Differential chatter

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Mar 19, 2010 | 08:39 PM

f250meangreen

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Differential chatter

I replaced the diff fluid with Valvoline synth and added 4 oz of friction modifier. Seemed to run smooth for a while. Shortly after replacing stock 265BFG to 285BFG AT the chatter started when making turns. I added 4 more oz of modifier but it did not seem to help. I backed up a incline the other day and turned, that really made it chatter. What do you think? I might do another change out and start all over but looking for advice.

Mar 20, 2010 | 05:51 AM

Maxium4x4

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I bumped you to SuperDuty for a better response.

Mar 20, 2010 | 06:49 AM

thedaddycat

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I take it you have a LS diff then? If it's still chattering more than you like I'd try adding more friction modifier until it stops the chatter. That said, it seems like most folks find that the OEM LS is pretty much junk and does not work very well if at all. I think you're the first one I've seen with an issue where it worked too well...

Mar 20, 2010 | 07:49 AM

f250meangreen

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That is why I am scratching my head over this one. Everyone seems to have the exact opposite issue. I know my LS is working right now, pulled a stump out and all tires where digging in. I just don't want to burn it out. I tow a fifth and I am worried the clutches are going to burn up quicker when I start pulling it for the season. I already have 8oz of modifier in it so I was not sure is adding more would be a good idea. I will give it a shot and see what happens I guess.

Mar 20, 2010 | 08:16 AM

Zmann

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what weight valvoline ? I could only find the proper weight at ford ..the rearend fluid , ...modifier and a gallon of coolant was 110$

Mar 20, 2010 | 11:39 AM

WestxSRT10

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Quote:

Originally Posted by Zmann

what weight valvoline ? I could only find the proper weight at ford ..the rearend fluid , ...modifier and a gallon of coolant was 110$

You used 85w-140 right?

Mar 20, 2010 | 05:23 PM

Zmann

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From: AZ

spec is synthetic 75 -140 and the additive .. so I went with oem fluid because my local autozone wasn't stocking anything but the front dif fluid

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Mar 20, 2010 | 09:04 PM

nghtrgr

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The Valvoline Synthetic I used said Limited Slip on the bottle. I did not put any fric mod in. I have no issues.

Mar 21, 2010 | 06:07 PM

#10

Zmann

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From: AZ

Quote:

Originally Posted by f250meangreen

Spec is 75w-140. Got it at Napa. I think it was less than $10 a bottle.

it is a synthetic that is speced .. did u use syn?

Mar 21, 2010 | 07:35 PM

#11

nghtrgr

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Yep the stuff I used was more like 14-16 dollars a bottle. Gotta read the labels close to make sure you aren't getting a syn blend or something like that

Mar 22, 2010 | 06:21 AM

#12

f250meangreen

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It is synth. not a blend. I double checked it with a bottle I had left over. I replaced the cover with an aluminum one that holds about 1/2 quart more. I add more friction modifier and the chatter seems a little better so far. I will test it some more and check to see if my limited slip is now all slip. If it does not get any better I guess I will drain it and start all over.

Mar 22, 2010 | 08:12 AM

#13

Zmann

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From: AZ

I sure learned allot reading this thread ,, then searching the net ,,
I just put an 08 diff cover on mine and swapped the fluid ,, I wish I would have done the clutch packs at the same time

Mar 22, 2010 | 01:17 PM

#14

jim henderson

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From: So Cal

Most of the larger diffs using syn need about 8-12 oz of modifier, you using a high capacity cover, moved the amount up a bit.

Like the other guys said keep adding a little til the chatter goes away. Different brands and types of diff lube will require a little different amount of modifier. Some don't need any at all, read the label.

A good test, like you found is to backup slowly in a tight turn. Add maybe 2-4 oz each time till the chatter is just barely noticed or gone.

You don't want to add too much modifier, it will be smooth but also slip a lot and be useless for traction.

Good Luck,

Jim Henderson