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Discussion Starter #1
Does anyone know the best gear oil to use for the rear end. I switched to 373. Put them in myself but they do whine. I have had them for alittle while and was told to change the oil after breaking them in for alittle bit. Will the more expensive brands like Royal purple or lucus oil cut down on the whining or should I just stick with the motorcraft with friction modifier. Thanks
 

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blmarlow said:
Does anyone know the best gear oil to use for the rear end. I switched to 373. Put them in myself but they do whine. I have had them for alittle while and was told to change the oil after breaking them in for alittle bit. Will the more expensive brands like Royal purple or lucus oil cut down on the whining or should I just stick with the motorcraft with friction modifier. Thanks
Oil is the least of your problems, it sounds like you didn't get the run out of the gears set correctly. Regards of what oil you use there shouldn't be a whine-

I suggest you take your car to a pro and have him set them up correctly before any damage is done. At that time you can change your oil to a synthetic with Ford modifier.

I only let a certified gear man install my gears, it's something a novice shouldn't attempt with out assistance from a professional.
 

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240_Bullitt said:
if they are whining now get them fixed asap before they are toast
+1!
 

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What brand of gears did you buy? If they are ford racing you shouldn't need to shim them side to side, just the pinion depth. If they are ford racing there should be a number stamped on the end. Then go to autozone or Orielly's and rent a gauge from them.
 

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This is not my area but some would say that even if you use something like Royal Purple, you should use a friction modifier. I know that Amsoil synthetic says in their advertising that you don't need a friction modifier with it but some say to use the friction modifier regardless.
 

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blmarlow said:
Does anyone know the best gear oil to use for the rear end. I switched to 373. Put them in myself but they do whine. I have had them for alittle while and was told to change the oil after breaking them in for alittle bit. Will the more expensive brands like Royal purple or lucus oil cut down on the whining or should I just stick with the motorcraft with friction modifier. Thanks

How bad is the whine? How many miles? How was the tooth pattern? You may have to take it apart and reshim. There is a good dvd out there that shows how to set it up its made by badshoe productions. They do a step by step with a ford mech. Its better spending 40 bucks for the dvd then taking it to someone for $350. Plus you got this far with it. Check out the dvd very informative.
 

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Discussion Starter #8
Well like the haulk said i had heard the same thing about the stock shims with ford raceing gears. So that is what i did. I had a ford mechanic help me install them. They do whine but the mechanic said it is probley becauce the gears were used when i bought them. He said he thought they felt good. Hey I only payed 45 bucks for the gears becauce the guy was moving to Hawii. I just wasnt sure if it was worth the extra money to speed on the oil. :confused: O yea and i have had them in for about 3 months but only drove it for about a month before putting in garage.
 

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Do the gears whine at all speeds and loads,or only at light throttle at 45-55 MPH?
I installed my FORD 3.73 gears in 0503,some years ago,and they only make a very slight whine only at the 45-55 MPH range in 4th gear. Never has gotten any worse over time.
The Motorcraft gear lube is a great choice for normal use,as it is a synthetic lube.
The fact is some gears,even depending on ratio can make noise just by how they were machined,or the material hardness.
In my 85 LX,I have a set of 9 inch 3.89 gears that made noise from day one,and no matter the amount of resetting,still made some noise. I then later installed some used OEM 3.50 gears,out of a truck, and they are dead quiet. Also a set of 4.10 gears from Richmond gear were quiet as well.
 

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Discussion Starter #10
yea they pretty much always whine. the faster I go the louder it gets.
 

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I am thinking you should have it rechecked. the wine may be a gear issue that you need to get taken care of. but good luck. I bought a set of used gears once they were noisey too so i had them removed and bought a new set had them installed nad quiet as a mouse. so I wont be purchasing any used gears ever again. not worth the savings, actually no saving when I had to have it redone. Live and learn..
:confused:
 

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Yep, the only place used gears go is in the race car.. (can't hear them in there!)
I prefer Mystic gear lube (red in color) and Justice Brothers gear lube additive.
Tried many others over the years, and have had the best results and longest life using this combination.
 

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Discussion Starter #15
Thanks for all the feedback it helps alot
 

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I just had FRPP 3.73s installed in my car. They have a whine at around 60 mph under light throttle. There seems to be a little more driveline clunk than there used to be. I go the FRPP because everyone said they were the best and the quietest, but now I almost wish I had gotten Motive. The guy swore they were set up perfectly and my son was there and thought it was perfect also. I'm not thrilled with the noise and the little extra driveline clunk, but the 3.73s feel pretty good and I feel they should be a good all around gear. I may change the differential oil and check the backlash at some point just to make sure it is about right. I've been pretty nervous about it, but sounds like there are several other cars that have a similar whine.
 
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