Twin Grip very tight

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   I have a 390, manual transmission, 69 AMX running a AMC 20 differential.  It seems like the rear-end nearly acts like a locker when turning right or left.  When turning sharp the inside wheel nearly locks.  I was wondering whether the tension of the clutch pack maybe too tight?  I heard, can't remember where, but the tension can vary, and I may have this wrong, from 70 - 200 foot pounds of torque.  Can this simply be an adjustment, shims, extra disks/clutches in the pack? When I have the rear wheels off the ground they turn very freely with no indication of tightness and yes the wheels rotate in the same direction.  I have added a friction additive to the oil.  Axles have been changed to one piece if that would have any bearing on this problem.
Would very much appreciate your opinions on this problem.

Many Thanks
I.B.Sorgn    

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IB Sorgn Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Dec/17/2012 Location: Kentucky Status: Offline Points: 192	Post Options Post Reply Quote IB Sorgn Report Post Thanks(0) Quote Reply Topic: Twin Grip very tight Posted: Jan/27/2021 at 12:52pm
	I have a 390, manual transmission, 69 AMX running a AMC 20 differential. It seems like the rear-end nearly acts like a locker when turning right or left. When turning sharp the inside wheel nearly locks. I was wondering whether the tension of the clutch pack maybe too tight? I heard, can't remember where, but the tension can vary, and I may have this wrong, from 70 - 200 foot pounds of torque. Can this simply be an adjustment, shims, extra disks/clutches in the pack? When I have the rear wheels off the ground they turn very freely with no indication of tightness and yes the wheels rotate in the same direction. I have added a friction additive to the oil. Axles have been changed to one piece if that would have any bearing on this problem. Would very much appreciate your opinions on this problem. Many Thanks I.B.Sorgn
	Madd X

Trader Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6913	Post Options Post Reply Quote Trader Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 3:01pm
	I doubt changing the axles has anything to do with this if nothing else was done. If the car sits for any length of time the oil will get squeezed out of the clutch/shim interface and grab. The top of the clutch pack is not sitting in oil. Every spring, the first thing I do is take the car out to a parking lot and do some figure 8's just for this reason. If the clutch pack was replaced and assembled dry the same thing is going to happen. The clutches should sit in oil for 24 hours before installation. The figure 8 thing will usually work for this also but take it slower and give it more time. You don't want the clutch packs to get too hot.

304-dude Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082	Post Options Post Reply Quote 304-dude Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 3:26pm
	Try more like 250 foot pounds to break free. I swear the 2 piece AMC and Mopar limited slips are much tighter than ford and chevy. My 71 before removing the rear would keep locked under light power in parking lots. I had to stay off the pedal when turning. Then again I had 78 series on stock steel rims.
	71 Javelin SST body 390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker

IB Sorgn Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Dec/17/2012 Location: Kentucky Status: Offline Points: 192	Post Options Post Reply Quote IB Sorgn Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 4:19pm
	Been driving the car for over 50 miles so I'm sure the clutch packs are well oiled. Don't know about how the diff was assembled but the more I investigate I'm starting to believe that the discs may have not been installed correctly. I agree that the axles should not effect this situation but just wanted to make sure that I mentioned that. It's a tough problem but I Appreciate your reply
	Madd X

IB Sorgn Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Dec/17/2012 Location: Kentucky Status: Offline Points: 192	Post Options Post Reply Quote IB Sorgn Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 4:22pm
	This is definitely not normal. Appreciate your reply.
	Madd X

Mopar_guy Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jun/07/2009 Location: Ohio Status: Offline Points: 4837	Post Options Post Reply Quote Mopar_guy Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 4:29pm
	Try doing some tight figure 8s in a parking lot. If I had a chattering limited slip and I changed the lube, it would still chatter so I usually did about 8-10 figure 8s and that would do the trick before giving it back to the customer.
	"Hemilina" My 1973, 5.7 Hemi swapped Javelin

madams Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jun/26/2017 Location: Duncan OK Status: Offline Points: 609	Post Options Post Reply Quote madams Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 4:32pm
	Don't want to overlook the obvious, but I assume you put the limited-slip additive in the oil or used an oil that already included it.

Rebel Machine Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/03/2007 Location: Western Il Status: Offline Points: 5121	Post Options Post Reply Quote Rebel Machine Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 7:04pm
	Was the carrier rebuilt recently? I did one several years ago and missed removing one of the discs so it was bound up when I reassembled it. Same behavior your describing. The axle nuts have nothing to do with it. There is no adjustment on the carrier to set the friction plates, they're simply sandwiched together when the two halves of the carrier are bolted together. -Steve-

troutwilly Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Sep/14/2007 Location: Carriere, MS Status: Offline Points: 994	Post Options Post Reply Quote troutwilly Report Post Thanks(0) Quote Reply Posted: Jan/27/2021 at 9:25pm
	Just another thought. You said you added the limited slip fluid. Did you add enough? And maybe adding just a little more will give the slippage you desire. Years ago I got tired of my truck having trouble in the sand and mud so I replaced the diff fluid and added less slip fluid than called for. Worked like a charm. Kind of the opposite result you're looking for but an idea.
	Bill O. 70 AMX

iapexl8r Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Apr/13/2008 Location: north idaho Status: Offline Points: 639	Post Options Post Reply Quote iapexl8r Report Post Thanks(0) Quote Reply Posted: Jan/30/2021 at 5:38am
	if the axles were swapped they may require triming. there is a possibility that this may be an issue caused by the axles being to long. I have done a few of the Moser solid axle mods and I recall something in the instructions about them possibly needing trimmed. just my 2 cents Chris