727 peace of mind

[JackBEEQuick]

Hello B body fam, having owned the zombee for almost a year, installed new S60 rear end with P295/65-15 M/T rears fit nicely on 15x10 Cokers with 5.5"BS, front end rebuild, front disc swap and its now very nice to drive on the street with hopes to drag it in the near future. However, I recently stumbled upon a post of a 727 stock drum grenading and having some parts come through the floor and visit the driver. which led to more and more hear-say of this issue with similar results across the board, thanks A LOT internet lol. I understand what SHOULD be done, billet drum, bolt in sprag, low band applying valve body and proper 1st gear usage. However the shape of the 727 in my car is pretty much unknown, outside of it functioning well on the street and all otherwise seeming sound and shifting well, I do not know if its suitable for the track yet or even safe to launch on the street. It does have a reverse manual valve body but it doesnt apply low band (freewheels in 1st), so I will assume no other upgrades were made to it either. its a mild built 440 6 pack car, we'll call it around 475-500hp, stock stall somewhere around 2000, if the sprag is damaged, my concern is if my car and myself are at a high risk with that kind of power and low stall? as most of the info I find are of drag cars likely running much more HP and high Stalls are the ones grenading their 727s. I only will get about another month to a month and a half of driving this year so I do plan to pull the 727 over winter and take a look. Im just kind of looking for some peace of mind in the meantime if im safe to drive this on the street or if its a ticking bomb waiting to happen, thanks for reading my rant guys

 

[Dave6T4]

A lot of these grenade situations happen when some inexperienced driver does a crazy burnout in LOW range, and lets off midway through it. This takes out the sprag clutch, and then allows the front drum to spin at 2 1/2 times engine speed. ALWAYS do your burnouts in SECOND.

 

[Darter6]

Don't do 1st gear burnouts to save the sprag. As you have no idea of how or what has been done to the transmission.
Yes you can drive it on the street till you have the chance to pull it and see just what you have.
Just don't go nuts on it.You can drive it hard but respectfully. TorqueFlights are tough.
You didn't say what rear axle ratio you have. If 4.10's or so you may just want to use 2nd over 1st tooling around the streets

 

[R413]

Don't let off the gas pedal in first gear. Always be moderately accelerating and shift to second before letting off the gas pedal.

 

[JackBEEQuick]

appreciate the responses guys! running 3.54s. So for curiosity sake, lets assume I have a broken sprag, being as that I have already been in the 5K+ RPMs around 100mph, if there was a bad sprag, wouldnt the drum still be spinning 2 1/2 times engine speed like Dave said, or does that math only apply in 1st gear? you would think it should have already went boom or atleast gave me some symptoms maybe?? or you think they go boom from that initial impact from a launch.. hmm just thinking out loud

 

[RemCharger]

If your sprag was broke you wouldn't have 1st gear.

 

[RemCharger]

Make a poll about how many people have exploded a drum.

 

[dvw]

If the drum doesn't over speed it won't fail. It will over speed if the sprag fails. Will it explode if this hapens. Maybe, maybe not. If it's a stock valve body there is no low band apply in the drive range. The low band is only applied in the manual low selection. If a sprag fails on a stock valve body one of two things is going to happen. If it's in manual low the band is applied. If it's in D it will upshift to 2nd. Sprags can fail. Does it happen often on the street? No. Keys to having a good survival rate with a non low band apply full manaul valve body; Never back off in 1st gear and reapply the throttle. If you back off? Shift into 2nd before appling throttle. Driving thru parking lots, slow speed traffic? Just use 2nd gear. No 1st gear burnouts. Been building Torqueflites for over 40 years. Running manual valve bodies on the street for that long as well. Personally have never built a unit that has grenaded a drum. Have I seen them grenade? Yes, and not just in pictures. Taken more than a few apart with destroyed sprags that had no other issues. The norrmal bolt in sprags are useless. Even broken a few of the $200 Super sprags. The only fool proof way to prevent drum explosion is a good billet drum. I've raced plenty of cars with stock drums. If it's a dedicated racecar it's a pretty good idea to run a billet drum. Street car? Could it happen? Yes. But unlikely when driven properly.
Doug

 

[JackBEEQuick]

thanks Rem, I thought of that, I seen a poll on the A body forum, although many commented having done it or seen it, im sure its a decimal compared to number of 727s in action, unfortunately it was enough to concern me lol I think ill just pull it this winter and remove all doubt

 

[Dave6T4]

Like DVW, I have rebuilt quite a few 727's, but I am not a racer, so I bow to his experience. I have only seen about 3 with a wrecked sprag in about 35 years. No exploded drums, because owner could feel something bad was going on, and pulled the transmission for inspection/repair. The 727 is a pretty tough bird.

 

[Project66]

That's one of the reasons why I went to a manual trans (along with the desire to have overdrive and the fact that my 904 was hanging during 2-3 upshifts). I didn't really understand how sprag failures happen and how to avoid it, so this is some really useful information.

 

[JackBEEQuick]

If the drum doesn't over speed it won't fail. It will over speed if the sprag fails. Will it explode if this hapens. Maybe, maybe not. If it's a stock valve body there is no low band apply in the drive range. The low band is only applied in the manual low selection. If a sprag fails on a stock valve body one of two things is going to happen. If it's in manual low the band is applied. If it's in D it will upshift to 2nd. Sprags can fail. Does it happen often on the street? No. Keys to having a good survival rate with a non low band apply full manaul valve body; Never back off in 1st gear and reapply the throttle. If you back off? Shift into 2nd before appling throttle. Driving thru parking lots, slow speed traffic? Just use 2nd gear. No 1st gear burnouts. Been building Torqueflites for over 40 years. Running manual valve bodies on the street for that long as well. Personally have never built a unit that has grenaded a drum. Have I seen them grenade? Yes, and not just in pictures. Taken more than a few apart with destroyed sprags that had no other issues. The norrmal bolt in sprags are useless. Even broken a few of the $200 Super sprags. The only fool proof way to prevent drum explosion is a good billet drum. I've raced plenty of cars with stock drums. If it's a dedicated racecar it's a pretty good idea to run a billet drum. Street car? Could it happen? Yes. But unlikely when driven properly.
Doug

thanks for that DVW appreciate it

 

[oldkimmer]

A lot of these grenade situations happen when some inexperienced driver does a crazy burnout in LOW range, and lets off midway through it. This takes out the sprag clutch, and then allows the front drum to spin at 2 1/2 times engine speed. ALWAYS do your burnouts in SECOND.

Wrong

 

[oldkimmer]

Oh boy, This thread will be filled with totally wrong advice

 

[HEMIB]

Check the PK number on the pan mounting area if it is the original 440 6 pak it will have heavy duty planetaries if using a steel front drum you can also fit the extra clutches & steels

 

[RemCharger]

A lot of these grenade situations happen when some inexperienced driver does a crazy burnout in LOW range, and lets off midway through it. This takes out the sprag clutch, and then allows the front drum to spin at 2 1/2 times engine speed. ALWAYS do your burnouts in SECOND.

Wrong

Exactly. It's doing a burnout in  D and letting off while the trans is in 1st gear. Starting off in second wont help, it will still be in 1st. Low band applies in low range , on a stock style automatic

 

[dvw]

Exactly. It's doing a burnout in  D and letting off while the trans is in 1st gear. Starting off in second wont help, it will still be in 1st. Low band applies in low range , on a stock style automatic

First off the original poster has a reverse manual valve body. So yes starting in 2nd is the answer. Second if you back off doing a burnout with an auto valve body at enough rpm that the drum could come apart? The trans will shift into 2nd in the D posistion. Never seen or heard of a drum coming apart with an auto valve body in the D range.
Doug

 

[not so famous bob]

Make a poll about how many people have exploded a drum.

been there , done that ....

 

[JackBEEQuick]

correct dv, its RMVB. D is 1st on mine, 2 is 2nd, 1 is 3rd... I need to find or make a custom indicator. Im in tune with it, but confusing for the uninitiated.
I would agree with the 2nd gear burnout in my case, when I let off in 2nd and 3rd, the engine brakes, for lack of a better term. it does not do that in 1st.

 

[dvw]

There used to be someone who made the reverse pattern insert. This is where it gets tricky. Do a push button.
Doug