Hey guys, I am having troubles with my transmission. I bought a 74 scamp and pulled the motor and tranny. The motor was blown. I put the 904 behind another 318 and dropped it in my roadrunner. Well the first time I took it out I found out I have problems..It wouldn't shift worth a crap. When I got it up to about 60 it would either not shift up or shift really quick then it would randomly shift back down. I thought maybe this could be why the motor blew in the scamp. I do not have the kick down linkage hooked up because a piece on it was broken. I was going to get a 727 and have it rebuilt but I got to reading and someone said that you have to have it hooked up for it to work right. Should I rebuild this transmission or try to get the linkage hooked up? Do you think that could be my problem? thanks and sorry for the dumb question. Ive got 4 months before I am 16 and need to get it going!

 

Try hooking up the linkage correctly and try again.

If you still have problems, try pulling the valvebody out and cleaning that out. Pull it apart, clean all the insides. Also check the bands to make sure they are not broken.

 

i my self cant see not havin the kickdown installed being the problem. i could be wrong but? not having a kick down hooked up could ruin a tranny if you dont manually shift it down when it needs to be.. if it were me i would drop the 904 and get the 727 going.

 

good call gts

 

I agree with Fury. I perfer 727s myself..

 

Thanks for the quick replies! I will try that.. I dont have a 727 yet I was just saying if I do rebuild one. Ive heard the 904s suck.

 

If they are rebuilt correctly, they are fine. Put a manual valvebody in it and you're set.

They just can't hold up to alot of power, and a 727 is just the way to go.

 

74 -

Can't tell ya either way about the kick-down linkage ...

Yes, check and clean the valve body, making sure all the passages are open.

Regarding the bands: careful when you drop the valve body. Watch for wedge shaped or rectangular pieces of metal ... they are the pieces that hold tension on the bands - they can break (don't ask me how I know...). The wedge should be about 1.25" x 1.25" and the rectangle about 1" x 3" (guesstimates). If broken you'll need new ones, and yes they make heavy duty ones, and don't close it up until you account for all the pieces.

I'm a big fan of the 727s, even on small blocks, but some of the more serious (small block) racers around here, prefer the 904s. Less weight, less rotating mass. Fine for a race only car, maybe not so good for a street car. Just a thought.

Archer

 

The kickdown linkage is very important to have hooked up. Without it on these vehicles, the tranny will not shift properly. Install it, adjust it properly and see how it acts.

While I agree that a 727 is the better choice, if you are keeping the motor stock, I would see how much shops would quote you to have the 904 rebuilt. If it is close the the price of a rebuilt 727, new 727, or buying and rebuilding a 727, then go with a 727 (confused yet? )

 

I watch a 904 run very strong and consistently behind a 600 HP 340 in a 9 second car.

Hook up the "throttle pressure linkage" and try it. Without the "throttle pressure linkage" you will burn the trans up.

 

Alright guys, I got the kickdown linkage hooked up and took her out for a spin. She deffinately worked right but its slipping sooo I guess Im gunna take the valvebody out and check the bands. Is this very hard to do?

 

Ask the guy after how many passes he has to pull it out, tear it down, inspect/replace parts

I bet he rebuilds it atleast 2 times a year.

Guy i know has a high 9, low 10 sec small block w/ a 904, he rebuilds it anywhere between 2-3 times a year.


The pan has probably 14 7/16th or 9/16th bolts, can't remember off the top of my head. then the valvebody has i think 8. Believe they are 7/16. Be careful pulling the valvebody out, if it doesn't want to slide out, its bound up.

also, its most likely slipping in the clutch pack. Friction plates and clutch disks are prob toast.

 

4 years maybe 5 now zero issues. Hits it at 3400 off the trans brake to launch. The good thing about a 904 if built correctly it will withstand it. He has been racing the car with the 904 in it for 30 years now. A 904 trans also has a lot less parasitic drag which equates to more horsepower to the rear wheels. I'm not saying that 727's are a bad transmission, but they eat up a lot more horsepower than the 904.

This guy is my neighbor so we are all the time talking about our cars, and I know that twice in 30 years he has had problems but it was a cracked housing once and a broken tail stock once. Never any internal issues.

 

No, it's not a hard job to do. Just take your time with it. You may want to bring it to a tranny shop and have them flush the whole system depending on when you last had it serviced. While your in there, maybe replace the filter (if it's not new). They are only a couple of bucks and usually worth it.

 

Badsport; I just cracked my tail housing in my 727 and it puked out all the oil which is the first time that I've ever experienced something like this. I limped it home, added some oil; and although it all leaked back out the crack, it still engages in all gears so I'm not sure if I'm going to find any internal damage? Would you mind asking your neighbour what he found to have caused the problem, was it just the torque or was it a misalignment or a worn tail bushing? I was shifting hard into 3rd when it happened and it nearly shook the car apart trying to come to a stop. Anyone else have this happen?