VLSD Installed, Now Loud Strange Noise

[moyea]

I finally had my S14 VLSD installed on my S13. I used the S14 bushing and order some half-shafts from some other guy. One long, one short. Once installed the car makes this loud WRRRRRRRRRRRRRRRRRRRRRRRRRRRRRMMMMMMMMwhen I slow down to a stop. Its embarassing and loud! No driveability issues yet! Its hard to tell if this install has changed anything at all. The VLSD was sitting in my garage for long period (no oil in the housing). I hope this is not a bad diff.

Please help!

I'm concerned it might fail and kill me!

[tiger]

lsd's make a soft humming/winding type of noise... It shouldn't be bad..... i'm assuming you put oil in it... So have you tested it out yet? If you can feel it working then it's good... shouldn't be too loud where it's embarrassing. If it is, I dont know what it could be... get thicker oil in it... that's the only thing I can think of.

[moyea]

I'm sure there is oil in it but I'm going to drain and fill it again in a few days. I want to see if there is anything in the fluid that might indicate damage (metal flakes, etc.). I'm not sure what fluid was put in it at the time of install because I didn't install it myself but I plan on putting a GL-5/ 80W-90 like Mobil 1 and maybe a friction additive. I hoping it wasn't installed incorrectly. I am aware that some degree of noise is expected but if you were riding with me you'd be like "Jesus"!

As far as locking, I'm not sure. At times I feel I can accel out of corners at higher speed but this may be a percieved feeling. I recently installed some KYB AGX & Eibachs so it may be due to the lower center of gravity and reduced body roll. I haven't drifted with it yet because I wanted the gasket to seal up, nice a good first.

Another thing to add is when it was up in the air, after the install, I spun the R. rear tire foward (like I was driving foward) and the other tire didn't spin. Is this a good or bad thing?

[s13sr20chris]

stock vlsd should not make noise. you prob have a rotten bearing. that is fixable but requires some work and knoledge/special tools.

[moyea]

stock vlsd should not make noise. you prob have a rotten bearing. that is fixable but requires some work and knoledge/special tools.

How do I narrow down which one? There are several bearing in the diff.

[NISTECH]

You dont have a vlsd or you have a axel shaft thats to smal and you are hearing its teeth drag when you slow down. When sping the wheels in the air on any VLSD the other tire should turn and it should turn in the same direction. Other wise its an open diff. The axle shaft being to small is a stretch I do not really think thats what wrong but if this is infact a VLSD I am thinking something is flat out broke in there since both tires dont move when you rotate one of the tires.

[AZhitman]

Did you change the input flange?

If so, you need to know that the depth you drive the flange nut on to has an effect on the pinion depth. THis HAS to be set with the diff out of the car.

How do I know? I just went through FIVE differential pulls / reinstalls.

[ricebike]

I'm sure there is oil in it but I'm going to drain and fill it again in a few days. I want to see if there is anything in the fluid that might indicate damage (metal flakes, etc.). I'm not sure what fluid was put in it at the time of install because I didn't install it myself but I plan on putting a GL-5/ 80W-90 like Mobil 1 and maybe a friction additive.

Well, if it is a true vlsd (the viscous coupling as indicated by # 31 on that pic) is a sealed unit & u don't need that friction additive; that's for clutch-type lsd's only.

Another thing to add is when it was up in the air, after the install, I spun the R. rear tire foward (like I was driving foward) and the other tire didn't spin. Is this a good or bad thing?

Doesn't the viscous coupling needed to be up to operating temperature to "lock" both wheels? the heat would "expand it so both wheels would spin.

bring it to operation temp & lift it up to see if they do spin the same way.(i'm just using my common sense on this one since i only have an open diff)

[moyea]

You dont have a vlsd or you have a axel shaft thats to smal and you are hearing its teeth drag when you slow down. When sping the wheels in the air on any VLSD the other tire should turn and it should turn in the same direction. Other wise its an open diff. The axle shaft being to small is a stretch I do not really think thats what wrong but if this is infact a VLSD I am thinking something is flat out broke in there since both tires dont move when you rotate one of the tires.

I'm inclined to disagree with you on the tire spinning idea, because I'm certain this is a VLSD. Also my old Differential, which I think was open, would spin both tires either direction. I had replaced the back cover and saw it myself. Now my axel shaft being small is an interesting theory. I never knew that could be a problem. I will change the fluid tomorrow and post my results. If it is broke I'll be , but you live and learn. I'll just by another one some day.

Here is a picture of it when I had it in the garage: Visual inspection the only way to be certain!

[yellow_jacket]

If the Vlsd is functioning properly it should spin both wheels when they are off the ground.

As far as the noise. Where did you get the axles from? Are you sure they are the correct length? If they are long they can make all sorts of wonderful noises. I would also make sure that you didn't tweak the driveshaft or something along those lines when you installed the unit. Some of the Vlsd's have a longer snout than others, this can cause problems with the driveshaft if there isn't proper clearance.

The easiest thing to do is to get a stethoscope and track the noise down.

[moyea]

As far as the output shafts go, I had one long and one short. I noticed something odd about the short one though. Looking at pictures of other shafts I noticed mine did not have a ring at the top. This is the passenger side I'm talking about. The same side that I spun the tire on. Mine has a grove where this ring would go but no ring. Here is an example, mine's look exactly the same but no metal ring on the top. Do I need this? If it broke off can I replace it? How can I get it out of there if its stuck in there? This may be the culprit since when I take certain turns I can feel the left rear tire "grip".

I have yet to change the oil because I can't get my wrench in there. There is no room for me to turn or position it. Any suggestions on that?

I also noticed on my propeller shaft or drive shaft, whatever that big long shaft running from the front of the car to the final drive is called, has a yellow paint mark on it. It was pointed down when I slide under the car. Is that correct? Isn't that mark supposed to be straight up?
Modified by moyea at 7:36 PM 11/18/2005

[s13sr20chris]

teh driveshafts spins so naturaly the pain mark will move around a bit.

i have seen old worn vlsd units act like an open lsd untill you really work her hard. vlsd is smooth to the point of transparency. thats my favorite feature of the otherwise weak coupling.

[skydragoness]

Well, if it is a true vlsd (the viscous coupling as indicated by # 31 on that pic) is a sealed unit & u don't need that friction additive; that's for clutch-type lsd's only.

Please do not say that. Nissan themselves use a BG LSD additive for the 350z and all other vehicles that have a VLSD. Yes, the VLSD has a sealed coupling w/ goo inside, BUT the gears on a VLSD still see friction and therefore need an additive to counteract that. Now, if the new fluid already has friction modifiers in it, like some Mobil diff fluids already do, then using an additive is not necessary. You can't just put some regular open diff fluid in and expect the vlsd to keep working down the road, its a slow death.

[moyea]

Well the VLSD did lock. I haven't changed the fluid yet but I took it around the lot and made a few tight turns at speed. I heard one or both of my R. tires make a sudden screech(unlike before) similar to if I slammed on the brakes and my front wheels locked.

Here is a better picture of the stub shaft. The only difference is mine does not have that metal ring. Is this part # right? Which side should that shaft go on? Because the guys who installed it put it on the Right/ Passenger side and had a hard time doing so. That is why the ring is broken.

[moyea]

Recent sources tells me that the shafts may have been installed on the wrong ends. Mine were installed with the short end on the passenger side and the long on the driver's side. I heard this was wrong. Is it? Also I hear that the metal ring is important. Can it be replaced or do I need a new shaft?

[moyea]

Recent sources tells me that the shafts may have been installed on the wrong ends. Mine were installed with the short end on the passenger side and the long on the driver's side. I heard this was wrong. Is it? Also I hear that the metal ring is important. Can it be replaced or do I need a new shaft?

Well my theory of the shafts may be wrong. I got fed up and finally did the uninstall myself. Should have done it the first time and I wouldn't of had to fork up some cash. I tried to switch the shafts but the long one would not go in. It seemed to be hitting something. Beleive me, I hammered the crap out of it! Anyways I reinstalled my open diff and now the noise is gone.

So, here are the facts:

1) VLSD was purchased without stub shafts EBAY2) Stub shafts (short&long) seperately EBAY3) Midas installed the diff, broke the metal ring, may have installed wrong4) Loud whine noise came from rear end.5) Diff removed, attempted to switch shafts, unsuccessful.6) Original Open diff installed, no problems.

Now I'm confused. I will start over with another diff and this time I will make sure all parts match.

[AZhitman]

Did you change the input flange?

If so, you need to know that the depth you drive the flange nut on to has an effect on the pinion depth. THis HAS to be set with the diff out of the car.

How do I know? I just went through FIVE differential pulls / reinstalls.

Gloss over this at your own risk.

I'll bet the prior owner of the diff did this and freaked when the car made the RRRRRRRR noise.

[moyea]

You lost me AZ. Could you explain in greater detail what it is your describing? Is it something I can fix myself?

Off subject: Did you ever get that sponsorship proposal I e-mailed you?

[yellow_jacket]

I just noticed that he said he is missing the clip that holds the stub in place. I wonder what kind of wonderful noises it will make with that stub moving freely?

As far as the input shaft. Any time you change internal parts of a rear end, the backlash needs to be set. If someone swapped out internals and didn't set the backlash, all sorts of wonderful noises and problems will ensue.

[moyea]

Here is something new.

When I reinstalled my open diff I noticed my (passenger) R.rear tire still did not spin freely. It would spin and then get stuck on something. I would then have to push harder to get it to spin up until a certain point then it would stick again. The L.Rear spun fine. I can still hear a much lower noise even with my old diff on. Could this mean the problem may be something else? Like a wheel bearing or something? The noise could be something rubbing at high speed.