727 and burnouts

I know about the issue with sprags and LBA or not, relating to shock, freewheel at 2X the RPM and taking apart the drum. There are plenty examples out there. My question is, does it seem this is predominately an issue w/ slicks and racing?

Back in the day, we used to do burnouts all the time in 1st, pedal the car on and off the throttle with street tires and I never once heard of a 727 coming apart on the street back then. Granted HP/TQ was not what it is now for a healthy 440 like now.

Just trying to get a better understanding if this is just a slicks/track issue as I've always started burnouts in 1st. The reason I'm asking, I now have a fairly quick 440 and guess at the very least I should add a blanket to the trans. But I have no plans to run slicks.

Helpful comments appreciated.

I think you can get away with starting in 1st if you have a generic 727, but when you add some stall, MVB and such you really should start in 2nd. The Turbo Action instructions give you a good idea why. You can go to their website and print it out. I typically start in 2nd then hit 3rd at 5k and roll out of it and up to the line. You tires will spin faster and heat better in 2-3 than 1-2.

Just to reiterate, I'm talking about street driving, not track and heating tires. The trans is a built 727 with a MVB.

Its been my IMPRESSION this is more of a problem with slicks since it is the shock of the slicks suddenly stopping the drivetrain motion that damages the sprag assembly.

It could be a problem on the street with sticky drag radials. Average street tires are too slippery for the drivetrain shocking.

That being said; I still make sure I'm not in first when letting off the loud pedal on the street out of habit.

If you just want to do a burn out on the street I don't think you are going to hurt anything...

This is the way I understand the function of the 727.
You have 2 scenarios:
1. Gear shifter is in manual low (L)
2. Gear shifter is in D, first/low gear is active.

In case 1 the low band apply protects/locks the sprag, while in case 2 the sprag is active (no low band apply).

I believe the danger in case 2 is that while doing a burn out in low gear (shifter in D) a slight disturbance in the engine (like hitting the rev limit, misfire, fuel problem, or pedal the throttle) will/may cause the sprag to start free wheeling...and now a moment later when/if the full engine power is restored, the sprag will, with full power, slam back into locked position, and this causes a huge load on the sprag, and may destroy it.

So, never a burnout with the shifter in the D-position. A burnout in manual low (L) is a lot safer, if I understand things correctly.

The question was regarding a reverse manual valve body trans.

The question was regarding a reverse manual valve body trans. [/quote]


You start in second or high gear... heavy car.. start in
second... my car is light so I start out in high gear...
speed of the tire is what your after to heat it up

LBA or no? Since most street burnouts don't involve a water box, trying to start a burnout in 2nd (depending on tires) will be a non-starter (pun intended) so you're stuck starting in 1st. If no LBA, you're laying with fire.

Not sure on the LBA? I did not have the trans built. The car has a line lock and enough HP to kill the tires in 2nd, so I guess I will just have my fun in 2nd from now on. I'm still just wondering how we did all those street burnouts back in the day with 727's never having issues. I will do them in 2nd from now on. I like my feet!

Maybe I'm missing the point in this discussion but even the standard 727 has LBA in manual low (L) as far as I understand.
Presumably a manual valve body has it too?

From my point of view it should be perfectly safe to start in manual low (L) and shift up when needed???

On the LBA .. he would have to figure out who made
it and see if it it LBA... my old TA valve body is
a RMVB with a trans brake... it is not a LBA.. the
stock valve body is a LBA.. but you never know for
fact on a aftermarket RMVB... he can test it... put
it in low gear.. run up to 20 or so MPH and decell the
engine... if its a LBA it will slow the car with the
engine... if not LBA the car will just coast

You presume wrong; I'll go out on a limb and opine that the majority of RMVB's don't have LBA. Easy to test, place the shifter in low, roll up to about 20 mph and throttle back to idle; if it has LBA the car will nose over under compression braking, if not, the car will just freewheel and coast with no braking effect.

I see, thanks for the good info.

It just seems very odd to me that the LBA-feature in the stock valve body would most likely be missing when investing in a RMVD. Maybe there is a technical reason for it...difficult oil routing in the VB, faster shifting, less drag or other?

My manual valve body which has been in the car for 25 years has no engine braking in first gear. Turbo Action unit.

I will go and try the 20 MPH and off the throttle this weekend. If not, like I said, it's got the HP to kill the tires in 2nd on radials.

Exactly how to do it at the track or on the street
If you have the power to start in top well do it. I have belted piss out of my 727's without a failure, street, strip, slicks, radials, strokers, nitrous and wheelstanding 9's. I have killed convertors, diff centres and axels though.
A car with a bit more HP may have a positive affect on trans as it have the wheels spinning with ease rather than struggling or labouring.
Love burnouts. Is there a burnout thread ?

I always started my burnouts in first before I got a line lock, it never really free wheels against the brakes and I shift to 2nd quickly. It took me 20 years to finally put a line lock on my car and now that I have one I start my burnout in 2nd gear. This is with a turbo action non apply manual VP

Hey Tempest might be time to sweep the floor in there, it's looking a little untidy

The major reason for a non LBA valve body is to eliminate overlap in the 1-2 shift. In an LBA valve body the low reverse band has to release while the intermediate band applies. If the release of the LR band is too fast or the INT band to slow, you will get a flare in the shift. If the opposite is true, you get a bind up. Even when it is timed perfectly, there is still a short period of time when they are both applied and cause a slight delay in the shift.

In a non-LBA valve body, the sprag or roller is holding the LR drum and when the shifter is moved to second the Int bad applies and the roller clutch unlocks as it is turning in the direction in which it freewheels so the release is immediate. No overlap to deal with.

This is correct and is why RMVB were no low band apply for many years. Basically a faster shift and no worrying about any shift overlap from two elements on at the same time. You wont get a flare but you can have a drag if the kickdown (second gear) band applys before the L/R band releases. It wont flare if the L/R band releases to fast because the overrunning clutch (sprag) will still be holding just like in a no low band apply. Ron

Excellent info guys! Many thanks.
Now I know why things are the way they are and I can rest peacefully

I know about the issue with sprags and LBA or not, relating to shock, freewheel at 2X the RPM and taking apart the drum. There are plenty examples out there. My question is, does it seem this is predominately an issue w/ slicks and racing?

Back in the day, we used to do burnouts all the time in 1st, pedal the car on and off the throttle with street tires and I never once heard of a 727 coming apart on the street back then. Granted HP/TQ was not what it is now for a healthy 440 like now.

Just trying to get a better understanding if this is just a slicks/track issue as I've always started burnouts in 1st. The reason I'm asking, I now have a fairly quick 440 and guess at the very least I should add a blanket to the trans. But I have no plans to run slicks.

Its due to roller spit back and shock load. The ORC has rollers and waffle springs. Spit back comes from when the rollers get locked then unlocked then locked again - think wheel hop. Slicks will compound the problem since you load the ORC more each time after it is unlocked - then you either spin the ORC cam in the case or you cock the rollers then things go to Haiti after that.
When I started with Chrysler I authorized ALL the transmission replacements for the U.S. - and cop cars (especially NY cop cars) broke the ORC with regularity. And they didn't have slicks on them. They had manual low block out - that prevented manual low band apply even though the cops thought they had them in low gear.
Came from two basic events - running across railroad tracks deep throttle (wheel hop)while in first gear auto, and neutral drops.

Moparts has scared the poop out of me with 727 explosions. I remember when I bought my first MoPar when I was 16, a '67 440/727 GTX, and thought it was bulletproof. All I ever heard was the 727 is a tough rugged mother, 8 3/4 tough as nails behind a Torqueflite. Didn't know anything about RMVB, but the car had one, which I figured out once I got it running.

Nice running 440, I used to put that sucker in low, punch it and absolutely annihilate the H78-14 white walls off the back of it. Had 6000 RPM in about 15 feet, didn't know better, it sure was fun, and that tranny snapped 2nd gear real nice. Never hooked in first, and never really pedaled it though. And never drove it really on the street much, just pulled it out and went around the neighborhood leaving H78 lines all over the road since it was rough and I didn't own it long.

Spend enough time on here and you think a 727 is a ticking time bomb made out of glass. I always thought it was the best 3 speed automatic. This site makes me afraid of a non-LBA 727. Maybe I got lucky. I don't even like to go near the starting line when a 727 MoPar is launching now.

I went with a "cheetah" valve body. It has low band apply. Besides manual shifting, it will also up-shift automatically if you leave it in drive. I come out of the water box in drive ( 1st) and feather the throttle as it upshifts in to 3rd applying more power as I leave the box. Works great.

More excellent info!

Yes Transman, I didn't think of that, but wheel hop could certainly be a bad case with a non-LBA valve body.

Interesting Crizila, sounds like the Cheetah would be my type of valve body!

The more I learn, the more satisfied I am with still having the stock (although modified...) valve body!

As I tell everyone... DONT DO STUPID STUFF with
the 727 and it wont blow... I still have a stock
drum in the race car.. if you ever have to get
out of the pedal SHIFT IT out of low... I've had
this trans in it for 15 years and I have NEVER
blown up a 727(driving mopars for 50 years)

So did it go into low and not apply the low/reverse band, or it just wouldn't go in? And they took the ORC out in 1st gear auto, but did that explode the drum? I'm a little confused.

No.. you couldnt pull the shifter into low position.. it had
th blocker that didnt allow it.. the cops had a issue of
forgetting to shift out of low.. they would just float the
valves and half the time blow up the engines.. so the trans
was in low BUT the shifter was in second so it would shift

and since the cops couldn't have the shifter in manual low...the low band wasn't applied, and full throttle in 1:st while wheel hopping over railroad tracks caused the overrunning clutch (sprag) to freewheel momentarily and they broke the sprag...

They COULD have.. I never watched them on the job..
but most times they blew up the engines(before the
blocker)
EDIT
If I recall correctly they started putting the
blocker on in 74'

Gotcha, but it didn't blow up the drum?

It takes like 6200 rpm... if you blow the sprag
the drum will spin 2.2 times the engine rpm.. from
MOST testing on the drum it will self destruct at
13,000 rpm +/- some

Sure, we all did it but time is supposed to make us wiser. My very first 727 for pay was from a bone stock '69 Dart GTS 383 that rolled the sprag and took the case with it on the street.

Why wouldn't a WOT downshift into first with the selector in D roll the sprag? Or can it? Sorry to hijack the thread but I can't help myself.

Update: So took car for a drive and it's a no low band MVB. So digesting all of this info, one last question:

Sounds like nothing short of a LRB valve body and billet drum will solve the problem. However, if I stick to 2nd gear burnouts, that will "reduce" my chances of catastrophic failure correct since if I do have a failure the drum will be at 6,500 instead of 15,000 RPM?

Not looking to change parts at this time, this is a street car. Just trying to find most appropriate way to keep it in one piece as I do drive my stuff hard. I am going to get a blanket just in case.

Once the trans shifts out of 1st gear the sprag just becomes a roller bearing...no load on it. Your car has the capability to do 2nd burnouts dry?

Thanks John for the info.

Yes it should do a dry burnout in 2nd. Rear is 4.56 and the street tires are 31". I have a line lock and it absolutely kills the tires on a roll in 2nd. Car went 11.42 @ 125 on the radials through the exhaust, so it seems to be making some decent power for a street car.

I recently acquired the car, so have not had a lot of time trying different things. To date, was launching in 1st, pedaling car in 1st and shifting to 2nd, pedaling again to get it to hook. Will try it this weekend with a 2nd gear dry start and let you know what I find out.

Ugh. I remember those days. Had a fleet of Diplomats set up that way - with 360's in them. Actually some of the best squads we ever had from a non-destructible drive train stand point. Suspension / steering was another story.

With all these cars making the power that everyone says they make - DON'T DO A FIRST GEAR BURNOUT. Start in 2nd (shift to third if you are making lots of power) and when you feel the tires start to grab start to roll off the throttle to let the converter stator ORC start to catch up with things. Otherwise you will fail the converter ORC next.

Just because "stuff" happens, it may be wise to buy a high quality billet front drum to basically eliminate the chance of a drum explosion. For about $700 you can get a front drum that won't blow up and will probably last a lifetime. Your right foot and trans tunnel may thank you. Expensive, but it sure gives me peace of mind running an 11 sec street car with an automatic valve body and drag radials...

Or you could change out the valve body to one with LBA.
Cheaper and easier to do.

Put in a super sprag... they are suppose to be
bullet proof... if it doesnt blow/roll over the
sprag then you wont hurt the drum

Is there an automatic shifting valve body that has LBA in drive?

I agree that the ultimate sprag is money well spent. The billet drum is just insurance in case it ever lets go. I have both.

The sprag is only engaged in low/1st gear.. so
thats the only time you need to worry about it
EDIT
the stock VB has LBA.... on your question... no

Do you know how much they cost as I would like to put one in mine the next time I pull my trans ? Ron

They are like a $150.... I think

Thank you. Ron

I put a Coan super sprag and LBA valve body in my transmission expecting to drive on the street.

I understand do not pedal in first great and most people start out in second gear. I like to start out in first gear (never free wheel it) I Just shift into second gear and shift 3rd gear. No brakes or line lock. My burnouts are for distance I guess, alway increasing throttle. My car is mostly a street car, track maybe once a year. Trans is build for the street with a lot of goodies talked about above.
440 702 hp and 650 torque at the flywheel. 727 MVB 9 inch tight convertor. New motor has not been to the track yet. So is this way ok for the trans? If I do a brake stand burnout always 2 to 3. Great info guys.