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727 performance rebuild parts list


Well-Known Member
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6:38 PM
Aug 27, 2012
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Dallas TX
I have a core 727 from a 66 charger that someone gave me and I'd like to do a performance build on it. Will be behind 600hp/625lbft with 3.55 gears and street tires. I'm trying to get a sense of what all will be needed. I have Munro's 727 book and the stock trans but no parts yet. I want to keep auto shift but firm shifts with something like a TF2. Looking at this kit:


Is this a good combo of parts? I'm wondering if I need a bolt in sprag or anything else. Goal is for it to be reliable, not break, and shift like hell. Any part suggestions would be appreciated.
Do you have a source for performance torque converters for the 19-spline input shaft?
I would convert the pump stator support, input shaft, and front clutch drum to a 1971 and up style.
The '71+ has the best support for aftermarket torque converters, and billet drums.
I have used the Alto Red eagle clutches and kolene steels.
I would look for a kit like this:

And the get a TransGo TF-2 shift kit:
A set of Alto red frictions, Kolene steels, Kevlar KD band, any reverse band, and the Transgo TF-2 shift will fix you up. I would also recommend a 4 disc later model front clutch drum/pump assembly as previously mentioned. Make sure all the clearances are set to specs and every part is clean as a whistle.
The last few years I've used the parts from Cope. The kits are good. The clutches and steels are real good. Very happy with his bands. In general I'd swap in a '71 & later pump support/front wide bushing drum. But the 70 & earlier works good too. Use 12 springs in the front drum. The front servo can be either the '71 later or '70 & earlier I've use both behind 600 HP. Front drum needs to be 4 disc maybe convert to 5 disc. Use a 3.8 lever in the front servo with both springs.
My car and goal seem similar to yours. I'm not a tranny guy, but the stuff mentioned above is what I did with mine. And, not sure if its been mentioned already, but I think adding a steel billet drum and 16 roller sprag, like A&A's Ultimate Sprag is a good addition for safety reasons.

I also played around with the governor and 1-2 shift valve spring to make it automatically up-shift at my desired WOT rpm while in "D".
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I have used kits from A&A Transmissions, near Indianapolis. Boss guy is Rick Allison, and they have a very comprehensive catalogue available. They have a kit to put 5 clutches in the front 4 clutch drum. As others have said, try to swap in a 1971 and newer front end, to ease converter choice. Saying that, if you are scavenging a newer trans for parts, you would likely be better off building the newer transmission. As a bonus, 1971 and newer transmissions have part throttle kick down valve bodies. Also order the sprag spring and rollers kit. Make sure you get new pump bushing and front drum bushing. I use 4.2 lever and 9 or 10 springs in front clutch, depending on style of piston. I also have a machinist friend who modifies the stock low performance governor weights to lighter high performance specs. A&A also sells these lighter weights. These make quite a difference in shift points.
BTW, I ran the stock sprags behind my 550 to 600 HP motors for several thousand runs in my drag cars. No breakage. The sprag needs to be in good condition. You need good burn out procedure to keep it alive. A top quality sprag is sure a good idea, but for a street car without perfect traction probably not required. Just MHO.
If I understand correctly, the sprag holds the drum for 1st gear when the transmission is in Drive or 2nd with a standard non-manual Valve Body.
The Low/Reverse Band will also apply if you shift to 1st gear manually.

I think this is where confusion happens on burnout procedure.
The instructions for the Manual valve bodies usually say to start burnout in second gear so you bypass the 1st gears need to use the sprag or rear band.
If you try to start in 2nd with a standard valve body, the trans still starts in first gear , but without the help of the rear band, do it is better to start in manual 1st gear and then shift into second gear.
The 727 trans has always been known as an extremely durable unit. For that hp, keep it simple. Pay close attention to lip seals, not to cut or roll them on installation. I always install a new spray roller and spring kit. They are about 4 bucks. Pre soak clutch discs. Get a few selective thickness snap rings for the clutch packs, or a few of the thicker steel plates. Easy to set clearance that way. Transmission assembly lube is nice, basically colored Vaseline. Have a small pan of trans fluid handy, it’s nice to rub on seals over top of the assembly lube, making it super slippery. Also, on the bottom side of the sprag, there is a small Allen set screw. Tap the sprag into the case so it seats into the case, then snug the Allen screw. It’s always loose. Bolt in sprags were designed to repair damaged cases, and adapted by racers. If your burnout habits are proper, a stock sprag is near bullet proof.
These are great suggestions. I'm going to use the ebay kit that 451 sent for starters and go from there. Mopar parts are not easy to come by here in Texas so the likelihood of getting a 71+ 727 big block core is not high. Can I get brand new parts to convert a pre 1970 727 into a 71+? If you have a source please let me know. I think the part throttle kick down valve body is worth installing. I could check with Stevens performance or cope for used 727 parts.

Right now I have a 2800 stall converter in the 1970 trans in the car but I'm thinking to get a custom convertor with this new build. When I first built the car I was set on converting to 4spd but I am enjoying the current 1970 727 with TF2 a lot.

Can I get good parts out of a motorhome 440 trans? Those I have seen here.
The '70 style pump and front drum are just fine. The '70 narrow bushing drum may wear a little more, but works real well. With 600 HP /625 TQ, I would surely put 5 discs in the front drum. I used the Turbo Action modified top steel for many years that allowed the 5 discs. In the last few years I've used Cope's clutches and steels to put 5 discs in the 4 disc drum, work great. I was very happy with the TransGo kit I used in my tow vehicle. I think it was a TF2. Easy modification and install.
As I understand it there are several versions of 727's that were used in motorhomes. Seems like you would have to take one apart to see what's usable.
The motor home 727's will usually have front and rear 4-pinion planetaries. I usually do not reinstall the spring on top of the accumulator piston when I do a shift kit. I used to install the blocker rod under the piston, early on. But, I no longer do this because some part throttle up and down shifts were pretty harsh for street driving.
For my drag racing 7'27's I prefer the 4 pinion front and rear. Others have a different opinion. On my my drag race 727's never use the accumulator spring or a blocker rod. Worked OK. On my customers 727's I use the blocker rod. But these have been manual shift trans. No idea what a part throttle valve body would like. I would never use one for a HP application.
Yes, many good parts in motor home units. I will caution you on using late , like 1977-78 and up planetary sets, unless you use a matching output shaft. Somewhere in that timeframe, they did a spline pitch change. I forget the exact details.
The TF kits are good, and have great pics in the instructions. I will give you a little hint: if you have not done this before, take a shitload of pics and lay out everything as it comes out. Use some tooth picks or something like that to stop each "Row" of valves and springs from rolling into the next batch. Many of those shuttle valves and such look the same on each end, so you won't know which way to re-install. The theory of "it will only go back together one way so I'll figure it out" does not apply to valve bodies.
Great suggestion on valve body disassembly. A few of those valves do look about the same and which end is which can be confused.