doing rebuild on 904 what needs upgrade?

-
Hersbird

Hersbird

Well-Known Member
Joined
Feb 20, 2010
Messages
945
Reaction score
39
Location
Missoula, MT
I am getting ready to put a mild 360 into my 68 Barracuda. It is pretty stock rebuild with 340 cam and magnum heads about 9:1 compression so I would guess about 330-350hp hopefully. My car currently is a 318 with a 904. The 904 leaks pretty good around the shifter so is often low on fluid and seems to be slow to shift. I figured I would rebuild it while it is out. I was going to order the ATSG manual and the "street" rebuild kit from Cope which is red eagle clutches and stock steels. I was going to use the B&M 10239 flexplate and the stock 904 converter.

1) I have seen the multi-spring back for the front drum is a bad design but it's $100, is it really necessary here?

2) is a shift reprogram really a big plus, I was just thinking of getting the basic transgo tf-1, but is the tf-2 much better or is just the stock setup good?

3) if I get the transgo is the aluminum Low/reverse servo for $85 really necessary?

4) is there anything else I am missing? Like 4.2 lever or 5.0 or stock?

5) I also have a 727 and stock 727 360 converter I could use instead. I'd have to shorten the drive shaft and probably do the same basic rebuild on it was well, I don't know really know the condition but was told it worked just leaked bad. Is that a less expensive option?

I get $326 for the 904 with just tf-2, flexplate, and rebuild kit, no other upgrades
The 727 would be $244 for similar no flexplate, but would still need drive shaft and I dodn't know what that would run.

Still just thinking here, but I may need a shorter drive shaft anyway as the 7 1/4 rear may not hold up, thinking about a ford 8.8 swap there.

I am just a poor, married guy with kids with lots of higher priority stuff in real life. I have been working on this 360 swap and saving/working on it for literally years but think I can finally finish it this spring!
 
Does "stock converter" mean the one in your 68? If so, you need a spacer ring for the snout of your converter to match the larger hole in the 360 crank (all ~71+? LA engines). Also make sure the 360 was for an auto since the crank hole might differ in manuals.

I always wondered if the racing type clutch plates buy much for a daily driver. They sure cost more. Do they give more life? A standard 67+ 904 rebuild kit is ~$90 w/ steels (ebay). I haven't done a 904 but rebuilt the similar A-413 torqueflite a year ago. I got the Mopar "Diagnositics and Repair ..." or such-named manual off ebay ~$10. I later found the ATSG manual on the web and found it a straight copy and even less info. Might be true for 904's. The manual is very easy to follow, with detailed drawings for each step. The trans looks fairly simple when taken apart and not many ways to put parts in wrong if you sign-off each step. Just get a set of snap-ring pliers w/ some big ones (Harbor Freight).

I think the servo piston upgrade is to fix a common cocking problem. I thought the upgraded one cost ~$25, at least it did for my A-413. Shop around.

A shift kit is a good idea, but I would stay with a street version. It gives quicker, firmer shifts, which will save your clutch plates wear and maybe improve mileage. I didn't notice any kick after doing so in my Newport's 727. I can feel the shifts and maybe I never did before the kit. The factory always designed slow, slippy shifts because that feels smoother and sells cars to the undeducated public who think smooth shifts are the sign of a good transmission. If you want to feel a kick, drive almost any 1980's Mercedes 300D, like mine. They slam into 2nd, usually due to problems in their quirky vacuum controlled shifting.
 
Hersbird said:
I am getting ready to put a mild 360 into my 68 Barracuda. It is pretty stock rebuild with 340 cam and magnum heads about 9:1 compression so I would guess about 330-350hp hopefully. My car currently is a 318 with a 904. The 904 leaks pretty good around the shifter so is often low on fluid and seems to be slow to shift. I figured I would rebuild it while it is out. I was going to order the ATSG manual and the "street" rebuild kit from Cope which is red eagle clutches and stock steels. I was going to use the B&M 10239 flexplate and the stock 904 converter.
Click to expand...

Hersbird said:
1) I have seen the multi-spring back for the front drum is a bad design but it's $100, is it really necessary here?
Click to expand...

IMO opinion, no.

Hersbird said:
2) is a shift reprogram really a big plus, I was just thinking of getting the basic transgo tf-1, but is the tf-2 much better or is just the stock setup good?
Click to expand...

The TF2 is a good one. Also Superior makes some nice shift kits as well. We use both here.

Hersbird said:
3) if I get the transgo is the aluminum Low/reverse servo for $85 really necessary?
Click to expand...

No, but it's a good idea.

Hersbird said:
4) is there anything else I am missing? Like 4.2 lever or 5.0 or stock?
Click to expand...

Yes, a few things. You should upgrade to a 5 disc direct drum. The extra holding capacity will be of great benefit. You can get one here for like 18 bucks.

https://www.wittrans.com/SchematicParts.aspx?Transmission=A904&LinkCode=555

You CAN use the 5.0 Hemi kickdown lever, BUT, you need to upgrade to the WIDE kickdown band. The 1.750" band. You can get one here for like 12 bucks.

https://www.wittrans.com/SchematicParts.aspx?Transmission=A904&LinkCode=022

Also you should upgrade to a 4 disc forward drum. You can get one here for like 10 bucks.

https://www.wittrans.com/SchematicParts.aspx?Transmission=A904&LinkCode=554

If your transmission does not have 4 pinion planets, you can get the large steel 5" forward planet here for like 32 bucks. Make sure you also get the 5" ring gear if your transmission doesn't have it.

https://www.wittrans.com/SchematicParts.aspx?Transmission=A904&LinkCode=582

And the rear 4 pinion steel planet here for like 8 bucks.

https://www.wittrans.com/SchematicParts.aspx?Transmission=A904&LinkCode=582

Hersbird said:
5) I also have a 727 and stock 727 360 converter I could use instead. I'd have to shorten the drive shaft and probably do the same basic rebuild on it was well, I don't know really know the condition but was told it worked just leaked bad. Is that a less expensive option?
Click to expand...

I would stick with the 904. Lighter and takes less power to drive and will hold up to most anything if you use the parts I outlined.

Hersbird said:
I get $326 for the 904 with just tf-2, flexplate, and rebuild kit, no other upgrades
The 727 would be $244 for similar no flexplate, but would still need drive shaft and I dodn't know what that would run.

Still just thinking here, but I may need a shorter drive shaft anyway as the 7 1/4 rear may not hold up, thinking about a ford 8.8 swap there.

I am just a poor, married guy with kids with lots of higher priority stuff in real life. I have been working on this 360 swap and saving/working on it for literally years but think I can finally finish it this spring!
Click to expand...

As I oultined, I would stick with the 904 come hell or high water. To hell with the phord stuff. The 8 1/4 is plentiful and strong enough to hold up. No need to get ghey usin phord stuff.

Oh and I forgot....use kevlar bands. Make sure you use a rigid kickdown band, not a flex one. Alto red clutches. I just took for granted that was a given.
 
Poison dart thanks for the google advise, never hear of that before... now if I'm going to build a wheels pulling 10 sec drag racer I will know what to use.
Maybe I didn't make myself clear here, I don't have money.

Strokerscamp that is much more helpful but all of those extras combined make it cost more then just doing the 727 and shortening the drive shaft. Sounds like the 904 would be just as strong though. I suppose I'll stick with the 904. I saw the WIT website but it was hard to navigate if you don't know what to buy. Now I do so thanks a ton for that!
Final question on that though I wasn't planning on replacing the bands, is that really a must.

Yes the 360 is from an auto and the 727 I have is the one that it was pared to.
I didn't know the 68 converter was incorrect so thanks Bill for that tip. Are you sure about that though? Most aftermarket converters don't list anything other then the 904 as the application, year or motor doesn't seem to matter. I just need the balanced flexplate or put the weights on it. I just looked again, it looks like that small snout 904 was pre 1968 273 and sixes, so I should be OK.

I know 8.8 pisses people off, but it is stronger then a 8 1/4 and I can't find any of those around here anyway, especially in limited slip. Seems like $1000 is cheep for a good mopar setup where you would have less then 1/2 that in the plentiful 8.8 and probably end up with rear discs to boot. I'll let the 7 1/4 try and live, usually when I drive I don't hammer on it from a dead stop, Just roll into it from 15 mph. It will probably never see a drag strip.

I used to hate Ford but ever since this bailout of Chrysler and GM, they are now my new favorite brand. It wasn't just the bailout, but how they did it. I'm not buying new cars so it's pointless, but I would never give GM or Chrysler a dime of my money again. Used car sales are another story as they don't get that money.
 
Hersbird said:
I am getting ready to put a mild 360 into my 68 Barracuda. It is pretty stock rebuild with 340 cam and magnum heads about 9:1 compression so I would guess about 330-350hp hopefully. My car currently is a 318 with a 904. The 904 leaks pretty good around the shifter so is often low on fluid and seems to be slow to shift. I figured I would rebuild it while it is out. I was going to order the ATSG manual and the "street" rebuild kit from Cope which is red eagle clutches and stock steels. I was going to use the B&M 10239 flexplate and the stock 904 converter.

1) I have seen the multi-spring back for the front drum is a bad design but it's $100, is it really necessary here?

2) is a shift reprogram really a big plus, I was just thinking of getting the basic transgo tf-1, but is the tf-2 much better or is just the stock setup good?

3) if I get the transgo is the aluminum Low/reverse servo for $85 really necessary?

4) is there anything else I am missing? Like 4.2 lever or 5.0 or stock?

5) I also have a 727 and stock 727 360 converter I could use instead. I'd have to shorten the drive shaft and probably do the same basic rebuild on it was well, I don't know really know the condition but was told it worked just leaked bad. Is that a less expensive option?

I get $326 for the 904 with just tf-2, flexplate, and rebuild kit, no other upgrades
The 727 would be $244 for similar no flexplate, but would still need drive shaft and I dodn't know what that would run.

Still just thinking here, but I may need a shorter drive shaft anyway as the 7 1/4 rear may not hold up, thinking about a ford 8.8 swap there.

I am just a poor, married guy with kids with lots of higher priority stuff in real life. I have been working on this 360 swap and saving/working on it for literally years but think I can finally finish it this spring!
Click to expand...

1. multispring kit is needed for racing..the single wound spring unwinds at high rpm and allows clutch disc to drag..

2. transgo tf2

3..sonnax reverse servo can be had for 15 bucks...got about 6 of them in use...

4. you can use with 4.2 or 5.0 lever...i got 5.0 in 904 trans used for drag racing ...and not using the larger band..I would use the 4.2 on the street.

5. you can put 5 disc in the front clutch pack by using the thin .068 disc with .061 steels...look for at least .060 clearance in clutch pac.....you can not use the 5 disc drum from the factory unless you get the matching pump to go with it..
 
More good stuff. I wish somebody just did a complete kit. Looks like I might have to order from 3 different places!
 
I'm building a 904 right now for a 72 Dart w/360 around 450hp.
TF2
Sonnax rear servo
Alto Red frictions/5 thin for 4drum
Kolene steels
4.2 lever(factory)
Kevlar front band
4 pin planetaries

Will hold up just fine.
 
Hersbird,

I did some searching, and you are correct. I thought the change occurred ~1971. Only 273 engines of 1967 & earlier had the smaller 1.55"D pilot hole for the "small snout" torque converter. All later SB's and any SB's with a 727 transmission (1968 318 ) had the larger 1.81"D pilot hole. At the same time, they changed the splines on the input shaft from 18 to 27. Mopar left lots of holes to step in, but GM & Ford did too.
 
You must log in or register to reply here.
-

Back
Top