

Well, last year after the revision of the tranny everything was quit, It seams strange that the gears are damaged in 8000 miles.

Maybe the gears weren't so great after all? Moderate wear is easy to miss. And add in some drag racing?
Bearing failure is even less likely in that amount of time.

Whine is likely gears, roar is often bearings.

Those trans are generally OK, but won't take much punishment. Some 240sx Turbo KA/SR guys runs Z32 trans w/custom bellhousing. J

Hi Peter, I was thinking about your transmission some more and remembered that a few of the 240 SX boxes did have some whine to them, even with all the upholstery that the 240 has.

I would add 1 pint of lightweight Redline shockproof and see if it quiets things down.

You do not have much to lose at this point, and if nothing fails catastrophically, it could go for a very long time, just a bit on the noisy side.

Up to a quart of shockproof would probably be OK as long as you don't notice any difference in shifting. As far as protecting the gears, I don't know of anything better.

Since today my engine and gearbox are out of the car to do maintenance this winter, I will replace the counter bearing and the big main bearing for a closed type and see then next year how it works. But for next year I keep your product in mind.

I run the Redline MT90 in my trans, and it has held up extremely well to what many would call abuse.. The shockproof is a last ditch ultimate protection.

My friend Sean runs shockproof in the R32 GTR he drag races, and he swears by it..

G M syncromesh fluid also is worth a try sometimes , depending on how loud
I would drain the trans and look for fragments .running on a lift wheels spinning same noise ?
Yes I see its already apart

Thank for the info, I see that I can buy it here in the Netherlands as well, so after the winter I will try the lightweight shockproof into the gearbox and Diff.

For the diff there is nothing better. Will literally save your rear!