Rear diff chatter - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hemi43 · 03-19-2016, 05:24 PM

Got most of my truck debugged, but can't seem to be able to get the posi to stop chattering. I had originally put in Amsoil and added 2 of their posi additives but the chatter was still there. Today I dumped that out and replaced it with GL-5 petroleum based 80W-90 and a bottle of GM limited slip additive. Chatter is still there. It's especially noticeable after a long steady drive.
Any secrets to get this thing to quiet down?

Mike C · 03-19-2016, 05:45 PM

Have you tried doing tight figure 8's in a parking lot? That will distribute the oil through the plates and hopefully break them loose.

I've never seen one that wouldn't smooth out after doing that and using new fluid. I've got a Moroso Brute Strength in my Camaro with the heavy duty preload springs and it works smooth as glass.

hemi43 · 03-19-2016, 08:55 PM

I've put almost 100 miles on it this past week, including going around in circles. I decided to throw another bottle of additive in today, but may have to wait a week or so because we got some crap weather coming. Is it possible that the friction material has worn of the clutch plates? This was a low mileage truck, and I didn't even bother to take the posi apart because it was so clean inside.

**GMC-YA68** · 03-19-2016, 09:20 PM

i've got castrol 80-90 with the limited slip additive in it. No issues and have about 400 miles. What posi do you have?

hemi43 · 03-19-2016, 09:31 PM

Quote:

Originally Posted by GMC-YA68

i've got castrol 80-90 with the limited slip additive in it. No issues and have about 400 miles. What posi do you have?

Stock GM clutch type.

warbucket · 03-19-2016, 10:58 PM

I know it's just not right but I use ford friction modifier cm-19546-a1 in my 70 chevelle 12 bolt with factory limited slip. A local speed shop recommended it. It stopped the chattering years ago and I love to launch the car hard.

03-19-2016, 05:24 PM	#1
hemi43 Registered User Join Date: Mar 2015 Location: Ontario Canada Posts: 1,500	Rear diff chatter Got most of my truck debugged, but can't seem to be able to get the posi to stop chattering. I had originally put in Amsoil and added 2 of their posi additives but the chatter was still there. Today I dumped that out and replaced it with GL-5 petroleum based 80W-90 and a bottle of GM limited slip additive. Chatter is still there. It's especially noticeable after a long steady drive. Any secrets to get this thing to quiet down?

03-19-2016, 05:45 PM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,712	Re: Rear diff chatter Have you tried doing tight figure 8's in a parking lot? That will distribute the oil through the plates and hopefully break them loose. I've never seen one that wouldn't smooth out after doing that and using new fluid. I've got a Moroso Brute Strength in my Camaro with the heavy duty preload springs and it works smooth as glass. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

03-19-2016, 08:55 PM	#3
hemi43 Registered User Join Date: Mar 2015 Location: Ontario Canada Posts: 1,500	Re: Rear diff chatter I've put almost 100 miles on it this past week, including going around in circles. I decided to throw another bottle of additive in today, but may have to wait a week or so because we got some crap weather coming. Is it possible that the friction material has worn of the clutch plates? This was a low mileage truck, and I didn't even bother to take the posi apart because it was so clean inside.

03-19-2016, 09:20 PM	#4
GMC-YA68 Senior Member Join Date: Mar 2004 Location: Lee's Summit, MO (KC) Posts: 742	Re: Rear diff chatter i've got castrol 80-90 with the limited slip additive in it. No issues and have about 400 miles. What posi do you have? __________________ -Keegan- '72 Jimmy 4x4 - 5.3/4L65E/NP205 swap http://67-72chevytrucks.com/vboard/s...d.php?t=663780

03-19-2016, 10:58 PM	#6
warbucket Registered User Join Date: Mar 2011 Location: Havertown Pa Posts: 392	Re: Rear diff chatter I know it's just not right but I use ford friction modifier cm-19546-a1 in my 70 chevelle 12 bolt with factory limited slip. A local speed shop recommended it. It stopped the chattering years ago and I love to launch the car hard. __________________ 72 CST 4x4 Blazer, 1 ton 70 SS Chevelle, L78, 396 Everytime someone calls your Blazer a Bronco, God kills a kitten.



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