proper th400 burnout

[Hutch]

This rule goes for ALL 3 speeds.

Hutch

[IHI]

Originally Posted by Hutch

This rule goes for ALL 3 speeds.

Hutch

Exactly since your spreading the "coming out of the box" shock throughout the entire transmission. But the I like the added benefit of the increased wheel speed with lower engine revs

[freezy74]

Originally Posted by Hutch

This rule goes for ALL 3 speeds.

Hutch

So I should just start in 3rd. You would think that's a lot of load getting the tires going, but like you were saying, I guess the way the power is transfered its just better for it.

[grinertech]

This is from another thread, it is a torque flight and they are more prone to explode but it can happen to any 3 speed.

http://www.turbodieselregister.com/f...explosion.html

[WJ Birmingham]

Originally Posted by grinertech

This is from another thread, it is a torque flight and they are more prone to explode but it can happen to any 3 speed.

http://www.turbodieselregister.com/f...explosion.html

wow... ugly.

Since I'm not a member, did they post what caused it?

[Mod]

Originally Posted by grinertech

This is from another thread, it is a torque flight and they are more prone to explode but it can happen to any 3 speed.

http://www.turbodieselregister.com/f...explosion.html

Ouchie!

[procharged 79]

Holy crap, the dude is lucky it punched a hole in the passenger side door, would have really been ugly if it went the other way.

[Hutch]

Originally Posted by WJ Birmingham

wow... ugly.

Since I'm not a member, did they post what caused it?

That is the result of a damaged low roller clutch in a 3 speed trans. If the clutch gets damaged ( improper burnout, broken driveshaft , rear gear at launch, sudden unloading) the direct clutch drum can get into an overspeed until it bursts and that mess is the result or an exploded drum.

Hutch

[Long_Stroke]

Random, but what about a C4?? Is it kinda the same??

[Hutch]

Originally Posted by Hutch

This rule goes for ALL 3 speeds.

Hutch

Hutch

[Long_Stroke]

Hutch? Any info on a C4??

[WJ Birmingham]

Originally Posted by Hutch

That is the result of a damaged low roller clutch in a 3 speed trans. If the clutch gets damaged ( improper burnout, broken driveshaft , rear gear at launch, sudden unloading) the direct clutch drum can get into an overspeed until it bursts and that mess is the result or an exploded drum.

Hutch

So that's why you wanted me to check that low roller clutch after we shredded the carbon driveshaft. Aha.

[Hutch]

Originally Posted by Long_Stroke

Hutch? Any info on a C4??

As the post above yours says, this rule applies to ALL 3 speeds and that would include a C4.

Hutch

[Blownalky]

Originally Posted by coupe

Here's a detailed explanation from THIS THREAD on the same subject:

Question :


Answer :

The loading & unloading of the low roller clutch causes the rollers to slam against the springs & flatten them. If the low roller fails under load it will send the dirct drum to 3.25 + times engine speed, usally very bad when there is a cast drum involved.



Been there, done that!

Had a blower burst panel blow and the idle went to 4000 RPM. Stupid me got it off the track by going from neutral to first gear several times (reverse pattern with trans brake). Didn't know I had an issue, replaced the burst panel and went back to the line.

I always do a third gear burnout and did one here across the line as usual. Backed up using the trans brake, put it in low and staged the car. I use to not use the brake for a launch, I always foot-braked it. When the light turned green, I floored it; the R's went to the rev control and BOOM! This was in my stock floored 71 Chevelle. The trans had a blanket on it and the straps were tight. The explosion stretched the blanket, bent the steel floor up and knocked my foot off the accelerator pedal. I walked with a limp all day after that thinking if I didn't have the blanket, I'd have no foot or be dead.

After pulling the trans apart, the low roller clutch had beat itself up and rolled over. No doubt from me throwing it into first at 4k RPM. When I floored it, the direct drum went to like 20K or so RPM and the cast iron drum exploded.







I have since replaced the direct drum with a billet aluminum
piece from Coan. I've also replaced the low roller clutch with one from a 64-65 Turbo 400 that has a 36 element sprag clutch. Zero problems and peace of mind as to my safety. Still use a Kevlar CSR shield.

So, here is my question to Hutch and F.Rizzo. Since the Intermediate sprag in a 400 is changed from a roller clutch to either a 34 element or 36 element (Coan super sprag) assembly for strength so you don't blow 2nd gear, why would you not eliminate the low roller clutch and replace it with a 36 element sprag from a 64-65 400? I know these are hard to find but why not make a new reaction carrier that can use this sprag or modify the roller clutch unit to accept it? You can also us a sprag from a Ford E40D trans that has 45 elements (more surface area than the stock 64-65 sprag) for more strength and it fits right in. It just seems to me that if you can eliminate another weak link, why not do it? Am I off base on this? I’m trying to build a 400 trans that will go into the 6.20’s at 2600LBS. I know that this may not apply to a lot of folks but it seems that if you can eliminate a weak link, why not do it?

Thanks.

Tom

[grinertech]

I got to jump in here, Ive got one of my sprag less (intermediate sprag) valve body's, in a door car owned by Mark Micke. This car has gone 6.25.

You ask a good question, and I'm not against using the early sprag if you can find them. But that sprag can lose its tension too.

This stuff scares the hell out of me when you try to go that fast with parts designed for a passenger car.

Take 6 people and let them work on the same problem, and you will come up with 6 different solutions.

So here's mine. And I'm working on this at this moment. Clamp the rear band on in low gear, This has been done for years with the torque flights and its a tremendous sprag saver. But, theres a down side to this, the band has to be out of the way on the 2nd gear shift (timing), and you cant shift to 1st gear while rolling at any speed.