1969 Plymouth 318 904 Transmission questions

[mutt71]

I have an all numbers matching 1969 Plymouth Satellite. It has a 318, that I am going to tweak a bit (headers, aluminum intake, 4 barrel carb, dual exhaust and a mild cam) I want to know if there is anything that I can do with the 904 Transmission that is a light duty. I don't really want to replace it, but, if I have to, I will. Ideas, or suggestions, anyone? Thanks in advance.

 

[mopar 3 B]

If the number matching is such a big deal why the modifications? If you do the modifications and are worried about the transmission its worst enemy is heat, just add an external cooler.

 

[mutt71]

Thanks mopar 3b. The matching numbers are not a really big deal, but, when I see light duty on the build sheet, it made me pause. I don't have any experience with the 904 trans at all. I have had a '70 RR with the 727 and never had any issue with it. The trans fluid cooler is a great idea. I sincerely thank you for the post and the advice.

 

[Cranky]

The 904 is just a smaller version of the 727 and can use the same hop up mods as the bigger sister uses. Many racers use it in drag racing since it is smaller and lighter and the smaller diameter rotating parts spool up faster. If it's high mileage, go through it and add in better clutches and a shift kit etc and don't worry about. However, the 318 is a small engine and doesn't produce much torque and being in a heavy car, it's going to need some help. A steeper rear gear helps a lot but then it'll hamper your highway cruising. If the car will be mostly used for cruising around, then the trans will do well with a shift kit for firmer shifts and a higher stall converter will help the engine gets things moving.

 

[mutt71]

Cranky, Thanks for the info on this. I am looking for a shift kit for it but B&M does not make a kit for a 1969 Model 904! I called and verified this, and was told that they make them for 1971 and up Models of the 904 Transmission. Do you know of a reputable manufacturer of a shift kit, by chance?
It is an under 30K mileage car (Documented), so I have reasonable confidence in it. Any recommendations for the torque converter? Thanks

 

[mutt71]

Cranky, I found a Transgo Shift Kit (TF-2) and bought it. I also found an OEM Transmission pan that uses another quart of trans fluid. Itfor it as well. also came with an extended fluid pickup, filter and gasket. I am shopping around for a cooler for it as well.

 

[acme rat killer]

I had a 69 satellite with a 318, 904, 8.75 back in 81 used a edelbrock street master 318 single plane intake, crane fireball cam, and blackjack headers, 1850 holley 600 cfm stock long block, B-M transpak setup for race and 3.91 suregrip ran low 14s high 13s on a good cool night. Now if I had to do it all over I would go with a duel plain switch to electronic ign. a little less cam, same carb and headers tone down the shift kit to street strip and keep a set of 3.55s handy. Bet it would run as fast. Its all about the combo and intended use. PS never had any problem with the 904 even set to kill and bang shifting every gear yes it would get rubber shifting to drive. God i miss that car.

'

 

[mutt71]

Thanks acme rat killer. I have the carb, intake, Trans shift kit and headers. Saving up for the camshaft, timing chain etc. Thanks again for the info.

 

[rumblefish360]

The old MP shift improved kit was a nice upgrade.
Add a cooler &/or a deep pan and you'll be fine for most applications.

Are you replacing pistons?
What cams are you looking at?
Name the performance parts you have by name.
What intake?
What carb?
What headers and tube size?

 

[mutt71]

Hello rumblefish360,
I have not done anything to the block or the heads. I bought summit Racing Headers, that are 1 5/8 tube diameter Part #SUM-G9040.
Intake is a Edelbrock 2176 Performer Aluminum intake.
Carbeurator is an Edelbrock #1801 Thunder Series AVS

I have not installed these onto the car. The camshaft I am looking for will be something for Street/ Strip. I do also have a Mopar Trans cover, that will add one qt. also got the Transgo TF-2 Shift kit. I will be getting a trans cooler setup when I get the camshaft.

 

[rumblefish360]

OK, so with these parts on the 318, your looking to compliment the set up with a cam in a street strip manor.
I forgot to ask do you plan on changing the converter with a higher stall and what gear ratio do you have now?

 

[mutt71]

rumblefish360,
I have no idea what the torque converter is other than what came with it from the Factory line. The gear ration that I got from the 2 build sheets I have both say the ratio is 2.76 to 1. I do NOT know what the rear end housing is, but on the same sheets it says that it is a "51" whatever that means. The last tine I was under the car, I counted the bolts on it. There were 10, if that is any help to identify it. You are correct, I want to take advantage of anything that I can and do it all at once, instead of doing things multiple times,

 

[rumblefish360]

10 bolts points to a 8-1/4 rear. These are inexpensive to upgrade and easy to get parts for. The 2.76 ratio is one very friendly hwy. gear. It is among the worst for performance. (The 2.45 is the worst.)
Suregrips are available for this rear (In expensively by compare to the other reads) along with a decent selection of ratios.

Since the torque converter is stock, not changing it limits cam selection to cams with a duration @ .050 to 218*'s. I would suggest a split duration cam to help the stock heads breath better. Crane has a Hyd. 218/226 (IIRC) .454/.480 on a 112, Comp has a similar cam as well as Lunati and Howard's cams. They will all work with the stock converter.

If you change the converter, (pricey) then the cam size can go up.
I would for certainly change the rears center section out to a suregrip and use a min. Of 3.21 gears. No higher than 3.73.

 

[mutt71]

rumblefish360, How can I get a sure grip with those gears? I doubt a scrapyard would have them. Do you have any suggestions? Thank you for all of this information, it really does help.

 

[rumblefish360]

Don't doubt. Though finding aged OE is hard, you can look to newer stuff.
The Dakota rears are 8-1/4's thou listed as 8-3/8. They are slightly different but will bolt in. (There set up for anti lock brakes. A non issue. But the spline count is different!)

New sure grips an be found at Summitracing.com.
3.21's may be hard to find there. If you do t find them at Summit, poke around the net. Also try Manciniracing.com.

- - - Updated - - -

This should be Mancinis 8-1/4 offering on the sure rip unit.
http://www.manciniracing.com/aub814proser.html

3.21/3.23 gears for the 8-1/4 from Mancini.

http://www.manciniracing.com/814gearsets.html

Check Summit and Jegs for a price match. Also figure on an installation kit ?$100?) and labor. Maybe an additional $300 or a grand in total, give or take.

 

[mutt71]

I will gladly use this information. I really appreciate your taking the time to help me out on this. I will scour the internet and check for a Dodge Dakota unit as suggested, I will find something that will work. I found a couple of units on Ebay last night as well as some gear. I will also check Summit and Jegs as well.

 

[rumblefish360]

Just I case you missed it, the Dakota and other modern 8-1/4's have a different spline count for the axles, this I'm pretty sure of.

DOUBLE CHECK ME!

 

[mutt71]

From what I have found on the internet, there are differences, as you stated. I have found some new center sections with 3.55 Gears in them with the correct 27 splines. I will continue to look for some with the 3.21 gears and 27 splines. I am very encouraged by this. I have a leaky transmission right now and need to take care of that. Depending on what that issue is, will determine what I can do next. Transmission rebuild, or just a gasket change. (Keeping my fingers crossed) Thanks again

 

[rumblefish360]

No problem. Leaky trans? Me to. Very upset about this, but, whatcha gonna do? Teething pains of a new build! Always a pain!

 

[mutt71]

Hopefully an easy fix, for both of us. I am dying to get mine registered and insured on Wednesday, so that I can get it out and get that fixed right away. It is in a storage unit right now. I'm not looking to tear up the pavement right now, I just want to cruise in it.