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Model 20 groaning on turns |
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7172AMX
AMC Apprentice Joined: May/20/2015 Location: South Carolina Status: Offline Points: 124 |
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Posted: May/13/2021 at 10:24pm |
Evening,
Model 20 w/71 twin grip carrier. I've rebuilt several of these over time and never had issue. Since build when it gets warmed up (somewhat hot to be honest) she'll groan when the clutches slip around turns. Quite noticeable on tight turns. Could it be the synthetic lube? (limited slip purple stuff) Its the first time not using conventional base gear lube. The build was specd in every aspect per the FSM, preloads, runout, backlash, R&P inked, etc used a new set of clutches bought from AMC dealer circa 1980's! If it cant be the lube, its coming apart. thanks and God bless
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GoPacKman
71 JavAMX 401 T-10 354TG 72 JavSST 360 727 315TG 98 Jeep Cherokee Classic 4.0 4WD |
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THE MENACE
AMC Addicted Joined: Nov/04/2008 Location: So. California Status: Offline Points: 4428 |
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When you install or rebuild a limited slip carrier it takes a bunch of tight figure 8"s to work the lube into the clutch packs to work properly. The clutches would not slip smoothly in tight turns. It kind of popped instead. On top of that the cover gasket started leaking which I had never had a problem with ever with a rigid aluminum diff. cover.
I drained the synthetic and filled it with conventional limited slip gear oil and it started working as it should again and the leak was gone too. I won't do that again!! |
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Former Owner of:
The Craig Breedlove "AERO AMX" Still Owner: SS/AMX #9 replica (THE BIG MENACE) 70 AMX 416, EFI, Nash 5 speed 70 Javelin 401, 727 (Wife's) 72 Gremlin Autocross Project. |
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
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Gear oils that say "for limited slip" on them often do not have enough friction modifier in them in my experience. The "for limited slip" on the bottle is more or less meaningless...
I'd squeeze in a bottle of friction modifier and run it for a while to stir it in before going any further. I've gotten so I just automatically add a bottle of friction modifier every time I change the fluid.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19611 |
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I haven't bought friction modifier in many years, don't recall what it costs! Shouldn't be enough for you to try that first, and if it doesn't improve things after driving a bit (maybe a 6-12 tight figure 8s then a short drive around a few curves/blocks?) drain and try conventional lube. Some of the old parts just don't like synthetics, which are generally a bit thinner when cold for improved gas mileage, but hold up better under heat without thinning as quickly as conventional oil.
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Frank Swygert
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7172AMX
AMC Apprentice Joined: May/20/2015 Location: South Carolina Status: Offline Points: 124 |
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Consensus! Thanks to you all and will try a lube swap ASAP and report in.
Cheers
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GoPacKman
71 JavAMX 401 T-10 354TG 72 JavSST 360 727 315TG 98 Jeep Cherokee Classic 4.0 4WD |
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Steve_P
AMC Addicted Charter Member Joined: Jun/28/2007 Status: Offline Points: 3760 |
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I've used Mobil 1 75W-90 in the clutch plate LSD without issues. Agree about adding the friction modifier; the LSD spec gear oils often don't have enough additive as said.
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bobsterfl
AMC Nut Joined: Jun/18/2009 Location: Orlando, Fl Status: Offline Points: 260 |
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Try this stuff by Motorcraft.
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Bobsterfl
1970 BBO Javelin 390 - Torqueflight |
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tufcj
Supporter of TheAMCForum Supporter of TheAMCForum Joined: Jul/10/2007 Location: Watkins, CO Status: Offline Points: 4066 |
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I've been using the Motorcraft stuff for years with no problem. Bob tufcj |
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69 AMX
74 Javelin AMX 67 Rogue If you need a tool and don't buy it... you'll eventually pay for it... and not have it. Henry Ford |
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