2003-04 Mach 1 Registry Owners Club

2003-04 Mach 1 Registry Owners Club (http://www.mach1registry.org/forums/index.php)

- Engine & Drivetrain (Including trans & rear axles) (http://www.mach1registry.org/forums/forumdisplay.php?f=64)

- - Differential fluid (http://www.mach1registry.org/forums/showthread.php?t=136754)

Davidw04

03-17-2019 05:27 PM

Differential fluid

What’s everyone using? I just got some royal purple 75w90 and a bottle of fords friction modifier. Will this work or should I have gone with the 75w140?

j rick kirby

03-18-2019 02:10 PM

Re: Differential fluid

I use the RP 75w140 but I track the car so you're good. You won't need the friction modifier.

311-420

03-18-2019 08:44 PM

Re: Differential fluid

The rp says it contains a friction modifier, but from my experience it wasn't enough as both of my old FR diffs would chatter pretty good in a hairpin (parking spaces, tight garage entries etc) while running straight rp 75-140.

j rick kirby

03-19-2019 09:03 AM

Re: Differential fluid

Mine have never chattered with the straight RP.

311-420

03-19-2019 08:32 PM

Re: Differential fluid

Quote:

Originally Posted by j rick kirby (Post 1633722)

Mine have never chattered with the straight RP.

Which diff are you using? My first one I used rp in was the stocker from my old 04 IRS setup. I had it rebuilt back to FR specs with new carbon discs and gears. The second one was a brand new FR piece I ran for a short while in my (now) SRA setup.

j rick kirby

03-20-2019 08:12 AM

Re: Differential fluid

It's a FPRP 31 spline with the carbon fiber clutch pack.

gfong

03-20-2019 09:08 AM

Re: Differential fluid

Just put the Ford friction stuff in along with whatever other diff oil brand you are going to use. Unless it requires non friction oil which it doesn't then adding the 4oz little bottle of Ford stuff is better in it than not in it!

Our cars and Cobras from the same years use 75W140 in the rear end. :gears:

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