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View Full Version : Differential (VLSD) Hissing Noise

DirtyS14
11-19-2007, 12:32 PM
Yesterday I installed an s13 vlsd from an s13 into my s14. The diff fits in nice and cosy, everything is torqued to factory spec, diff is full with oil. When the car starts moving there's a hissing noise from the back and it gets louder with speed. I only got upto about 30mph before I stopped the car. At 30 its loud enough that you really can't hear someone talking.

I drove with this exact diff in an s13 and it was as quiet as a mouse. I looked under the car and can't see any marks of anything rubbing on anything 'cause that's seriously what it sounds like. The only thing I can think of is this... the s14 has bushings in the front two mounting bolts.. this could hold the front of the diff a little lower... so when i put the s13 (non bushing) setup in, the front of the diff is elevated a little bit causing the diff flange/driveshaft flange to be elevated enough to rub on the body. But thats the thing, I can't see any rub marks on anything in that region.

And yes i've searched like a dog....

Thanks in advance...

Edit: The entire s13 case is in there, I didn't mess around with the internals, just switched the diff covers.
stinky_180
11-19-2007, 01:14 PM
i know the s14 front diff mounting bolts are longer then the s13 bolts. did you put the correct amount of fluid into the diff?
MrChow
11-19-2007, 01:23 PM
^^ how much oil did you put in?
silnismo
11-19-2007, 01:45 PM
Maybe somthing fell in the diff while installing.
DirtyS14
11-19-2007, 02:56 PM
i know the s14 front diff mounting bolts are longer then the s13 bolts. did you put the correct amount of fluid into the diff?

^^ how much oil did you put in?

I basically filled it with a syringe until the level came up to the fill nut and it started to overflow... Oh yeah, i used the s13 (shorter) bolts because there are no bushings on the s13 diff. I used 80w-90 GL-5.

Maybe somthing fell in the diff while installing.

Yeah but wouldn't that prove for a clunking, locking, exploding situation? All I have here is a hiss.. but I was super careful to not drop stuff into it.

Thanks for your help/time guys!