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Post by PHAT69AMX on Jan 19, 2022 14:22:05 GMT -8
Might anyone be able to share specifics about the 1968 1969 & 1970 AMX Rear Axles, Housings, Twin-Grip Carriers, & Clutch Packs? I am attempting to remotely help a friend in Ohio who has a 1969 AMX. He had a rear end that years ago he put a "New" 1-Piece Posi Twin-Grip Carrier in that he bought NEW from APD. It no longer functions properly, it no longer works as a posi. I helped him locate and get a good 1968 dated 1969 Model 2-Piece AMC Posi Twin-Grip Carrier. He ordered a New Clutch-Pack & Diff Rebuild Kit from APD & the New Clutches DO NOT MATCH what came out of the 1968 2-Piece Carrier. Digging in the Parts Manual suggest the 1-Piece Posi Twin-Grip Carrier was a 1971 Model year mid-year phase-in.
Is it that the Clutch Pack for a 1-Piece Carrier is different than that for a 2-Piece Carrier? The 2-Piece Carrier has (1) Clutch Disc that is "Thin", either .030" or .060" Thick, & the other discs are .090" thick. Where the 1-Piece Carrier all the Clutch Discs are the same .090" thickness? Which is what APD sold & shipped him, and is incorrect for his 1968 2-Piece Carrier.
As a side question, why in the Parts Manual does it show for 1970 ONLY, that only the passenger side axle is SHORTER that it is for the 1968 & 1969 cars, yet the documented "Rear Track Width" or "Rear Tread Width" dimension of 57.00" is the SAME for all three years 68, 69, & 70 ?
Understand that 1971 & Up for the Lumpy Javelin's they all got like what 3 inches wider? But that doesn't really matter here, just sayin' belief is that 1968-69-70 all 3 were the same.
Thanks.
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Post by landbarge on Jan 19, 2022 14:51:32 GMT -8
As I hear, there's only 1 place that has the 2 piece carrier clutches( forget the name). Most everyone else is selling the clutch packs for the 1 piece case which don't work.
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Post by sc397 on Jan 19, 2022 15:28:43 GMT -8
The carriers all interchange up to and including the 2.87 gear. The 2.73 gear uses a different carrier. Some are bolted together and some are not. The '68-69 rear ends are the same. The 1970 is different like you state with a different axle length. It seems that if you go through the Jeep suppliers they have a better handle on which AMC20 rebuild kit works with what.
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Post by spud on Jan 19, 2022 18:47:59 GMT -8
The “one peice carrier posi” is called a “ trac lock” and it was used from 71 forward. The confusing “ twin grip” moniker, foolishly applied by amc to the total junk 71 up TRAC LOCK, has no commonality to the early posi, which is called a “ power lock”. The power lock is arguably the best and most durable posi or “ limited slip” created. It was available in gm and mopar rear ends too. You can get clutch packs from yukon, i buy them from summit. The label says….YPKC8.75-pc. 8.75” chry & 55P chevy P/L clutches, m20 also, “ OEM POSI ONLY!!***. 16148 Made in usa. These kits come with the identical clutch pack configuration as amc standard POWER LOCKS. If greater torque bias is desired for drag racing ONLY You can order extra kits and create custom clutch pack stack ups to increase torque bias to the point of having pretty much a spool if desired. Thats free proprietary spudtech but if I can figure That shit out then any bozo probably could. I know its probably wasted breath but most folks know a traction lock is a piece of shit. You can get clutches from many sources but why. They only last a couple minutes. They have only one clutch pack. The power lock has two clutch packs . A true twin grip. Like Rick stated, MOST, but not all, 70 jav/ amx’s have a one inch narrower housing , with associated shorter axles. This makes it pretty unique. The posi units are the same as 68/69. One point of aggravation is the unusual axle thrust parts in a POWER LOCK, two rivet like parts with a pin inside, that goes through the spider gear cross shafts. This son of a bitch can drive you nuts if it comes apart or out when you remove the axles as it is a total whore to get back in place. You will see. If you break or lose part of it, you can get replacements from summit for a 8-3/4 mopar POWER LOCK. Beware the bolts that hold the power lock case together. They are mostly reverse rotation bolts, however, i have found one that had standard rotation bolts. I normally use a wrench on the bolts when its still in the car with wheels on the ground to loosen them, and be carefull when workin them and make sure they get loose, and not tighter when you turn them, because if you break one off you are so totally fucked it aint funny.
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Post by PHAT69AMX on Jan 22, 2022 18:11:46 GMT -8
Thanks y'all. Pretty wild that the 1970 is different... not that it matters, it's only paper & doesn't matter, but strange that the SAE Paer shows the same 57" Track Width for all three years 68, 69, & 70, where real-world info has the 1970 as different. Papers suggest the stock rim backspace is also the same for all three years, so track width wasn't "fixed" with different rims. So a pair of wheels & tires say on a 1969 say leaves about 1" leaf spring to sidewall clearance. Those very same wheels and tires swapped onto a 1970 and there will be LESS leaf spring to sidewall clearance then ? Yeah, and the 2-piece carrier LH thread case half bolts can mess a feller up, thanks for pointing that out. Stupid me who reads the TSM points that out and says ONLY the 390 car carriers have LH thread bolts, which seams odd. Ok, so the (1) thinner "clutch disc" in the "Power Lock" 2-piece Carrier Clutch Packs... Is the "thin" disc supposed to be .03" or .06" thick
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Post by spud on Jan 22, 2022 20:29:24 GMT -8
I dunno how thick it is, but its the first one in, the outermost “ disc”. They aint really clutches. They are bare steel washers. Some have outside diameter lugs that engage into the case, some have inside diameter lugs that engage onto splines cut into the spider gear hubs. There is two cupped bellville type washer that acts as a springs to preload the “ clutch” pack. There are variations on how to assemble a clutch to get higher torque bias, the power lock used in dana 60’s in hemi cars had another cupped washer for higher torque bias. There is a website that shows how to assemble the discs for more or less bias … somewhere. I found it once. Google dana powr lok … You’ll find a pdf page at “media.spicer parts.com. something er other…. Its got a fuckton more info than you’ll ever get on the gaymc forum straight from the manufacturer of the DANA POWR LOK locking differential. If i could link you i would. You’ll find a 15 page manual about dana 60-70 series axle powr lok assemblies showing all manner of stuff, and four variations on clutch pack stack up. I dunno why i help out the goddamn gaymc forum like this. Tell those douchebags to suck it for me please. Its just more proof amc didnt make the twin grip. I really dont believe they made the model 20 axle either. I always thought dana made it. Since its got standard dana sized bearings and a dana integral case and all . Oh but hell no the die hard amcers all swear amc manufactured it. Bah! I doubt that. Shit dana spicer made axle assemblies for all the manufactures. Why wouldnt amc take advantage of that? I dont really care who made it. My advice to anyone is get a new eaton trutrac. Its about 700 bux or so. Way better than powr loks, on the street or track and dont wear out
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Post by PHAT69AMX on Jan 22, 2022 21:13:38 GMT -8
Spud, ok, will check that out. Yeah, have some stuff saved on the PC about the different disc stacks for different torque bias. I'm helping an old friend in Ohio who is in his 30's, replacing a 1-piece with a good 2-piece I located for him here in Charleston WV which he came down and bought, housing & all. Then even though I suggested otherwise, he orders from APD and things go off the rails... He did find it had left hand thread case half bolts when he took it apart, which I had warned him about before hand and to be careful. I'm tryin' to guide the feller in the right direction, sometimes it's a challenge - LOL But I hear what you're sayin' and all the info helps, and gets added to other saved old info.
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Post by PHAT69AMX on Jan 22, 2022 21:42:08 GMT -8
SPUD, OK, PRETTY SURE i FOUND THE 15-PAGE DANA SPICER 60 "SERVICE MANUAL" WITH THE DISC STACK OPTIONS DIAGRAMS ( eh... didn't see caps locks was on & I ain't retyping it... )
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Post by spud on Jan 23, 2022 8:15:31 GMT -8
Good. I have an interest in model 20 assemblies. In my opinion, a good selection of model 20’s is a great asset to having a performance amc “ operation”. Factory gearsets and locking diffs are really worth finding and saving. Aftermarket gears are generally not as good. Even richmonds are going cheapo. The most usefull “ economy ratios like 2.87, 3.08,. 3.15 are no longer produced. 3.31 and 3.54 ratios need an overdrive for hiway use. All model 20 axle assemblies and parts should be treated with care and respect and given a nice cozy home out of the rain and elements !
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Post by PHAT69AMX on Feb 1, 2022 18:40:10 GMT -8
Got some info today from Yukon, their # 16148 Clutch Kit is "correct" for the AMC Model 20 2-Piece Twin-Grip carrier, and what it contains WILL work, although it's contents does DIFFER from what is shown in that Service Manual Spud mentioned and was found and downloaded. That Manual shows 4 Stack Options, BUT it "uses" 4 different "Discs" including a DISHED Tang Disc & a DISHED internal toothed Disc in 2 of the 4 possible Stacks. The Yukon Kit does NOT include a DISHED internal toothed Disc, so it allows only 2 possible different "Stacks" for 2 different level of Bias. The Kit APD sells is only for the later, 1971 ? mid-model-year & Up 1-Piece Model 20 Twin-Grip Carrier, which DOES use 5 Discs ALL THE SAME .092" Thickness. The "early" 2-Piece carrier has 1 or more Discs that are thinner, STOCK. So the correct Yukon Kit for the 2-Piece Carrier will work since it does have 1 Disc that is thinner at .062" thick, but it is not exactly like factory stock, and offers only 2 different stck Bias choices rather than the original 4 possible stacks & bias choices. Clear as mud, eh ? Thanks for all the helpful info, thought no harm in sharing what's been recently found. Peace.
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Post by spud on Feb 1, 2022 20:32:43 GMT -8
What you think, what you believe and what you know, are three different concepts. And none of them are nessesarily true. I chose to buy the yukon kit, install it and somehow it worked. Since its the only kit i know of, i bought a couple more. Does it have the gaymc god seal of approval? I dont care. It is what it is whatever the fuck that is and what it is it shall be untill it is not anymore. And the way its going it wont be long untill it is not what it was pretty soon. Thats why i bought extras. With that in mind i also recomend you buy your trutrac quickly since they are made in taiwan and that may not be what it was pretty soon too.
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Post by sc397 on Apr 11, 2022 15:30:36 GMT -8
We carried a few AMC20's in to the shop last week and dam those thing are heavy! Anyway, I have been trying to get a handle on over all widths and spring perch distances. I did finally came up which is what I think is all of the ratios were for the 20. Thanks to the Jeep thing we have quite the verity and can still buy new ring and pinions. I will put them in order of ratio, 2.56 2.73 2.87 3.08 3.15 3.31 3.54 3.73 3.91 4.10AMC20Ratios by Rick Jones, on Flickr Here is some info from a Jeep site: Narrow Track AMC 20 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 AMC 20 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 The Trac-Lok is a limited slip differential. You may have to scrape away a lot of mud, paint, and rust to uncover the code. If you can't find the code on the rear, check the tag on the front axle. Both axles should be geared the same. The R&P ratio ranges supported by the carriers are 2.73 and 3.31-5.13. The 5.13 gear ratio is not available for the Dana 30 though, so it is rare to see it. 4.56s are the lowest common ratio between the Dana 30 and AMC 20. 5.13s are available for the Dana 44. CJ AMC 20 The CJs used two versions of the AMC 20, the narrow track from '76-'81 and the wide track from '82-'86. Both versions use keyed, two piece shaft/hub design and 5 on 5.5" wheel bolt pattern. Supplies of AMC 20s were exhausted in 1986 and some Dana 44s were used instead in the last of the CJ-7s. Note: I have one of these from a 1980 CJ and it has a Trac-Lock with a 3.07 Ratio with a "Y" stamped on the housingFrom 1976-1978 a larger 11x2" drum brakes was used on the AMC 20. After 1978, a 10x1.75" drum was used. SJ AMC 20 The Wagoneer and full size Cherokee also used a narrow and wide track version of the AMC 20. Both SJ versions used once piece shafts and 6 on 5.5" wheel bolt pattern. Since the length and bolt pattern is different from the CJ version, the SJ shafts are not compatible without resplining and redrilling. I've never heard of anyone going to the trouble. Model/Version Spring Pads Wheel to Wheel Years AMC 20/CJ Narrow Track 36" 50.5" '76-'81 AMC 20/CJ Wide Track 36" 54.5" '82-'86 AMC 20/SJ Narrow Track AMC 20/SJ Wide Track This is a good site that lists them all as well. www.drivetrain.com/parts-catalog/rear-end-a-differential-ring-gear-and-pinion-sets/amc-20-ring-and-pinions
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Post by sc397 on Apr 11, 2022 15:56:05 GMT -8
Now to try to make some sense out of the width and spring perch centers. I will try to list them in order of the leaf spring cars narrowest to widest not counting the Jeeps. Please add any more info that you guys might have. I will clean this up as I get the information.
Rambler American. Width drum to drum Spring perch cc 2" Width
1968-69 Javelin & AMX. Width drum to drum Spring perch cc 2.5" Width
197O Javelin & AMX. Width drum to drum Spring perch cc 2.5" Width
1970-77 Gremlin & Hornet. Width drum to drum Spring perch cc 2.5" Width
1978-80 Spirit & Concord. Width drum to drum Spring perch cc 2.5" Width with large rubber mount
1975-78 Pacer. Width drum to drum Spring perch cc 2.5" Width.
1971-75 Javelin & AMX. Width drum to drum Spring perch cc 2.5" Width
These are my guesses but the Pace may actually be wider than the big body Javelin. Now to get the measurements. I just went through and measured 7 rear ends that I have and the only difference in all of these is the passenger side axle tube. Some are at 18" inside axle flange to center housing and some are at 18 1/2" All of the axle tubes on the driver's side measure at 17 5/8" - So all the axles on the driver's side are the same. The spring perch cc are all the same at 43 3/8"-43 1/2"
All of these rear ends have the 18" tube on the passenger side 68 AMX - Original from my car. 69 AMX - Original from a scrapped AMX 70 AMX - I measured the one in my AMX that is original 70 AMX - N2oJoe's late 1970 AMX 71 Hornet - original in my car.
All of these rear ends have the 18 1/2" tube on the passenger side 4.10 gear unit out of a Gremlin but unknown if original. It does have a later casting number on the center section 3212478 vs 3186891 on all of the rest. 3.54 gear unit out of I don't know what. 4.56 gear unit out of I don't know what.
N2oJoe's 74 Jav/AMX. Driver's side = 19 5/8". Passenger Side = 18 1/8"
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