A look at the inside of a 727 that lives

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

Wow, looks brand new, especially the band. Can't believe there is 700 runs on it. Good for you. Also goes to show how good a 727 is even when a converter fails and sends metal through it.

I was very surprised when I had sent converter metal through my trans this past month that nothing inside looked bad at all. The only place I found metal was in the pan, and in the cooler lines. I was lucky and didn't need to change the pump, which was my main concern when I saw all the steel in the pan.

Happy nothing other than the pump needed replaced. Do you have a spare converter to put in?

There was very little metal. Some inside the rear drum and some behind the governor support. It was all fine dust. I wanted to wash out all the Torrington's and the roller bearings in the governor support and tail shaft housing. Speaking of the roller bearing in the governor support. Originally the lube hole to the rear shaft was restricted by the roller bearing. My friend Paul again worked his magic on the governor support and whipped up a spacer to keep the roller captured in the right spot. Here's the pics and his work on the sun shell as well.
Doug

I have absolutely no idea what any of this stuff is, but nice to see a detailed post about it.

LMAO!

Great post Doug! I'm still learning about the innards of these 727s...posts like these help a lot.

Jeff!!

Really appreciate the detailed pics, I'm trying to learn as well and this is all super helpful!

So a few mods I do. Pic 1 is the reaction shaft support. This a 71 or newer wide bushing version. The oil feed hole to the front clutch has been widened. Its done with a used cut off wheel that's worn down to about 1 1/2 " diameter. Or the high end guys can mill it. This also gives a good shot of the reaction shaft ring grooves. They are square and smooth. this can be verified by inserting the ring in the groove and holding it up to the light. You also want to look inside and see where the input shaft rings ride. That area should be smooth as well. The 2nd pic is the OE front pump vent. Drill it with a R drill. Then tap for 1/8 pipe and plug with an Allen plug. I'll go into detail where to locate it in the next post. Pic 3 is what's left of the parking gear/governor support. All cut down to reduce weight. We did cut a new snap ring groove in the output shaft further forward to retain it. The last pic is the accumulator blocker rod. You can really use anything. A piece of rod, an old bolt. Just make sure its not to long that it holds the valve body up off the case.
Doug

Doug…. What’s your feelings on oil relief holes in the drums (help evacuate fluid/centrifugal weight)? Both of my older Lofgren builds had them including the 904 I’m currently beating on.

I've never used them. How much oil is in the drum when the piston isn't applied? Good question. However the only time pressurized oil is in the drum is when the clutch is applied. That clutch pack always applys plenty quick. We all know the dreaded overlap. So why do we need them? Maybe someone smarter than me can shed some light.
Doug

Thanks for sharing this. Very appreciated.

B&M found a decrease in parasitic loss in first gear with the holes.

In 1st gear, the front clutch retainer turns at 80% of the input shaft speed in the opposite direction, so this means that the released clutches see a surface speed of 180% of input shaft speed; the trapped fluid in the drum creates lots of parasitic drag so drilling peripheral holes allows the trapped fluid to escape. I drill 3/16" holes in a staggered row.

Nowadays, lots of builders place small pieces of rubber tubing between the disc floater ears to help keep the discs separated but the trapped fluid is still there with no place to go.

how do those holes in the drum affect it's balance ?

Evenly spaced around the periphery, no balance change.

This is a good thread......you learn something every day,i look at one of john cope videos on a 46/47 transmission rebuild video where he did some mods on it. he modified the input shaft, hub by enlarging the holes. Never seen a modified drum like that.

I've long thought about the silicone O ring material between the high gear clutch stack up. The clutch drag would certainly be reduced in 1st and 2nd. I may drill the holes on the next go round as well. A lot of this stuff gains very little in ET. But all together you can see something. Got some time today and putt he trans back in. spent some time making sure the converter lined up properly fore/aft. On the 2 Mega blocks that I've used the rear block face is to short. Both of them required 1/8 aluminum spacers between the trans and block. Other wise the starter gear engages the flywheel teeth about 1/2 way. Also some converters bottom in the crank. Spacing the trans back also allows you to space the converter rearward from the flex plate to gain crank to snout clearance. Another mod is to drill the lower trans to engine mounting holes. then you can use a 3/8" bolt and nut instead of trying to put the 7/16" bolt through from the engine side. Many times the headers interfere with bolt removal in this area. It takes a little case clearancing around Where the bolt head will seat. A small head or allen bolt works well. A hole saw makes for a nice radius for the converter access.
Doug

To add the RH46/518 repop pans are nice and cheap to boot. They are deeper than anything else. Structurally strong against leaks with a reusable gasket. Mines still using the same gasket from 2013. They do need a little notching for cable shift transmissions near the park housing. Being deep we made (Paul again) a longer 1 3/4" filter spacer.
Doug

I’m also a fan of the 47/48RE pan….. especially when there were some trans that’s didn’t have a core charge at work so they were free .
Doug I tagged you on a cable shift 727 for sale on FB. Not sure if there any hard to find specific parts with those. Not like they’re laying around like they used to be

Thanks for the interesting notes on the oil reliefs John….. but I can’t read that without hearing cliff clavins voice! great stuff!

Doug,

Nice autopsy man! Even though I don’t run a 727, I’ve learned some new stuff for sure. Thank you for taking the time to share.

Wes

Do those pans fit 727?
What brand part number for the spacer if you don't mind sharing that info?

I have the same spacers in mine. I believe from Cope Racing Trans.

The aluminum Summit pan I picked up last year looks to be as deep as that one based on the filter extension size, but doesn't have a sweet reusable gasket like that one. I like it!

Spacer is home made.
Doug

i used to have the part number for the factory reusable 727/518 pan gasket, but now, i can't find it.
can someone help ?
TIA

Can someone tell me what the accumulator piston & circuit does? I always see them blocked off when using a manual valve body. Although I though I read somewhere that ProFlites still use them?

Thanks in advance

2464324AC

Thank You Leigh !

I purchased mine from A&A
http://www.aandatrans.com/Products/727-Deep-Steel-Pan-(Includes-AandA-Transmission-Billet-Aluminum-Extension-22321BE--Molded-Pan-Gasket-3859MR--Dacron-Filter-12776C--Drain-Plug-(1962-65)__22730DE.aspx