Light Thump when Turning...AMC20 w/ QT

Light Thump when Turning...AMC20 w/ QT

007

Crazy Sr. Respected Jeeper
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#1 - 1977 CJ-7 Renegade (Daisy Jane), Levis trim, 304, TH400, BW1339 (MM), D30/Auburn Max, AMC20/Trac-Lok/G2's, 4.88's, 33" BFG MT KM2's, Edelbrock Performer intake, Holley Sniper 4bbl EFI, MSD6, MSD ProBillet distributor, OME shocks, 4" ProComp lift.

#2 - 1984 CJ-7 Laredo (The Texas Hooker Project - Incomplete/Undecided)
I got my Jeep running for the first time last night and took it for my first spin today. Seems to be working well. I did notice something that didn't seem right though.

When I make turns on pavement, I feel a small thump or something in the rear end, like it's not slipping as it should (or maybe it is)?

I have a 400/QuadraTrac and the offset AMC20 I believe. No other noises, etc quiet as a mouse. I have checked the switch in the glove box and it is set to normal AWD.

Any thoughts?
 
Is it possible I have a trac-loc rear end? Would this do this?
 
Possible.. Unlikely but possible. From what I hear the trac lock in these go poop the bed pretty early on in life. Pull the cover and see if you can spot it. Or look for the letters to the right of the diff stamped on the flat spot of the housing.. if memory serves me right if its a double letter stamp like DD or BB you should have a factory LSD
 
Possible.. Unlikely but possible. From what I hear the trac lock in these go poop the bed pretty early on in life. Pull the cover and see if you can spot it. Or look for the letters to the right of the diff stamped on the flat spot of the housing.. if memory serves me right if its a double letter stamp like DD or BB you should have a factory LSD

Well, this one has only 48k on it. I'm just wondering if it's an issue or if it's normal...
 
007
Check your u-bolts, springs and bushings back there, might be something loose.
 
007
Check your u-bolts, springs and bushings back there, might be something loose.

That's a great thought... I gave it a good look at lunch and this thing has 35 years of Indiana salt and rust underneath and every thing with threads under there is rust-welded. I didn't see any signs of movement, but I will have it checked out nonetheless by someone who can raise it up and stand beneath it.

Any other ideas from anyone?
 
Q-tracs have a Limited slip diff inside the T-case, They are basically full time 4x4 to a point, when you turn, the shafts will spin at different rates and you get a little thump when it slips. When you flip the switch inside the glove box, that locks the diff in the T-case. Good idea to check everything out, but it's a good bet that's all it is...
 
Q-tracs have a Limited slip diff inside the T-case, They are basically full time 4x4 to a point, when you turn, the shafts will spin at different rates and you get a little thump when it slips. When you flip the switch inside the glove box, that locks the diff in the T-case. Good idea to check everything out, but it's a good bet that's all it is...

Super, that's what I was "thinking." I think I'd read on here early on that that was how it worked. It seems like it's the inside rear wheel that drags a bit on a turn, regardless of which way I'm turning on pavement.

I know the switch is on normal / green in the glove box, but should I check anything else? I want to make sure I don't have a vacuum problem and I'm in full-time FWD - or would that just negatively affect the front?
 
Super, that's what I was "thinking." I think I'd read on here early on that that was how it worked. It seems like it's the inside rear wheel that drags a bit on a turn, regardless of which way I'm turning on pavement.

I know the switch is on normal / green in the glove box, but should I check anything else? I want to make sure I don't have a vacuum problem and I'm in full-time FWD - or would that just negatively affect the front?

It wouldn't hurt one bit to pull the rear diff cover if that's what you feel is going on, always better safe than sorry.. as far as the q-trac, while the engine is running and in park, just switch the E-switch in the glove box a few times and make sure you can hear it engage and disengage, and if not start checking vacuum lines up top and down below on the t-case. Other than that, you can find the CORRECT fluid on this forum (I can't remember where) for the Q-trac, change it and make sure you have it at a proper level, and then after all that, find a nice field or pasture somewhere and drive it in figure 8s for a while, I read somewhere this helps the chain lubricate properly in all the links or something on that order, but it's supposed to help.
 
It wouldn't hurt one bit to pull the rear diff cover if that's what you feel is going on, always better safe than sorry..

What would I be looking for once the cover is pulled?
 
Ive never been around a qtrac but a locker will do that also.

You should be able to make the noise happen if you jack up the rear axle and move one wheel.
 
Possible.. Unlikely but possible. From what I hear the trac lock in these go poop the bed pretty early on in life. Pull the cover and see if you can spot it. Or look for the letters to the right of the diff stamped on the flat spot of the housing.. if memory serves me right if its a double letter stamp like DD or BB you should have a factory LSD

I found this online - now I need to check my diff...

Gear Ratio Codes

Gear Ratio Codes
Narrow Track AMC20
Code Gear Ratio Diff Type
AA 2.73 Open
DD 2.73 Trac-Lok
BB 3.31 Open
CC 3.31 Trac-Lok
A 3.54 Open
N 3.54 Trac-Lok
GG 3.73 Open
Q 3.73 Trac-Lok
L 4.10 Open
M 4.10 Trac-Lok

Wide Track AMC20
Code Gear Ratio Diff Type
D 2.73 Open
DD 2.73 Trac-Lok
B 3.31 Open
BB 3.31 Trac-Lok
A 3.54 Open
AA 3.54 Trac-Lok
H 3.73 Open
HH 3.73 Trac-Lok
C 4.10 Open
CC 4.10 Trac-Lok
 
I found this online - now I need to check my diff...

Gear Ratio Codes

Gear Ratio Codes
Narrow Track AMC20
Code Gear Ratio Diff Type
AA 2.73 Open
DD 2.73 Trac-Lok
BB 3.31 Open
CC 3.31 Trac-Lok
A 3.54 Open
N 3.54 Trac-Lok
GG 3.73 Open
Q 3.73 Trac-Lok
L 4.10 Open
M 4.10 Trac-Lok

Wide Track AMC20
Code Gear Ratio Diff Type
D 2.73 Open
DD 2.73 Trac-Lok
B 3.31 Open
BB 3.31 Trac-Lok
A 3.54 Open
AA 3.54 Trac-Lok
H 3.73 Open
HH 3.73 Trac-Lok
C 4.10 Open
CC 4.10 Trac-Lok

So do I!! Cool!
 

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