rumble from gearbox on over-run/decceleration

[jhinchy]

Hi all,
I have a couple of unusual noises from the box in my 99 spec R.
It happens in 3rd, 4th, 5th, but not in 6th. At about 3-4k rpm, i get a rumble or groan from the gearbox, it is very loud. The box behaves perfect in every other way, no problem selecting gears, not jumping out of gear etc, just this rumble on the over-run.
I dropped out the box last night, will probably open it tomorrow night.
Do the dual mass flywheels cause any problems? Im getting a groaning noise when lifting the clutch after a cold start?
Also, should there be a bearing in the crankshaft for the input shaft to locate in? Every other rwd car ive had, has had one, but there was none in my Silvia. Is that correct?
There was a fair bit of side to side play in the input shaft, so im pointing the finger towards the bearings.
Is there any known concern, or anybody actually experienced this problem?

 

[Paddy]

It happens in 3rd, 4th, 5th, but not in 6th. At about 3-4k rpm, i get a rumble or groan from the gearbox, it is very loud. The box behaves perfect in every other way, no problem selecting gears, not jumping out of gear etc, just this rumble on the over-run.
Do the dual mass flywheels cause any problems? Im getting a groaning noise when lifting the clutch after a cold start?
Is there any known concern, or anybody actually experienced this problem?

My 5th gear is noisy, as you say at 3000rpm to 3500rpm, and a noticable vibration through the car too. never found out why though.

because its not happening in all gears, it would suggest to me that its in the gear box itself. maybe a shaft bearing or something like that, but you wont know until you split it.

As for the dual mass fly, personally i think they're a curse, in any car. i've never had any problems with mine, nor have many other people. but any dual mass can die, just like a clutch. 2.0 D4D corolla's, 3.0 isuzu troopers... i've see dual mass failure in them.

The groan when lifting the clutch may be the release fork... try a bit of wd40 on it and see how ya get on.

Btw, are you running any transmission mods? diff/ locking collars/ uprated clutch etc?

And if youre splitting the gearbox, you may want to look into the 4th gear circlip issue.

 

[jhinchy]

I have a paddle clutch, 2 way lsd, subframe collars etc. so it would be quite harsh on a gearbox i suppose.
I done a bit of searching last night into the circlip problem, but i couldnt find any concrete evidence, just seemed to be hear'say. No pictures or advice from anyone that had actually done it themselves.
Im going to split the box tonight, see what it looks like.
The oil was didnt seem to have any metal fragments in it, so i reckon i will probably just put a set of bearings into it, and that should cure it.

Interesting thing about the clutch fork, its not the clutch making the noise, and it couldnt be the gearbox as its not even rolling at that stage. Il check it and see is there any signs of vibration on it.:thumbs:

 

[R-Spec]

Im going to split the box tonight, see what it looks like.
:thumbs:

would be great if you could get a load of photos :nod:

 

[jhinchy]

would be great if you could get a load of photos :nod:

Would be even better if i could fix it:rotfl:

 

[R-Spec]

true

 

[jhinchy]

i stripped the box earlier tonight, and everything seemed in order, but found one suspect bearing on the front of the layshaft. (in diagram labeled "counter gear shaft bearing")
Going to order one of these tomorrow.

does anyone know if there should be a bearing in the crankshaft to locate the input shaft? There was none on my one, and i reckon it might have something to do with the noises im hearing:ghey:

 

[Paddy]

Dont think so.. the crank appears to be supported by 5 sets of shell bearings inside the block and you'd also have a rear oil seal before you can get to them. you'd be looking at a bottom end rebuild to do those bearings.

Tbh, i'd say its mostly the aftermarket parts that would be contribution to the noise. when i put my locking collars in, my G/B got a good bit louder. you much more transmission mods than me, so i can only imagine how much louder over standard it would be.

I know on some cars, when you fit a new clutch to a car, there are alignment marks, ie engine to be at TDC on cly1 etc. I dont know if it applies to the s15, but if it did, it could possibly cause the vibration and groan in the clutch and excessive wear of the g/b internals. I'll have to read up on it though.

As you suspect the layshaft bearing is gone, it may explain the noise in 3rd and 4th.

also while you've the gearbox out, check the flywheel for excessive play. its a sign of it going in most cars.

 

[Nicely]

I agree. You should hear the noise mine makes with a Nismo Super Coppermix and lightened single mass fly....

 

[jhinchy]

Ive just come from an s13 silvia with similar mods and it was a lot quieter. I test drove a few similarly modded 15s before i bought mine, and they were silent in comparison.

The bearing in the crankshaft im talking about is recessed into the flywheel side. Its a needle bearing about the size of a penny.
When the input shaft goes through the clutch splines, it then locates inside this bearing, which supports the input from the front.
Every other rwd car ive had, has used them, mantas, sierras, bmws etc.

Anybody know if there is an online version of the nissan parts catalogue?

 

[Nicely]

Yeah, but this isn't an S13 Silvia. Its a completely different box and fly. Mine was quiet before I uprated all the clutch parts - and it was running 277bhp at the wheels.

There is no online parts catalogue. FAST is available for download to all Contributing Members though (see the announcement at the top of every forum)

 

[Paddy]

Okay, had a look at FAST
I dont see any bearing for the imput shaft to locate. however there is a bush there that 'may' do the same job. P/N 32202-b9500

Also, that counter shaft bearing that yoou suspect. i think i found the P/N for it too. 32219-89f01

For some reason i have it in my head that they'd need measurements of diameter etc. if you have it out, take it to a bearing specialist and i'd say thed have something similar for a fraction of the price.

 

[jhinchy]

The small bearing/Bush, also known as a pilot bearing, i have one on order from the Local dealer,
And the Counter shaft bearing is a standard size bearing, which the local bearing supplier had on the shelf:thumbs:

Progress progress progress

What oil is recommended?

 

[R-Spec]

A high grade good brand API5 I seem to remember
Have you got the box apart yet?

 

[slammedmind]

redline lightweight shockproof, great stuff and only the best

 

[Pazz]

75W-90 SAE - API GL4/5

The manual suggests GLI 4 but I got some GLI 4/5.

 

[R-Spec]

:wack:

A high grade good brand API5 I seem to remember
Have you got the box apart yet?

:wack::annoyed:

Sorry GL4 yeah! I did try to research the difference with GL5 but found it hard. I was trying to find out if it was purely better or if one is more suitable. In the end I did what Nissan said.

GB GL4
Diff GL5 - whats the recommendation on this?

 

[Pazz]

:wack::wack::annoyed:I did try to research the difference with GL5 but found it hard. I was trying to find out if it was purely better or if one is more suitable. In the end I did what Nissan said.

I also didnt fully understand the difference between GL4 and GL5, I always presumed GL5 was better. I went for Silkolene SILKTRAN SYN 5 Gear Oil in the end which has API classification of GL4 & GL5 just to cover my back.

I believe you can also use this for final drive applications such as diff's.

 

[jhinchy]

i have one on order from the Local dealer,
And the Counter shaft bearing is a standard size bearing, which the local bearing supplier had on the shelf:thumbs:

Turns out the bearing supplier couldnt come up with the goods, so i have both bearings on order from nissan, but been snowed under with other work since. I have the box stripped, just waiting on the bits to arrive..