Question on TF727 (overrun clutch, burnouts, explosions, etc.)

[98 SNAKE EATER]

I have a 69 RR with a 440 and TF727 w/reverse manual valve body

I know there's a danger of grenading if I were to do a burnout in 1st, but can someone explain exactly why? (like I'm a 5 year old please)

Also, would the same danger persist if I were to do a dry hop or launch in 1st and immediately get off the gas due to spinning on a launch?

 

[SwedCharger67]

Here is an article that I think is nearly useless, but it shows some photos.

http://www.moparmusclemagazine.com/...ransmission_drivetrain_breakage/photo_10.html

I'm far from any expert in this field, but the way I understand it :

The standard 727 has 2 different styles low gears, the low in "D" position puts all load on the sprag (see the pic in the article). When the shifter is in manual low "L" both the sprag and one of the bands (reverse band?) are taking the load. Thus the manual low "L" can take much more power than low gear in "D" position.

One bad case is wide open throttle in low "D" and you get for example ignition problems causing the sprag to start free wheeling, and suddenly the engine works normally again with full power...and the sprag goes back to locked position taking the huge sudden load...

I'm sure we'll get more accurate and more correct info from people who know what's really going on...:icon_cool:

Don't know how your shift kit is working, it might fix the potential problem.

Cheers,

 

[Budnicks]

great book to get & read, if you plan on running a 727 TF for racing or a hot street/strip car, "Torqueflite A-727 Transmission Handbook" by Carl Munroe HPBooks-1399... if you get a proper style valve body, with rear band apply, they are fractionally slower in all out racing maybe .005 sec. max, "I highly doubt you could even tell, the differences" & it will help to prevent some of the issues of sprag/overrunning clutch possibly exploding, while either downshifting or starting burn-outs in 1st gear, you could also have the trans case modified, to have a bolt-in or @ a minimum, pinned to the case for the sprag/overrunning clutch {old style fix}, with out the rear band application the sprag/ORC revs to about 12-15k or more depending on what gears you have, with the engine @ 5k RPM's, triple minimum, in low gear, they weren't "ever" intended for that kind of RPM's.... I run a Cheetah Pro-Street forward shift pattern manual Valve-body, in quite a few of my cars now, never had any problem yet...

I'm no trans expert, by any means, have been thru many of them too... but from what I've learned & told by the experts is, "it's the sudden bite or hard hook" {or downshifting with out a rear band apply VB}, that causes the explosions, usually, more than the rpm's, it's an inertia thing, mass spinning fast & suddenly stopping/slowing drastically...

 

[Meep-Meep]

As I understand it you can do serious damage to the overrunning clutch if you do a first gear burn out and have the tires suddenly catch traction (like coming out of the water box). And even at that I have read that the trans MAY explode; not necessarily will. I have done low gear burnouts on dry pavement and let off the gas with no problems but I always come out of the water box in second.