external balance 904 converter

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Optik

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hey everyone,
i am rebuilding the '77 904 trans that i swapped into my 64 dart, this trans is behind a 360. this requires the converter to have balance weights on it, right? so, how do i know if its bolted up with the wieghts in the correct spot to keep everything in balance? the last thing i want to do is have this thing in there wrong and it hammers the mains out of the motor....
thanks in advance for any help!!!!
-tim
 
Tim,
Get yourself a B&M-10239 flexplate.

This flexplate is externally balanced for the 904 trans with a 360.

So what you will have is a internally balanced torque converter (stock) with a externally balanced flex plate.Done.

Summit B&M-10239 $79.95

PS:Make sure you use your original (Thin) flexplate bolts.Hopefully you kept your originals.If not Mopar Performance has them.
 
I believe this is the type of flex plate JohnnyDart was talking about.
This is my B & M plate for the 727 tranny. My torque converter has NO weights on it

bal07.jpg


bal04.jpg


We spun it with the converter just to see how good the balance was
on the converter. I'm not sure what the numbers mean, but the
guy doing the work said the converter balance from the factory
was right on.

bal02.jpg



Doing it this way I can change out the converter
in the future and not worry about having to balance anything.
 
So if I'm buyin an already put together 360 do I have to take her apart and buy this flex plate and have it balanced? Or can Ijust buy the flex and it will already be balanced for me no matter what 360 I'm running?

JAson
 
If I'm not mistaken, I believe the flex plate has to be part of the rotating
assembly and also the damper on front. This is according to my engine
builder. He is the one that got me on to the B & M plate and the balance
procedure. He said the 360 was an externally balanced motor and must
be done this way.

If anyone has any better info, please chime in.
 
USCG CHARGER said:
So if I'm buyin an already put together 360 do I have to take her apart and buy this flex plate and have it balanced? Or can Ijust buy the flex and it will already be balanced for me no matter what 360 I'm running?

JAson
Click to expand...

No,you do not need to take apart the motor.The B&M 10239 flex plate is already balanced for the 360/904 combonation.Take off the stock flexplate(which is a internally balanced flexplate) and bolt on the B&M.Done
Your 360 motor should already have the correct 360 harmonic balancer.

The 273,318,340 motors are all internally balanced motors.All the balancing is done with the crank.These motors all share the same flexplate and harmonic ballancer.

The 360 motor is externally balanced.The harmonic balancer and flexplate do the balancing.This motor uses a different Harmonic balancer/flexplate than the other 3 motors.
 
Thanks for the correct info Johnny Dart. I get a little confused with the
whole internal/external stuff. I was going on memory from a year ago when
my engine builder was talking to me. I should have been paying attention.

thanks again
Tony
 
Tony Fields said:
Thanks for the correct info Johnny Dart. I get a little confused with the
whole internal/external stuff. I was going on memory from a year ago when
my engine builder was talking to me. I should have been paying attention.

thanks again
Tony
Click to expand...

No worries.Dont claim to be a expert on this.Just happen to be going through the same 360/904 swap as the others.I agree on the whole external/internal confussion.Best way to learn is :read2:Hopefully I was able to shead a little light on the subject.
 
thanks for the tip on the flexplate. the problem is that i already have a new externally weighted converter and i don't have any more money to spend on a new flexplate.

so i still need to know how to get everything bolted up correctly so its still in balance using the stock parts that i already have.

hope you guys can help me out here, need to get this car back together asap as its my daily driver.

thanks!
-tim
 
Assuming your externally weighted convertor is from a 360, it should be a bolt up and go deal with the stock neutral balance flexplate. The flexplate/crankshaft bolts are not equally spaced so there's only one way the flexplate will bolt on and have all 6 holes line up. Pretty much a no-brainer. I believe the flexplate to convertor bolt pattern is similar, it only can bolt up one way which means as long as all the bolts go in, it should be orientated to be balanced properly.

I bought the B&M ext. balance flexplate for my 360/727 combo that's going into my Demon in the spring. Going that route opens up a world of aftermarket neutrally balanced convertors for the application. Good for a cheapskate like me who prefers to graze in my friends parts piles than to buy new. ;)
 
DemonDave is exactly right. The holes are not equally spaced so you can only bolt it up one way. No possible way to bolt it up wrong.
 
fishy68 said:
DemonDave is exactly right. The holes are not equally spaced so you can only bolt it up one way. No possible way to bolt it up wrong.
Click to expand...


And when you find the "one way" it lines up, mark the stall converter with a marker so you know where it goes.I use a paint pen.Makes it much easier when you are installing it.
 
awesome! thanks so much guys for the help. that was the answer i was hoping for!!!
cheers!
-tim
 
DemonDave said:
Assuming your externally weighted convertor is from a 360, it should be a bolt up and go deal with the stock neutral balance flexplate. The flexplate/crankshaft bolts are not equally spaced so there's only one way the flexplate will bolt on and have all 6 holes line up. Pretty much a no-brainer. I believe the flexplate to convertor bolt pattern is similar, it only can bolt up one way which means as long as all the bolts go in, it should be orientated to be balanced properly.

I bought the B&M ext. balance flexplate for my 360/727 combo that's going into my Demon in the spring. Going that route opens up a world of aftermarket neutrally balanced convertors for the application. Good for a cheapskate like me who prefers to graze in my friends parts piles than to buy new. ;)
Click to expand...


what if the convertor is from a ext balanced 318 and you are putting it on a 360? what other steps are needed?
 
razorback said:
what if the convertor is from a ext balanced 318 and you are putting it on a 360? what other steps are needed?
Click to expand...

You would only need to install the appropriate B&M 360 flexplate which matches your transmission because all 318's are internally balanced so the torque converters do not have balance weights.
 
fishy68 said:
You would only need to install the appropriate B&M 360 flexplate which matches your transmission because all 318's are internally balanced so the torque converters do not have balance weights.
Click to expand...

i think the convertor i have from the 318 has a weight on it?

i thought only the steel crank 318s were internal?
 
Where is that weight located? If it's on the outer diameter of the converter that is just a converter balancing weight. Not for balancing the engine. If it's between the flexplate mounting bosses it is for an external balanced engine. There's alot of controversy about some 318's being internal balanced and some being external. In the 28 yrs. I've been working on them I have never personally seen an external balanced 318 (although I have read some guys say the cast crank ones are) and I have a book written by Jim Szilagyi that has worked for Chrysler in the Dodge motorsports engineering dept. since 89 and he states in his book no 318's were externally balanced. That's what I base it on.
 
fishy68 said:
Where is that weight located? If it's on the outer diameter of the converter that is just a converter balancing weight. Not for balancing the engine. If it's between the flexplate mounting bosses it is for an external balanced engine. There's alot of controversy about some 318's being internal balanced and some being external. In the 28 yrs. I've been working on them I have never personally seen an external balanced 318 (although I have read some guys say the cast crank ones are) and I have a book written by Jim Szilagyi that has worked for Chrysler in the Dodge motorsports engineering dept. since 89 and he states in his book no 318's were externally balanced. That's what I base it on.
Click to expand...

let me run outside and take a picture of it, when i pulled the balancer off, it looked like a external balance one, IIRC.

its on the side, and looks to be on the other side of the drain plug. maybe it is a neutral balance?
 
Yeah if it's on the opposite side of the drain plug it's just a balancing weight for the converter. It's neutrally balanced if it don't have any weights between the flexplate bosses. Post a pic of it if you can. That way I can say positively.

Could the wrong balancer have been put on the engine at some time? I haven't ever seen a 318 with a ext. balanced balancer. Not saying it couldn't be. Just saying I haven't seen one and Szilagyi's book says there aren't any.
 
i uploaded photos to my gallery on here. i hope its a neutral balance, makes my life easier. i looked at it again and didnt see any weights other than that little one.
 
All 318/340 motors are internally balanced.

Never have heard anything different.
 
razorback said:
i uploaded photos to my gallery on here. i hope its a neutral balance, makes my life easier. i looked at it again and didnt see any weights other than that little one.
Click to expand...

I looked at it in your gallery and that's just for balancing the converter. Not an engine balance weight. Looks like you lucked out.:cheers:
 
Ok so my 727 has a balanced TQ converter....not the flex plate.. The question I have is can I have the wieght removed from the TQ convert. and the just balance the flex plate? I dont want to be stuck w/the same verter for ever.

Jason
 
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