A904 high performance rebuild--advice wanted

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MRGTX

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Hey, guys. I previously got some good advice on the forum that helped me to decide to rebuild the 904 rather than replace...so I'm going to be hauling my trusty old 904 Torqueflight up to Best Transmission in Springfield, MA (supposedly a well known shop going back to the old days).

The guy I spoke with on the phone seemed pretty comfortable what I was asking for...but I'm much more familiar with manual transmissions so I'm relatively ignorant with how to set up an auto and I want to be sure I know what I'm talking about. Of the ten or so cars I have owned since I started driving, they have all been RWD/Manual transmission aside from the Dart!

Can anyone steer me in the right direction on an adequate A904 setup? The budget is relatively tight...

-I will be running a mild small block at first ~300hp range, but I'd like some margin of safety and/or some potential to accommodate a bit more power down the road. Does this require anything special?

-I plan to take the car to the strip on occasion but it has to be at least somewhat civilized for driving around town.

-I'd like to retain the stock column shifter and stock pattern...any drawbacks to this? I know most folks reverse the pattern...

-What kind of stall converter (RPM/brand) should I be considering?

-Will I need a transmission cooler? What would be a good one?

-Any suggestions on ATF would be greatly appreciated as well.


Thanks to anyone with experience/advice on a build like this!!
-Mike
 
since I have ever started messing with mopars they sayig always was, a 904 is lighter then a 727 but will cost more then a 727 would to build, go with a 727 and have no problems.... that being said I have found that converters are way harder to come by used and a lot more expensive to buy new for a 904. I have changed my build and I am now getting ready to send off my 727 for rebuild and shelf my 904
 
300 HP is nothing for a 904. I currently have PTC building me one to handle 550 HP with automatic (kick down) shifting. They are also building me a 3800 or so converter for the combo. I will shake the combo out on the strip in my drag Demon but in the end it will be the combo for my street Barracuda.

PTC is an easy choice for me though as they are just down the road a bit and the owner is a Huge Mopar fan / racer.
 
Cope racing transmission just rebuilt my 904 that I am putting in a 71 dart with a fresh 360 magnum. Best guess is around 425hp. He has stock rebuilds on the shelf basically. For the pro street 2 was $1,100.00 plus another $320.00 for the tc. the 904 is good to 500 hp. The reason I went this way was because I didn't want to cut the drive shaft. As far as the atf, I was told Valvoline. You should check out copes web site. It will give you insight to cost and what you get for your money. As far as torque converters, all he uses is PTC. I don't know a hell of a lot about it, I just want a fast, dependable ride. But, that's the way I went.
 
hmm i dunno...i'd stay with a 904. they are a wonderful transmission, easy to build, yes lighter, and of course take less power to operate. especially for a small block car, a 904 is a perfect match. they can handle a great amount of power.

when my brother and i built mine; i used red clutches, kolene steels, a heavy duty band strut for 2nd gear, 4.2 lever, heavy duty semi rigid front band with red linings, low reverse band with red lining, and of course new rollers and springs, new bushings. For a shift kit we used a transgo tf2, with a PTC 3000 stall converter. I used a summit brand aluminum deep pan, and an external B&M trans cooler.

use chrysler/mopar at4. its a good proven trans fluid.

just an example of what I have done to my 904, behind a hot street 318.
 
the biggest thing when doing is a 904 is to make sure the guy building it knows what they are doing. after that i would say some kind of shift kit.. store bought or builder built. and then the use of quality parts. a 904 will easily hold up to what you have planned for it.. hell the one in my car had the ever living crap beat out of it from 2005 till 2012 when i pulled the car apart. my buddy just put it into his 11.50 cuda the other day.. still working great..:)

-I'd like to retain the stock column shifter and stock pattern...any drawbacks to this? I know most folks reverse the pattern...

judt personal preference

-What kind of stall converter (RPM/brand) should I be considering?
all depends on your combo. personally i don't care how mild it it. i would call dynamic,ptc and ultimate and get their opinions..

-Will I need a transmission cooler? What would be a good one?

i would run a cooler. the biggest i could fit is what i would run..

-Any suggestions on ATF would be greatly appreciated as well.

dextron


only other thing i would have put in is a Bolt-In Sprag just for the added safety.
 
I learned a long time ago that it costs me more to get stuff fixed after I fixed it. I'm a believer in "I'll do what I do for a living and let other people do what they do for a living"
 
About the easiest auto transmission to rebuild.

Get past the "black magic" about difficulty sold by rebuilders, IT'S NOT HARD...

If you can build an engine, you can build a 727/904 TF trans.

$25-50 in Videos, books and you can teach yourself to fish! Heck, youtube has a rebuild series for TF... I have a copy of the trans rebuild video.
 
$700 for a stock rebuild and $1500 for a street build up 904???

No thanks.

I wish Butch around here still did stuff. $500ish for the same deal as that $1500 rig...
 
hahahah DAMN this thread you guys are talking me into sticking with my 904 that has low miles on it.... hmmmmm think im going to save money and just throw a bigger TC in and go.....
 
Awesome info, guys. Thanks to all of you.
I'm already feeling better prepared.

Learn to do it yourself is my suggestion. For about $200 in parts you can do one at home. No need to spend a ton of money on a trans for that build.

http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=9099

I'm inclined to agree with you in regards to most topics...in the long run it's more affordable and more gratifying to learn these things on your own. That said, pyrojim nailed it:

I learned a long time ago that it costs me more to get stuff fixed after I fixed it. I'm a believer in "I'll do what I do for a living and let other people do what they do for a living"

My experience exactly. I'd probably make it worse. :p

If I had more time off from work or wasn't hoping to have the car on the road in the next couple of months, I'd give it a try. I know it's not magic...but I have a relatively limited space to work in, no access to a lift, still only building up my tool box.

I can see both sides...but in this case, I think it's worth my $ to let a reputable shop take care of it and I'll write the check.
 
You might change your mind.....................watch these videos on Youtube:

There's 20 of them. I downloaded them and saved 'em.

[ame="http://www.youtube.com/watch?v=xzJhCBZ1wMY"]Rebuilding 727 torqueflite 600hp part1 - YouTube[/ame]
 
It really isn't that hard. I did mine, and I'm having to tweak it here and there but it also helped me understand better how an auto trans works.

It's kind of ridiculous how much people charge. It probably takes guys that know what they're doing just a few hours to build a trans, and for $200-$300 in parts (plus TC) for the good stuff, they're probably making $300 per hour on labor...crazy.
 
Simple trans to rebuilt..got 3 of them in race cars..with another waiting to go racing shortly, one of them has 5 or more seasons of racing on them with transbrakes in them...

if you want to go HIPO...get the alto red disc and kolene steels...if it helps you sleep at night, get rid of the large wound spring in front clutch pac and install the 24 spring kit...

the rear spraq in the 904 is held in with rivets, there is nothing to gain with a bolt in spraq in a 904...just replace the springs and rolls with a 5 dollar kit from bulkparts.com..if you ever destroy the sprag...then the bolt in kit will save the trans....904 do not explode like a 727 because of the smaller mast size of the drum

with good bands and clutch/disc plus the new spring kit,,,,you should not spend more the 350 bucks on parts...I use the Sonnax rear servo upgrade...about 15 bucks..

As far as converters..pick your brand and spend your money...
 
UPDATE:

OK... dropped off the transmission last week. The shop had lots of high performance stuff around, seemed to be living up to their reputation as a hot rod transmission shop. The guys seemed to know their stuff though they had doubts about the A904....despite my insistance that I wasn't "reinventing the wheel."

They said they would call me back by the end of the week after they had a chance to check out the condition, then they would give me a quote on the build and I would give them the specific components that I was looking for.

I never heard back so I called this morning...they said the transmission was ready to pick up! GRRR!! What? Basically, they did a standard rebuild with a mild shift kit.

I said that this wasn't what I had in mind and I was never given a chance to talk specific components (as you guys mentioned above).... he admitted the mistake and said that it was no problem, they would take it apart and do whatever I was looking for....but he was pretty sure that it would hold up. :rolleyes:

In the case that this WOULD hold up, it would be a great thing since I'm at 50% of my rebuild budget.

So my question is this- what would happen if I ran the transmission as-is? Would it slip? Would it burn up? The crate motor will only be putting out 300ish hp this year but I'd like to start modding and adding power in the near future. I'd like to take it to the strip a few times this summer...

Thanks for any additional advice, guys...
 
UPDATE:

OK... dropped off the transmission last week. The shop had lots of high performance stuff around, seemed to be living up to their reputation as a hot rod transmission shop. The guys seemed to know their stuff though they had doubts about the A904....despite my insistance that I wasn't "reinventing the wheel."

They said they would call me back by the end of the week after they had a chance to check out the condition, then they would give me a quote on the build and I would give them the specific components that I was looking for.

I never heard back so I called this morning...they said the transmission was ready to pick up! GRRR!! What? Basically, they did a standard rebuild with a mild shift kit.

I said that this wasn't what I had in mind and I was never given a chance to talk specific components (as you guys mentioned above).... he admitted the mistake and said that it was no problem, they would take it apart and do whatever I was looking for....but he was pretty sure that it would hold up. :rolleyes:

In the case that this WOULD hold up, it would be a great thing since I'm at 50% of my rebuild budget.

So my question is this- what would happen if I ran the transmission as-is? Would it slip? Would it burn up? The crate motor will only be putting out 300ish hp this year but I'd like to start modding and adding power in the near future. I'd like to take it to the strip a few times this summer...

Thanks for any additional advice, guys...

To answer your specfic question, no it won't slip or burn up just because it doesn't have high performance parts in it.
Since you are concerned about budget, just run it and spend the money on the recommended converter.

What's a "mild" shift kit? (This will make a pretty big difference)
If it's not at least a TF2 or equivelent, then have them do that and let it go.
That and an external cooler should get you through multiple racing seasons.

JMO
 
To answer your specfic question, no it won't slip or burn up just because it doesn't have high performance parts in it.
Since you are concerned about budget, just run it and spend the money on the recommended converter.

What's a "mild" shift kit? (This will make a pretty big difference)
If it's not at least a TF2 or equivelent, then have them do that and let it go.
That and an external cooler should get you through multiple racing seasons.

JMO

That's encouraging... thanks! I'll verify which shift kit they used...
Absolutely going to run an external cooler.

What benefit would the high performance clutches, etc. provide?
 
That's encouraging... thanks! I'll verify which shift kit they used...
Absolutely going to run an external cooler.

What benefit would the high performance clutches, etc. provide?

They are tougher, as in 5-600 HP.
One of the main upgrades for HP is the direct clutchpack, as it takes all the input torque in the forward gears.
A 5 clutch drum would be nice, but at 300 hp it not too big an issue and could be swaped in down the road as HP increases.

What would be really nice would be to pick up a spare along the way, and start collecting HP parts for it a little at a time.
Then you could swap it out when the engine gets bigger.
 
Ok...Thanks again, Trailbeast. :cool:
I think I'll give it a try and look for a core to build as you suggested.

This frees up some budget for thea better rear axle too. :)
 
Ok...Thanks again, Trailbeast. :cool:
I think I'll give it a try and look for a core to build as you suggested.

This frees up some budget for thea better rear axle too. :)

There ya go.:D
 
For a mild build you don't need the fancy clutches that cost 3x as much. Heat, lack of hydraulic holding power from floppy shifts, and loose build tolerances are what kills transmissions, not if they are red or blue.

The borg warner tan and the like are all you ever need.

A popular way to add that 5th clutch pack is to take the piston from the direct drum and have it machined down the thickness of the a clutch and steel.

Before you order anything, it would be wise to check end play before you disassemble and then check your tolerances so you can get the parts to tighten them up before you pull the trigger on a kit, snap rings, and most likely thrust washer, all inexpensive items, but not when you have to go back and do it again. Build to the tight side of factory specs.

Check out WITtrans.com, they are sweet and very helpful people, did I mention their prices are cheap as dirt?

Finally, go easy installing the piston lip seals, triple check everything before it goes back together, and air test your clutch packs and as an assembly! PM fishy68 for the picture of the test ports.
 
Simple trans to rebuilt..got 3 of them in race cars..with another waiting to go racing shortly, one of them has 5 or more seasons of racing on them with transbrakes in them...

if you want to go HIPO...get the alto red disc and kolene steels...if it helps you sleep at night, get rid of the large wound spring in front clutch pac and install the 24 spring kit...

the rear spraq in the 904 is held in with rivets, there is nothing to gain with a bolt in spraq in a 904...just replace the springs and rolls with a 5 dollar kit from bulkparts.com..if you ever destroy the sprag...then the bolt in kit will save the trans....904 do not explode like a 727 because of the smaller mast size of the drum

with good bands and clutch/disc plus the new spring kit,,,,you should not spend more the 350 bucks on parts...I use the Sonnax rear servo upgrade...about 15 bucks..

As far as converters..pick your brand and spend your money...

With all the parts on hand. How long does it take you to tear a 904 down and put it back together with all the good stuff?
 
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