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998 vs 727 |
Post Reply | Page 123 4> |
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Smitty52
AMC Apprentice Joined: Aug/05/2008 Location: Bolton Landing Status: Offline Points: 227 |
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Posted: Feb/21/2018 at 6:13pm |
Going through the 74 Jav and have the 998 tranny at the shop for seals and whatever. They say the case is worn and we are searching for a good core to use the case. Is the 727 a direct bolt in. Drive shaft length, crossmember location, tranny mount etc? I am going from the stock 304 to a very mild 360. Since the 727 was used with the 360 I thought it might be best to upgrade. I will admit that my days of stop light grand prix's are a thing of the past but a romp on the loud pedal still seems to happen on occasion. Thoughts?
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AMO#8454, AMCRC# 8066
69 Ambo coupe, 401, M12, 66 Ambo 990 Wagon, 327,PW,PB,PS,posi,AM/FM,AC 74 Jav 360 auto ac 2003 FLHTCI, 1977 Yamaha XS750 2015 Chry 200, 2006 Pacifica |
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DaemonForce
AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070 |
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Use the 727. It will not let you down like the 998.
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1971 Javelin SST
American 304 2v | FMX | AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI | 1982 NWC T-5M (4.03/.76) | Dana30IFS/35-2.72 |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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If you are going 360 I'd do what AMC did and put a 727 behind it.
The 998 can be one tough transmission, light and strong, but a 360 is no slouch, and since you need to replace yours, why not do the upgrade now? |
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Smitty52
AMC Apprentice Joined: Aug/05/2008 Location: Bolton Landing Status: Offline Points: 227 |
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That is the way I am leaning, just want to know if it is a bolt in. It should be but I am not sure if the case length is the same or if I need a different mount/crossmember |
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AMO#8454, AMCRC# 8066
69 Ambo coupe, 401, M12, 66 Ambo 990 Wagon, 327,PW,PB,PS,posi,AM/FM,AC 74 Jav 360 auto ac 2003 FLHTCI, 1977 Yamaha XS750 2015 Chry 200, 2006 Pacifica |
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LakesideRamblin
AMC Addicted Joined: Dec/21/2015 Location: So. California Status: Offline Points: 2694 |
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A little contrarian view versus other wise sages. Your 998 will be fine behind a mild 360. You can even beef up the 998 and not worry about buying a 727 which probably needs to be rebuilt anyway and it will save you $. 904 - 998 trannys get bad reputations mainly because of a poorly completed rebuild. My two cents of course. I have a built up 904 (more of a 998 now) behind a moderate 360 and I have had no problems at all. And I have stomped it hard. After all, many use them for racing with great success. But for full disclosure, I have a 69 Rambler and wanted to keep it more simple and lighter.
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LakesideRamblin
69 Rambler 360 73 Javelin 360 "If you could kick the person in the pants responsible for most of your trouble, you wouldn't sit for a month." T. Roosevelt |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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His problem is that they say his 998 isn't fine and the case is bad...........
If his was rebuildable I'd concur, build it and not worry. But he said ->>They say the case is worn and we are searching for a good core to use the case.<< So he's got to buy an AMC transmission either way. I figured since he had to buy a transmission, buy the heavier one and be done. If his was fixable, I'd say fix it. True that 998s aren't bad transmissions and many have been built to take hard use and been fine. |
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1970390amx
AMC Addicted Joined: Jul/11/2008 Location: colorado Status: Offline Points: 3314 |
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My first question is what is wrong with the original case? Other than the servo bores being damaged I cant think of anything else that would trash a torqueflite case. Maybe dowel pin holes if bolts were loose. A 727 is not a direct bolt in,the driveshaft will need shortened and the yoke is different. Dipstick and tube are different. Unless my motor was making huge horsepower I would stick with the 998. I dont know which planet set this trans has in it, There is one that has a lower first gear ratio, lower than a 727 first gear. Gives the car a better launch, kind of like having lower diff gears. Its a lighter trans that uses less HP to run. Some will complain that the converter is weak, simple enough to use a 32RH pump body and gears. This trans uses flats to drive the pump not slots that cause the hub to crack. If your builder cant set this trans up for 450HP he needs to find a new job. Should not cost a arm and a leg.
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1970 390 4speed Bittersweet shadow mask AMX
1970 Amx missing most everything, or in a box |
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billd
Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894 |
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Not sure how servo bores would get damaged........... about all I've ever seen on those I've rebuilt is the piston sticks/wedges but then it's stuck, stopped, and really no real damage (not that it can't happen but can't be common, either)
You can buy performance planetary sets for the 998............. Good point - ask what's bad about your case. |
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amx2bfast
AMC Apprentice Joined: Aug/07/2013 Location: middlesex nc Status: Offline Points: 217 |
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I run the 998 behind my gremlin with a built 360 with no problems. running 5000 stall converter. Buy a good converter as that is the weak link.
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1975 gremlin
1973 javelin 1976 pacer wagon |
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Smitty52
AMC Apprentice Joined: Aug/05/2008 Location: Bolton Landing Status: Offline Points: 227 |
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The case is worn where the sprag clutch sets.
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AMO#8454, AMCRC# 8066
69 Ambo coupe, 401, M12, 66 Ambo 990 Wagon, 327,PW,PB,PS,posi,AM/FM,AC 74 Jav 360 auto ac 2003 FLHTCI, 1977 Yamaha XS750 2015 Chry 200, 2006 Pacifica |
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