low gearset 904?

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abodyjoe

abodyjoe

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what my best bet for gathering the parts.. i have a few good std. 904 transmissions laying around that can use. is it better to just find a non lock up version? if so what am i looking for and how do i identify?

the friend that does my transmissions says i need:
pump
direct drum
sun gear
sun shell
front planetary and ring gear
forward drum
3 ring non lock up input shaft.


does that sound correct? if so where is the best place to source this stuff?

thanks in advance guys.
 
Pretty sure all of the later versions of the 904, which are 998 & 999 transmissions had the low first gear sets. To be able to quickly tell if they are lockup or non lock up, look at the input shaft. The non lockup will have an input shaft that is the same size all the way to the tip, like a 904. A lockup will have an input shaft that is stepped down to a smaller size at the tip of the shaft. If you can find a core, you may get all of the parts cheaper than buying new and just take it to your transmission guy and let him harvest what he wants/needs to fix you up.
 
It's easy to tell if it's a lock-up trans/converter. May have to get inside to confirm if it has the 2.74 low gear set. I don't think a lock-up will automatically :p have a low gear set but I'm not sure. Lock-ups started in the late '70's. JW Trans. in Rockledge, FL built my regular 904s with the OEM low gear for my 3,540+ lb Dart Sport and it worked well. Light cars and/or high torque engines may not need it. Any other aftermarket ratios will be on the expensive side.
1707843042228.png
 
i used to know all this **** but it was so long ago since i thought about it i've forgotten most of it.. uw put a liw gearset 904 in my buddies 66 barracuda and it works well.. that thing has a stock long block, hemi gring cam and a street tunnel ram with that low gear 904 ans a 3.23 gear. damn thing runs mid 12's and he can drive it anywhere..
 
Pro Trans in California, a friend of mine used one of the weirdly low gears sets in his R 3 built to the hilt stroker motors.
 
A&A will have them. Like Locomotion said, they're mostly found in '78-up 904s but not all units have them. The info below is cut and pasted from this thread;

Differences in 904 sun shells

Something to be aware of is the later ('78-up) low gear sun shells are different than earlier models. You have to get everything that goes with it to make it work - the planetary set, the shell, sun gear, snap rings and bearings, etc.

The low gear shell is on the left. See the step at the bottom? The step accommodates a spacer used with the 'low gear' planetary. You have to have that piece or it won't work.
IMG_0717.JPG


I believe all 904 sun gears are the same except the low gear one uses this machined spacer. I don't know why they went with this setup, maybe has to do with the lockup feature on the later units. The lockup units have different input shafts and I think the overall stacking tolerances might be slightly different. Either way, you can definitely use the low gears in an earlier unit but again, you need all the parts.

IMG_0732.JPG
 
i just ordered the low gear set from A&A. i got the reinforced (welded) one for my piece of mind.. probably didn't need it but felt better about it.
 
rmchrgr said:
A&A will have them. Like Locomotion said, they're mostly found in '78-up 904s but not all units have them. The info below is cut and pasted from this thread;

Differences in 904 sun shells

Something to be aware of is the later ('78-up) low gear sun shells are different than earlier models. You have to get everything that goes with it to make it work - the planetary set, the shell, sun gear, snap rings and bearings, etc.

The low gear shell is on the left. See the step at the bottom? The step accommodates a spacer used with the 'low gear' planetary. You have to have that piece or it won't work.
View attachment 1716206726

I believe all 904 sun gears are the same except the low gear one uses this machined spacer. I don't know why they went with this setup, maybe has to do with the lockup feature on the later units. The lockup units have different input shafts and I think the overall stacking tolerances might be slightly different. Either way, you can definitely use the low gears in an earlier unit but again, you need all the parts.

View attachment 1716206727
Click to expand...
The planetary gear is unique to the low gear set as well. The bigger diameter at the bottom of the pic is what is different.
 
the parts showed up today. I'll get the trans to my buddy as soon as i can. forgot to order a deep pan for it. I'll order that this week.

IMG_20240307_120651.jpg


IMG_20240307_120634.jpg


IMG_20240307_120626.jpg
 
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