my trans exploded into little pieces!!...why???

[dusta340]

i am currently running a freshly rebuilt 340 in a 72 plymouth duster. i have a 727 trans with a 3500 stall and a cheetah full reverse manual valve body. the trans has only 4000 miles on it and was professionally built and ran and shifted fine before valve body swap with fresh motor. it worked good for the first 50 miles or so and then after tuning in the driveway i noticed first gear was slipping. all others were good so i gave it some gas and the floor board gave ay and mashed my best buddy in the mouth and broke some of his teeth out. which makes me angry because i dont know why this would happen without really beating on the car. i could see if i was at the track and beating on it, but in the driveway just playin around a little bit? it anyone has any ideas please let me know. especially if you suspect it could be the valve body. thanks.

dusta340

[dusta340]

i could use some advice here

[Steve1118]

You rolled the sprag sometime during the four thousand miles you put on the trans. This caused the drum to explode! You are lucky to have escaped with just the damage you did.

This was caused by (A) a drive train failure, driveshaft or axle, causing the engine to overrev with the trans in gear and under load; or (B) a low gear burnout, or by overrevving the engine while the trans was slipping in low gear.

With a manual shift valve body such as a Cheetah, one must NEVER, NEVER, EVER perform a burnout in low gear. ALWAYS use second or high. This is opposite of the procedure with a stock valve body. This information is readily available in all the Chrysler manuals, or can be obtained by any long time racer.

I have been racing Hemi SS cars since 1964, and the amount of trans explosions just in recent years is mind boggling to me. I have seen/heard of more trans explosions in the last two years on this board (and similar boards) than I have seen in the past thirty. My personal thought is, and please accept my apologies if this does not apply to you, is that there are too many kids just running out there buying stuff and bolting it in without "coming up through the ranks" and actually having any practical knowledge on how to use it.

Anyway, I am glad that no one was seriously injured, as someone could have been killed. As it was, you can learn from it, fix it, and move on.

[1972roadrunner]

Originally posted by Steve1118
With a manual shift valve body such as a Cheetah, one must NEVER, NEVER, EVER perform a burnout in low gear. ALWAYS use second or high. This is opposite of the procedure with a stock valve body. This information is readily available in all the Chrysler manuals, or can be obtained by any long time racer.

why not??? i still have the stock valve body, but i might go to a cheetah manual in the future...

[Kevin Garceau]

Man, you are LUCKY.... you did roll the sprag in it. Steve was dead on! I imagine without any knowledge that you did it at one time or many times you were doing burnouts with it and it caught and took off hard, or snubbed down, while in first gear.

727's are really scarey when they brake as you found out. Probably the worst of all of them, the drum literally grenades and the result is what you have witnessed. I am currently racing a 727 but it will be out as soon as this season is over. Not for this reason but its always in the back of my mind during burnouts, and such.

[dwc43]

I agree with Steve and Kevin. You guys got very lucky too. Hope all turns out o.k. for the minor injuries that did occur. All might consider a bolt on scatter shield and flex plate shield in the future. I know tey are hard to work around and install, but the added safety and insurance is mandatory. We make so much more horse power these days with less and less bolt ons and stuff breaks now a days since quality is not what it used to be. So use all the safety equipment that's available, go fast, and be safe.

[Mister Fiberglass]

how much "gas" did you give it?

[John Kunkel]

Part of the problem is lack of education.

Along with all the things Steve1118 pointed out, there is a general lack of knowledge of the symptoms of a failed sprag. Once the sprag fails and the car fails to respond to the throttle, it's somewhat instinctive to apply more throttle. WRONG THING TO DO!!! More throttle means more rpms and, with a failed sprag, a front drum explosion is a good possibility. Whenever the car fails to respond to the throttle in 1st gear, immediately lift your foot and shut down. The problem might not be a failed sprag, but don't take the chance.

A failed sprag forces the front clutch drum into a 220% overdive condition and the cast steel drum can disintegrate from the excessive centrifugal force.

[skydome]

No one has really explained to the fella exactly what happened to his trans. When you shift a tf manually into 1, the valve body applies the low/reverse band to help the sprag hold the drum. The problem is, when you pop it into 2, the kickdown band hits before the l/r band can drop out. The chirp you hear is actually the back wheels locking up for an instant. As you can guess, this is not good for parts or et's. Enter the manual valve body. It eliminates the low/rev band in manual 1, but low can ONLY be used for accelerating because as soon as you decelerate in manual 1 , you are depending only on the sprag to hold the drum. If it rolls, the next time you hit the gas in manual 1 you put the drum into forced overspeed. When it reaches critical mass, as that one did, LOOK OUT!
This is why a tf at breakaway in drive, will always go right into second when you release the throttle, even at creepy low speeds.
Thus, the sprag is protected.

[Tarrbabe]

I assume the sprag that everyone is talking about is the over-running clutch, the peice in the very back of the trans case. Yes - they will fail if you suddenly get traction and the next time you get into it hard, IT CAN EXPLODE the trans. The 727 is most likely the most durable trans out there but it can be broke. I have never exploded one, but have failed several over-running clutchs. This is usually followed by a screeching noise from the trans. I was bracket racing for the money of the day against a 6 cyl. Ford truck and failed one during a burn out. I had to spot him about 7 seconds and I heard the trans noise. I sat thru the light hoping he would red light. No luck. He took off and I turned the wheel and went to the pits. Had I tried ---- well I guess you already know.

[Kevin Garceau]

Another thing to rememer folks....these parts in these stock tranneys. No matter how good they were from the factory, they are 30 plus years old!

[Billydelrio]

... and in my pushbutton 727, closer to 40+ years old.

dusta340, I too am wondering how much gas you gave it. Have you taken whats left of that 727 apart yet? Hope your friends teeth damage can be fixed.


Does the aluminum style shield really protect the driver from a front drum explosion?

Billy

[dwc43]

It's supposed to but it's not as good as a blanket. But blankets are filthy and hard to mess with plus there's cooling issuse with them.

[dusta340]

ok sorry to take so long to get back to you guys We still made to the nats. and im gonnin to give as much info as possible....
Yes i am young 18 years old... but i did not do any dry burn outs and i read the instructions on how not to do burn outs in 1st gear.. the trans only had 4k on it but not with that vavle body it was a fresh moter and i and a certifed tech put the vavle body in and i was driving all nite the nite before and thats were the 50 miles came from i pulled the car out th next day to do some final tuning and i noticed that 1st gear was out but it was creeping foward so i was like what the hell so we checked the trans fluid and it need about a quart so we added thinking may be it was lo so i put it in to 1st again and gave it some gas my be up th 4500 rpm and then BAM. so i didnt do any thing as far as the burn outs wrong or any thing like that and by being young and inexperienced i didnt know or ever hear about this kind of thing happening.. but now i do i am not made that this happend im glad becuase no one got hurt really bad and i am now more experienced than befor u live and learn

[#nineteen]

IF you throw that junk T/A Valvebody in the junkpile where it belongs, you absoluley, positiveley have to have a VB that uses low band apply...this reduces the load on the sprag in 1st. I rolled the sprag on mine at the track, at the hit of the throttle, BOOM. I always do burnout in Hi..those little rollers can only take so much...

[Glen440]

Should I be worried about my Cheetah valve body in my street car thats coming out in a week? I have no choice but to run a full manual or I have to come up with a cable kick down lever. I tried a B&M transpak that converts the valvebody into a forward pattern manual but what a piece of crap.

[creative1]

sorry about your luck, dusta... but the first clue that something had gone terribly wrong inside the tranny was the lack of 1st gear. thats when you should have stopped and realized that there was a problem. fyi, if there is enough fluid in the tranny to operate at all, it will have 1st gear. it may not shift to 2nd, but it will have 1st (and reverse). count your blessings that no one was seriously hurt, and remember this experience. and as some other posts have said, there are manual vb's out there that keep the 1st gear band apply, which protects the sprag and keeps low gear engine braking. "coasting" in low gear with a manual vb (that has no low band apply) also overspeeds a clutch, which in turn overspeeds the sprag... someone said by 220%... that would have been in the neighborhood of 10,000 rpm in your case, even if the rear wheels were off the ground. it doesnt take long at those speeds...

[creative1]

Glen, just dont use low to do burnouts, and dont coast in it. use 2nd for daily driving, and use low only for racing... for the launch.

[John Kunkel]

Even if one avoids 1st gear burnouts and the other things that abuse the sprag, the fact remains; with a manual VB without rear band apply, the sprag takes the entire reaction load of the planetary gears and sometimes it just isn't up to the task.
Like #nineteen said, going to a VB with rear band apply is the safest way to go.

[b-1ken]

Back in the 70's I ran a high ten second '67 'Cuda with a 440 and a 727 with a stock valve body. I always did burnouts in 1st, but the rear band was applied with the stock valve body. One time, after doing a burnout, I hit the throttle and it felt like I was turning the tires, so I decided to do another burnout on dry pavement. The trans blew completely apart, leaving the input shaft and some clutch plates hanging out in the breeze. The rear band didn't keep that thing from grenading. About 8 months later, I grenaded another one. These days I run 'Glides and don't think about such mishaps. I realize that there are plenty of racing Torqueflites out there behind real powerful engines, but I never quite got over my fear of them.

[dusta340]

so should I call cheata and bitch? what are the other vavle bodies that i can use that apply that band. where can i buy them and how$$$


Thanks for all the advice

[dwc43]

I'd go with TCI. Never let me down so far.

[dusta340]

how much did it run u
where to get it

[chargerfreak]

That is such a drag about your tranny. I hope your friend is Ok. I just wanted you to know that I didn't know anything about NOT doing burn outs in first gear. This is my first muscle car, and 727, and I had no idea. As it turns out my Charger wasn't ordered for speed so the rear end gears are so small I don't even bother trying to do burn outs. One of the next things to swap is the rear, and I've already had the 727 rebuilt, it was busted when I bought the car, so I'm really grateful to learn this valuable lesson. Just wanted you to know that without a doubt you saved my trans and my health by posting your story. Thank you, and good luck with the repairs.

[atoetly]

This thing about Power glides being the way to go is a bunch of crap. I hear over the loud speaker at almost every race I go to (does anyone have a spare power glide?) If your running a glide take a spare with ya!

[ajmopar]

I have seen the Race Powerglides, not one GM part in them to get them to stand up, yet people are getting upset about 727s with stock drums in them exploding? Let's see you bolt a stock powerslide (or tubo 400 for that matter) to an 800 horse big block and let it wail!

People drop thousands on heads, cams intakes etc without a second thought, but putting some saftey in their trannies never comes to mind. There are lots of places selling aluminum and billet steel drums, tougher input and output shafts, lightened internals, rollerizing kits, you name it for torqueflites (Bolt in sprags don't cost that much either). Those kevlar tranny shields look like a good investment to me.

Hope your buddies teeth are repareable, that was a very unfortunate incident, but a hard lesson learned I hope.

[b-1ken]

Originally posted by atoetly
This thing about Power glides being the way to go is a bunch of crap. I hear over the loud speaker at almost every race I go to (does anyone have a spare power glide?) If your running a glide take a spare with ya!

I would imagine that the reason that you hear that announcement is because there are 400 Powerglides for every Torqueflite at the track. I have only broken ONE stock gearset in the 10 years that I have been running 'Glides. That gear set had four seasons behind 800 + HP B-1 engines. Also, when 'Glides break they don't explode. I don't really suggest that everybody that has a TF should immediately run out and convert it to a 'Glide but I, personally, would not build a bracket or Super Class car with a Torqueflite.

[dwc43]

Originally posted by dusta340
how much did it run u
where to get it

www.tciauto.com

Got mine from Summit Racing www.summitracing.com

[#nineteen]

Go with Griner or Tranzact...I wouldnt put anything TCI in my trans...

The Glides will live, but the guys that run em with stock gears sets are usually the ones breaking them...they ARE the ticket for lighter cars or real high HP cars. a good one will set you back $3500 or so, plus converter and driveshaft. plus they are about 65 pounds lighter.

[b-1ken]

Originally posted by #nineteen
The Glides will live, but the guys that run em with stock gears sets are usually the ones breaking them...they ARE the ticket for lighter cars or real high HP cars. a good one will set you back $3500 or so, plus converter and driveshaft. plus they are about 65 pounds lighter.

This year, I finally broke a stock gear set (1.76) and bought one of those $1200 aftermarket straight cut gear sets. The thing is, that I had four seasons on the set that broke, all behind 800+ HP B-1 engines. The engine that broke it is my new 511 B-1 which I calculate to be about 870 HP. The 'Glide in my '67 'Cuda has been in there since 1999 and is still going strong. It had 4 years behind a 560 HP 440 and 1 season behind a 499 840 HP B-1. It also uses stock 1.76 gears. To be truthful, I would never have expected these transmissions to take this much abuse, but they do. The only parts that aren't stock is the input shaft, the front clutch drum and the valve body. I usually spend about $550 building one. This is including the trans brake valve body and a free 1.76 transmission core. How a transmission, that was originally designed to go behind a 220 HP 283, can hold up behind a 800+ HP engine with a transbrake, 16" slicks on a glued track is beyond me, but facts is facts.