727 case & guts edit: autopsy photos
#2658410
05/23/19 02:08 PM
05/23/19 02:08 PM
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Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
OP
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OP
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Joined: Jul 2007
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Philadelphia
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Howdy!
I posted a thread about my recent trans carnage- I shattered a stock slip yoke and took out my tailshaft and trans case. I called A&A trans (board sponsors) and ordered solid 1350 universals and billet steel trans and pinion yokes.
Now I’m looking at options for my next 727 build. The numbers on my current broken trans say it’s out of a ‘77 2wd pickup truck. I would ideally like to find a similar trans so that I can pick the healthiest parts from both cores to use. I’m looking stuff up in my books and in the tech archives and I think I have a good idea of what to look for but I’m posting now to get more experienced opinions.
If my info is correct my valvebody will work in any post ‘65 727. My oil pump and front drum will only work in a late trans- 76+? And my planets and forward clutch will not interchange at a certain year down right- output spline change?
Am I correct that all my guts will work in any post 65 case + tail? I want to stay with direct interchange for all or most parts if possible though. I don’t really care if I have kickdown or neutral safety switch- my ‘54 has NSS in the slap shifter and didn’t come with reverse lights.
I want to use my current B&M neutral balance non lockup converter- it was working great, along with my clutch drums, planets, shafts, clutches & steels. I might play with a higher numerical kickdown lever but I dunno.
Any input on what years I should be looking for? I can get a good ‘67 core but I don’t know how much of my guts could swap and if the planetary gears and clutch drums are different (oil passages, oil pump, splines?) then I’d have less parts to pick from and no spares if the new core turns out to be beat up.
Thanks Moparts!
Radar
Last edited by radar; 06/06/19 01:07 PM.
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Re: 727 case & guts interchange?
[Re: radar]
#2658418
05/23/19 02:38 PM
05/23/19 02:38 PM
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Joined: Dec 2005
Posts: 11,551 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,551
Fulton County, PA
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1971 is when there were a number of changes done, both to the 727 and the 904 in the range of PK35XXXXX and up. Cases, fluid passages, etc. should be the same except for some servo sizes on the small transmission, except for the mid 60s. style units. Internal parts have been changed. I would think anything in the mid 70s would be fine. I'm sure others can be more specific and will chime in.
If that thing was broken that bad, I would check shafts for being bent and closely inspect everything else.
If the results don't match the theory, change the theory.
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Re: 727 case & guts interchange?
[Re: radar]
#2658427
05/23/19 02:55 PM
05/23/19 02:55 PM
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Joined: Jan 2003
Posts: 25,785 Rio Linda, CA
John_Kunkel
Too Many Posts
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Posts: 25,785
Rio Linda, CA
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In the year range you're proposing there were lots of changes that can get you in trouble when swapping parts. For instance, besides the changes to the case and VB in '71, there was a change in the output shaft spline in '76 that affects front planetary interchange and there was a change in the lube circuit in '74 that affects the valve body and input shaft interchange.
Best to ask the exact year you're planning to interchange,.
The INTERNET, the MISinformation superhighway
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Re: 727 case & guts interchange?
[Re: John_Kunkel]
#2658460
05/23/19 04:13 PM
05/23/19 04:13 PM
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Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
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OP
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Ok. Will my tf2 modded 1977 valve body go in a ‘72? How bout a ‘68? Again- I don’t use the trans nss or reverse light.
Last edited by radar; 05/23/19 06:24 PM.
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Re: 727 case & guts interchange?
[Re: radar]
#2658575
05/23/19 09:51 PM
05/23/19 09:51 PM
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Joined: Mar 2006
Posts: 9,835 MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,835
MI, usa
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Why not just repair the on that broke? Take it apart and see what broke. You'd be surprised how much power you can put through one. I know, all 727's blow up and kill people. A good drum, front planet and valve body will hold a fair amount of power. We have 2 push button units that hold north of 800hp with mainly stock parts. Mine is nearing 600 passes with no real failures. Doug
Last edited by dvw; 05/23/19 09:59 PM.
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Re: 727 case & guts interchange?
[Re: dvw]
#2658590
05/23/19 10:29 PM
05/23/19 10:29 PM
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Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
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OP
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Why not just repair the on that broke? Doug That’s pretty much what I need to do- I need a case, tail, output shaft & matching parts- possibly a governor, park stuff, etc. Buying those ‘a la carte’ will quickly exceed the cost of a whole used trans. And if I find a similar year I can even see if any of its parts are healthier than mine. Either way I need to build a whole trans and I wouldn’t use anything from the sprag back in mine. So all I have here for sure is a non lockup converter, ‘77 clutches, drums, bands, servos, pump, struts, and my modded valve body with deep pan & filter. I want to use those parts to ‘fix’ my trans but if I can’t find a compatible core it is actually cheaper to just buy a complete rebuild kit for whatever I can get a hold of- unless I end up needing planetary gears or some expensive part that’s worn out. That’s why a trans that my parts swap into makes a new core less of a gamble that way as long as the tailshaft contents are good I have my pick of two sets of parts. I’m just studying my books and looking at date interchanges on parts for sale and asking questions here to try and educate myself on the interchangeability of all the 727 guts cases and valve bodies.
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Re: 727 case & guts interchange?
[Re: 440Jim]
#2660057
05/28/19 03:33 PM
05/28/19 03:33 PM
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Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
OP
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OP
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Thanks Jim
I am not really racing this thing unless you count trying to beat mustangs and camaros from 0-35 at a light. I am trying to be a grownup with this build and basically made healthy modern diesel power but in a 3200lb pickup on premium pump gas. I just wanna cruise around and occasionally lay some stripes and stuff myself and passenger into the seatback.
I had already ordered billet steel 1350 slip and pinion yokes. Today I ordered some more stuff from A&A - a 4.2 lever, reinforced band strut, and a billet low/reverse servo piston kit, along with an overhaul kit so I have plenty of seals, bushings, red frictions & kolene steels in case the 100 miles I had on the trans were harder than I thought.
I also got an iron front high groove drum. It’s not that I don’t think my right foot is worth $700- it’s just that I launch at 3000, shift at 4500, and my spark rev limiter is set at 5500.
I think I won’t do any more holeshots in Drive though- 2nd gear only from now on.
I was looking hard at the billet steel drums and ultimate sprags but I just can’t justify the cost for a maybe 12 second street machine.
Plus if I ever get bored with my HP and get trickflow 270s, roller cam, and big headers I will have enough trans parts on hand to get a good headstart on building safe high rpm 727 for the strip.
Am I a fool? I already will have around a G in this rebuild once I get a new driveshaft made up for the 1350 u joints.
Last edited by radar; 05/28/19 03:39 PM.
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Re: 727 case & guts interchange?
[Re: 440Jim]
#2660076
05/28/19 04:28 PM
05/28/19 04:28 PM
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Joined: Jan 2003
Posts: 25,785 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,785
Rio Linda, CA
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The controlled-load front servo is easy enough to defeat, Transgo kits supply a spacer to eliminate its function or you can drill and tap its feed hole (red circle in pic below) and block the hole with a set screw.
The INTERNET, the MISinformation superhighway
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Re: 727 case & guts interchange?
[Re: radar]
#2660614
05/30/19 12:52 PM
05/30/19 12:52 PM
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Joined: Jan 2003
Posts: 25,785 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,785
Rio Linda, CA
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You have to remember that the servo piston is restrained from moving by a large coil spring that keeps it seated in the bore when no pressure is applied. When pressure is applied to the servo, the spring resists piston movement until a certain pressure is attained to overcome the spring but the same pressure is also entering the small hole in the piston and its weaker spring allows the plunger in the piston to move at a faster rate than the piston itself, thus the pressure under the plunger gives a cushioning affect on application and a delay on release. Plugging the hole or blocking the plunger defeats the cushioning and makes the servo, in effect, the same as the early servo.
The thing I dislike about the controlled-load servo, other than the cushioning effect, is that the plunger remains extended from the piston even after the 2-3 upshift; this closes up some of the free play that is adjusted in and mandates looser band adjustments. As you can see in the pic below of the piston in 3rd gear, the plunger is still extended even though the piston is firmly seated in its bore.
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Re: 727 case & guts interchange?
[Re: radar]
#2660769
05/30/19 09:41 PM
05/30/19 09:41 PM
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Joined: Jul 2007
Posts: 1,682 Philadelphia
radar
OP
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OP
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Posts: 1,682
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I couldn’t wait- I took the other ‘77 case down, simple green’d, scrubbed, power washed, dried with compressed air, and hosed the sprag race with wd40.
It looks much better than the first one off the complete trans core I disassembled this morning- tight sprag race, all tapped holes good, all sealing surfaces smooth.
It’s interesting that the casting dates are only 9 months apart but the good one has more ribs/reinforcement in the starter area. Had to do a double take and measure the top bolt holes to be sure they’re both big blocks!
Edit: left is dodge truck rt is chrysler car that could explain it? Truck bell beefier?
Last edited by radar; 05/30/19 11:47 PM.
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