727 4 pinion planetary....

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sthorvictor75du

sthorvictor75du

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hey guys, I know I have a few threads open on here right now, have a pile of stuff going on at once it seems. anyhow, I pulled my 727 apart last night because the casing has a few cracks in the bellhousing. plan is/was to remove all the guts and the output shaft and housing and discard the casing. I picked up a 73 rv 440 with the mated 727 which has the tail shaft with the bolt on yoke and support bearing. the plan is to gut the new transmission and swap out the tail shaft and housing, and rebuild one good one. however, I have no idea what the old 727 came out of I bought it for 50 bucks 4 years ago and put it though the stocks, upon disassembling I noticed that the rear band to be cast iron, and that the front planetary is a steel casing 4 pinion planetary, I looked at the clutch packs and such and they seem to be the standard duty 4 steel 4 friction setup and the springs in the rear drum I counted 9 out of the 15 possible, what throws me off really is the front planetary and the hd band.
the other reason I was picking up this other trans was I thought it would have had the beefed up components am I wrong in this thought? as far as the other trans i was told it came out of a cordoba any thoughts to what i have here? or is the 4 pinion planetary standard for the front and the rear is the one that needs to be beefed up? i can get numbers off the casing but have no idea where i would begin to look them up?
thanks
 
Pretty sure the planetary gears are four gear normally and a five and six gear can be had for them (kinda pricey) though.
Cast iron rear band is a normal factory band.
 
..........Its the 2nd gear band that is older cast, newer 1s r the flex band......the rear planetary is usually only 3.......i may have some around depending on the year of the trans.....there is #s on the drivers side pan rail...post them...........kim......
 
found the trans numbers on the side... as far as the bands the first was flimsy as all hell and the second Is heavy cast.. rear planet is 3 pinion, ill see what comes out of this motorhome 727 as far as planetary, as far as rebuilding have you guys ever heard of guys running reverse steels and frictions in the other drums because they are thinner and can pack more in? or should a guy just rebuild with the same amount? trans 'shouldn't' see over 600 ft lbs... however some abuse...
pk4028424-5711-8580
 
A 4028424 is a 76-77 trans. The guys are right about the bands. All rear bands are solid steel. Older front bands were solid but the newer ones were flex bands. Not sure when they started doing that but I think it was around 70. I'd bet the RV has 4 pinion planetaries front and back but you never know for sure until you take them apart. Yes using thinner clutch plates in the front carrier works so you can put more in it. Factory steels are all the same thickness but you can get aftermarket ones in different thicknesses. Just gotta have an assortment of selective snap washers to set the clearance right. Mopar made a spline angle change in 76 on the input shaft so make sure you use the correct front planetary gear set for a 76-90 trans. The older planetary from the RV may slip on but it'll strip out. If it a HD unit you want to use you'll have to find a pre 76 output shaft. The rear planetaries will exchange no problem.
 
because of the leve of abuse and performance - I'd recommend a billet steel high gear drum. It will allow you to run a larger number of frictions, the wider hemi kickdown band, and remove the possibility of drum explosion if the rear sprague is damaged. I'd also assume you're replacing the rear sprague with a bolt in...
 
fishy68 said:
A 4028424 is a 76-77 trans. The guys are right about the bands. All rear bands are solid steel. Older front bands were solid but the newer ones were flex bands. Not sure when they started doing that but I think it was around 70. I'd bet the RV has 4 pinion planetaries front and back but you never know for sure until you take them apart. Yes using thinner clutch plates in the front carrier works so you can put more in it. Factory steels are all the same thickness but you can get aftermarket ones in different thicknesses. Just gotta have an assortment of selective snap washers to set the clearance right. Mopar made a spline angle change in 76 on the input shaft so make sure you use the correct front planetary gear set for a 76-90 trans. The older planetary from the RV may slip on but it'll strip out. If it a HD unit you want to use you'll have to find a pre 76 output shaft. The rear planetaries will exchange no problem.
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I thought by 76-77 that everything had gone over to lockup converters already?? I will defineatly be looking closely at the slip splines for the drums and the bushing diameters... I would end up re using the planetariy ring gear and the planets as an assembly, I mainly want to swap out the output shafts and the tail housing onto the rv trans and build that one up... not planning on mixmatching parts too much unless I have too... also never hurts to have parts kicking around...

will definitely be putting in a bolt in sprag regardless of trans abuse lol, haven't decided on a tci or spending the money on a billet coan unit..
 
I thought they were all 4 pinion in the 727, guess not.
It has been some time ago since I was doing them.
This is what I was saying about the 5-6 gear planets.
 

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TrailBeast said:
I thought they were all 4 pinion in the 727, guess not.
It has been some time ago since I was doing them.
This is what I was saying about the 5-6 gear planets.
Click to expand...

thought stock was 3, factory HD was 4 (taxi and RV, hemi) then aftermarket 5 and 6
 
sthorvictor75du said:
I thought by 76-77 that everything had gone over to lockup converters already?? I will defineatly be looking closely at the slip splines for the drums and the bushing diameters... I would end up re using the planetariy ring gear and the planets as an assembly, I mainly want to swap out the output shafts and the tail housing onto the rv trans and build that one up... not planning on mixmatching parts too much unless I have too... also never hurts to have parts kicking around...

will definitely be putting in a bolt in sprag regardless of trans abuse lol, haven't decided on a tci or spending the money on a billet coan unit..
Click to expand...

Forget Coan go to TCS in Langley BC they carry their own billet units in both steel and aluminum and include the 24 spring return module in the price , I put a steel one in , my 904 along with their race rebuild kit been back and forth across Canada with no problems 524hp/527tq . you can find them at tcsproducts.com .

PS their Mopar guys and race a 1400hp car of their own not a bunch of chivy guys trying to make a few bucks on the side .
 
sthorvictor75du said:
I thought by 76-77 that everything had gone over to lockup converters already?? I will defineatly be looking closely at the slip splines for the drums and the bushing diameters... I would end up re using the planetariy ring gear and the planets as an assembly, I mainly want to swap out the output shafts and the tail housing onto the rv trans and build that one up... not planning on mixmatching parts too much unless I have too... also never hurts to have parts kicking around...

will definitely be putting in a bolt in sprag regardless of trans abuse lol, haven't decided on a tci or spending the money on a billet coan unit..
Click to expand...

904's were lockup but 727's are almost never a lockup trans. 727 lockup trans. are as rare as hen's teeth. The bushing diameters are the same I believe but you will not be able to tell the difference in the slip splines by looking at them because the angle change is ver small. Absolutely do not mix the 72 planetary with the 76 output shaft or you will be sorry, guaranteed.
 
fishy68 said:
904's were lockup but 727's are almost never a lockup trans. 727 lockup trans. are as rare as hen's teeth. The bushing diameters are the same I believe but you will not be able to tell the difference in the slip splines by looking at them because the angle change is ver small. Absolutely do not mix the 72 planetary with the 76 output shaft or you will be sorry, guaranteed.
Click to expand...

I was talking about the 'straight' splines on the output shaft... I was going to just to re use the later output shaft and re use all the guts out of the earlier rv trans? I know that the helical cut of the planet gears are slightly different between the sets? but the shaft splines should be the same?? or am I completely mixing this up?
 
sthorvictor75du said:
I was talking about the 'straight' splines on the output shaft... I was going to just to re use the later output shaft and re use all the guts out of the earlier rv trans? I know that the helical cut of the planet gears are slightly different between the sets? but the shaft splines should be the same?? or am I completely mixing this up?
Click to expand...

I can't comment on the cut of the planetary gears but I absolutely guarantee the splines on the output shaft where the front planetary slips on are different from 72 to 76. You cannot use a 72 planetary set on a 76 output shaft. Like I said earlier you cannot see the difference with the naked eye but it's there.

Read this page concerning the difference in spline angles

https://www.coperacingtrans.com/product_info.php?cPath=97_55&products_id=356
 
you guys were right I apologize, the number on the spines is identical but the backlash/spline size is different ever soo slightly, the rv trans has 4 pinion's on both sets while my 76 trans has 4 and 3, interesting. thanks. rv trans low/reverse band is completely chewed out however everything else looks barely broken in, have to check out a few trans shops and find an output shaft that will work for the 73...
 
sthorvictor75du said:
you guys were right I apologize, the number on the spines is identical but the backlash/spline size is different ever soo slightly, the rv trans has 4 pinion's on both sets while my 76 trans has 4 and 3, interesting. thanks. rv trans low/reverse band is completely chewed out however everything else looks barely broken in, have to check out a few trans shops and find an output shaft that will work for the 73...
Click to expand...

No problem. If you don't find one local check out www.wittrans.com They sell good used parts really cheap. The only drawback for you would be the shipping cost and waiting time.
 
thanks guys, I ordered some goodies from tcs, and found a pre 76 ouput shaft locally, and assembled the thing, fingers crossed she works, if not shes easy enough to do again, still need to install a deep pan and manual valvebody
 

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sorry more pics..
 

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