i just installed my diff with motorklasse 4.44s in it. i did the 'heat cycle' break in. After parking my car in the garage and shutting it down, i hear a strange 'sizzling' sound from the rear. Sounds like its coming from the diff. or behind the rear wheels somewhere. Anyone know what it is?

ramjet (who installed the gears in the diff) painted the black part of the diff housing.. maybe paint is boiling? I dunno if the diff actually gets that hot.

 

do you have enough differential fluid? esp. the right kind?

 

look for something touching your exhaust piping.

 

diff is mobile 1 70w90, yes its the right one.

Ill check the exahust piping. thanks all.

 

Was the diff really hot?

I notice when I crack open the fill plug i can hear little hiss or sizzle sometimes. Maybe it's air escaping out of the fill plug?

 

i hope not!! i torqued it down to spec... is our diff ventilated? I noticed a little knob on the top of the diff (impossible to see unless the diff is removed) that i thought might be a vent valve. Hmmmm...maybe the noise was always there, but i never checked for it so never noticed....

 

IIRC, there is some sort of vent on top of the diff. PM hardtopguy or sanmarinocoupe and ask them if it can make noise.

 

I personally would ignore the sound and see if it happens again. Noises when the car is not moving are not a problem for the rear end. You might have heard the evap system or something. The S2000 makes plenty of noises.