Gear Box Grinding Noise At Adle In Netural

[PHATR32]

hey guys,

My gearbox is making a grinding/whining noise at idle when its in netrual.

When i push the clutch in, the noise goes away.

What happened was, i had everything out, so all the oils were drained.

I put the box and engine back in, and for a while i let the engine idle while i was sorting out small prblems etc.

the thing is there wasnt any oil in the box or trasnfer.

I never drove it with out oil, it just sat idling and after a while it started making the noise.

even now with new oil in everything it still makes the noise, i though if i drove it slowly sround the block the oil would spash up on what ever is grinding and stop making the noise but it hasnt stopped.

have I damaged something??

steve

[Mr GTS4]

my gtr box does the same thing. don't know. i changed the oil in both box and transfer case and it wasn't as loud but yeah don't know exactly what it making the noise

[PHATR32]

scary thing is when i first started the car it wasnt making the noise.

Unless i didnt hear it over the sheer excitemnt of starting my car for the first time in over a year!

steve

[Tommyk]

Its to do with the thrust bearing or spigot bearing or whatever its called. There are two cases. one where it makes a noise when the clutch is pushed in (which is what i had) and the other is when you have the clutch depressed and it makes noise. You need to remove the clutch and box and replace one of the bearings

[benm]

Thrust bearing / Spigot Bush ?

Mine used to do that and that's what the cause of the problem was!

[PHATR32]

no its not that, the noise seem to be coming from withing the box.

sounds like metal ginding metal.

[krizza_ca18det]

Symptoms point to it being the input shaft bearing, mine makes quite a racket after the box has warmed up. When the box is in neutral and the cluch is not depressed the input shaft is turning, when the cluch is depressed the flywheel is disconnected from the gearbox. You might want to get onto it before the hardening is worn off the shaft.

[PHATR32]

spew, i would have though that the oil would quieted it up a bit at least.

[Syphon]

deleted cause I am a retard

[PHATR32]

well i hope yous a right!! im a dickhead for not changing it while the box was out.

it noise doesnt bother me, i was just worried it was the box it self!

thanks guys

steve

[wrxhoon]

Sorry but that information is incorrect.

The input shaft is always turning, whether the clutch is depressed or not, end of story. The spline feeds into the flywheel which obviously is bolted to the crank. When the motor is turning, so is the input shaft

Noise when in neutral and clutch out, thrust bearing

Noise when clutch is either in/out, driving through gears = most likely input shaft bearing = rebuild not too far away.

Noisy thrust bearings are pretty common, few hard launches seem to get em grinding away. If it bothers you that much, you can remove the box, and just replace the thrust bearing and throw it all back together. Honestly I would keep driving it until the clutch is fubar, and replace the whole lot in one go. Thats what I would do, doesn't mean its correct way to approach it haha.

I think you will find you have it wrong here .

When the car is stationary and engine running the input shaft is turning but as soon as you depress the clutch it will stop turning in a few seconds .The flywheel still turns, the pressure plate still turns but the clutch plate is not touching the flywheel and the pressure plate so its not turning !!

When the car is moving then yea the input shaft is always turning the same speed as the engine but as soon as you press the clutch in they can turn at different speeds as they are not touching any more.

Say you are going 120 kmh and the tacho is showing 3000rpm clutch in the tacho is now 800 rpm or whatever the iddle speed is set at . Thats because the the clutch is not touching the fly+ pessure plate .

I hope you can understand how it works now ..

Now to FHTR32's problem . It sounds like when you started the engine and you had no oil in the gearbox the input shaft bearing ran dry and you did some damage there thats the reason it stops when the car stationary and clutch in ( as the shaft is not turning ) To test if thats it drive at say 60 kmh down a hill somewhere in say 4th gear then put your foot in the clutch if the noise is still there thats probably it then take it out of gear and see if the noise goes away but you still have to have the clutch pressed in .

If the noise is very bad you should take the box out and replaced it , if its a very mild noise leave it until it gets worse .

When you do a clutch you should always change the thrust bearing too . I assume you a skyline so it will have a spiggot bush not a bearing .

[PHATR32]

SH!T!!!!

i just remembered!!!!!!!!!!!!!!!!!!

the spigot bush is in the center of the flywheel right? and the tip of the shaft sits in the middle of it? mine didnt have one!

steve

[wrxhoon]

SH!T!!!!

i just remembered!!!!!!!!!!!!!!!!!!

the spigot bush is in the center of the flywheel right? and the tip of the shaft sits in the middle of it? mine didnt have one!

steve

Yes thats the one and its brass, How can you say that yours didnt have one ? IF it didnt you should drop the box out and put one in there . $12 for the bush and 3-4 hours work to R+R g/box .

[Syphon]

Woops my bad, I should really read my replys before I post, I didn't explain that very well rofl

wrxhoon is spot on

[PHATR32]

sh!t! will there be any damage cause if there isnt one there?

steve

[Cubes]

I'm with wrxhoon on this one..

----

If the spigot is not there do not drive it as there is no support for the input shaft.

You have most definitely damaged the input shaft bearing if not furthur down the line.

A mate of mine accidently forgot to remove the auto spigot and use a manual item.

We replaced the spigot, instantly it was better but still very grindy and vibraty.

His box has since been driving around for ~1year, still hanging and grinding in there.

[Bl4cK32]

I'm with wrxhoon on this one..

----

If the spigot is not there do not drive it as there is no support for the input shaft.

You have most definitely damaged the input shaft bearing if not furthur down the line.

A mate of mine accidently forgot to remove the auto spigot and use a manual item.

We replaced the spigot, instantly it was better but still very grindy and vibraty.

His box has since been driving around for ~1year, still hanging and grinding in there.

wonder who that could be

Such a simple thing, can mean a wasted afternoon, and a few skinned knuckles.

Im amazed how tough the r33 box is though. Around a year of abuse behind the 3lt, with shagged bearings, and it still hangs in

Edited February 24, 2006 by Bl4cK32

[T04GTR]

dude. oil is your friend

with it ideling in neutral the gears in the box are spinning at engine speed!

the transfer case will be sweet as it only spins as you drive

chances are youve damaged a bearing in the box from no oil. if it makes a knocking type noise. one of the roller bearing "cages" has broken.(the metal cage that seperates all the ball bearings in a roller bearing)

did heaps in my old dr30. not from no oil just revs.

the noise will only get louder. so start saving for a box

sorry to put the scare on but the reality is it is dying now

[PHATR32]

great, thats exactly what i needed at this point in time. the freaking piece of crap isnt every registred yet.

stupid thing is i noticed it didnt have the bush, so i checked the shop manual and it didnt mension anything about a spigot bush or bearing, so i just assumed it didnt have one.

was gonna ask on the forum but i completly forgot.

also, when i took the box and clutch out it didnt have one, so the owner in japan must have been driving around with it like that. except it didnt make this noise till after i pulled it apart.

dam it

steve

[T04GTR]

dude. oil is your friend

with it ideling in neutral the gears in the box are spinning at engine speed!

the transfer case will be sweet as it only spins as you drive

chances are youve damaged a bearing in the box from no oil. if it makes a knocking type noise. one of the roller bearing "cages" has broken.(the metal cage that seperates all the ball bearings in a roller bearing)

did heaps in my old dr30. not from no oil just revs.

the noise will only get louder. so start saving for a box

sorry to put the scare on but the reality is it is dying now

ps.. the bloody input shat bearing is the last to go. its quite large.

the first one to go is the countershaft bearing on the sandwich plate. or the input shaft gear itsself.

this is speaking from experiance having poped 12 fj20 boxes over the past

by the sound of it youve iether galled a mainshaft bearing(most likly)(the ones the driven gears spin indipendantly on)

or done a sandwich plate countershat bearing.

either way. its easy to check anyway. if its noisy in 1st. its the counter bearing.

if its noisy in 2nd or 3rd its the maishaft ones.

if the noise goes away in 4th its the input shaft gear(very unlikly)

other than that just drive it and find out what gear its noisiest in. try to keep the revs at around 2000rpm in each gear so you can acuratly guage the noise

hpoe that helps