Oh no, why it has to be my LSD :(

[Dongoesby]

So I found there is noise coming from the back of my 98' 240sx 5spd, and I took it to a shop since it is getting louder everytime I turn in a low speed. The mechanic used a tool like what the doctor uses to listen how the rear wheels run. After he found nothing wrong with the axels, control arms and other suspension parts, he suggested the gear box might be the problem. And I asked: "Isn't the gear box, so called transmission, located in the front right under the shifter?" (wtf?) He said something like the gear box is in the rear while pointing at where the LSD is located.... Maybe he thinks I'm not knowledgable about cars, but I think he knows less about my car than I do.

After that, I told him that the car is equiped with am aftermarket 1.5 lsd, and it might be low on fluid, so maybe that is problem because the noises only come out when the car turns. He still insists that the car has no lsd, but after couple simple tests, he found out the lsd is not installed with a complete housing, instead, just the gears inside. (which also surprises me too). The mechanic said the lsd is not installed properly, because, first, it wasn't swapped with the complete housing which would required more skill to fit the gears in the housing, second, the noises from the rear are maybe the evidence that shows the gears in the LSD aren't installed precisely.

Finally, after my suggestions to him that it is not the gear box and we should put oil in the lsd to test it out, and it turns out the noises are minimized! However, the noise still exists but just not as noticable. And then he charged me 75$ for hourly labor...

Here are my questions: Are the gears in my LSD already worn out? Is it too late to open it up again and adjust it? (how much will it cost?) Or if I leave it be, and the gears will fit themselves perfectly by a little bit of time to break in? (as the previous owner told me that he just got it installed by a reputable shop)
Modified by Dongoesby at 10:19 PM 4/13/2007

[180fan]

That's a new one. But yes, just cramming crap in on something that requires proper positioning will cause it to fail prematurely.

My question since you seem to be in my neck of the woods, is

1. which shop did you take it to to get that bit of advice? 2. did you see the receipt for the "reputable shop" that did the work let alone the part? If not, yet another reason why it's important to be willing to pay a bit more for a car with complete records...

[Dongoesby]

First of all, thanks 180fan for replying my question! I feel lucky that I have a nico moderator in my city And I wish to meet you sometimes in the city.

Now to my car. I think I'd never bought a used car like this one which has all the records from day one; however, not the lsd receipt of that reputable shop. (I will try to contact the seller again to obtain the receipt).

To answer your questions. I brought it to a shop on Mission street between Ocean and Geneva where across the street of Safeway. I think it is called "Reliance", and it has a Chinese owner. I went there because a knowledgable friend of mine introduced it, but still didn't get any discount..

Can anyone still answers my questions?

Frank
Modified by Dongoesby at 4:49 AM 4/14/2007

[LayNLow240]

if the previous owner installed a clutch type LSD then the noises are normal.(generally its a knocking sound while turning. the sound is just from the clutch plates engaging/disengaging because the rear tires travel different distances around a corner) the only noises from a bad install would be a whining sound while driving if the pinion and ring gear arent meshed correctly. to find out if it is, take it to a competent shop that deals with modified imports and ask them to check the mesh of the gears. it wont be free as they have to open the diff up to check it. this would also be a good time to change the fluids. speaking of, find out what brand LSD the previous owner installed then buy their oil, or what they recommend to use. either way, i suggest getting a fluid change with whatever brand the LSD is. it will be a little costly, but if you dont get the right fluid then it might not work properly or it may be louder than it is.

[Dongoesby]

Thanks for answering me my question. That helps alot!

I'm not sure what is a clutch type LSD and the differences between the sounds of knocking and whining. I only know it is a 1.5 LSD, and it came with a NISMO box. (not sure if this mean anything, probably i can ask the seller for its brand) Also, the noise only comes out when my gear is engaged, which means if I turn in a low speed with neutral, the sound does not exist. Anyways, I contacted a the seller, and he suggested me to change the oil to synthetic 75w90 gear oil along with some friction modifider.

I will go and check what the oil I'm using now.

Frank
Modified by Dongoesby at 9:25 PM 4/15/2007

[RICERMAN]

I always charge more when the customer has already figured out what I need to do to fix it. I often dont even let them come into the shop if the are moving their lips. labor fee= 50 bucks and hour, 70 if you watch and 125 if you try to help.

[LayNLow240]

Thanks for answering me my question. That helps alot!

I'm not sure what is a clutch type LSD and the differences between the sounds of knocking and whining. I only know it is a 1.5 LSD, and it came with a NISMO box. (not sure if this mean anything, probably i can ask the seller for its brand) Also, the noise only comes out when my gear is engaged, which means if I turn in a low speed with neutral, the sound does not exist. Anyways, I contacted a the seller, and he suggested me to change the oil to synthetic 75w90 gear oil along with some friction modifider.

I will go and check what the oil I'm using now.

Frank

Modified by Dongoesby at 9:25 PM 4/15/2007

well you have a nismo unit, which is a clutch type lsd.knocking sound is like you knocking on an object, and whining is like wheeeeeeeeeee.it sounds like its just doing its job. with no load(via the engine) on the diff, it wont act. it has whats called initial torque, which is the amount of torque it takes for the clutch plates to do their job. so with it in netural or clutch in on a turn, you shouldnt hear the plates engaging/disengaging.what oil the seller suggested will work fine if you add the modifier to it.i would fill it up with redline or royal purple gear oil and add the modifier to it.

[Dongoesby]

Thanks again, LayNLow240. I'm pretty sure it is just knocking sound. The seller answered my question, which he said it is a performance LSD, so the sound in low speed is normal. However, I'm still trying to get a definite answer for the brand of the LSD, especially if it is clutch type.

RICERMAN, you must be kidding me. If you are really that strict, you shouldn't have let the customer in at the first place. For my situation, I supplied the oil for the LSD, otherwise, he wouldn't know what oil to use.

Where are you, 180fan?

[LayNLow240]

Thanks again, LayNLow240. I'm pretty sure it is just knocking sound. The seller answered my question, which he said it is a performance LSD, so the sound in low speed is normal. However, I'm still trying to get a definite answer for the brand of the LSD, especially if it is clutch type.

All nismo LSD units are of the clutch type. and i think out of the 2 or 3 units they have, only the SSS(IIRC, it could be the gtpro) unit is capable of being changed to 1.5 way.

[Dongoesby]

Finally got reply from the seller. It is a Nismo unit! And it is a 1.5 way clutch type LSD, so the sound at low speed is normal. I'm feeling contempted. Let's see how I can have some fun with it now

Thanks for the input, LayNLow240!