727 guru question...

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j par

j par

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I have a small block very short shaft 727 in my divorced transfer case power wagon..
QUESTION: If I wanted to put in a big block could I just get a big block 727 case and use my short shaft tail housing and guts?? Of course new torque converter...
Would the big block torque converter have the same pump and seal size?...
Thank you for anybody's knowledge on this... It seems possible but LOL maybe it's just wishful thinking...


@TrailBeast
 
That’s kind of a tough one. Sure, everything will fit over, but it doesn’t hurt to get near the same year of 727 from a HD application (Loadflite) to keep from dealing with different end play or lockup / non lock up variations. Better yet, get one out of a Motorhome. They usually have the short outputs and a 2 piece driveshaft.
But, something completely different and that you may not want to hear… if at all humanly possible, you’re better off to adapt over to a married transfer case and transmission. But that requires a different transmission output with the transfer case adapter, and a later model transfer case. There was enough wear and tear associated with the intermediate divorce drive shaft that Dodge saw fit to get away from it. What year is your truck and is it a 1/2 ton or a 3/4 or full ton?
 
Garrett Ellison said:
That’s kind of a tough one. Sure, everything will fit over, but it doesn’t hurt to get near the same year of 727 from a HD application (Loadflite) to keep from dealing with different end play or lockup / non lock up variations. Better yet, get one out of a Motorhome. They usually have the short outputs and a 2 piece driveshaft.
But, something completely different and that you may not want to hear… if at all humanly possible, you’re better off to adapt over to a married transfer case and transmission. But that requires a different transmission output with the transfer case adapter, and a later model transfer case. There was enough wear and tear associated with the intermediate divorce drive shaft that Dodge saw fit to get away from it. What year is your truck and is it a 1/2 ton or a 3/4 or full ton?
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74 power wagon dream truck...
74 3/4 ton...
 
Garrett Ellison said:
That’s kind of a tough one. Sure, everything will fit over, but it doesn’t hurt to get near the same year of 727 from a HD application (Loadflite) to keep from dealing with different end play or lockup / non lock up variations. Better yet, get one out of a Motorhome. They usually have the short outputs and a 2 piece driveshaft.
But, something completely different and that you may not want to hear… if at all humanly possible, you’re better off to adapt over to a married transfer case and transmission. But that requires a different transmission output with the transfer case adapter, and a later model transfer case. There was enough wear and tear associated with the intermediate divorce drive shaft that Dodge saw fit to get away from it. What year is your truck and is it a 1/2 ton or a 3/4 or full ton?
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The motorhome transmissions I've seen I'll have the e-brake connected to the tail shaft?.
 
I'm looking at building a big block for my dream car and the engine will likely be done many years before the car is purchased.. soooo.... Maybe put it in the truck for a while...
 
oldkimmer said:
Yes, no problem. I have done a few. The spline was changed slightly in 1976. It’s at a different angle and is a little bigger where the planetaries slide on. So just us your sb parts there. Kim
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I just completely rebuilt the small block one I have and it's got two trips to the end of the block and back LOL... I would like to just clean a big block case up and put all my guts shift kit valve body and whatnot and just put new front and rear seals in...
 
Some of the small motorhome/camper van transmission didn’t have the drum on the back of the output, as well as some of the commercial Transit bus vans, which were essentially the same platform.
 
Garrett Ellison said:
Some of the small motorhome/camper van transmission didn’t have the drum on the back of the output, as well as some of the commercial Transit bus vans, which were essentially the same platform.
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I had a 77 Foretravel, 440, based off a D-300. Should have kept it. Beautiful, all new inside. Point of use hot water, bedroom, bathroom, kitchen, new fridge/ freezer, new carpet 2 roof top a/c units, she was older, but rehabbed and clean as heck. Never used Her, a Family in Gainesville needed a home so I sold it to them. Been sitting for Years, they drove from Zephyrhills to home.. unfortunately, I didn't look at the 727 that close, but the sparkplugs drove me nuts....Peanut plugs.... took 2 trips to the parts place to get it right.( didn't think I'd have to take one with me...)
 
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j par said:
I measured the tail shaft.. 8"...
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That’s what the last one out of a camper van that I seen measured. It had a 400 in it and no brake drum on the tail shaft. I’m not familiar enough with the tail shaft brake version and how the drum and drive yoke attaches and if it’s possible to eliminate the tail shaft brake, but it may be worth looking into.
 
Garrett Ellison said:
That’s what the last one out of a camper van that I seen measured. It had a 400 in it and no brake drum on the tail shaft. I’m not familiar enough with the tail shaft brake version and how the drum and drive yoke attaches and if it’s possible to eliminate the tail shaft brake, but it may be worth looking into.
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It looks like I'll keep my eyes open for the correct one... Lord knows I have years of time.. and if a big block automatic comes by me extremely cheap that's a long shaft I'll probably snap it up.. that way worst case scenario I can use the case...
Again I would just prefer the correct one..
 
j par said:
I have a small block very short shaft 727 in my divorced transfer case power wagon..
QUESTION: If I wanted to put in a big block could I just get a big block 727 case and use my short shaft tail housing and guts?? Of course new torque converter...
Would the big block torque converter have the same pump and seal size?...
Thank you for anybody's knowledge on this... It seems possible but LOL maybe it's just wishful thinking...


@TrailBeast
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727 Front pump seal all the same from 1962 on. 727 front pump bushing the same. 1962 on, although you can get it either in babbit or bronze. No difference in the size of the converter hub, regardless of engine in front of it. There are 3 different sizes though for the extension seal.
 
Nothing to it. The bb will probably have different converter imbalance, and the valve bodies might not interchange; depending on the case configuration just in front of the rear servo. And always keep the front planetary matched up with the output shaft. 3 different splines.. All the guts will interchange as a unit. Pump covers changed and forward drums too; some were two ring; some three. Front seals and bushings etc same.
 
CudaFactHackJob said:
Nothing to it. The bb will probably have different converter imbalance, and the valve bodies might not interchange; depending on the case configuration just in front of the rear servo. And always keep the front planetary matched up with the output shaft. 3 different splines.. All the guts will interchange as a unit. Pump covers changed and forward drums too; some were two ring; some three. Front seals and bushings etc same.
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I was really kind of hoping that my valve body would switch over if anything just cuz it already has the trans go to shift kit in it... I figured at that point it was just following the instructions on how they want the front and rear bands adjusted?..
 
The 1962-1966 727 converters have different spline count and smaller Input shaft. So the reaction shaft and input shaft are smaller. Yes the seal & bushing are the same but you can’t swap anything else. 1967 and newer are different.

You can just swap the case like you want to but the cases and valve bodies had a slight change around 1971 so just get a case the same year as your case is now and you can swap everything over.

some MH had a drum on back, some not.
 
CudaFactHackJob said:
You could post pics of the vbs and the cases.
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Screenshot_20220411-105939.png
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The first one is my small block one that's in the truck now and the next couple are local Craigslist ones that are motorhome and claiming short shaft and the last one is an eBay one I think in Louisiana or something. None of those other three look like the tail housing is as short as mine...
 
Uh, no, those pics don't show anything. Why do you want ANOTHER short trans? You already have one. Just find a bb case for $100-150. You'll need it with the vb if you can't compare them.
 
CudaFactHackJob said:
Uh, no, those pics don't show anything. Why do you want ANOTHER short trans? You already have one. Just find a bb case for $100-150. You'll need it with the vb if you can't compare them.
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That was more or less the original question if I could do that or not and that's pretty much being answered now thank you...
 
Although if the correct short shaft big block transmission comes along I would just rather have a second one and not have to get one to fill the other.. the difference would be probably an additional $100 rebuild kit..
 
If you search youtube for John Cope Racing you will find he has a bunch of short tech videos posted. One of them discussed the differences and showed examples of the differences to watch out for. Basically, consider the main case, the front section, to be the universal part. Get the one the fits your engine (big block). Then always keep the output shaft matched to the tail housing due length and installation type, such as slip yolk, drum parking brake, or the output flange secured with a nut. The fun starts with keeping the gear set splines matched to the shaft splines, which is where the year differences really get important. Then, make sure the pump stator support matches the high/reverse (front) drum machining for seal rings and bushings.

The pictures in post 17 are all considered short shafts but it shows a bunch of the variations. Your 74 model year truck is getting really close to one of the spline angle changes, so be careful and keep your output shaft and gear sets together.

NOTE: Don't use this post as 100% accurate info. Watch the videos and look at the parts to be sure I did not mix up the details.
 
No, dude, you just think it was answered. There's a reason I said for you to post pics of the valve bodies...you might have to find out the hard way..
 
CudaFactHackJob said:
No, dude, you just think it was answered. There's a reason I said for you to post pics of the valve bodies...you might have to find out the hard way..
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So if I got a car transmission you're saying it would be best to keep its valve body with it as well?
 
No. The first thing I do when I take apart a trans is to make sure all pats are compatible. They are MOST of the time, but very often I find mixed and matched parts that are NOT compatible. So, NO, I don't recommend keeping any vb with any case; because they might be mismatched. I get transmissions all the time that are still under warranty from somebody else with mismatched parts. "If it's still under warranty, why don't you take it back to the original rebuilder?!?" ...."Cuz we're tired of taking the mox?er$!<>er back out AGAIN!!"
 
CudaFactHackJob said:
No. The first thing I do when I take apart a trans is to make sure all pats are compatible. They are MOST of the time, but very often I find mixed and matched parts that are NOT compatible. So, NO, I don't recommend keeping any vb with any case; because they might be mismatched. I get transmissions all the time that are still under warranty from somebody else with mismatched parts. "If it's still under warranty, why don't you take it back to the original rebuilder?!?" ...."Cuz we're tired of taking the mox?er$!<>er back out AGAIN!!"
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Likely since I have so much time I'll just keep my eyes open for the correct 727..
 
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