904 5 Clutch drum swap

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Wheel Chock

Wheel Chock

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I have a 72 904 on which I did the wide ratio gear swap about 10 years ago. I am now going through it as I am replacing the engine in my Duster and I would like to install the 5 clutch drum and wide band from a 999. I have the drum and band, but am running into a clearance problem with the pump. The 4 clutch and 5 clutch drum have the same inside diameter where the sealing rings ride, however the 5 clutch drum makes contact at several points around the pump stator. It appears that I could dress these points with an angle grinder in order to get clearance. Is this the way to go or is there another (inexpensive) approach that I should take?
 
You also need the corresponding reaction shaft support that is designed for use with the A-999 wider rev/high clutch drum
 
Just put 5 thin disc and steels in the 4 disc drum.
 
70aarcuda said:
Just put 5 thin disc and steels in the 4 disc drum.
Click to expand...
This is what you want to do, i had someone install a 5 clutch drum in a early trans, and one day at the track it shattered the case and broke the lower ears off the engine, wasted the driveshaft and ring & pinon. NOT WORTH IT!!
 
Been racing since 1993 with that setup in we have 4 904 with same setup using transbrakes. ..find someone who knows what they're doing
 
As kickdown stated earlier, you need the correct stator support for the wide drum, back of support will be tapered to clear drum. Lon
 
65Vsignet said:
You have a 999 5 clutch drum in a early 904? what year 999 drum?
Click to expand...

NO...I take the standard 4 disc 904 drum....and put 5 clutch disc in it using the thin clutch disc.....
the standard disc are like .086 thousand...thick....I use the thinner .061 disc.....been there...done it many times...
I have no idea what year the trans are....

In fact the 1st I did was way back in 93 or whatever....my transbrake from tranzact was not working correctly...I called Joe there and he explained what i needed to do...not knowing anything about transmissions I called Dave Smith at a place called Pro Trans in Palmdale and explain what I was told to do....He said no problem...he said to go to a 5 disc drum I needed to change pumps and other stuff in the trans...but he would and does put 5 disc in 4 disc drums....he shipped me a loaded drum for 69 bucks......used that 904 up until 2004 went I broke a ring gear in the 8 3/4. We decided to rebuild the 904 then....and If you know anything about Torqueflite trans in drag racing ...the Stock/Super Stockl mopars ...Pro Trans is the place to go.
 
70aarcuda said:
NO...I take the standard 4 disc 904 drum....and put 5 clutch disc in it using the thin clutch disc.....
the standard disc are like .086 thousand...thick....I use the thinner .061 disc.....been there...done it many times...
I have no idea what year the trans are....

In fact the 1st I did was way back in 93 or whatever....my transbrake from tranzact was not working correctly...I called Joe there and he explained what i needed to do...not knowing anything about transmissions I called Dave Smith at a place called Pro Trans in Palmdale and explain what I was told to do....He said no problem...he said to go to a 5 disc drum I needed to change pumps and other stuff in the trans...but he would and does put 5 disc in 4 disc drums....he shipped me a loaded drum for 69 bucks......used that 904 up until 2004 went I broke a ring gear in the 8 3/4. We decided to rebuild the 904 then....and If you know anything about Torqueflite trans in drag racing ...the Stock/Super Stockl mopars ...Pro Trans is the place to go.
Click to expand...

I run the same set up in all of my cars with 5 discs in 4 drum, i was told you there is certain years of the 999 5 disc drum that could be used, but not many of them around anymore. Pro Trans is the place, i need to get an alum drum from them for my Stocker.
 
Unfortunately you need a new pump support designed for a 5 clutch drum. You’ll notice the foreward side of the drum is tapered and the pump support you have is not tapered to accept the drum.

This is why folks put 5 thin clutches and steels in a 4 clutch drum. Or use thick ones and shave down the piston or the the other side of the stack (I don’t recall it’s nomenclature)
 
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