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998 vs 904 |
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KLW
AMC Nut Joined: Sep/02/2012 Location: MN Status: Offline Points: 488 |
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Posted: Jul/30/2021 at 3:04pm |
does anyone know if the torque converters are the same between a 904 and a 998 assuming they are both lockup? OR, do they even make a 904 with a lockup converter?
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1981 Spirit
(420 cu in stroker - 570 hp) 1966 Ford Fairlane Convertible (331 Cu In - 450 HP) |
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WhatISit
AMC Addicted Joined: Aug/07/2017 Location: Phoenix, AZ Status: Offline Points: 0 |
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I believe 904 and 998 converters are the same. The AMC version does not have lockup.
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KLW
AMC Nut Joined: Sep/02/2012 Location: MN Status: Offline Points: 488 |
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Are you sure about the lockup part? I was always told the 904 had a lockup version and the 998 was a lockup tranny. I could be wrong.....
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1981 Spirit
(420 cu in stroker - 570 hp) 1966 Ford Fairlane Convertible (331 Cu In - 450 HP) |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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998 was always the heavier duty version of the 904, with 4 disc clutches packs instead of 3. AMC used the 998 version with the 304, mopar with the 318. IIRC the 999 version was initially used with 360 Mopar and has a 5 disc hi/reverse clutch pack. All of these bits are fairly interchangeable so a lot of people just call them 904's. Later stuff gets all confusing in applications, and the last ones went to the newer 30/1/2 rh nomenclature.
It's quite easy to build a strong 904 with factory parts.
Lock up converters are newer and have a different and hollow input shaft to feed the converter clutch. |
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Heavy 488
AMC Addicted Joined: Apr/27/2019 Location: In the Status: Offline Points: 3529 |
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At least in the AMC world, 998 came in 2 flavors. Lockup and non.
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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A lot of these differences were year based. Lock up converters initially became available in 78 and were hydraulically (not computer) controlled. Also not all transmissions were lock up; often heavy duty applications did not include lock up.
The wide ratio 2.75 low gear set was a little later, 1980 I believe. Some sites have this information wrong. The initial 999 was a HD 904, 5 hi/rev clutch discs, 4 direct clutch discs, standard 2.45 low, and no lock up converter. The way to tell LU or not is the input shaft spline. The LU converter uses a 26 tooth spline, the non LU 27 teeth. This is not including the early (way before AMC used them) small input.
Edited by Ken_Parkman - Jul/30/2021 at 7:13pm |
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purple72Gremlin
AMC Addicted Charter Member Joined: Jul/01/2007 Location: Illinois Status: Offline Points: 16591 |
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1979 998 was the first year for the lock up. 1980 904 haa lock up. Later some did not..so it all depends.
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KLW
AMC Nut Joined: Sep/02/2012 Location: MN Status: Offline Points: 488 |
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are the torque converters the same between the two (lockup to lockup, nonlockup to nonlockup)?
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1981 Spirit
(420 cu in stroker - 570 hp) 1966 Ford Fairlane Convertible (331 Cu In - 450 HP) |
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Ken_Parkman
AMC Addicted Joined: Jun/04/2009 Location: Ontario Status: Offline Points: 1815 |
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Mostly I think. There are AMC/Dodge differences of course as Dodge put the ring gear on the converter. At some point they change the pump drive on the converter hub from slots to flats and I think that went with the bigger oil pump that went in about 93 on the OD trannies. Think that reads across on the 3 speeds, but not absolutely sure.
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
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AMC 904 and 998 torque converters will interchange if the 998 is non-lockup. AMC 904's were never lockup. AMC 998's were lockup (and wide ratio) starting in 1982.
I'm not sure if you can put a lockup converter in a non-lockup trans or vice-versa without bad things happening. Of course the lockup won't work. I wouldn't try it.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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