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.

727 parts are not going to fit into a 904 case....so ever is telling you that dont know anything about 904s

use good alto disc...kolene steels...and good bands...

x2 ...NO WAY will 727 parts fit in a 904

What ROCKET SCIENTISTS have been telling you that they will ? You can put-together a real decnt 904 with stock-stuff ... not to worry.

Okay, well, lets talk about it some. This is the original slant 6 904 that will go back behind the built up slant. Other then the silly 727 into 904 stuff, I've also heard to empty the 904 case and install A998 or 999 internals. What problems will I run into trying that? Could I just install the drums and gearsets? Maybe the input shaft? Or are other parts from the original 904 still too weak? Any writeups on doing this anywhere?

First, you will get a lot more accurate answers if you state what you are trying to do - street car, drag race, a little of both. And with what - car, horsepower, gear ratio, etc. It is IMPOSSIBLE to answer your Q's without this info. Next, you need to decide what type of valve body (V/B) you want to use - full auto w/linkage, stock V/B w/shift kit, reverse pattern, reverse w/low band apply, etc. Why? Because all the good hard parts WILL NOT LAST with a crap V/B. Also, you don't need high $ clutches, bands, steels for a stock rebuild. So after you post what you are trying to do and what you are trying to do it with - I bet you will get some good advise on how to build your trans.

The car is an early 70's Dart 2 door. The original 225 slant 6 will be turbo'd for between 250-300HP. Building for street/strip. Will use the stock valve body with a Transgo kit, maintaining the auto function. Rear is a 8-1/4" with 3.23's.

GUYZ .... what is this crap VB thing ?

I have done plenty of TF's and I have maybe found one or two TF's that had faulty VB's.

You have to TWEAK a stock VB for a HP application ... but you do not need a high$ piece to make-it-live OR make it perform well.

I don't think you need anything super special to make a 904 happy behind a turbo'd slant in that power range (assuming torque is around similar levels). The key is quick shifting valve body with higher line pressures to hold things. My tranny runs 190 or 210 (can't recall) with a 4.2 lever and I put around 550 ponies though it and only slightly less torque. Mine is a 999 case and internals because the case is supposedly stronger than the early 904's, and it had a low gear set (2.74 instead of 2.54). For whta you're building, you don't need a limits pushing setup, or even the setup that I run. A good basic build with an eye to quality clutches bands and good Valvebody selection and you'll not have a problem.

BTW, I love the idea of a turbo slant

Greg

Sadly, a small block V-8 998-999 won't bolt to the slant block, which is why I was thinking of putting the 999 guts into the slant case. But I DON'T want a lockup converter, which I understand the 999's had. What can I do about that? Seems no one here has done this.

Put any power to it and be ready to start replacing front pumps.

My mild street 318 with 360 heads combo (right at 300hp) used to destroy front pump ears on my 904 about every 6 months on cue.

No trick parts needed to make a 904 live for years with more HP than the op wants to make.

No, probably not necessary, but the reliability factor goes up with stronger parts.

But i was not asking if I should do it, but HOW to do it.

I guess this subject come up once a month or so about how 904 can not hold the power...

i been using a 904 ...the same 904 since 1993 in my 69 Barracuda that has run 10.70s out here in las vegas..

it has been rebuild once back in 2004...

the 904 has the same pump...only part that has broken was the rear sprag due to ring and pinion breaking....

904 has 5 disc in front clutch pac...uses kelvar bands and alto disc/kolene steels..

the big spring in the front clutch pac has been replaced with a 24 spring kit...

been using the same tranzact pro transbrake since 1993...so the poor little 904 is getting slammed with a transbrake too...

got another 904 going on it 4th season...same parts as above in 71 dart that has gone a best of 11.03...while changing engine last month...I took this 904 apart to check it out..everything looked great...just replace sealing rings ...it is back in service...

car is on trailer to go racing tomorrow...

so if you are breaking parts...find another trans guy..or read a book...

i put 5 disc in the 4 disc front drum..and using the stock 2.45 gearing.

Evil Spirit said...

>"Ideally, if you could find a non lockup 999 you could pretty much drop in the guts as a whole..."

That's pretty much what I wanted to know, and I understand that the pre 80 999's (found particularly behind 360's) were non-lockup. Unless anyone disagrees with this, I'll take it from here. Thanks!