Rearend Advice

[jod man]

No, this is not a proctology thread!

I just got my TSM in the mail today and have been looking through it. The first thing I noticed was that, if my truck is stock, I have a AMC 20 not a Dana 44 like I thought. I have yet to physically identify it for sure, as well as determine the gearing, (still at the tranny shop) but my question is valid either way.

I plan to use this truck mostly for work. Spring, Summer and Fall Driving will be 40% hyway, 30% gravel road and 30% mud. I will be carrying a 400-500 pound quad in the back almost all the time. Winter driving will be on snowy/icy roads 80% of the time (no quad then). It is in the mud and during winter that a limited slip diff would help me most obviosly.

I had looked at a locker for the rear at first, but dismissed it because of the price. I do not want something that I have to have a air pump or cable system for, as I will be doing very little off-roading (sorry but it is too nice a truck).

My questions are:
1) How would a factory Trac Lock perform under the kind of driving I will be doing?
2) If I was able to find a used (or new) complete carrier, how hard would it be to change ? What modifications if any would I have to do? Do I have to change the axles?
3) How solid are these units, would I just be asking for trouble down the road? Anyone currently using one and had trouble?
4) Would it benifit me to do this change?

Thank you for your kind input (I know Scotty and joe will post on this one)


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'74 J-10
'83 J-10
Sportside Honcho
258 I6 (.03 over), T-176, NP208 all totally rebuilt Dec. 2000
Totally restored to stock except for K&N and Nutter Bypass done
Juicebox ignition upgrade, Dyno Flow muffler & 2.5 inch exhaust next
lonely for other FSJers near me!!

[This message has been edited by jod man (edited January 10, 2001).]

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by jod man:
I just got my TSM in the mail today and have been looking through it. The first thing I noticed was that, if my truck is stock, I have a AMC 20 not a Dana 44 like I thought. I have yet to physically identify it for sure, as well as determine the gearing, (still at the tranny shop) but my question is valid either way.<HR></BLOCKQUOTE>

Jod, your manual is correct, it's an AMC20 if stock. The diff cover will be smooth and round unlike that of the D44 front cover with the bump for the ring gear.
<BLOCKQUOTE>quote:</font><HR>I had looked at a locker for the rear at first, but dismissed it because of the price. I do not want something that I have to have a air pump or cable system for, as I will be doing very little off-roading (sorry but it is too nice a truck).
<HR></BLOCKQUOTE>

Personally I don't care for lockers or LSD's for street driving in the winter. They're great if you get stuck but they can "get" you stuck too. They get to be a little exciting on an icy roads with a crown especially going uphill.

<BLOCKQUOTE>quote:</font><HR>
My questions are:
1) How would a factory Trac Lock perform under the kind of driving I will be doing?
2) If I was able to find a used (or new) complete carrier, how hard would it be to change ? What modifications if any would I have to do? Do I have to change the axles?
3) How solid are these units, would I just be asking for trouble down the road? Anyone currently using one and had trouble?
4) Would it benifit me to do this change?
<HR></BLOCKQUOTE>

First off if you have the complete 83 TSM it'll be a combo of a full 82 TSM with the 83 supplement. The 83 supplement alone won't do much for you. The axle section will tell you what/where the ratio codes are on the AMC20. And the codes will tell if you have the factory Trac-Loc but since the rig is 18 years old it's prolly worn out if you do.
1)and 2) A new carrier runs about $75-$100 alone and $125-$150 with spiders but you won't need that for just adding a Trac-Loc. If you go to lower gears then you will but you'll also need to do the same for the front. See if you can drive someone elses rig with an LSD before you invest any money and see if you like the handling on icy roads.
3) The AMC20 is a good unit and the Trash-Loc opps Trac-Loc is marginal. Under mild/med use it may last 50,000+ miles but if it's kicking in-out a lot during hard use expect 30,000 miles out of the Trac-Loc.

If "I" wanted to go either locker or LSD(Limited Slip Diff)in the rear I'd go with a Detroit rather than the LSD. The Detroit is a lot tougher, no clutches to wear and you don't need an air pump etc as with an ARB. I think the new version called the Detroit Soft Locker even eliminates most of the clunk when it engages but I haven't driven one. All in all though the Detroit is good equipment and will last a lot longer than the Trac-Loc.
That's my $0.02($0.03 Canadian) http://www.ifsja.org/ubb/smile.gif

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Regards,
-joe
63 2-dr Wag, 73 J-4000, 82 CJ-8

[scotty]

i agree with everything joe said. the trac lok is a marginal unit that is notorious for breaking spider gears under hard use(like towing or hard wheeling),and if you tighten up the preload enuff to actually get it to act like a LSD rather than an open diff,the clutches will not last long.the only real advantage is that a tac lok is cheap.a brand new unit can be gotten for about $169. you pretty much get what you pay for. you might also look into an auburn gear,or a detroit true trac. the true trac is a nice,gear driven unit with no clutches to wear out.all of these units replace your existing carrier. if you are not changing gears,you can ususlly swap carriers using the same shims and be ok.you can use chalk to check and verify the contact pattern,or take it to a pro to have it verified,proper gear set up costs may need to be also figured in to overall cost. you definately dont want your new locker or lsd destroying your gears. if you want to lower the gears,obviusly,youll also have to figure in the cost of new front gears(and new carrier if needed) and the cost of having it all properly installed.

i also feel that an open diff is better for snow/ice driving.id defiantely try and test drive one before spending any cash.i personally dont think youll ever have a prollem,especially when carrying that much weight. i drove my j20 to work the other day,and didnt even need to put it in 4wd.the weight of the cap and diamond plate bed gave me plenty of traction.

for inclimate weather street driving,4wd with open diffs should get you anywhere you need to go.

for the little time that you need extra traction while unloaded,consider simply airing down your tires(assuming youre not running 16.5 inch rims) you would not believe how much extra traction you get from dropping tire pressure from 30 to 10.

if youre still lacking in traction,another option may be to add a locker or lsd to the front instead of the rear.depending on how much you need 4wd. the advantage is that it will be completely transparent with the hubs unlocked,but it will make steering hard,and almost double the truning radius with the hubs locked.this would make for some hairy winter driving,and would only be an option if you only need to use 4wd occasionally in muddy road-type conditions.another thing to consider anyway.

hope this helps.i really think youll be fine with open diffs front and rear http://www.ifsja.org/ubb/smile.gif

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scott
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd

T18/dana-spicer 18 with drum E brake and PTO,and offset dana 44 swap very soon
BIG tow truck PTO winch and full roll cage install shortly thereafter
searching for jeep 4.0 six engine

now we can do some 'wheelin!

[tuckers89GW]

For mostly road driving try "PowerTrax" I ran across that web site the other day. They have lockers and a limited slip traction system that looks pretty cool.

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Mike
<UL TYPE=SQUARE>
<LI>'89 GW
completely stock
<LI>'99 Windstar
under WARRANTY
<LI>see JEEP (http://tuckermj.tripod.com/jeep/)[/list]

[bigblack'74]

speaking of lockers..,i have got a spool in the rear of my .74 wag., but i need to know if any type if traction aiding device can go in the front other than an ARB..i have QT.thanks

[Gladi8r]

Rearend advice?? That like when Wifey(bless her heart) ask me "Does my butt look big in these"?? http://www.ifsja.org/ubb/biggrin.gif


I used to have an 83 CJ-7(baby Jeep days) with the AMC20 rear-end. Not sure the trucks had the same set up but mine had the 2-piece axles. Well, one day it failed and I replaced them with solid one-piece axles from Summer Brothers and installed 4:56 gears all around. Was running 35's on it with a rebuilt 360 under the hood and the Chry 999 tranny with the lock-up converter. That thing was great for mud,snow on/off road. Had great traction http://www.ifsja.org/ubb/biggrin.gif without Lockers. AMC20 is a good axle if you set it up right. I would just look into installing 0ne-piece axles if not already done.

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DON

1988 GW mostly stock, &lt;---Wifey's truck (won't let me "fix it up")

1971 J-4000,Rhino Grille(to be installed)
360 CID 8.5/1 ratio 2v, 245 HP, 365 ft/lb
T-18A, Dana 20, PTO, DANA 44 (Front/Rear)
Soon to be torn down for Resto
71 Gladiator Pics (http://briefcase.yahoo.com/bc/gladi8r1971?d&.flabel=fld2&.src=bc)

78 GW (parts truck)
360 4v Th400
Dana 44 F/R
http://www.j-trucks.freeservers.com/
78 Wagoneer Pics (http://briefcase.yahoo.com/bc/gladi8r1971?d&.flabel=fld3&.src=bc)

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Gladi8r:
I used to have an 83 CJ-7(baby Jeep days) with the AMC20 rear-end. Not sure the trucks had the same set up but mine had the 2-piece axles. <HR></BLOCKQUOTE>


Don, The AMC20's used in FSJ's have always had one-piece axles right from the factory.


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Regards,
-joe
63 2-dr Wag, 73 J-4000, 82 CJ-8

[Gladi8r]

Cool, shoulda put them in CJ's too!!! http://www.ifsja.org/ubb/biggrin.gif

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DON

1988 GW mostly stock, &lt;---Wifey's truck (won't let me "fix it up")

1971 J-4000,Rhino Grille(to be installed)
360 CID 8.5/1 ratio 2v, 245 HP, 365 ft/lb
T-18A, Dana 20, PTO, DANA 44 (Front/Rear)
Soon to be torn down for Resto
71 Gladiator Pics (http://briefcase.yahoo.com/bc/gladi8r1971?d&.flabel=fld2&.src=bc)

78 GW (parts truck)
360 4v Th400
Dana 44 F/R
http://www.j-trucks.freeservers.com/
78 Wagoneer Pics (http://briefcase.yahoo.com/bc/gladi8r1971?d&.flabel=fld3&.src=bc)

[scotty]

the amc 20 with 1 piece axles is a very stout rear end.the only prollem is that the diff is so big.i have 38s on my amc 20,but a friend with 33s and an offset dana 44 goes thru about the same ruts that i do. i didnt have much trouble getting around without lockers,either,and the only reason mine is welded is that i broke the carrier,and that was the easiest fix.

bigblack74, you cannot run a locker in a QT rig unless you convert it to part time,or at the very least install hubs and drive with them unlocked and the case in e drive.

a rear spool and a front locker with a full time front end will make for nex to impossible street driving. you could possibly run a tight LSD,like an auburn,or true trac,but expect to slide sideways on snow and ice.

is your rig street driven?what size tires do you run?



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scott
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd

T18/dana-spicer 18 with drum E brake and PTO,and offset dana 44 swap very soon
BIG tow truck PTO winch and full roll cage install shortly thereafter
searching for jeep 4.0 six engine

now we can do some 'wheelin!

[bigblack'74]

yeah i drive it on the street, but not that much, i have learned to take corners wide and i got used to the hopping of the backend... i run 32's..locked is the only way for traction...but dont use it for snow and ice, because the combo of a 401 and big tires and spool make for a way out of control truck

[nograin]

My questions 'zactly jod man.

and -Joe. Thanks. Finally got off more of the grime and found the D stamp. Not a very deep stamp. So looks like an 85 is the same. Also, this thread seems to support one your guesses as to why the trac-loc was not offered with the trailer package (in 85).

kinda wanted the LSD, but thinking about it, the viscous coupler to the front is actually a more effective way to do what I wanted. Too many years driving RWD cars I guess. LSD and studs are major helps in that case, but yea, even then the LSD makes it easy to loose the whole back end, if not being super careful.

Never tried the lower pressure trick in snow. Will have to this winter to try it out. Def noticed major difference between worn tires and new tires.

------------------
360 auto select
body by beer (PO)
carries wood inside
no "wood" outside

[scotty]

the tread pattern and rubber compound will have alot to do with it as well.a harder rubber will not give as much traction.

i have a 77 cmaro with a LSD trans am ws6 disc brake,posi rear end.with 225/60r16 goodyear LS(not a tire designed for snow) with marginal tread,i i cannot hardly get it in and out of the driveway if it snows. a very bad combo of heavt front,light rear,posi and por tire choice for snow. i used to drive this car yer round,and with an open rear and different tires it did OK. now it has to stay parked from fal to next spring,it is completely unsafe in snow and ice.

just goes to show there lots of factors involved. http://www.ifsja.org/ubb/smile.gif

------------------
scott
85 grand wagoneer
258 with motorcraft 2bbl/904/twin stick dana 300/dana 44/welded amc 20
38x15.5 gumbo mudders
snorkel/dual batteries/onboard air/"custom" convertable
3 inch body lift/mostly stock suspension/"modified" fender openings
custom front/rear bumpers and brushgaurd

T18/dana-spicer 18 with drum E brake and PTO,and offset dana 44 swap very soon
BIG tow truck PTO winch and full roll cage install shortly thereafter
searching for jeep 4.0 six engine

now we can do some 'wheelin!