727rebuild/ front pump questions

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mtolley

mtolley

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Thanks in advance for any help. My 727 lost reverse/high. Pulled tranny and dissasembled. Found high/reverse clutch pack destroyed. Input shaft, clutch drum not useable. Purchased a core tranny from a mid 80's van. (Non lockup) Can i use everything from input shaft to output shaft in my tranny? Old tranny date codes to 1971 but unsure if it has ever been into. Core tranny looks fresh. Everything in it is fine to the output shaft. Mike t
 
Unless you need the 71 date code, I would just swap the whole thing. If you need the date code, you could swap the inerds. Need to be careful about mixing early and late pieces when it comes to input, front drum, and pump/reaction shaft.
 
408 swinger said:
Unless you need the 71 date code, I would just swap the whole thing. If you need the date code, you could swap the inerds. Need to be careful about mixing early and late pieces when it comes to input, front drum, and pump/reaction shaft.
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No, date code doesnt matter. Going back into my d150. At my shop today,i started looking at everything really well, and i think if i use the input shaft,pump, hi/reverse clutch, and direct clutch pack it will work. Ill reuse everything original from output shaft back( shaft, original planetary's etc. Will that work? Tranny was run hard and put up wet for nearly 25years, cant fault it
 
Is there any reason, then, to tear it apart? I would just swap th e whole thing.
 
Oh, gotcha. Make sure the parts you replace are identical.
 
408 swinger said:
Oh, gotcha. Make sure the parts you replace are identical.
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No, they are not identical, which is why im asking. I want to use eveything forward of the output shaft from the core tranny in my tranny. I would be gaining a 4clutch hi/ reverse( mine was 3). Core tranny also has a bolt in overrunning clutch that i plan to use
 
If you decide to swap in the planetaries from the van, be advised that Mopar changed the shape of the drive splines, somewhere in the late seventies I think. The spline count is the same but the shape is different. It is possible to swap them , but in a few miles the old shaft will nicely machine out the splines in the replacement planetaries, and forward locomotion will completely stop. If this happens at WOT, your revs could go thru the roof. I don't recall what year this changeover occurred, so it's probably in your best interest just to not do it,lol.
 
AJ/FormS said:
If you decide to swap in the planetaries from the van, be advised that Mopar changed the shape of the drive splines, somewhere in the late seventies I think. The spline count is the same but the shape is different. It is possible to swap them , but in a few miles the old shaft will nicely machine out the splines in the replacement planetaries, and forward locomotion will completely stop. If this happens at WOT, your revs could go thru the roof. I don't recall what year this changeover occurred, so it's probably in your best interest just to not do it,lol.
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I have learned that about the spline change and also i believe a gear pitch change with the planetaries themselves. Which is why im going to keep all of my original output shaft componets together and just swap everything from in front of the output. Tranny lasted years (@25) with a 3500 converter and turbo action rmvb.
 
AJ/FormS said:
If you decide to swap in the planetaries from the van, be advised that Mopar changed the shape of the drive splines, somewhere in the late seventies I think. The spline count is the same but the shape is different. It is possible to swap them , but in a few miles the old shaft will nicely machine out the splines in the replacement planetaries, and forward locomotion will completely stop. If this happens at WOT, your revs could go thru the roof. I don't recall what year this changeover occurred, so it's probably in your best interest just to not do it,lol.
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1976 was the change year.
 
mtolley said:
I have learned that about the spline change and also i believe a gear pitch change with the planetaries themselves. Which is why im going to keep all of my original output shaft componets together and just swap everything from in front of the output. Tranny lasted years (@25) with a 3500 converter and turbo action rmvb.
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The van shortie trans may have the desirable 4 pin planetaries. If they are in nice shape you could likely sell them, hell I might be interested!
 
d55dave said:
The van shortie trans may have the desirable 4 pin planetaries. If they are in nice shape you could likely sell them, hell I might be interested!
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Yes, it does have 4 pinion planetaries in it. My original has a 4pinion front/3pinion rear. Wish the 2 were interchangeable. Look at the 2 sets, i can see the difference in gears, which is why im keeping my orginal output shaft componets together
 
Forget about what year the trans is or even what the numbers say. That means nothing. Compare rings. Don't mix pumps and drums without checking the rings. Don't switch planetaries from their original output shaft; sometimes they get burred and feel like they fit. Careful about the size of the locating dowel on the output shaft matching the back of the input. Direct drum bushing size changed; plus the corresponding journal on the pump. Check the direct drum for ring scoring. You can change a three plate direct to a four sometimes by using a forward bottom pressure plate on the top, but you might get a hard reverse engagement; have to use a C6 snap ring sometimes.
 
AJ/FormS said:
If you decide to swap in the planetaries from the van, be advised that Mopar changed the shape of the drive splines, somewhere in the late seventies I think. The spline count is the same but the shape is different. It is possible to swap them , but in a few miles the old shaft will nicely machine out the splines in the replacement planetaries, and forward locomotion will completely stop. If this happens at WOT, your revs could go thru the roof. I don't recall what year this changeover occurred, so it's probably in your best interest just to not do it,lol.
Click to expand...
Not swapping the planetaries. Leaving the ones that came out of my transmission in it.
 
CudaFactHackJob said:
Forget about what year the trans is or even what the numbers say. That means nothing. Compare rings. Don't mix pumps and drums without checking the rings. Don't switch planetaries from their original output shaft; sometimes they get burred and feel like they fit. Careful about the size of the locating dowel on the output shaft matching the back of the input. Direct drum bushing size changed; plus the corresponding journal on the pump. Check the direct drum for ring scoring. You can change a three plate direct to a four sometimes by using a forward bottom pressure plate on the top, but you might get a hard reverse engagement; have to use a C6 snap ring sometimes.
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Ill try and explain what i want to do if it will work. My tranny: everything attached forward of the output shaft is trashed. Everything attached to output is fine. Core tranny: everything attached to input is good. Not using anything attached to output. Now, the "pilot" on both output shafts ( portion in front of splines that rides on a bushing in direct drum) is the same size and length. Only difference is my original did not use a 3 eared thrust washer where the other does. Unsure if that matters as long as I use a 3 eared washer. So, in short, i want to use the entire input,pump both clutches from the core tranny and my original entire output in one tranny and it work. Will it work and work properly? I am keeping my turbo action rmvb.
 
Yes it sounds like you're on the right track. Keep the same vb with same case; keeping everything together from the front out of the donor. Just air check the seals and rings and clutch clearance by installing the pump into a vise and stacking the front guts on it. You'll figure out which holes feed which drums. After that, l always assemble the trans without clutches, band, front gasket or pump o-ring; in order to check endplay; considering a pump gasket adds .010 and a hot case will have .020 more endplay than a cold one. Minimum endplay adds longevity to the direct rings.
 
CudaFactHackJob said:
Yes it sounds like you're on the right track. Keep the same vb with same case; keeping everything together from the front out of the donor. Just air check the seals and rings and clutch clearance by installing the pump into a vise and stacking the front guts on it. You'll figure out which holes feed which drums. After that, l always assemble the trans without clutches, band, front gasket or pump o-ring; in order to check endplay; considering a pump gasket adds .010 and a hot case will have .020 more endplay than a cold one. Minimum endplay adds longevity to the direct rings.
Click to expand...
Thanks for the info
 
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