904 hesitation to shift gears

by **Wojpi** » 08 Jul 2007 19:37

Hi, I have 904 trans that was working fine till last week. First i started to hear some noise like metallic pinging under acceleration in drive, later probelms with kickdown has started, when i put full throttle it reduce so much that rpm goes mor than 7000. When i change gears manualy it takes around 2-3 seconds for trans to shift gear since i move the lever, this happens also when I try manulaly reduce gear, 2 secs of hesitation and the gear goes down. During normal drive in D works good changes gears normaly but under hard acceleration is bad. My engine puts around 400 hp so maybe this was to much for old transmission.

Any suggestions please ? I think that if i am going to rebuild will be better to go for 727 and buy another one. I will also change the converter so if you have suggestion whats the best please let me know.

by **ianandjess** » 09 Jul 2007 3:22

i dont think you should put 400hp through a 904
cheers ian

by **Wojpi** » 09 Jul 2007 6:51

Now i am afraid i think the same but had no option at the time of engine rebuild, so i tried to live with 904

by **70 340** » 09 Jul 2007 13:49

If you did not rebuild the trans at the time you did the motor I think by the sounds of it you might have killed it. A well built 904 I think should hold about 350hp-400hp (CRANK HP).

by **dave-r** » 10 Jul 2007 19:35

Sounds like it is loosing oil pressure.

First check the oil level. Then the filter (it might be clogged). A rebuild or new trans sounds very likely though.

by **Wojpi** » 11 Jul 2007 19:50

Thanks for advices but I am afraid that 33 years without rebuild + new engine that was much stronger than stock was too much for this trans. I will go for 727 with shift kit + new converter 2500 stall. I was proposed B&M Holeshot. I am also afraid that i will have to make new drive shaft and change the flexplate when i switch to 727 from 904.
There is no other choice i am fraid as during the winter i plan to build new engine, that will aim in the range of 600 hp. so for this baby 904 would be to weak for sure.

by **dave-r** » 11 Jul 2007 19:58

Wojpi wrote:during the winter i plan to build new engine, that will aim in the range of 600 hp. so for this baby 904 would be to weak for sure.

You will need a MUCH higher stall speed than 2500 with an engine like that. Probably over 3000rpm. It depends on cam duration and engine size. As well as car weight and axle gear.

by **70 340** » 12 Jul 2007 12:51

If you are going for 600HP out of a small block that is one very strong motor. You will need a 727tf to hold that sort of power. Rember to build that trans to suit the motor. With the drive shaft you will need a 727tf shaft the front yoke is biger. good luck

.

by **transman** » 12 Jul 2007 19:31

If money is no object , then a 904 can be built to withstand 1200+ horsepower. :thumbsup:

transman

by **ianandjess** » 13 Jul 2007 13:57

thats good to know transman can you give me a few pointers as i would rather keep the 904 in mine but i want to warm the motor up a bit
cheers ian

904 Trans