When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Recently acquired a 2004r transmission to put in a 71 corvette with a 350, probably around 300Hp.
I'm in 2 minds if I should or shouldn't rebuild it. My plan was to put a transgo shift kit in there, suitable torque converter and a lockup kit. Ofcourse, while it's still on the bench (and the car still underway. ETA 6-7 weeks), it would make sense to rebuild it, add a hardened stator and new fluid pump. My main concern are the seals, given that it's an almost 30 year old transmission I'm thinking the seals might be aged by now.
What would you do? How hardy are these? Any things I can check to determine if it has been rebuilt before?
I assume its used, not a never run nos trans? I know id be going through it. A firm shifting 700r with a converter is fun
Run a good trans cooler heat is the enemy of those.
DID you wipe any gunk out of the pan before you took the pic? Gunk represents worn seals/worn clutch discs.
From what I have learned.......
Does the fluid have a "burnedsmell" compared to the smell of new fluid.
Was the viewable filter material black-looking/gunked-up/coated with minuscule metal-flakes?
Many things depend on how often the trans fluid & filter were changed...how aggressive the driver(s) were.
Seals begin to harden/shrink after 20 years ( you may get lucky, though)
Clutch discs are a certain thickness..unless you can check the thicness with dial calipers, you would have to remove some discs to see if the friction material is worn thin/worn off.
The steel plates between the clutch discs should not be discolored because of overheating/slipping.
Planetary gears usually remain usable...but can fail whenever they "get the urge to disintegrate".
Input / output shafts can be twisted but still function.
Kickdown solenoids & Lock-Up solenoids can gradually "go bad".
Steel Check ***** can damage the holes in the Separator plate which hinders/prevents up-shifts and down-shifts.
SO...if you are going to upgrade One Area....
OR.....
just to be safe....
rebuild or upgrade everything if you have the $,$$$
I've rebuilt a few of the 2004R's. What is the tag code on yours BRF are the sought after ones, but the 3AA and CZF work well too. It doesn't look like too much debris in the pan, you might take a chance on it and see what happens. If you do decide to rebuild it, your power level shouldn't require too many upgrades. I always use a super servo, hardened sun shell, and modify the overdrive piston to hold an extra clutch plate. Bigger boost valve and a few other minor things all help, but near stock should hold up to 300 hp. CK Performance wrote a book on all the upgrades and tricks that is well worth the money and he also sells all the upgraded parts. I've used the transgo kit on all I've built, but Chris' recalibration kit is probably superior.
I would build it, just because.
Either way, 2 things jump out.
The proper stall rpm of the converter and proper setup of the TVS cable.
A maladjusted, wrong throw length of the cable will burn up a good trans before you have a chance to find out if it is usable.
DID you wipe any gunk out of the pan before you took the pic? Gunk represents worn seals/worn clutch discs.
From what I have learned.......
Does the fluid have a "burnedsmell" compared to the smell of new fluid.
Was the viewable filter material black-looking/gunked-up/coated with minuscule metal-flakes?
Many things depend on how often the trans fluid & filter were changed...how aggressive the driver(s) were.
Seals begin to harden/shrink after 20 years ( you may get lucky, though)
Clutch discs are a certain thickness..unless you can check the thicness with dial calipers, you would have to remove some discs to see if the friction material is worn thin/worn off.
The steel plates between the clutch discs should not be discolored because of overheating/slipping.
Planetary gears usually remain usable...but can fail whenever they "get the urge to disintegrate".
Input / output shafts can be twisted but still function.
Kickdown solenoids & Lock-Up solenoids can gradually "go bad".
Steel Check ***** can damage the holes in the Separator plate which hinders/prevents up-shifts and down-shifts.
SO...if you are going to upgrade One Area....
OR.....
just to be safe....
rebuild or upgrade everything if you have the $,$$$
I doused it in brake fluid from the outside, but didn't touch the inside. Thanks for the info!
Originally Posted by '75
I've rebuilt a few of the 2004R's. What is the tag code on yours BRF are the sought after ones, but the 3AA and CZF work well too. It doesn't look like too much debris in the pan, you might take a chance on it and see what happens. If you do decide to rebuild it, your power level shouldn't require too many upgrades. I always use a super servo, hardened sun shell, and modify the overdrive piston to hold an extra clutch plate. Bigger boost valve and a few other minor things all help, but near stock should hold up to 300 hp. CK Performance wrote a book on all the upgrades and tricks that is well worth the money and he also sells all the upgraded parts. I've used the transgo kit on all I've built, but Chris' recalibration kit is probably superior.
Do you need to machine that overdrive piston? Just in a lathe? I've seen the extra clutches being used as well on Art cars articles in a magazine. Might lend my uncle's lathe if a lathe is all I need.
The way I cut them down is just scribe a line around it at the proper height and grind down to the line. Lathe not needed, although if you have access to one it would work also. Seemed like it would take longer to get it chucked up straight than it takes to just grind it. It's made of thin steel.
You've not mentioned from what vehicle the transmission was removed (engine option is important) and how many miles are on the unit. If it is from a Grand National Buick or a Cadillac with a 'healthy' engine, the internals are already tough enough for your build. But if not, or if it has more than 50-60K miles on it, you probably should have the unit rebuilt for the power level you will have (or more, if you envision further build with the engine).
Rebuild it for sure with new seals, clutches, frictions, band and upgrade the servo. The need to upgrade the hard parts will depend on the year of production. The factory continued to make improvements to them just like the 700-R4's and later units will already have hardened internals. If it's pre-1986 at a minimum I would install hardened pump rings, stator shaft, sun shell and for sure put a good converter in it. There is a clutch in the converter as well plus it will hold quite a bit of old trans fluid that woln't drain out.
At your power level and application certainly no need for a lot of high dollar billet internals but for sure improve the shift program and take the time to get the geometry and cable adjustment correct. They aren't nearly as fussy as some folks will lead you to believe, but for sure the cable controls line pressure and shift function and if set up too loose you will smoke the unit in short order........Cliff
You've not mentioned from what vehicle the transmission was removed (engine option is important) and how many miles are on the unit. If it is from a Grand National Buick or a Cadillac with a 'healthy' engine, the internals are already tough enough for your build. But if not, or if it has more than 50-60K miles on it, you probably should have the unit rebuilt for the power level you will have (or more, if you envision further build with the engine).
My understanding is the Cadillac trans is NOT the ideal setup. The governor is all wrong ... If its not the GN trans which is likely than either the 86 or newer monti carlo ss or olds 442 coded transmissions are the ideal choices.
I have a monti ss trans thats just been build and I am having the trans go shift kit installed which comes with the 2 billet servos if im not mistaken which allows for up to 400hp I believe.. The kit is $175 shipped on amazon and can be installed with the trans in the car.
Last edited by augiedoggy; Jun 13, 2021 at 02:27 PM.
Thanks guys, the shift kit I'll use is the transgo with the billet servos.
Tore the trans down today, everything looked good. Only 1 of the servos had a broken spring which ( I believe) is quite common.
now on to find a th350 slip yoke as the 71 I bought will probably come with a th400. Oh the joy ^^
My understanding is the Cadillac trans is NOT the ideal setup. The governor is all wrong ... If its not the GN trans which is likely than either the 86 or newer monti carlo ss or olds 442 coded transmissions are the ideal choices.
I have a monti ss trans thats just been build and I am having the trans go shift kit installed which comes with the 2 billet servos if im not mistaken which allows for up to 400hp I believe.. The kit is $175 shipped on amazon and can be installed with the trans in the car.
The first 2004R I built is a code 3AA from an 83 Cadillac Brougham with a 4.1 V8. It works well, WOT shift points are in the 4500 to 5000 range. If I want higher shift points, I just manual shift. After that I built a BR from a buick regal, it was good. Next I built a couple from the Monte SS, one from 84 and a CZF from an 87. I can't tell much difference between the SS trans and the Caddy operational wise. The one advantage of the BR trans is that it won't shift to OD till 43 to 45 mph with a 355 gear.
First hiccup: can't for the life of me find the bronze washers that go on the planetary gears. The rear has too much play (30 thousands, limit is 27 according to my book).
First hiccup: can't for the life of me find the bronze washers that go on the planetary gears. The rear has too much play (30 thousands, limit is 27 according to my book).
So, I'm planning on going to the boneyard in a couple of days. Now I know to look for caddys also. In the end I'm not sure which way to go? Get one already built? Or get one at the boneyard? Guess I oughta ask that art carr place about core charges.
So, I'm planning on going to the boneyard in a couple of days. Now I know to look for caddys also. In the end I'm not sure which way to go? Get one already built? Or get one at the boneyard? Guess I oughta ask that art carr place about core charges.
From some research Ive done today the 86 and newer 2004r stock transmissions can handle 300hp stock with no mods. They are supposedly good to 400hp in normal use and if drag racing they are supposedly only good for like 300-350hp... I'm sure this opinion varies but thats what google states.
To (re)build a 2004r?
