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| Building a strong 904? https://slantsix.org/forum/viewtopic.php?t=43969 |
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| Author: | polkat [ Wed Mar 09, 2011 8:52 pm ] |
| Post subject: | Building a strong 904? |
I've asked this question at a few sites. I have 727 rebuilding experience, but no 904 experience. I get many responses that say to just drop 727 guts into a 904 case to make it stronger, but these responses are not specific. Okay, that all sounds good, but it begs the question: Since the cases are somewhat different in size, will everything transfer over between them? Or are there some areas where I will encounter problems? What won't fit? What, if anything, from the 904 should be retained? Any responses will be appreciated. ________ VAPOR TOWER VAPORIZER |
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| Author: | Joshie225 [ Wed Mar 09, 2011 8:57 pm ] |
| Post subject: | |
You don't put 727 guts in the 904. You put V8 904 (technically the A998 or A999) guts in the slant six 904 case. Going A904 to A998 nets you 4-plate clutch packs and 4-pinion planetaries rather than the 3 and 3 of most /6 904s. The only stuff from a 727 that fits is the valve body and a few minor parts like the speedometer adapter. The drums, gear train and shafts do not interchange. If you've rebuilt a 727 you can do the 904. |
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| Author: | polkat [ Wed Mar 09, 2011 9:06 pm ] |
| Post subject: | |
Okay, that makes sense. I assume that I'm looking for a A998 or 999 from a 318 to 360 engine. Any specific years for these trannys? Or, to get more specific, could I just use the 999 drums and gears (maybe the shafts as well) with the existing 904 stuff? Or would something still be too weak? ________ M F L B |
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| Author: | pishta [ Wed Mar 30, 2011 12:02 pm ] |
| Post subject: | |
Dont go 727, you can make a 904 strong enough for 99% of all 6's. And it is more efficient, less parasitic loss. Guys put 904 guts in 727 cases for drag racing as they have less rotating mass and generate quicker ET's. |
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| Author: | Greg Ondayko [ Wed Mar 30, 2011 2:09 pm ] |
| Post subject: | |
Quote: Dont go 727, you can make a 904 strong enough for 99% of all 6's. And it is more efficient, less parasitic loss. Guys put 904 guts in 727 cases for drag racing as they have less rotating mass and generate quicker ET's.
umm no they don'tJosh just corrected this above  They use 904's in place of 727's Geeze! Greg |
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| Author: | Joshie225 [ Wed Mar 30, 2011 2:37 pm ] |
| Post subject: | |
Greg, I do believe there are big block bracket racers that do use 904 internals to reduce their ETs. I believe this is mostly in the 'stock' classes. I'm sure others here know more about this than I do, but it's certainly not the first time I've heard this. |
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| Author: | turboram [ Wed Mar 30, 2011 3:45 pm ] |
| Post subject: | |
I believe they use 904s with adapter plates, besides there are enough light parts available for the 727 to make it much lighter |
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| Author: | Joshie225 [ Wed Mar 30, 2011 4:39 pm ] |
| Post subject: | |
It's true their are light 727 parts. Certain class racers are required to use a stock transmission casing which precludes the use of adapters. I don't think this is a common thing and I can't see it being done outside Stock Eliminator and Superstock Eliminator. |
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| Author: | pishta [ Wed Mar 30, 2011 5:16 pm ] |
| Post subject: | |
Quote: Quote: Dont go 727, you can make a 904 strong enough for 99% of all 6's. And it is more efficient, less parasitic loss. Guys put 904 guts in 727 cases for drag racing as they have less rotating mass and generate quicker ET's.
umm no they don'tJosh just corrected this above They use 904's in place of 727's Geeze! Greg Uhh, yes they do.  Josh said no such thing in his post. He stated that they don't put 727 guts in a 904. PRO from Moparchat:".....We have 2 national record holders at our track,a 70 dart,runs 12.0 with a 4 spd and a 72 demon that uses a 727 case with 904 internals that runs 12.1,They both say this:the 904 is 2 tenths quicker than the 727 at this level..." Geeze is right! Google, try it sometimes. |
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| Author: | Volare4life [ Wed Mar 30, 2011 5:19 pm ] |
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you ever price out those 727 "light weight" parts ??  i was checking it out when i was thinking about rebuilding my 727, ill stick with stuffing new HP 998/999 parts in a 904 case,-Mike |
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| Author: | volaredon [ Thu Mar 31, 2011 8:43 am ] |
| Post subject: | |
in my experience 904s just don't hold up like a 727. Every V8 I have had with a 904 in it has wound up with a 727 swapped in for that reason; the /6s I was stuck with nasty 904s, because I could never find a 727 case w/ a /6 bell. "but that is me" and yes I have been inside both; and other than size of parts they are nearly identical in design. if you have rebuilt either you have seen what the inside of the other" looks" like. the 727 is just bigger. But with either trans, there are varying numbers of clutch discs in a clutch pack, among different examples of the same tranny. depending on app; even among 727s one meant for use behind a 318 in a car might only have 3 discs in the front clutch pack where a 440 or Hemi or SB in a heavy truck can have 5. both are "727"s though in this case. If you look in a FSM it usually gives a chart of which engine/body combo had what, originally when it comes to the differences in # of discs in a given clutch pack. |
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| Author: | Greg Ondayko [ Mon Apr 04, 2011 11:11 am ] |
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Quote: Uhh, yes they do. Josh said no such thing in his post. He stated that they don't put 727 guts in a 904. PRO from Moparchat:".....We have 2 national record holders at our track,a 70 dart,runs 12.0 with a 4 spd and a 72 demon that uses a 727 case with 904 internals that runs 12.1,They both say this:the 904 is 2 tenths quicker than the 727 at this level..." Geeze is right! Google, try it sometimes. You learn something new every day. I guess I should have read and understood what I was reading before I typed. Greg |
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