AMC 20 noise

Sounds like the backlash needs to be adjusted. It will cause excessive wear if left alone. The problem is finding a competent shop that can do it right.

Later!
Mr. Ed

2014 Jeep Grand Cherokee Laredo "Gwendolyn."
1978 Concord Sport coupe "Mr. Black".
1982 Concord wagon. The Admiral. FOR SALE!
1976 Sportabout X, 304, auto, air. The Bronze Goddess

Its a posi AMC 20, 3:15 I put new clutch discs in about 10,000 miles ago.

1970 AMX 390 5 spd full Control Freaks front and rear suspension
2014 E63 AMG-S wagon
1965 Austin-Healey 3000 MK III

Typically if backlash is out, it shows up as noise as you gently on and off throttle and the load shifts from one side of the teeth in the gear set to the other. Noisey under load...is it after the rear is warm??? All the time? If the pinion gear has been removed previously, the issue may be the collapsable spacer was not done right and the preload of the pinion bearings is off. Setting the correct load is a real female canine job and usually takes way more effort and torque then most expect. My 200 lbs son on 8 foot cheater on my 3/4" Snap On Ratchet is scary!! You must set slow or you will exceed the "running torque value on the bearings" and have to start over. I know the Jeep group came up with a fixed spacer to replace the collapsable spacer to try and solve this issue, but I have rebuilt 50 + (probably closer to 100) rears from scratch back to exact factory spec and never had issue. It is really difficult to troubleshoot problems in the AMC 20, if not obvious broken or slop issue!! Most times I just tear down to bare and start with a known baseline and back together!! Having all the factory tools and other aids I have built over the years is a must. I hope this helps.

Ross K. Peterson
68X,GoPac,343,AT,52A(1stCar)
68X,GoPac,390,4sp,52A
69X,GoPac,390,4sp,64A
70X,GoPac,390,4sp,87A,8
70X,GoPac,390,4sp,BBO,8
70 Jav SST,390,AT,BSO
74MatX,401,AT,Prototype
74MatX,401,AT

EGADS! I have a 4 post lift, if I do this with the axle in the car and ratchet strap the car tight to the lift , I wonder if that will give Me enough leverage to play with the pinion nut? The noise is mostly when warm. When I changed fluid a few months ago there were no visible signs of wear. The control Freak suspension is so quiet compared to stock it has led to finding new sounds and drove me to get rid of My electric fuel pump. lol The car is a '70 AMX and the gears as You all know are right behind the seats plus I don't have much sound insulation and nothing at all in the trunk.

Edited by BDCVG - Apr/24/2014 at 10:02am

1970 AMX 390 5 spd full Control Freaks front and rear suspension
2014 E63 AMG-S wagon
1965 Austin-Healey 3000 MK III

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BDCVG Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Dec/19/2007 Location: Endless Mtns. Status: Offline Points: 993	Post Options Post Reply Quote BDCVG Report Post Thanks(0) Quote Reply Topic: AMC 20 noise Posted: Apr/21/2014 at 11:45am
	So how much gear noise is too much? It's quiet when I coast and in neutral but noisy under load. The Control Freak suspension is so quiet I'm hearing other noises now plus I do not have any sound deadening material in the trunk and just the pad that comes with a carpet kit. The gear oil is new not synthetic and has friction modifier in it.
	1970 AMX 390 5 spd full Control Freaks front and rear suspension 2014 E63 AMG-S wagon 1965 Austin-Healey 3000 MK III

Mr. Ed Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Nov/12/2010 Location: Sewell, NJ Status: Offline Points: 4916	Post Options Post Reply Quote Mr. Ed Report Post Thanks(0) Quote Reply Posted: Apr/21/2014 at 12:06pm
	Sounds like the backlash needs to be adjusted. It will cause excessive wear if left alone. The problem is finding a competent shop that can do it right. Later! Mr. Ed
	2014 Jeep Grand Cherokee Laredo "Gwendolyn." 1978 Concord Sport coupe "Mr. Black". 1982 Concord wagon. The Admiral. FOR SALE! 1976 Sportabout X, 304, auto, air. The Bronze Goddess

vinny Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jan/05/2012 Location: Calgary Status: Offline Points: 2837	Post Options Post Reply Quote vinny Report Post Thanks(0) Quote Reply Posted: Apr/21/2014 at 2:26pm
	You haven't stated what car but if it is an open drive shaft you might get a feel for if something is wrong with the pinion and crown stuff by wiggling it around to check for movement and excessive back lash. I had one that had been run low on oil and made noise under load. Changing out just the carrier bearings took all the noise away.

BDCVG Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Dec/19/2007 Location: Endless Mtns. Status: Offline Points: 993	Post Options Post Reply Quote BDCVG Report Post Thanks(0) Quote Reply Posted: Apr/21/2014 at 2:50pm
	Its a posi AMC 20, 3:15 I put new clutch discs in about 10,000 miles ago.
	1970 AMX 390 5 spd full Control Freaks front and rear suspension 2014 E63 AMG-S wagon 1965 Austin-Healey 3000 MK III

72GremlinKid Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Jul/29/2008 Location: marlton nj Status: Offline Points: 482	Post Options Post Reply Quote 72GremlinKid Report Post Thanks(0) Quote Reply Posted: Apr/23/2014 at 7:44pm
	Mine makes some noise on load over 50 mph been through 3 different gears and shops and still little bit of noise.
	1972 Gremlin X 360/727/AMC20 It's a Control Freak!

401MATCOUPE Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: May/20/2010 Location: Salisbury, MD Status: Offline Points: 5367	Post Options Post Reply Quote 401MATCOUPE Report Post Thanks(0) Quote Reply Posted: Apr/24/2014 at 2:56am
	Typically if backlash is out, it shows up as noise as you gently on and off throttle and the load shifts from one side of the teeth in the gear set to the other. Noisey under load...is it after the rear is warm??? All the time? If the pinion gear has been removed previously, the issue may be the collapsable spacer was not done right and the preload of the pinion bearings is off. Setting the correct load is a real female canine job and usually takes way more effort and torque then most expect. My 200 lbs son on 8 foot cheater on my 3/4" Snap On Ratchet is scary!! You must set slow or you will exceed the "running torque value on the bearings" and have to start over. I know the Jeep group came up with a fixed spacer to replace the collapsable spacer to try and solve this issue, but I have rebuilt 50 + (probably closer to 100) rears from scratch back to exact factory spec and never had issue. It is really difficult to troubleshoot problems in the AMC 20, if not obvious broken or slop issue!! Most times I just tear down to bare and start with a known baseline and back together!! Having all the factory tools and other aids I have built over the years is a must. I hope this helps.
	Ross K. Peterson 68X,GoPac,343,AT,52A(1stCar) 68X,GoPac,390,4sp,52A 69X,GoPac,390,4sp,64A 70X,GoPac,390,4sp,87A,8 70X,GoPac,390,4sp,BBO,8 70 Jav SST,390,AT,BSO 74MatX,401,AT,Prototype 74MatX,401,AT

fasttony Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jan/09/2011 Location: US Status: Offline Points: 1188	Post Options Post Reply Quote fasttony Report Post Thanks(0) Quote Reply Posted: Apr/24/2014 at 4:28am
	I made a tool to set the pinion pre-load I had to use 4' pipes for leverage it's not an easy task. Tony

BDCVG Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Dec/19/2007 Location: Endless Mtns. Status: Offline Points: 993	Post Options Post Reply Quote BDCVG Report Post Thanks(0) Quote Reply Posted: Apr/24/2014 at 9:56am
	EGADS! I have a 4 post lift, if I do this with the axle in the car and ratchet strap the car tight to the lift , I wonder if that will give Me enough leverage to play with the pinion nut? The noise is mostly when warm. When I changed fluid a few months ago there were no visible signs of wear. The control Freak suspension is so quiet compared to stock it has led to finding new sounds and drove me to get rid of My electric fuel pump. lol The car is a '70 AMX and the gears as You all know are right behind the seats plus I don't have much sound insulation and nothing at all in the trunk. Edited by BDCVG - Apr/24/2014 at 10:02am
	1970 AMX 390 5 spd full Control Freaks front and rear suspension 2014 E63 AMG-S wagon 1965 Austin-Healey 3000 MK III