Moparts
904 Transmission gurus.....
Posted By: Wedgeman
904 Transmission gurus..... - 03/30/09 12:24 AM
What is the upgarde for a strong 904 that is behind a 360 ? What is it exactly I have to do/change for better strenght of the ttransmission ?
Any infos please..
Daniel
Posted By: dOoC
Re: 904 Transmission gurus..... - 03/30/09 12:45 AM
How HP is the 360 ? .. how heavy is the car ?
Posted By: 70AARcuda
Re: 904 Transmission gurus..... - 03/30/09 02:34 AM
i put 5 clutches in the front clutch pac using the thin clutches and steels..
for racing...i change out the big spring in the front clutch to the 24 small spring set up...
outside that and the valve body the trans is stock.
Posted By: Wedgeman
Re: 904 Transmission gurus..... - 03/30/09 03:07 AM
For 5 disc, I have to change the clutch housing, more room for 5 disc can I take it from a A-500 ?
Or on what type of vehicule can I expect to find this set up ?
Daniel
Posted By: 70AARcuda
Re: 904 Transmission gurus..... - 03/30/09 03:27 AM
this is what i have done to several 904s
removed the 4 clutch/steels...
installed the 5 clutch/steels..using the thin ones..i get about 50-55 thousands clearance which i think is too tight... I take the pressure plate that is in the clutch pac to machine shop..have about .020 removed to get .070-.075 clearance..
so i am using stock clutch/drum..and stock pump.
Posted By: Wedgeman
Re: 904 Transmission gurus..... - 03/30/09 05:09 AM
Neat !!!!
These are my first pointers on transmissions...
Thanks
Daniel
Posted By: Mcode69
Re: 904 Transmission gurus..... - 03/30/09 05:51 AM
A good starting point is a '76 or later trans, they have most of the good mods done over the years by the factory. One of the weak points in the earlier trans's is they have aluminium planetary gear carriers which have been known to either chew the splines out or split in half. The '76 and later ones all had steel planetary carriers.
Posted By: Wedgeman
Re: 904 Transmission gurus..... - 03/30/09 02:19 PM
OK ! thanks, another good info
Daniel
Posted By: CJK440
Re: 904 Transmission gurus..... - 03/30/09 02:32 PM
Quote:
For 5 disc, I have to change the clutch housing, more room for 5 disc can I take it from a A-500 ?
Like was said you can fit 5 thin plates in a 4 clutch drum. Be carefull machining parts for clearance though. Take too much off and the steels won't engage the lugs in the drum.
You can upgrade to stock 5 clutch parts so you can use 5 thick plates but you need to swap both clutch drums and the front pump housing.
Posted By: Wedgeman
Re: 904 Transmission gurus..... - 03/30/09 03:02 PM
AARCUDA...
As stated, wouldn't it be better to dump my 67 and start with a later one ? '80-up ?
Daniel
Posted By: 70AARcuda
Re: 904 Transmission gurus..... - 03/30/09 04:47 PM
Quote:
AARCUDA...
As stated, wouldn't it be better to dump my 67 and start with a later one ? '80-up ?
Daniel
if you are talking about the whole trans ..probably yes.
but I would not mix parts unless you are positive they work.
actually the 72 and newer 904 are better due to a change in the servos...
some of the 904 came with 5 clutches aka 999 in the 80s.
mine are used for bracket racing and so far it has worked for me.
Posted By: 74Scamp
Re: 904 Transmission gurus..... - 03/30/09 06:04 PM
Quote:
Quote:
AARCUDA...
As stated, wouldn't it be better to dump my 67 and start with a later one ? '80-up ?
Daniel
if you are talking about the whole trans ..probably yes.
but I would not mix parts unless you are positive they work.
actually the 72 and newer 904 are better due to a change in the servos...
some of the 904 came with 5 clutches aka 999 in the 80s.
mine are used for bracket racing and so far it has worked for me.
Don't mean to hijack this thread, but for a mild 360, would you still machine to get the .70 to .75? Mine is a 999 and I'm getting ready to start putting it back together this weekend and was just wondering (my first tranny rebuild).
Dave
Posted By: Wedgeman
Re: 904 Transmission gurus..... - 03/30/09 06:06 PM
No problems.....btw...how do you tell a 904 from a 999 ?
Daniel
Posted By: 74Scamp
Re: 904 Transmission gurus..... - 03/30/09 06:09 PM
Not sure from the outside, but inside has the 5-disc clutch pak from the factory. Mine came out of a 78 Diplomat Police car.
Posted By: Wedgeman
Re: 904 Transmission...suite - 03/30/09 06:13 PM
OK....because it was a police car set up.......?
Daniel
Posted By: 74Scamp
Re: 904 Transmission gurus..... - 03/30/09 06:27 PM
Yes. I think that's correct. I was, at one time (a couple years ago) told that was what I wanted to look for - a police car.
Dave
Posted By: 70AARcuda
Re: 904 Transmission gurus..... - 03/30/09 07:01 PM
Quote:
Quote:
Quote:
AARCUDA...
As stated, wouldn't it be better to dump my 67 and start with a later one ? '80-up ?
Daniel
if you are talking about the whole trans ..probably yes.
but I would not mix parts unless you are positive they work.
actually the 72 and newer 904 are better due to a change in the servos...
some of the 904 came with 5 clutches aka 999 in the 80s.
mine are used for bracket racing and so far it has worked for me.
Don't mean to hijack this thread, but for a mild 360, would you still machine to get the .70 to .75? Mine is a 999 and I'm getting ready to start putting it back together this weekend and was just wondering (my first tranny rebuild).
Dave
what i have read...again no experts...
.015 per clutch....075 for 5
.060 for 4...
Posted By: HotRodDave
Re: 904 Transmission gurus..... - 03/30/09 08:03 PM
Another good thing about the early 80s trans is the low gear ratio 1st and 2nd gear sets they have.
When I build a 4 clutch drum into a 5 clutch unit I just change the snap ring thickness. Usually combining 2 thin flat snaprings and useing the thick waffle clutches you can get 5 in there. I don't like the flat ones because the fuid takes longer to get out from between them, the clutches will hydro plane over each other for a second. If my pack is still tight I might slide one flat clutch in there just to get the clearance.
Another good mod is to remove the wavy snap rings and install flat rings, this reduces slipage during engagement.
If you use the trans go kit don't be afraid to drill the shift holes to the max size, it still is not a hard shift.
One more thing I like to do is run type F fluid for an even faster shift.
Posted By: Wedgeman
Re: 904 Transmission gurus.....(suite..) - 03/30/09 08:18 PM
Wow.....that's a lot to assimilate......I'll work on all these infos..
Ok...took the trans apart looks great.....Is this the picture of worn clutches ? looks fine to me....has it been rebuilt ? or just a polite previous owner ?
Comments please....
Also.....yes the planetray carrier is aluminum...
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 03/31/09 07:05 PM
Do you think I still need to rebuild it ?
it's going behind a 360
Or I could get an '87 model that was in a Fifth Ave car with a 318 ?
Daniel
Posted By: capac
Re: 904 Transmission ..(suite..) - 03/31/09 08:08 PM
87 fifth will be a look-up trans.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 03/31/09 08:28 PM
So ?
Posted By: HotRodDave
Re: 904 Transmission ..(suite..) - 03/31/09 09:04 PM
I like lock ups, some guys don't. It locks the converter to keep it from slipping and building up heat in the trans and it also helps mpgs a little.
Those clutches should be the ones from the front clutch or the big drum. They look pretty good but dirty, still I would replace them since I had the trans apart, use good quality ones.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 03/31/09 09:33 PM
Ok, so I can use the lock up converter, I take it is neutrally balanced, so I can hook it up behind my 5.9l ??
Do you know if those have 4 or 5 clutch discs ?
Also, it has a 4 spd overdrive, does it require vaccum or electric device to go in overdrive when cruising ?
Thanks...
Daniel
Posted By: 68Fastback
Re: 904 Transmission ..(suite..) - 03/31/09 10:25 PM
Sorry to hijack but where on the tranny will you find what year it is.
Posted By: RapidRobert
Re: 904 Transmission ..(suite..) - 03/31/09 10:38 PM
Quote:
Sorry to hijack but where on the tranny will you find what year it is.
on the extension housing on one side(I forget which) about halfway back should be a real small 2 digit # such as "77"
Posted By: 74Scamp
Re: 904 Transmission gurus..... - 03/31/09 10:47 PM
Quote:
Another good thing about the early 80s trans is the low gear ratio 1st and 2nd gear sets they have.
When I build a 4 clutch drum into a 5 clutch unit I just change the snap ring thickness. Usually combining 2 thin flat snaprings and useing the thick waffle clutches you can get 5 in there. I don't like the flat ones because the fuid takes longer to get out from between them, the clutches will hydro plane over each other for a second. If my pack is still tight I might slide one flat clutch in there just to get the clearance.
Another good mod is to remove the wavy snap rings and install flat rings, this reduces slipage during engagement.
If you use the trans go kit don't be afraid to drill the shift holes to the max size, it still is not a hard shift.
One more thing I like to do is run type F fluid for an even faster shift.
Mine didn't have the wavy rings, just flat rings. I just received my new bands. So, I'm just about ready to start cleaning and putting back together. Should I be looking at rebuilding or replacing the pump? Tranny came from the car in a junk yard, so don't know if anything was wrong with it.
Dave
Posted By: RapidRobert
Re: 904 Transmission gurus..... - 03/31/09 10:54 PM
Quote:
Should I be looking at rebuilding or replacing the pump? Dave
Pump will be Ok but I'd have your shop R&R the front pump bushing & take the torque converter in with it so they can slide it in & check for any burrs & correct if necc.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 03/31/09 11:06 PM
Quote:
Ok, so I can use the lock up converter, I take it is neutrally balanced, so I can hook it up behind my 5.9l ??
Do you know if those have 4 or 5 clutch discs ?
Also, it has a 4 spd overdrive, does it require vaccum or electric device to go in overdrive when cruising ?
Thanks...
Daniel
So........any idea on that ?
Posted By: dOoC
Re: 904 Transmission ..(suite..) - 03/31/09 11:16 PM
What is all this HYPE about a 5 disc front clutch ?
LOOK at what they ran in the 727 ... for dump-trucks and motorhomes .. a FOUR disc.
Back when I had my Bantam-altered(bone-stock 383-thru cast iron mans and muffs) ....I even used a TWO disc front clutch in that 727.
Posted By: HotRodDave
Re: 904 Transmission ..(suite..) - 03/31/09 11:58 PM
A 727 disc has much more surface area than a 904, that is why they should have 5 clutches.
You can only use a LU converter in a LU trans.
The wavy snap rings are not obviously wavy, some times they lose most of their wave so you need to lay them on something very flat like a granite counter or a window. They also kind of hide, below the clutch pack against the aply piston. I have never seen a stock trans with out them but I have not disceted every single trans ever built and we all know how chrysler like to do weird stuff.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 04/01/09 12:03 AM
Dave, these '87 torque are neutrally balanced ?
The snap ring from my 67 is very flat....ok, so a good move to swap trannies ? an earlier will hold more power from what I've been told here so far right ?
Do most of internal components swap ?
Daniel
Posted By: dOoC
Re: 904 Transmission ..(suite..) - 04/01/09 12:12 AM
They SHOULD have 5 discs ? ..... according to who? .... the shop that has done probably more 904 "stuff" than anyone is Paul Forte.
And even in a heavy stock eliminator car ... he used 4 discs.
And I am very much aware the 727 clutch disc is lots larger than the 904.
B U T .. my point was to compare a car trans to a dump-truck trans. The hemi and some six-pack cars had MORE clutches than a motorhome trans?
And I have pulled-apart many MH transmissions with no negative clutch issues at all.
Posted By: HotRodDave
Re: 904 Transmission ..(suite..) - 04/01/09 12:15 AM
there should be at least 2 snap rings, one above the clutch pack and one below it. Sometimes they put a flat one against the wavey one so there could be 3 in one clutch pack.
The 82+ trans should have all the good stuff, 5 clutches, heavy duty steel low gear ratio planataries, and LU. When I build a trans for myself this is the one I look for. If you are going to run it behind an externally balanced 360 you can get weights from mopar to weld on the converter or you can order a converter from an aftermarket suplier that has whatever stall speed you want and has the weights on it, or you can get a BnM flex plate with the weights on it or you can order a LU 360 converter from most local parts supliers.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 04/01/09 12:29 AM
Quote:
there should be at least 2 snap rings, one above the clutch pack and one below it. Sometimes they put a flat one against the wavey one so there could be 3 in one clutch pack.
The 82+ trans should have all the good stuff, 5 clutches, heavy duty steel low gear ratio planataries, and LU. When I build a trans for myself this is the one I look for. If you are going to run it behind an externally balanced 360 you can get weights from mopar to weld on the converter or you can order a converter from an aftermarket suplier that has whatever stall speed you want and has the weights on it, or you can get a BnM flex plate with the weights on it or you can order a LU 360 converter from most local parts supliers.
Whoa !.....let me get this straight ! lolll
I have to get weight to balance the converter...balance it with what ??? the crank ???? I have to take the crank out to balance it ??? i'm very confused on that.....please be very specific because I'm totally lost there Dave..
Daniel
Posted By: 70AARcuda
Re: 904 Transmission ..(suite..) - 04/01/09 12:34 AM
removing the second snap ring allows the pistons to be removed and the seals on the piston need to be changed out...
Posted By: HotRodDave
Re: 904 Transmission ..(suite..) - 04/01/09 01:15 AM
A 360 does not have enough weight in the counter weights to counteract the weight of the pistons and rods so the factory threw a small amount of weight on the converter to help counterbalance the extra weight, the weight is a specific amount and all you need to do is add this weight to your converter, 360 converters already have this extra weight on them or you can add it to your 318 converter, mopar sells a kit with the weights and a way to locate them on your converter, no big deal really and no need to remove the crank, just weld the weight to the converter where it says to.
318s did not have the need for extra weight so there converters are neutraly balanced, no extra weight needed.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 04/01/09 01:28 AM
OK Dave !!!!!!
Now I get it..........do you have a part nnumber for those wieghts ??
Thanks, you are very helpful....
Daniel
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 04/01/09 01:37 AM
ok Dave I got it....P5249843.....thanks
Posted By: capac
Re: 904 Transmission ..(suite..) - 04/01/09 11:11 AM
Quote:
So?
I wasn't saying it is good or bad. Just letting you know.
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 04/01/09 02:27 PM
Great !
Thanks...
Daniel
Posted By: Wedgeman
Re: 904 Transmission ..(suite..) - 04/01/09 04:00 PM
Great !!
So I Guess that '87 trans is another lucky find !!
NO need to take it apart and change parts then...I" ll just add a deep oil pan and go !
Daniel
Thanks Dave