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Rear End Housing |
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Red Devil
AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743 |
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Are you aware of issues with the ring gear bolts on an AMC 20 and the situation / application under which issues occurred? Compare 8 x 7/16" bolts on the larger ring gear bolt circle diameter versus a typical 5 x 1/2" bolts on the smaller 4 1/2" wheel bolt circle diameter, then consider that with e.g. a locker, one wheel can take full torque. Now where is the weakest link? |
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Good catch, I missed that reply. It does happen with almost any ring gear. That is why ring gear bolt heads are wired in place on racing rear ends. It is that the shock of traction grab and slip happening like a jack hammer. The ring gear and pinion take the shock by drive forces being counter acted by wheels grabbing forces. The tires take some of the shock at the wheel and hub, while there is nothing between pinion and ring gear. |
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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 |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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Hi Red Devil, I'm a fan of the M20, but the ring gear bolt count is the thing that seperates our 8.875" ring & 1.625" pinion gear strength from the same sized Chevy 12 Bolt and nearly identical Ford 8.8" 12 bolt axle R&P strength. Lots of Jeep guys consider a 10 bolt 8.5" ring gear and 1.313" pinion D44 an upgrade over an M20, they're wrong, but not by much. I understand the 5 on 4.5" bolt circle argument, but when Chrysler figured out their 12 bolt 8.75" axles weren't strong enough for Hemi & 440 4speed cars, they went to D60's (12 bolts 9.75" ring gear 1.625" pinion), but kept the 5 on 4.5" bolt circle. 8 ring gear bolts over almost 9" of ring gear is a shortcoming, or everyone would have saved the weight and expense of the 4 extra bolts. |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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To sort of answer your question Red Devil, I'm assuming there was an issue with the 8 bolt attachment method in the R&P currently in my Javelin: ^This is a 3.15 M20 that I had gotten out of a 1971 401-auto Javelin 20+ years ago and never realized there was any issues with it. Somewhere along the line an earlier ring gear with 3/8-24 bolts must have been swapped in (1968+ M20's should have 7/16-20 bolts), I'm guessing shortly afterward that issues led to someone welding it to the carrier. Since AMC made the jump from 3/8" to 7/16" bolts in 68' my assumption is they also encountered enough attachment issues to merit the change. I started a thread on this when I had the issue here: Personally I would have liked to see AMC gone to 10 or 12 bolts back then, even if it meant keeping the smaller 3/8"-24's, but for stock AMC V8's, I'm sure 8 x 7/16-20's was, and still is more than adequate. My concern is that it's tough to increase the attachment strength further down the line when going for ultimate strength.
Edited by jpnjim - Jan/23/2019 at 8:52pm |
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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tufcj
Supporter of TheAMCForum Supporter of TheAMCForum Joined: Jul/10/2007 Location: Watkins, CO Status: Offline Points: 4086 |
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I have a NOS AMC20 housing. I believe it's the narrow one used in 70 AMX, Gremlin, and Hornet, so it would fit an American. It has a tag wired to it that shows P/N 8127749 GR. 9.001. It has a little surface rust from sitting in a shed for 20 years before I acquired it. It has spent it's whole life in the Denver area, so no serious rust. I might trade for a set of headers that will fit a 69 Rambler with Control Freak suspension. Bob tufcj
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69 AMX
74 Javelin AMX 67 Rogue If you need a tool and don't buy it... you'll eventually pay for it... and not have it. Henry Ford |
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A.R. Headers
AMC Nut Joined: Feb/28/2017 Location: Deer Park NY Status: Offline Points: 268 |
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Guys,
I’m extremely grateful for the insight you’ve all provided. I learned quite a lot in a very short time. I will make all the upgrades required using the very best available components throughout. I promise to make you all proud when it’s done. There will be social media involved in the process once it’s fully under way. Should be a blast. Thanks guys! Nick
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American Racing Headers
100% Made In USA Since 2005 |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676 |
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I went back through the posts. You said "64 Rambler", but didn't mention American or Classic. I think the assumption has been American since it used an open driveshaft and the 64 Classic/ambassador used a torque tube.... When you get a build page set up please post a link here!! I just put a Jag IRS in mine way back in 2003... (the 63 Classic wagon in my avatar) Lots of FSJ owners upgrade to a D44 because it's readily available for a bolt-in. The main difference is the one-piece axles. I agree -- differential wise it's not much of an upgrade, more of a lateral move. Good for about 500 hp. The AMC 20 has been run in the lighter cars (68-70 Javelin/AMX and American) with stock axles and 8" slicks (widest that fit stock wheel wells) with stock two piece axles. Cutting more keyways doesn't really improve strength much, keeping the axle nut torqued does. I believe when they used to cut additional keyways that hardened keys were used, otherwise it wouldn't help much, if any. The factory key is there mainly to make sure the hub goes back on the way it came off when changing seals or bearings. The old TSMs (58 for sure) say to mark the hub and axle before removing -- no keyway.
Edited by farna - Jan/24/2019 at 7:07am |
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Frank Swygert
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A.R. Headers
AMC Nut Joined: Feb/28/2017 Location: Deer Park NY Status: Offline Points: 268 |
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My apologies guys. It is an American 440 model. I’m definitely going with the AMC20 rear. A 9” or Dana 60 has been completely ruled out. Other than the trans I want this ride as much AMC as possible.
Nick
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American Racing Headers
100% Made In USA Since 2005 |
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graewolf
AMC Apprentice Joined: Feb/25/2012 Location: Richmond Va. Status: Offline Points: 135 |
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As you can see from my signature, I'm into the 64-up Americans. Can't wait to see some pics, will you be posting some here at some point or have you already and I just missed it? I don't have any type of social media, the closest I got is here. Please Post Pics
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Americans, 65 Convertible, 64-65 Wagons, 64 220 2Dr, 66 2Dr Hardtop..... They follow me home!!!
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A.R. Headers
AMC Nut Joined: Feb/28/2017 Location: Deer Park NY Status: Offline Points: 268 |
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Bob,
Check your PM please. Thanks. Nick
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American Racing Headers
100% Made In USA Since 2005 |
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