904 rebuild opinions

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74Scamp

74Scamp

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Hey guys I have a few questions concerning rebuild kits for my 904 trans I just picked up for $75. It hasn’t been used in about 10 years but was behind a 318 since 74’. I’m more than sure it’s gunna need to be rebuilt before I put it in my car.
Right now I’d like to just rebuild the transmission so I can drive the car with the 360 I’ll be putting in and save up money for my real build down the road. I’d like to just do headers and probably an intake on the 360 otherwise it’ll stay stock. What kit would be the best for a small budget that’ll hold up to the 360 for street driving?
Also should I get a B & M flex plate or get a weighted torque converter? Would I limit myself going either route?
Lastly I read a guy would need a small block trans cooler and lines for the small block 904, is that true or can I still use my /6 lines and cooler? Thanks fellas!
 
Cope Racing Transmissions has rebuild kits and solid flex plate for your setup. 65'
 
74Scamp said:
Hey guys I have a few questions concerning rebuild kits for my 904 trans I just picked up for $75. It hasn’t been used in about 10 years but was behind a 318 since 74’. I’m more than sure it’s gunna need to be rebuilt before I put it in my car.
Right now I’d like to just rebuild the transmission so I can drive the car with the 360 I’ll be putting in and save up money for my real build down the road. I’d like to just do headers and probably an intake on the 360 otherwise it’ll stay stock. What kit would be the best for a small budget that’ll hold up to the 360 for street driving?
Also should I get a B & M flex plate or get a weighted torque converter? Would I limit myself going either route?
Lastly I read a guy would need a small block trans cooler and lines for the small block 904, is that true or can I still use my /6 lines and cooler? Thanks fellas!
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I would contact Winners Choice Transmission Parts. I purchased a kit for my 904 behind a 340. They built my torque converter to match up with the specs of the 340. They know what they are talking about when it comes to tranny's.
 
Get this one B&M Flexplates 10239 that way you can use your neutral balance torque converter. You'll never tare up a 904 with a stock 360. You can get a soft rebuild kit at any parts store. I would think that cooler will be fine.
 
I’ll give them a call when I need a converter unless I get a flex plate and just reuse the converter that came with the transmission. Stall speed isn’t too different from a 318 to 360 would it?

I also figured the cooler would be fine, the post I read wasn’t informative about the fitment or length for the cooler lines but I’ll find out when I do the swap.
 
Stall speed will be the same. I have done the same swap many times. Bolt it together with the B&M plate and your done.
 
For stock and performance builds up to 400'ish hp I use the TransStar kits and a Trans-Go TF-2 valve body kit. Their cheap and up to snuff and contain all the normal wear items. You can get them both at www.bulkpart.com but Summit may be cheaper on the Trans-go kit
 
I was pretty happy with the transgo shift kit in my Ram so I was gunna use them again for this trans. This is probably gunna come off as a rookie question but regarding the torque converter in the trans; can a guy clean them out and reuse them with the fresh build or can’t you fully clean them out without cutting them open? I’m not opposed to buying a new converter but trying to be budget conscious here.
 
Call around. There is a transmission shop close to me that will rebuild it for 90 bucks. I would think there is one close to you. The torque converter is where are the junk ends up so no I would not reuse an unknown one.
 
There’s plenty of trans shops around here and back home. I’ll call around and see how much it’ll be to have them rebuild one and maybe go with a slightly higher stall than factory.
 
The biggest problem with the 904 converter is cracking forward from the pump gear slots. Double check both sides. Wipe it off and tap it with a hammer to see telltale oil lines. If the trans is fried inside then the converter is loaded with material. The fine particles go thru the filter and lodge in the converter; packed into the perimeter under centrifugal force. The problem is the new fluid washes it out and the compacted particles come out in chunks that clog the filter. Check the endplay before disassembly then dump out the two front drums for inspection. Don't even remove the output shaft snap ring if this is your first one and you just want to make sure that you have good clutches. The biggest problem with transes is reinstalling bad parts.
 
The transmission hasn’t been used in over 15 years, it’s gunna get rebuilt no ifs ands or buts. I will check out the converter tho for any signs of cracking.
 
"Rebuilt" is a generic term thrown about and interchanged with "overhaul" but both are dependent upon experience and knowledge base. Step one is to take it apart and see what's actually useable. I caution the novice against taking everything apart assuming reassembly will be obvious.
 
.....it’s getting fully torn down and rebuilt. I didn’t know I had to be precise with my wording. I’m a diesel mechanic not some shade tree one. I’ve torn down plenty of engines, differentials, etc.. and there’s plenty of literature to help so thanks for the kind words.
 
My responses were based on questions about cooling lines and torque converter contamination; both seemed to be novice questions that prompted me to promote caution concerning decisions that might impact the final outcome of having a transmission that performs well, doesn't leak and lasts for years to come.
 
CudaFactHackJob said:
My responses were based on questions about cooling lines and torque converter contamination; both seemed to be novice questions that prompted me to promote caution concerning decisions that might impact the final outcome of having a transmission that performs well, doesn't leak and lasts for years to come.
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My question about the cooling lines were if they would fit because another person in a thread said /6 lines wouldn’t work with a small block and I don’t have the lines in front of me to verify so I don’t see where it’s a novice question. I asked about the torque converter being able to be cleaned out because I’ve never reused one before, I’ve always bought new so figured I’d ask about the cleaning one vs buying a new one.
 
The converter is like any other part as far as judging its usability. If the fluid in it is clean with no metallic particles and it isn't worn anywhere on the back snout and not cracked then l would reuse it. Every part inside the trans has to be checked for wear; especially in certain areas. 90% of the trannys l do have already been rebuilt by somebody else. They missed something. They're filled with new parts; they just don't work right. So even if you put it back together exactly as it came apart, that doesn't mean it's right.
 
74Scamp said:
I was pretty happy with the transgo shift kit in my Ram so I was gunna use them again for this trans. This is probably gunna come off as a rookie question but regarding the torque converter in the trans; can a guy clean them out and reuse them with the fresh build or can’t you fully clean them out without cutting them open? I’m not opposed to buying a new converter but trying to be budget conscious here.
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You've answered your own question. The only way to clean a converter out is to have it cut open. Once it's open, and seeing how it's a stock converter, any good converter rebuilder will tell you to just get an exchange one.
 
I built a 904 to go behind a 408 Six Pack. You will be fine with a 904.

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