trans info needed

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mopar410

mopar410

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Ok I have a 904 trans.the engine is out of the car at the moment.When I would putthe car in gear idleing at about 1000 rpms or less the trans would jerk pretty hard,I would have to hold the brake hard to keep it from jumping.What I know about the motor is its a 318 has a 500 cfm eddy carb and intake,360 heads but I haven't removed them to see what valves are in them yet or if they are shaved,the cam is either a 270ish or 290ish the PO said it had a 400ish lift.I can call him to get the full details but he bought the car and I bought it from him a few months later.Hooker headers,*3/4 suregrip unsure of the gears.The car idels at around 750 rpms.
My questions are:
1 how is a 904 "beefed up"?
2 Is there any way to tell what stall the converter is,stock or higher stall?
3 is there any "secrets"to sealing the leaks?
 
1. by rebuilding it using premium clutch discs and/or kolene steel plates. Adding a shift improver kit or manual valve body. Those are the very basics but the list can go on and on.

2. Sounds like a stock converter cause they will jerk hard when dropped in gear at that rpm. They are designed to be dropped in gear at a much lower rpm. But to test it there are a few methods. First is come to a stop and brake torque it and watch the tach and see how high the rpm's go. That's called brake stall. Second is to stop and quickly floor it while watching the tach and see how high it jumps up to. That's called the flash stall. Another way to measure flash stall that's a little more accurate is by driving slow in 3rd gear (10 to 15 mph) and flooring it while watching the tach again to see how high it does. If the transmission wants to kick down into a lower gear while doing this you need to unhook the throttle pressure linkage for the test but make sure you hook it up again immediately after the test cause driving without it can burn the trans. up.

3. What is leaking?
 
Question one:Add clutch packs in direct drive,install a 5.1 lever,add a Transgo shift kit.Question two:put your foot on the brake/gas pedals.Slowly apply the gas pedal,watch the tach.The rear end should lift on the springs,then the tires spin. That is your stall speed.
Question three:If it has leaks,lack of ATF in the pan affects stall speed,reliability,and stall speed.Real world?Find cam specs,or use a vacuum gauge.Is it low vacuum? My guess?Big cam, no converter.Good luck.
 
thanks fishy68.The problem right now is I cant test it as the motor is out of the car thru my restore process.Looking for info on how to tell by looks or numbers.As you stated it sounds stock by the way it acts?And the upper radiator line is leaking but everything is wet so its hard to tell,I know my truck(97 2500 gas) leaks around a linkage that looks like there is no seal,any thoughts on the no seal areas?
 
mopar410 said:
thanks fishy68.The problem right now is I cant test it as the motor is out of the car thru my restore process.Looking for info on how to tell by looks or numbers.As you stated it sounds stock by the way it acts?And the upper radiator line is leaking but everything is wet so its hard to tell,I know my truck(97 2500 gas) leaks around a linkage that looks like there is no seal,any thoughts on the no seal areas?
Click to expand...

Gotcha. Look all over it for numbers and write them down then start searching the net and see what comes up.

The radiator coolant hose or one of the trans. cooler lines is leaking? Since there is only 1 linkage input area on a mopar trans. it's either the main shift shaft seal that's leaking or the throttle pressure linkage seal leaking or it could even be the front cooler line or front band adjustment leaking and running down on the linkage. You mentioned no seal area's but there are seals in the area you described. Your just not seeing them.
 
3. Do not put fluid in it, guaranteed not to leak....
 
Its the trans fluid line.I thuoght the shifter didnt have a seal but I may be thinking of my other trans(not sure what model it was).I was just getting advance info on getting it sealed up because its leaking so much i think I'll pull it out to seal it and possible beef it up.BTW any thing i can look for in the trans to say if it already has the heavier parts?
 
inkjunkie said:
3. Do not put fluid in it, guaranteed not to leak....
Click to expand...
LOL I don't have to worry about that its getting pretty low.When I bought the car zero leaks under the car,well I guess it was pushed there because I drove it on and off the trailer and in the garage alittle and its springing leaks everywhere.
 
Count how many friction plates are in the front drum. If it has 3 frictions it's stock and light duty. If it has 4 it's medium duty. If it has 5 it's heavy duty. BTW: You can convert a 3 friction drum to a 4 by using this plates designed for the rear clutch. Just make sure you set the clearance properly. I like to see .050-.065" clearance on a 4 disc drum. You can also convert a 4 disc to a 5 by the same method. Check the rear drum also. They can be a 3 or 4 friction drum. The rear drum is not a shifting clutch so it doesn't necessarily need 5 discs, but it doesn't hurt to have 5. If it's a 3 0r 4 disc drum the only way to add more is either changing out the drum for one that holds more or using a thin pressure plate. Check the ratio of the front band apply lever. A perf. lever is generally a 3.8 or 4.2 ratio and those #'s are stamped right on the side of it. If it's a 5.0 lever swap it out or you may have shift overlap (very detrimental to a trans.). The 5.0 lever was designed for the Hemi trans. that had a wider band that was harder to apply. Use a 3.8 lever if the front band is a flex band. Use 4.2 lever if it's a rigid band. If the accumulator is blocked (spring removed and a blocker rod installed) that's a sign it may have a shift improver kit in it.
 
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