Differential fluid? which kind?

[DemonGT]

have a leaky differential...when i change the gasket what fluid should i use...i just used cheap stuff with friction mod. last time....if i use synthetic do i need the friction modifier?

 

[gwhiz50]

I used Royal Purple last time I changed. Not sure about the friction mod but it is a perfomance base synthetic and I know alot of people that use in race applications.

 

[srothfuss]

Any name brand synthetic will be fine. I like the dino oils personally but I guess I am old fashioned. When you pull the cover, don't use a gasket next time. Instead just lay down a nice bead of RTV. Let it setup for 10 minutes and then reinstall the cover. No leaks and no gasket required...

 

[KDK1988GT]

i run this + friction mod

I run Mobil 1 synthetic,, yes always add the friction mod..

http://www.mobiloil.com/USA-English...bil_1_Fully_Synthetic_Gear_Lube_75W-90LS.aspx

 

[HISSIN50]

For a fluid that is left in for an extended drain interval, I prefer synthetic. I choose to use a gasket and RTV, which is unusual - most use gasket maker alone. Do use Modifier. All my personal preferences.
Good luck.

 

[5spd GT]

Dumb question: What does friction modifier do exactly?

 

[KDK1988GT]

what it does

Dumb question: What does friction modifier do exactly?

reduce the friction break-in of differentials, reducing break-in temps, Limited slip or posi units will often chatter without friction mod it also helps by not making the plates or clutches too slippery, which can cause the chatter...

 

[HISSIN50]

Hmm, I thought the chatter came from the plates biting too hard (too much friction) when there is a radial velocity or acceleration delta from one side to the other.

Auto X guys sometimes like to leave the modifier out for better bite while doing their thing.

 

[KDK1988GT]

well...

Hmm, I thought the chatter came from the plates biting too hard (too much friction) when there is a radial velocity or acceleration delta from one side to the other.

Auto X guys sometimes like to leave the modifier out for better bite while doing their thing.

humm well I'm not sure... all I know is that I left out the modifier once while changing my rear. After a few 1000km.. so 500-600 miles, mine started to chatter. It was shimmed up tight everything was new... and done right...

This year I changed my gears and everything in the rear and added modifier this time and I have had no chatter with 4000km on the car this summer..

I also figure the chatter would come from shimming the rear to loose. But I have heard that the a rear without the modifier would cause the chatter also..

With the auto x guys what kind of rear are they running a limited slip Or full locker? With a different locking differential or possi set-up maybe modifier many not need to be added??

Anyone else with some good input??

 

[jammer84_03]

all i can say is dont use red line....ive tried it a total of once on my formula mazda cars and its junk...royal purple aint bad...mobil 1 is the best

 

[srothfuss]

The FM actually softens the clutch material (more plyable) so the dics don't chatter. Doing this actually lower the coeffecient of friction betwen the disc's / metal rings but it makes for a smoother operating rear end in the street cars.

 

[HISSIN50]

The FM actually softens the clutch material (more plyable) so the dics don't chatter. Doing this actually lower the coeffecient of friction betwen the disc's / metal rings but it makes for a smoother operating rear end in the street cars.

That is what I thought, in regard to actually lowering the coefficient of friction.
Cool.

 

[jammer84_03]

the clutch only is used once a race....to take off...lol. i was refering to the tranny / diff fluid. the red line stuff clings to it and it just isnt good at all, all of our drivers liked the other better...at least they said it was the best box they ever used...and we didnt even have new gears in...lol all about the fluid baby!

 

[jammer84_03]

nvm...i feel dumb...the clutches in the diff...wow...mental lapse...i saw fm and thought you were refering to the formula mazda....i feel stupid...i need a owned sign.....lol

 

[DemonGT]

do auto part stores carry FM?

 

[KDK1988GT]

yes...

do auto part stores carry FM?

yes they should, your local ford dealership should have it also