727 rebuild help

[dan juhasz]

So I’ve located a correct part number trans for my A12 a 093 core 69 440 hp unit. Disassembled it today. Need advice on several things I see , some I know is bad others not sure what the issue is.
Please forgive me if I get the name of assembles wrong. I’m capable to follow directions and have rebuilt one other 727 that came out fine but I do not know all the nuisance.
The clutch assembly with the bellvue spring has four clutches, everything seems normal. The other clutch assembly has a standard .068 steel directly on the aluminum piston . Activating that 4 clutch pack. That steel is all bent up out of shape. And every steel in that assembly has hot spots all the clutch show uneven wear. Shouldn’t it have a much thicker .250/.280 steel directly on that piston? Shouldn’t it have it have 4 clutches or only 3. I think someone wanted four clutches and tried something dumb.
Next low reverse drum has heat spots all around , clean it up and use or replace?
Rear output shaft support looks like it was starting to fall and loose aluminum, replace correct.
The metal tab behind the sprag outer housing. Many of the spring tabs were bent fully compressing the springs. I was going to buy a bolt in sprag from Cope.
I measured overall input shaft clearance before disassembly, .130 only had one fiber washer and clip. Fiber was appears really squashed.
Appreciate all input, pictures below.
Also has an area in pan rail that was either cast that way or damaged. Should I get it welded up and machined down level?
One of the heavy .280 steels looks pretty blue, toss it?

 

[R413]

That trans was abused. I suspect a poor valve body timing, and bad driver error for a long time.

Shop for 727 parts at A&A transmission, not the other place.

Yes the rear support, sprague, and rear drum are junk. Is the .280 steel normal or smoked on the other side? Is it flat or warped?

Yes a thin steel goes on the piston. It has backing from the piston. You need a thick plate on top because the only backing pressure is the snap ring on the edge.

Should have 2 fiber washers in the front drum area. They should be flat and not steps or ridges. And also the little washer on the output shaft.

Yes it did have 4 clutches in the front drum when new.
I was building trans for a guy racing mid 10's. He needed a trans and all we had was 3 clutch drum so he used it. He has a manual valve body so max pressure all the time. It never failed.

 

[dan juhasz]

That trans was abused. I suspect a poor valve body timing, and bad driver error for a long time.

Shop for 727 parts at A&A transmission, not the other place.

Yes the rear support, sprague, and rear drum are junk. Is the .280 steel normal or smoked on the other side? Is it flat or warped?

Yes a thin steel goes on the piston. It has backing from the piston. You need a thick plate on top because the only backing pressure is the snap ring on the edge.

Should have 2 fiber washers in the front drum area. They should be flat and not steps or ridges. And also the little washer on the output shaft.

Yes it did have 4 clutches in the front drum when new.
I was building trans for a guy racing mid 10's. He needed a trans and all we had was 3 clutch drum so he used it. He has a manual valve body so max pressure all the time. It never failed.

That thick steel that shows the blue was towards the snap ring other side looks normal.

 

[gtx6970]

That thick steel that shows the blue was towards the snap ring other side looks normal.

If said plate is flat, clean it and reuse it putting clean side towards the disc, make sure its FLAT

Drum pistons push against thin steels. Goes thin steel, disc , thin steel , disc etc etc etc
The thicker steel ( aka reaction plate ) is outside , next to snap ring
ANY steel thats not flat is toast

Yes your stator support and low rev drum are toast

From what I can see , your case is fine

 

[gtx6970]

ps, why is the outer sprag ring out? Its staked in place
If it is that easy to r+r ,,,youre probably gonna need a bolt in sprag to save the case

 

[dan juhasz]

ps, why is the outer sprag ring out? Its staked in place
If it is that easy to r+r ,,,youre probably gonna need a bolt in sprag to save the case

All the fingers on the sprag were bent compressing some of the springs. I loosened the set screw and through the rear support bolt holes I gently tapped it out. I intend to install a bolt in sprag.

 

[dvw]

Post #4 is correct. The plate location and 4 friction front clutch appear stock. This unit looks like it suffered from lack of cooler oil flow. It has far more damaged hard parts than normal. Remove the rear cooler line fitting and make sure the passage isn’t plugged. You can drill a lube hole from the cooler line passage thru to the location of the low roller clutch inner race. A complete valve body disassembley, inspection, and cleaning should be on the list. A great time to install a TF2 kit. As far as the corrosion. Clean the area well with a small wire wheel. Dremel works well. Then spread JB weld on with a razor Blade flush to the surface.
Doug

 

[dan juhasz]

Post #4 is correct. The plate location and 4 friction front clutch appear stock. This unit looks like it suffered from lack of cooler oil flow. It has far more damaged hard parts than normal. Remove the rear cooler line fitting and make sure the passage isn’t plugged. You can drill a lube hole from the cooler line passage thru to the location of the low roller clutch inner race. A complete valve body disassembley, inspection, and cleaning should be on the list. A great time to install a TF2 kit. As far as the corrosion. Clean the area well with a small wire wheel. Dremel works well. Then spread JB weld on with a razor Blade flush to the surface.
Doug

Fitting and passage is clean. I have seen them plug completely on failed units. Is there a set size to drill that lubrication port?

 

[Dave6T4]

I have rebuilt a lot of 727's in my time, but have never seen one as totally used up as yours. I would try to find a '72-'75 727 out of a big old Chrysler that would not see that kind of abuse. Then, transfer all the guts out of it into your A12 case. This would upgrade the trans with Part Throttle Kickdown and the front drum with the wider brass bushing. On rebuilds, I rarely replace the rear drum, because the rear band is mostly grabbing a stopped drum, unlike the front band and drum. However, yours is certainly pooched, and needs to be scrapped. The used transmission would likely have a good rear drum and band. Along with 4-clutch drums front and rear, the A12 transmission would have 4-planet sun gear assemblies front and rear.
I have bought a lot of parts from A&A Transmissions over the years, and have always been completely satisfied. You can buy rebuild kits from them that include new friction plates and new steel separator plates. They sell a kit that puts 5 clutches in the front 4-clutch drum. I shoot for something like .015" clearance per clutch disc when assembling the front clutch pack. So, . 060" -.070" for 4 -clutch, and .075" -.085" for 5 -clutch. I shoot for .025" -.035" for rear clutch. If there is a fibre thrust washer between input and output shafts, I replace it with a brass one. Don't use a blocker rod under the accumulator piston, as it usually results in jarring downshifts. Mopar used anywhere from 6 to 12 springs in the front clutch pack, depending on application. I have always used 9 or 10, depending on the piston style. Make sure that you kickdown lever is either 3.8 or 4.2 ratio. This would be a good time to add a shift kit, too.

 

[dvw]

Fitting and passage is clean. I have seen them plug completely on failed units. Is there a set size to drill that lubrication port?

.060”

 

[493 Mike]

Clean the **** out of everything. Cleanliness is next to godliness when it comes to tranny rebuilding!!!!!!!!!!
Mike

 

[dan juhasz]

I have rebuilt a lot of 727's in my time, but have never seen one as totally used up as yours. I would try to find a '72-'75 727 out of a big old Chrysler that would not see that kind of abuse. Then, transfer all the guts out of it into your A12 case. This would upgrade the trans with Part Throttle Kickdown and the front drum with the wider brass bushing. On rebuilds, I rarely replace the rear drum, because the rear band is mostly grabbing a stopped drum, unlike the front band and drum. However, yours is certainly pooched, and needs to be scrapped. The used transmission would likely have a good rear drum and band. Along with 4-clutch drums front and rear, the A12 transmission would have 4-planet sun gear assemblies front and rear.
I have bought a lot of parts from A&A Transmissions over the years, and have always been completely satisfied. You can buy rebuild kits from them that include new friction plates and new steel separator plates. They sell a kit that puts 5 clutches in the front 4-clutch drum. I shoot for something like .015" clearance per clutch disc when assembling the front clutch pack. So, . 060" -.070" for 4 -clutch, and .075" -.085" for 5 -clutch. I shoot for .025" -.035" for rear clutch. If there is a fibre thrust washer between input and output shafts, I replace it with a brass one. Don't use a blocker rod under the accumulator piston, as it usually results in jarring downshifts. Mopar used anywhere from 6 to 12 springs in the front clutch pack, depending on application. I have always used 9 or 10, depending on the piston style. Make sure that you kickdown lever is either 3.8 or 4.2 ratio. This would be a good time to add a shift kit, too.

It does have 2 , 4 pinion planetary.

 

[dvw]

For what its worth. We run 3 pin planets in 9 second stuff. Some NHRA stockers even remove 2 pinions from the 4 pinion style and run only 2.
Doug

 

[gtx6970]

I have rebuilt a lot of 727's in my time, but have never seen one as totally used up as yours. I would try to find a '72-'75 727 out of a big old Chrysler that would not see that kind of abuse. Then, transfer all the guts out of it into your A12 case. This would upgrade the trans with Part Throttle Kickdown and the front drum with the wider brass bushing. On rebuilds, I rarely replace the rear drum, because the rear band is mostly grabbing a stopped drum, unlike the front band and drum. However, yours is certainly pooched, and needs to be scrapped. The used transmission would likely have a good rear drum and band. Along with 4-clutch drums front and rear, the A12 transmission would have 4-planet sun gear assemblies front and rear.
I have bought a lot of parts from A&A Transmissions over the years, and have always been completely satisfied. You can buy rebuild kits from them that include new friction plates and new steel separator plates. They sell a kit that puts 5 clutches in the front 4-clutch drum. I shoot for something like .015" clearance per clutch disc when assembling the front clutch pack. So, . 060" -.070" for 4 -clutch, and .075" -.085" for 5 -clutch. I shoot for .025" -.035" for rear clutch. If there is a fibre thrust washer between input and output shafts, I replace it with a brass one. Don't use a blocker rod under the accumulator piston, as it usually results in jarring downshifts. Mopar used anywhere from 6 to 12 springs in the front clutch pack, depending on application. I have always used 9 or 10, depending on the piston style. Make sure that you kickdown lever is either 3.8 or 4.2 ratio. This would be a good time to add a shift kit, too.

An excellent response btw