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904 vs 727 |
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speed_is_addictive
AMC Fan Joined: Nov/12/2016 Location: niagara falls Status: Offline Points: 24 |
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Posted: Apr/27/2018 at 5:26pm |
My hornet came with a 904.
i will be running a stout 360. is this trans able to handle the power built properly or should i just invest in a 727. . . im new to amc but not to power or drag racing. . . thanks |
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gremlin1945
AMC Addicted Joined: May/21/2008 Location: new jersey Status: Offline Points: 781 |
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A well built 904 will handle anything you'll throw at it, and it's lighter and smaller than a 727, a consideration installing it in a hornet/gremlin.
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former NHRA #1945
former IHRA #1945 T/SA |
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1727 |
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was it from a 6 cylinder or a 304
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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speed_is_addictive
AMC Fan Joined: Nov/12/2016 Location: niagara falls Status: Offline Points: 24 |
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hmmm, how do i tell the difference. . .
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gremlin1945
AMC Addicted Joined: May/21/2008 Location: new jersey Status: Offline Points: 781 |
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If you're putting it in without doing any rebuild I wouldn't do it you will have to have it rebuilt to the specs for high performance use a lot of guys run them and they don't have a problem with them it's not cheap though
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former NHRA #1945
former IHRA #1945 T/SA |
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16614 |
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a 304 runs a 998. which is a beefier 904.
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jpnjim
AMC Addicted Joined: Nov/25/2007 Location: New England Status: Offline Points: 2752 |
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They put small case 9xx series transmissions behind race Hemi's so they can be built to take the heat.
Racers even run 9xx series internals in 727 cases to cut down on weight/drag, so the small case parts can be made to live. If your Hornet is a 1970, the 9xx case would have been swapped from a 72 or later AMC (assuming it's an AMC case), so you'd want to identify it to be sure what you have. 9xx series transmissions are also easier to get with the 2.75 low first gear, if you want to run a little taller rear gear, the deeper first can help compansate, while still giving you a good gear to launch from. The 2.75 first for a 727 is much more difficult to get, and expensive. An AMC 360 with a 904/998/999 is a good combination. IIRC, the 999 was actually originally introduced when the Chrysler 360 came out, to handle the extra torque without going to a 727.
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71 P-code 4spd Javelin/AMX
some Jeeps and some Fords |
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BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1719 |
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I used to argue that the cost to beef up a 904 or 998 to take the kind of power that even a mediocre 727 will handle wasn't worth it. I still think so today but less strongly. If durability is your number one concern, then the 727 is still the best choice. But the rotational inertia of the smaller transmission is much less and frees up a lot of power. When I switched to a 998 from a 727 in a 360 American I picked up a couple of tenths just due to the rotational inertia improvement. One thing that isn't obvious when comparing the bigger clutches of the 727 to the puny clutches of the 998 is the quantity. Typical 727 has 3, maybe 4, and it takes some work or the right drum to get 5. Basic 998 has 5 already. Smaller clutches, but more of them so I would call it a wash. A second advantage to the 998 is that Chrysler made a lot of low gear planetary 998 transmissions and you have a decent chance of finding a low gear ratio where the 727 low gear planetary seems rare and/or expensive. That same 998 is now behind a 401 and we will see how long it lasts. Went 5 years without maintenance behind a 360.
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