Hawk's First 727 Transmission Rebuild

[HawkRod]

Hawkrod
Is there a specific upgrade kit you can put in the 727,
Or just need to source out individual parts. I will be at 550
hp ish, and like to do tranny soon. Thx

I'm not aware of any specific upgrade kits, since different transmissions have different internals. You will just need to tear into yours and see what you find. Mind you, I am just a novice transmission rebuilder, so others may chime in and offer some suggestions I am not aware of.

Good luck - you can do it!

 

[66Satellite47]

Hawkrod
Is there a specific upgrade kit you can put in the 727,
Or just need to source out individual parts. I will be at 550
hp ish, and like to do tranny soon. Thx

If you really are at 550 ish HP, there is no kit, you need a well built 727. As Hawk has demonstrated in this thread, building a HP 727 takes a lot of learning and experience. You can't just buy some parts.

 

[Dave6T4]

Hawkrod
Is there a specific upgrade kit you can put in the 727,
Or just need to source out individual parts. I will be at 550
hp ish, and like to do tranny soon. Thx

Talk to the guys at A&A Transmissions near Indianapolis. Jim Allison is the main guy there. They make/supply a lot of parts for high horsepower builds. Ask for their catalogue.

 

[66Satellite47]

I put a shift kit in the car around 1982. I used whatever springs were included with the kit and I was always happy with the way it shifted after that. When I rebuilt the transmission just now, I used a new A&A Transmission "red spring" later style servo piston assembly for the kickdown band. So yes, I guess it is now different than what I had after I installed the shift kit. If the band and pressure adjustments do not firm up the shifts, then I will try my old servo and spring. Some experimentation to get the right combination of parts might be needed here!

It HAS a drain plug! But the damn valve body drips like crazy for a long time after the ATF had been drained and the pan dropped. I inevitably stick my big, fat head right under a drip that is about to happen and get an ATF shower...

Hawk, how many turns do you have on the front band? If 2 try 1 3/4. The 3.8 lever takes more travel of the piston to apply the band than a lower number lever. That may be part of that issue. A tighter band setting will quicken the band apply. FYI the Hemi 727 with the 5.0 lever only used a light long inner spring in the front servo and 1 1/2 turns on the adjuster. The 5.0 applies more force to the band but takes more piston travel. The single red spring may be just fine with the 3.8. I just never had one. I've used the 5 .0 recommended by Turbo Action, 4.2, and 3.8. I decided the long light Hemi spring alone was not my favorite. I think the band life was bit shorter. The 4.2 worked well, with both the Hemi light spring or with the stock outer and inner. The Griner brake recommended the 3.8 lever, early style servo & spring combo. It shifted very well since I didn't use the brake.
Lots of choices in combinations.

 

[oldbee]

IMHO check ur pressures. Like dave(?) said, another turn/1-1/2.

 

[HawkRod]

Hawk, how many turns do you have on the front band? If 2 try 1 3/4. The 3.8 lever takes more travel of the piston to apply the band than a lower number lever. That may be part of that issue. A tighter band setting will quicken the band apply. FYI the Hemi 727 with the 5.0 lever only used a light long inner spring in the front servo and 1 1/2 turns on the adjuster. The 5.0 applies more force to the band but takes more piston travel. The single red spring may be just fine with the 3.8. I just never had one. I've used the 5 .0 recommended by Turbo Action, 4.2, and 3.8. I decided the long light Hemi spring alone was not my favorite. I think the band life was bit shorter. The 4.2 worked well, with both the Hemi light spring or with the stock outer and inner. The Griner brake recommended the 3.8 lever, early style servo & spring combo. It shifted very well since I didn't use the brake.
Lots of choices in combinations.

IMHO check ur pressures. Like dave(?) said, another turn/1-1/2.

Thank you both. I have my front band set to 2 1/2 turns, so it may just be a little loose for this combination. I will try to adjust it a half turn in (to 2 turns) and see what happens first. I am now getting more hopeful that a simple adjustment like this will improve the quickness of my 1-2 shift.

If that doesn't work, I will move to pressure checks.

Now to get that Impala off my lift!!!

 

[66Satellite47]

Hawk, 2 1/2 turns is too loose. Should be 1 1/2 to 2. I'd try 2 see how you like it. Go down to 1 3/4 if you want. 1 1/2 is lowest I've ever run.

 

[HawkRod]

Hawk, 2 1/2 turns is too loose. Should be 1 1/2 to 2. I'd try 2 see how you like it. Go down to 1 3/4 if you want. 1 1/2 is lowest I've ever run.

Thanks - sounds like a plan! Plus, I like potential fixes that don't require a lot of work!

 

[HawkRod]

Well, I crawled under the car and tightened up the kickdown band 1/2 turn (so it is now 2 turns out). Drove it and the 1-2 shift seems like it is really working nicely now. Previously, it misbehaved a bit when I shifted from 1st to second manually at a higher RPM. I duplicated the same thing today and it shifted well!

So I am happy I didn't have to dig back into the transmission for this adjustment!

So at this point, I believe the transmission is ready to go. I'll put some miles on the car when the weather improves a bit and hope all continues to go well!

As always, thanks to all of you that have followed along or provided valuable feedback - much appreciated!

 

[HawkRod]

So, a quick follow-up to this thread.

I drove the car across country both ways in May and June of this year (2022). That trip accumulated about 11,100 miles. Since the trip, I have probably put another 1,000 miles on the car. So the bottom line is the transmission now has over 12,000 miles on it and still works great. It still does everything it should without any complaints or issues. Let's hope it keeps going for many more years!

I wouldn't hesitate to rebuild another!

 

[oldbee]

Glad it all worked out, probably time for a 2nd gear adjustment. Sorry,,, Jeff. Wear & such, you had a lot of hills.

 

[HawkRod]

Glad it all worked out, probably time for a 2nd gear adjustment. Sorry,,, Jeff. Wear & such, you had a lot of hills.

Adjustment?!? This is in the RoadKill Runner! We don't do no stinkin' adjustments and maintenance - we drive it till it breaks and then fix it with bailer twine and zip ties!!!

OK, seriously, this is good advice. I think over the winter I'll give the 'ol girl some TLC and check all operating systems. I'm kind of enjoying driving this thing, so I want to keep it going!

 

[Mopars & Missiles]

..........I'm kind of enjoying driving this thing, so I want to keep it going!

All ya got to do is, Point it WEST and head for the coast again!

 

[zyzzyx]

So you gonna get the air fixed? How's that vibration doing? Glad youre still enjoying the fruits of
your labor!

 

[HawkRod]

So you gonna get the air fixed? How's that vibration doing? Glad youre still enjoying the fruits of
your labor!

I will get the air fixed, but after all the outflow of cash from the trip I am holding off for a bit.

Vibration is the same as before - all but gone but not 100% gone. At the moment, other priorities are keeping me from fiddling with it. I think I will reweld the axle perches next year so I can get rid of the 6* shims I have in there now. Then I can fiddle with the angles a bit more and hopefully get ALL the vibration out of there.