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Did I cook my gears

turbotim2

____________
Joined
Jun 26, 2003
Messages
1,954
Installed new gears in my 9". I set them up according to Yukon's instructions, got a great pattern. At the same time I installed new bearings and rebuilt the stock Trac Lok. I have maybe 75 miles on them and they are starting to growl around corners and I can feel what seems to be the teeth meshing together. They are quiet when driving straight. Thanks!
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
did you loctite the ring gear bolts? Still have backlash between the pinion and the ring gear?
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
/\/\ That +1
There are other differentials like the TrueTrac which do not need the friction modifier and tell you not to add any.
The oil companies only want to make one oil, so they leave it up to you to add it for those differentials that need it.
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
Lucas gear lube says you don't need to add friction modifier but I always have had to when using it in a limited slip.
 
Last edited:

cali_zuk

Jr. Member
Joined
Dec 11, 2006
Messages
66
Did you soak the clutch plates in friction modifier before re assembling it? If not, add some friction modifier, (I use dana spicer part number 43161) that should take care of it. I forgot to put friction modifier in a diff one time, and the noise it made sounded like it had been driven 100's of miles with no gear oil. Once I noticed my mistake, I put it in, and almost instantly the noise went away.
 

ribbits

Jr. Member
Joined
Jan 21, 2015
Messages
130
May be a dumb question but, I have a ford 9" with Detroit lockers.. Should I be using the friction modifier? Not having any noises but what can it hurt to add it? What about the front end Dana 44? Thanks
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
The chatter can sound like you've wiped the gears out, but it really doesn't affect the gears at all.

The difference is the OEM limited slip units aren't nearly as tight as the aftermarket units.
The oil with additive already in it is fine for OEM, but even my soft Yukon unit chatters with it unless I add the stinky stuff.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,834
As stated above, your ring and pinion are fine.
It is the limited slip that is giving you fits. You can tell because it only happens in turns, where the limited slip must allow a differential action between left and right sides. In a straight line it doesn't have to slip and only the ring and pinion are the moving gears. With things fine in a straight line, the ring and pinion are fine.

Additive for the fix. If that doesn't do it, there is a problem inside the limited slip.
 

ribbits

Jr. Member
Joined
Jan 21, 2015
Messages
130
The chatter can sound like you've wiped the gears out, but it really doesn't affect the gears at all.

The difference is the OEM limited slip units aren't nearly as tight as the aftermarket units.
The oil with additive already in it is fine for OEM, but even my soft Yukon unit chatters with it unless I add the stinky stuff.

Mine suppose to have Yukon gears?? Just wondering what it would hurt to add it because I really don't know if it has it (additive) in there or not?
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
Mine suppose to have Yukon gears?? Just wondering what it would hurt to add it because I really don't know if it has it (additive) in there or not?

You only need the friction modifier additive if you have limited slip. If you use it without limited slip, it won't hurt anything. Except maybe your wallet.
The brand of gears or brand of limited slip doesn't matter.
 

ribbits

Jr. Member
Joined
Jan 21, 2015
Messages
130
You only need the friction modifier additive if you have limited slip. If you use it without limited slip, it won't hurt anything. Except maybe your wallet.
The brand of gears or brand of limited slip doesn't matter.

Much obliged !!
 

sykanr0ng

Bronco Guru
Joined
Aug 11, 2014
Messages
5,363
May be a dumb question but, I have a ford 9" with Detroit lockers.. Should I be using the friction modifier? Not having any noises but what can it hurt to add it? What about the front end Dana 44? Thanks

NO
You have a Detroit Locker.
Only clutch type limited slip differentials need the friction modifier.
The Detroit Locker is not a clutch type or a limited slip.
 

ribbits

Jr. Member
Joined
Jan 21, 2015
Messages
130
NO
You have a Detroit Locker.
Only clutch type limited slip differentials need the friction modifier.
The Detroit Locker is not a clutch type or a limited slip.

Kinda what I thought,,,, now I feel like Johnny Ringo ??? Thanks%)
 

cs_88

Bronco Guru
Joined
Jul 28, 2005
Messages
1,321
I used one whole 3.8 oz bottle of the Ford Racing stuff.
 

Timmy390

Bronco Guru
Joined
Jan 1, 2011
Messages
5,609
Loc.
Conway, AR
As I recall I added 4 oz. to mine.

I've since moved to a Eaton True-Trac (parallel-axis planetary helix gears to provide a quiet, automatic splitting of torque. They perform like a limited slip differential under normal driving conditions, automatically transferring torque to the wheel with better traction when ground conditions warrant)

My 2014 Shelby has the Ford version called a Torsen Diff.

No special oil requited and they last a long time. Must be tough to handle the 662hp and 631 lb-ft of torque the Shelby is putting out.

Tim
 
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