Positraction problems
Thread Starter
Advanced
Joined: Jul 2003
Posts: 51
Likes: 0
From: Phoenix AS
Positraction problems
Hi All,
After driving my 67 on the highway for an hour or so, the next time I stop and turn (like at the exit ramp), I get a loud banging sound from the rear end, which I assume to be the positraction not slipping gracefully. What's the fix for this ?
Thanks
After driving my 67 on the highway for an hour or so, the next time I stop and turn (like at the exit ramp), I get a loud banging sound from the rear end, which I assume to be the positraction not slipping gracefully. What's the fix for this ?
Thanks
Le Mans Master
Joined: Nov 2000
Posts: 7,246
Likes: 21
From: Going too fast over the hill. Iowa
Re: Positraction problems (Blue67)
Try this: In a parking lot make a tight right circle then a tight left circle. If the noise goes away, the noise was the posi clutches.
Race Director
Joined: Jan 2000
Posts: 13,014
Likes: 2,257
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Re: Positraction problems (Blue67)
Many times, if the posi isn't hurt, you can make great improvements by changing fluid and adding new posi additive.
JIM
JIM
Thread Starter
Advanced
Joined: Jul 2003
Posts: 51
Likes: 0
From: Phoenix AS
Re: Positraction problems (427Hotrod)
Thanks for you note. I had the lube changed and had an emulsifier added, but it still acts the same. After a long expressway drive when I get off the expressway, stop and then turn I get a pretty bad clun or thud. If I just drive around town this doesn't happen. What's the next step ? IS there any information available on serviceing positraction units ?
Thanks
Thanks
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,923
From: Washington Michigan
Re: Positraction problems (62fuelie)
I don't know what "emulsifier" they added, but the only additive that works (and will almost always solve the problem you describe) is the GM Posi additive, P/N 1052358 (4-oz. bottle). Normally 1-1/2 bottles of the additive and 2 bottles of fresh GM Diff Lube (P/N 1052271), followed by ten miles of driving and a few low-speed figure 8's in a big parking lot will cure the "clunking" permanently. :thumbs:
Drifting
Joined: Jan 2001
Posts: 1,358
Likes: 26
From: Florida
Re: Positraction problems (JohnZ)
I have the same issue but it only pops up when it is real hot. I have been told, by the noted posi builder in this area, to use Mobile 1 gear lube? I do not not know if that will work for you? I am going to try it this week.
Andy
Andy
Race Director
Joined: Nov 2000
Posts: 10,340
Likes: 664
From: Beverly Hills (Pine Ridge) Florida
Re: Positraction problems (andy60)
I also have had this problem in several vehicles in which the magic GM additive just refused to do any good. Have found synthetic lubes to be far more "lasting" in curing this problem. In my case, Amsoil has worked for me each time, with no need for periodic drain/refills.
My first "problem" vehicle (that was "fixed" using Amsoil) was a 66 Vette, and after the typical add the GM additive (no change), then the lube drain & refill with the GM additive, it still did the same thing. Drained and added the Amsoil (on the advice of a friend - which I did not have much faith in!), and it worked perfectly thereafter. Now I don't bother with anything but the Amsoil. Used it in my 70 Vette which had a total of 247K miles when sold (had it for 15 years of daily Chicago area driving), and the Posi still grabbed when it should, and released when it should.
Plasticman
My first "problem" vehicle (that was "fixed" using Amsoil) was a 66 Vette, and after the typical add the GM additive (no change), then the lube drain & refill with the GM additive, it still did the same thing. Drained and added the Amsoil (on the advice of a friend - which I did not have much faith in!), and it worked perfectly thereafter. Now I don't bother with anything but the Amsoil. Used it in my 70 Vette which had a total of 247K miles when sold (had it for 15 years of daily Chicago area driving), and the Posi still grabbed when it should, and released when it should.
Plasticman
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
Le Mans Master
Joined: Jan 2002
Posts: 8,913
Likes: 283
Re: Positraction problems (Plasticman)
Had same problem after diff. swap. Added a second bottle of the GM lube and problem solved. The figure 8's were not working so we lifted one side of the car and slowly let the clutch out until the free wheel spun. Works perfect now.
Mark
Mark
Melting Slicks
Joined: May 2002
Posts: 2,225
Likes: 44
From: Penticton B.C. Canada
Re: Positraction problems (ghostrider20)
Had same problem after diff. swap. Added a second bottle of the GM lube and problem solved. The figure 8's were not working so we lifted one side of the car and slowly let the clutch out until the free wheel spun. Works perfect now.
Mark
Mark
Safety Car
Joined: Nov 2001
Posts: 4,424
Likes: 619
From: northern CA
Re: Positraction problems (Daren Schneider)
Had same problem in my 67 . Changed fluid, 2 bottles of GM fluid, Figure 8's forward and backward and no more crunching.
JohnZ and Daren's "fix" with the figure 8's sounds pretty cool .. ! .. - didn't know about that one .. Daren, how do ya' do those 8's in .. REVERSE .. !?! ..
:cheers:
