A lot of discussion about 727 strength. This trans has been in the car 10 years, over 850 passes. Car has been 1.27/8.98@149 3340lbs in poor air, 1.24/5,64@120.4 in decent air. It broke the converter this past weekend at NMCA at Norwalk. So the trans needed to be torn down to clean out the metal from the converter. All the metal found was steel. It appears to have ate the stator Torrington, maybe more? It ripped a mounting lug off the converter as well. In 2012 I traded a pair of 340 exhaust manifolds for the remnants of a blown up (low roller let go and took out the case) 65 push button stock eliminator trans. It had straight cut planets in stock carriers. Only 2 planet gears in the front planet carrier. The front and rear drums, and rear clutch retainer were aluminum. It had a straight cut sun shell, HD band strut and anchor. The rear was all Torrington. It also had a Turbo Action reverse manual valve body. The front drum had been machined for a 2 clutch capacity. Due to the snap ring location 5 clutches wont work. The steel falls into the snap ring groove. So a new A&A billet steel drum was used. I also removed the 2 straight cut planet gears from the front carrier(4 pin with 2 missing). A&A supplied a 3rd straight cut pinion which i loaded into a stock 3 pin carrier. A stock 65 core donor was used along with the usable parts. It ran this way for 2 years and then lost all forward gears. That fix will be in the next post.
Doug

Doug, do u have a steel or aluminum stator?

a mess but fixable. My 727 failed earlier this year , sheared and ground up oil pump lugs while cruising up the freeway @ 60mph . 15 year old probably 55/75000 miles , north of 1200 passes , Not as much HP as you but more weight . Only upgraded to a Griner rmvb and solid front band after breaking 2 flex bands . On the back burner as i have another built tbrake unit . Will get billet oil pump gears and super sprag this time . Pricey buying good parts with the Aussie peso .
They are plenty tough for most of us bracket racers .

Tex

Doug,

I read all of your posts about 727 torqueflite and I greatly appreciate the information and experience you share on this site. I constantly reference your posts when discussing 727s and building 727s.

I recently had a similar issue where my converter failed at the mopar nats. The stall speed increased which I caught on my MSD Grid data. With buying the trans used, putting 499 runs on it, and never having gone through it, it was time anyway. Luckily nothing inside was hurt. Just a simple freshen up and its back in business living happily in my car.

What is your plan for torque converter? Do you have a spare? Do you plan to send this one back to be fixed? Or do you plan to replace it with a new unit?

Keep the 727 world alive!

It's a steel stator. The only damage to the trans this time was some scoring if the main pump body and the pump gears from the steel grit. A good used stock pump housing and used stock pump gears and its all set. So as I said the first failure was around 200 passes in. The input hub splines pulled though the aluminum front clutch carrier. When that happened the piston cocked and tore the outer piston seal. Thus no forward gears. A stock steel carrier wouldn't have failed. I was able to repair the aluminum carrier by counter boring the carrier for snap ring clearance. Then cutting a groove in the outside of the input hub. Now the snap ring (904 front clutch snap ring) loads against the aluminum carrier. Never an issue for 8 years. Note the input shaft and hub are stock parts. The next failure was self induced. Rolling thru the staging lanes at National Trail. I went to hit the N button, shut off the engine and coast. But hit the R button by accident. All was good until the following weekend when it snapped the ear off the reverse band coming out of the trailer. We'll cover that story next.
Doug

Must be a weekend for trans. trouble. Mine broke the band anchor and smoked the band.

Put the silly fast stuff in there Doug! It’s simple mopar math the 904>727

I want to see that 904 BB with push button shifter case...

The converter is an Ultimate 9.5" It's been good. I will send it to be repaired. The back-up is an ATI 9.5". Both appear to be the same core, billet front half. Both run about the same. So the R instead of N incident. It broke an ear off the rear band pic 1. Found a core 65 trans in a racers pick up truck at Norwalk. Puled my trans and tore it apart. Had trouble removing the front planet. Also found a cracked flexplate. Inspecting the planet carrier I found some odd looking splines See pics 2&3. The font of the carrier looked ok. But from the rear you can see why its tight. Obviously my straight cut stuff couldn't be used due to the front planet. Put it all together at the track with the core geartrain and a borrowed flexplate. This was the only band failure it has ever had. Servos are stock. When I returned home I disassembled a stock front planet and swapped in the straight cut gears. I kept an eye on the splines during yearly inspections. Never looked bad again. Until it flat-out stripped last year pic 4. That was now 2 failures of the same component. Note: this is the early pre1971 shaft spline pressure angle. It was was changed. in 1971. How much stronger are they? I don't know as that shaft wont fit a 65 trans. The front planet is now a steel A&A 3 pin carrier with the straight cut gears transplanted into it. That's been it for my transmission failures. I have broken flexplates and converters. Along with Dana gear sets. Next post we'll get into what the rest of the sluff inside is.
Doug

Doug what's different about the 65 that the later shaft won't fit ?

Doug why do you think the earls on those solid bands break off like that?

The first change was in '76 then again in '94.

Later shaft doesn't have provisions for the rear pump drive.

Did this happen this year or were you talking about a previous mis hap

But..... It didn't live. It's broke.... lol

Just kidding. Glad is nothing serious!

Casey FJ

65 was the last year for the rear pump then ?

Thanks

Yes, and the only year for the slip yolk.

Casey you enjoyed the last failure. How could you forget working on your back. It had 250 passes, 2015. Besides this time its the converter. Band tab snapped off cause I put it in reverse while rolling about 15-20 mph. At 85 passes I had a look inside the trans. At that time the steel front drum was swapped for aluminum. My friend Paul also milled the sun shell to lighten it as well. I ran the trans 345 passes before a look see. This time I found the stator support rear ring groove worn to a taper. It also wore the rear side of the rear ring. I replaced the support and the rings (steel). The next winter it did the same thing. I talked with several high end builders. The conscious was the ring grooves may not be machined smooth enough. Also it is imperative that you start with a reaction shaft support that is straight and has square grooves. Again Paul to the rescue. He made a lapping stick and lapped the grooves to a fine finish. Have never had another ring/groove issue. So the trans is gutted to clean any metal from the converter. The band shown has over 700 passes. At the last freshen up (2018) the rear frictions were in the front clutch (Alto/Kolene) they were decent but the rear clutch had stock frictions. I slid the old front frictions except one that was slightly dark into the rear clutch. The front clutch recieved fresh frictions. new rings and seals were installed. Along with a rear roller bearing retainer which I will detail later. As you can see all is good. No side wear on the ring. Pressure plate isnt hot. Band, frictions and steels like new. This trans doesn't run a ton of line pressure either. about 125psi.
Doug

Yes, I fumbled the keyboard.
Doug

Ma Mopar changed the front input shafts spline and size and the outer part around it in either 1966 or 1967 the first time