Installed S14 VLSD into S13, now i have vibration in 5th gear

[skydragoness]

'Ello people.

Finally got a S14 vlsd installed into my S13. Works fine, my bf works at Nissan and after hooking everything up he put a nice pair of 'eleven's' in the garage. Anyhow. One thing i've noticed since its been installed is a very strong vibration when I am in 5th gear. It only occurs when i left off the gas and let it 'drag'.

As for the car itself, i *do* have aluminum subframe collars and I wondered if its just that. But I find it strange that it only does it in 5th. The car also needs a alignment quite badly, as it had out-of-spec rear toe before it was installed, and my bf supposedly doesn't have time to throw it up on the alignment rack for me. I saw that for the 92 S13, there's a technical service bulletin on ALLDATA that says something about the 5th gear and something that has to do with the transmission. Can't remember specifically. A new noise that has popped up (not when the VLSD was put in, but a week later) is what i think may be a whirring noise coming from the transmission ( i can hear it from my shifter) my bf said maybe it was the throw-out bearing going bad.

Any ideas? And what should i look for next time it's up in the air? Could it be an issue with the driveshaft?

[NISTECH]

Is it related to the speed your going? For example if you throw the trans in fifth gear at 40 mph do you feel the vibration but in 4th at 40 mph it doesnt have the vibration? I am thinking drivshaft but also wondering if the heel /toe set up on pinion to ring gear are correct. If you do determine it is isolated to fifth gear only then you likely have a problem with the fifth gear set in the trans. If you cant get it to do it at 40 mph try it at 50 in both gears. If its the diff its likely going to fall in the 50 to 60 mph range.

The whirring of the trans and you b/f's speculation of the t/o bearing. If it is the throw out bearing it will only do it when the clutch pedal is applied. When driving the car if you can hear the whirring noise from a take off and while you are driving listen to the noise carfully and see if it goes away in 4th gear. If it does its your countershaft bearings [inside the trans]

[skydragoness]

Thanks for the reply Nistech. As far as 5th gear, i noticed it happens between 45mph and 50mph in 5th gear but it goes away when i press the accelerator, as soon as i let off it just vibrates to the point that it resonates in the whole cabin

As far as the new noise coming from the transmission, i first heard it when i started the car when i picked it up from Nissan. I heard like a whirring sound, not very loud, so i put my ear down near the shift knob and it was coming from the transmission, although it was only in idle. I don't hear it while i'm driving, but then again i can't hear much over my exhaust and this screaming noise that's coming from a loose piece of something near the back window. I'm going to go insane. INSANE.

edit: so am i right about the tech bulletin? all i remember from reading it is its isolated to 92 coupes w/ the 5th gear making some humming noise or something. I do have a spare 5spd transmission from my dead white S13 (also a 92, haha) which shifts better than the one in my current S13. And I never remember hearing the 'humming' noise back then in the white car.

[NISTECH]

Will it do it in 4th gear at the same speed?

The TSB your talking about I am not familier with yet off the top of my head. I wil try to get a look on asist today to see what its about.

In the mean time get a look at your fluid in the trans make sure its level is correct just to be safe. Although if the bearings are infact making noise its probably a permanant thing. If you can only slightly hear the noise at idle I would just run it till it gets worse before swapping it out.

[skydragoness]

If your'e referring to the vibration coming from the rear-end, no it doesn't happen in 4th gearI could check the fluid I suppose. My bf and I put in Redline 75w140NS in it in the garage using a pump-gun thingy thru the side fill hole because i couldn't get the short-shifter out that night (couldn't get the snap ring out for the life of me). Did that job in July I think. When i first bought the car (June), the transmission was really pissed about going into certain gears. No grinding, just straight-up resistance to the point that I would have to double-clutch it to get it going in 1st or 3rd. After we changed the fluid to the Redline stuff that went away completely, and the car doesn't have the obligatory 3rd gear grind.

I don't know if this helps with your diagnosis, but i used to take this downhill slope to get to class, speed limit was 45mph, so i'd put it in 5th and just coast down letting the engine keep it at a decent 50mph or so. Before i had my catback put on (which muffles out a lot of little noises but creates new ones) I noticed that if my foot wasn't on the accelerator, and i was coasting down the hill i would hear a slight humming until i dropped it down a gear or put my foot on the gas again. I didn't think too much of it since I noticed the 05 rental Malibu i had made that noise too when i coasted down that same hill w/ no foot on the gas.

[574-240sx]

Does the S14 diff have the abs sensor thing with the little harness pigtail on it.

[skydragoness]

^ I can't remember. It's still sitting at Nissan on their transmission table though. I'll have to call up my bf and ask him.

[NISTECH]

Sky I havent got a look at the TSB's yet. But based on your last post I would say your problem is limited to the trans since the noise/vibration does not occur in 4th gear at the same speed it happens in 5th. You have completely eliminated everthing from the drive shaft back. I wil try to get a look at tsb's tomorrow. I have been flat swamped at work and havent had an opportunity to search for the tsb in asist. Ended the day today with 17hrs flat rate. If your b/f is a tech he can probably explain what that means and what kinda day I had....lol

[NISTECH]

Ok I got it. It is stated as follows." Some 1991-92 240sx models equipped with manual transmission may have a vibration and/or droning noise when driving between 45-65 mph in 5th gear. The vibration/noise will occur ONLY in 5th gear and may be caused by the dynamic balance of the over drive countershaft being out-of-specification. In these cases, the O.D. gears and countershaft will have to be replaced as a set."

These are internal trans parts. Now this TSB is dated very early [april 30 1992] This suggests if there was a problem it would have been identified very early on in the trannies life, it is not something that would come on gradually over time. This gives me the impression this may not be your problem. but in any case the part number for the gear set is 32310-55s5a.

[skydragoness]

Ok I got it. It is stated as follows." Some 1991-92 240sx models equipped with manual transmission may have a vibration and/or droning noise when driving between 45-65 mph in 5th gear. The vibration/noise will occur ONLY in 5th gear and may be caused by the dynamic balance of the over drive countershaft being out-of-specification. In these cases, the O.D. gears and countershaft will have to be replaced as a set."

These are internal trans parts. Now this TSB is dated very early [april 30 1992] This suggests if there was a problem it would have been identified very early on in the trannies life, it is not something that would come on gradually over time. This gives me the impression this may not be your problem. but in any case the part number for the gear set is 32310-55s5a.

You think so? I mean, in other words is it possible for the car to go on in that state (w/ the vibration/whirring in 5th gear) until now? It doesn't sound like a catastrophic transmission failure. Unless, the fact that the gears/countershaft being out of spec causes failure or problems later in the car's life.

So you think my transmission should be fine to go on a while longer? What are the tell-tale signs that its time to swap it out for my other one? Probably what will happen is i'll swap it out when it comes time for a clutch (probably in the spring)

Thanks!!!

[NISTECH]

I dont think it would come on over time like this based on when the TSB was prouced. It seems it came out shortly after the car was manufactured which tells me it rolled off the line with the problem. Its been almost 15yrs since that transmission was built, I would think it would have acted up a long time ago if that was the problem.You can drive the car till it finally goes out [probably wont go into 5th gear at that point.] If it were my car I would hold out till the clutch job. Kinda doin that right now with an oil leak from the rear main. Not gonna fix it till I swap out the auto trans for the 5 or 6spd trannies I have layin in the garage....lol