Anyone running a 904 behind a 340?

['68cuda416]

727 Bla Bla Bla , race car only has to do it's thing Bla Bla Bla , Fact #1 nobody has ever had a leg torn off or been killed by an exploding 904 , you will however find thousands of pics from blown up 727's , Fact#2 Most of the top pro racers in the day used to put the guts from a 904 into a 727 case to fool tech inspection and these were 1000hp+ cars , Fact#3 My home rebuilt / upgraded 904 which was the first automatic transmission I ever even looked inside of has been across Canada 6 times and has more than 40k kilometers behind my 410 including a few 10k+ RPM episodes without ever missing a beat or needing a top off .

I would like to see video proof of that 10k plus action.......while your at it you may as well include the I was going 185 mph speedo shot too

 

[Bakerlite]

There is also a larger diameter sprag in the late 80,s 999 that does not use that snap ring on the drum.
If you order the 30 element roller clutch from ati, they will ask you what diameter.

Now why would you need an upgraded sprag if you use a valve body with rear band apply?

 

[Duane]

Now why would you need an upgraded sprag if you use a valve body with rear band apply?

As was explained to me by Paul Forte of turbo action, if the band is on during transbrake, after the launch, and depending on the valve body design, if the slicks were to hook, slip, and rehook while still in first gear, you would be on the sprag without the band on to help. I purchased a brake that leaves the band on till second gear is pulled. This comes with the complication of band overlap.

 

[Bakerlite]

As was explained to me by Paul Forte of turbo action, if the band is on during transbrake, after the launch, and depending on the valve body design, if the slicks were to hook, slip, and rehook while still in first gear, you would be on the sprag without the band on to help. I purchased a brake that leaves the band on till second gear is pulled. This comes with the complication of band overlap.

That's a bit of a messy mixed up answer..
I think you will find, that's what happens when you use a valve body without rear band apply.
The sprag is not designed to take shock loading, no matter how many rollers you shove in there.
I have seen plenty of race built TF's with stock sprags in them and rear band apply valve bodies.

 

[Duster346]

John Cope built my 904. It has been in my 71 Swinger for over 10 years. 408 stroker making north of 500 hp has not shucked it yet.

Awesome! I have several 904s out there with 500hp+ that work very well.

Keeping on theme with the original intent of this thread, yes, I would absolutely encourage folks to use a 904 behind a small block. They are lighter and quicker as we all know.

With that said here's a car we put together several years back that was originally a slant 6, 3 speed manual, 8 1/4 car. We installed a 340/904/8.75" and it worked very well.

 

[Duane]

That's a bit of a messy mixed up answer..
I think you will find, that's what happens when you use a valve body without rear band apply.
The sprag is not designed to take shock loading, no matter how many rollers you shove in there.
I have seen plenty of race built TF's with stock sprags in them and rear band apply valve bodies.

Not correct. What I am saying is that all low band apply brakes are not created equal.
John Cope makes all his valve bodies, brake and manual shift, with the band on until you pull second gear. To get a clean 1-2 shift with no band overlap requires a billet low reverse servo with increased spring pressure to get the band off quickly before the second gear band comes on. Most standard low band apply brakes release the low band as soon as you let go of the switch. Perfectly fine if your car always sticks. If it doesn’t, there is still a risk off sprag failure, hence the justification for a stronger sprag.

 

[Bakerlite]

Maybe before you tell me I'm incorrect,you should study this.

Most standard low band apply brakes release the low band as soon as you let go of the switch.

No they don't.. I think your still a little mixed up with what actually does what.
If you released the low band as soon as you let go of the switch, then you would also have no 1st (low) gear.. It would be in 1st (Drive) with the sprag carrying all the load.
The transbrake uses 1st (low) and Reverse at the same time to lock the trans.
Can you tell what gets released to unlock the trans? (Hint, it's not the Low-Reverse band.)
You don't jam a super sprag in there to try and fix the issue, you lock the Low -Reverse drum,which is a better, stronger way of doing it.
The whole idea of applying the Low band is to prevent 1st gear shock loading to the sprag..and engine breaking.
If your going to load and unload the trans off the start line in 1st gear, then your going to want that Low band applied.
That's why Chrysler designed it that way..

 

[volaredon]

Built to the max a 904 will handle 1000 hp

Yeah but how many go to that extent with a Nasty 904? I've blown up more 904s and replaced them with 727s than you can shake a stick at.
This is normal driving, never had a race or street/strip car. I was happy (and quite surprised) to discover that my newest (to me) D150 came with a/6 and a 727!!! My 1st couple of vehicles were a 76charger SE and a 75 Cordoba back in the 80s both 360/904 2 barrel carbs and both wound up with 727s in them. And those were just the start.

I do have an A500 here (yeah I know 904 based) that I may tempt fate with and "build up" if I can find a adapter to put a SB trans behind the/6.

 

[Bakerlite]

Sounds like you just abuse your transmissions, I can blow up a 727 any day of the week if I abuse it.
What you've just said is pointless.

 

[volaredon]

No, I don't abuse them and yeah I could blow up a 727 but unlike a 904 that actually takes a bit of effort of which I don't exert.... I don't like pulling tranny's and paying for their parts.

 

[Duane]

Maybe before you tell me I'm incorrect,you should study this.
View attachment 1715979462

No they don't.. I think your still a little mixed up with what actually does what.
If you released the low band as soon as you let go of the switch, then you would also have no 1st (low) gear.. It would be in 1st (Drive) with the sprag carrying all the load.
The transbrake uses 1st (low) and Reverse at the same time to lock the trans.
Can you tell what gets released to unlock the trans? (Hint, it's not the Low-Reverse band.)
You don't jam a super sprag in there to try and fix the issue, you lock the Low -Reverse drum,which is a better, stronger way of doing it.
The whole idea of applying the Low band is to prevent 1st gear shock loading to the sprag..and engine breaking.
If your going to load and unload the trans off the start line in 1st gear, then your going to want that Low band applied.
That's why Chrysler designed it that way..

I understand exactly how it works. The chart you posted is for a bone stock tranny. A transbrake is not bone stock. Ask yourself what is gained by a billet bodied transbrake.
This is not my explanation, it is the explanation of reputable builders. Turbo action uses a timed release. Others leave the band on right until second gear is pulled. The front drum unlocks the trans, but that has nothing to do with the 1-2 shift. What I am saying is that some brands leave the low band on longer than others. The longer it is kept on, it becomes difficult to get a clean 1-2 shift.
The second gear band could potentially be on at the same time as the low/ reverse band causing a bind up in the 1-2 shift. But this method fully protects the sprag. To get around this problem, the servo spring pressure, size of the fluid passages and minimal low band adjustment achieve a clean 1-2 shift with the band on right up until the 1-2 shift. Some brands of low band apply brakes still can damage the roller clutch in certain conditions. Why is it common practice in any 727 build to upgrade the roller clutch. The 904 is no different.

 

[Jadaharabi]

Why is it common practice in any 727 build to upgrade the roller clutch. The 904 is no different.

In the 727 the sprag is pressed into the aluminum case then held in by a set screw.
In the 904 the sprag is riveted in to the case.

 

[lemondana]

Both your 76 Charger and the 75 Cordoba had the 999 transmissions. You must be doing something wrong or maybe not had the kickdown adjusted correctly. The 999's are pretty tough. Just saying.

Yeah but how many go to that extent with a Nasty 904? I've blown up more 904s and replaced them with 727s than you can shake a stick at.
This is normal driving, never had a race or street/strip car. I was happy (and quite surprised) to discover that my newest (to me) D150 came with a/6 and a 727!!! My 1st couple of vehicles were a 76charger SE and a 75 Cordoba back in the 80s both 360/904 2 barrel carbs and both wound up with 727s in them. And those were just the start.

I do have an A500 here (yeah I know 904 based) that I may tempt fate with and "build up" if I can find a adapter to put a SB trans behind the/6.

 

[Bakerlite]

The front drum unlocks the trans,

Releasing the front CLUTCH unlocks the trans..not the drum..
I can see, this is going to be like pulling teeth.
Look at the chart, it shows what clutches and bands are engaged to select which gears, regardless of whether it's stock, racing, or even if a trans brake is being used. THAT CHART APPLIES TO ALL OF THEM..
I should know, I actually build them, but hey don't listen to me .
You just go ahead an keep repeating what you think you remember from a conversation you once had with a guy..no skin off my nose.

 

[Bakerlite]

In the 727 the sprag is pressed into the aluminum case then held in by a set screw.
In the 904 the sprag is riveted in to the case.

What really secures the 727 sprag in the trans is its serrated OD. All those little teeth biting into the alloy.
That set screw will not stop the sprag from spinning because it goes into a slot which is machined all the way around the OD of the sprag. All it's going to do is stop the sprag migrating forward in the case..

 

[Duane]

What really secures the 727 sprag in the trans is its serrated OD. All those little teeth biting into the alloy.
That set screw will not stop the sprag from spinning because it goes into a slot which is machined all the way around the OD of the sprag. All it's going to do is stop the sprag migrating forward in the case..

Totally agree. Bolt in is better, but the better sprags also increase the roller count as well.
My point was on any torqueflite it is a common practice to upgrade the roller clutch.
The 904, because it is riveted into the case,
Was a better design, but there is now an upgrade as well for the 904.

 

[Duane]

Releasing the front CLUTCH unlocks the trans..not the drum..
I can see, this is going to be like pulling teeth.
Look at the chart, it shows what clutches and bands are engaged to select which gears, regardless of whether it's stock, racing, or even if a trans brake is being used. THAT CHART APPLIES TO ALL OF THEM..
I should know, I actually build them, but hey don't listen to me .
You just go ahead an keep repeating what you think you remember from a conversation you once had with a guy..no skin off my nose.

If you want to sweat details to give the illusion that I don’t know what I talking about, that’s your choice. You thought I didn’t know how a transbrake releases.
I think you are not looking at your own posted chart. It clearly shows that the rear band is on in manual low. It clearly shows the low band is off in second gear and that the front band is on in second gear. In order to get a clean 1-2 shift the low reverse band on a transbrake must release fully before the front band comes on. All transbrakes, all of them apply the low band when the brake is on. You have to or you would break the sprag. How and when that band is released varies by manufacturer. Thats all I am saying. Because of this variation, it is still possible to hurt the roller clutch if the slicks lose traction and then regain it again after you have left the line if the car is still in first gear because the low band may have already released.
A better stronger roller clutch might prevent
A failure in that scenario. To prevent this, manufacturers try to leave the low band on as long as possible, but leaving it on too long can mess up the 1-2 shift with band overlap.
Drive any bone stock torqueflite in manual low (when the band is on) and quickly throw the shifter to 2nd gear and tell me what kind of shift quality you get. The shift is crap because the band doesn’t release fast enough.
I build all my own trannys too. Look at the photos in my signature. John cope is not some guy and neither is Paul Forte of turbo action.
These guys are premiere torqueflite valve body designers. I learned something too when they explained it to me.
Trans act used to have 2-3 different transbrake versions.
Since all brakes apply the band when the brake is on, what do you think the low band apply option is in his other models ? It refers to when it shuts off and the billet models deal with that better with enlarged and rerouted oil circuits.

 

[Duane]

That's a bit of a messy mixed up answer..
I think you will find, that's what happens when you use a valve body without rear band apply.
The sprag is not designed to take shock loading, no matter how many rollers you shove in there.
I have seen plenty of race built TF's with stock sprags in them and rear band apply valve bodies.

How do you get a clean 1-2 shift with a manual shift non transbrake valve body that has low band apply. Think about that.
John Cope sells that.

 

[Duane]

Releasing the front CLUTCH unlocks the trans..not the drum..
I can see, this is going to be like pulling teeth.
Look at the chart, it shows what clutches and bands are engaged to select which gears, regardless of whether it's stock, racing, or even if a trans brake is being used. THAT CHART APPLIES TO ALL OF THEM..
I should know, I actually build them, but hey don't listen to me .
You just go ahead an keep repeating what you think you remember from a conversation you once had with a guy..no skin off my nose.

A bone stock torqueflite is designed primarily to be driven in drive, not manual low.
An educated driver may select manual low perhaps if pulling a heavy trailer up a hill or descending a steep hill and needed engine braking and wanted to protect the roller clutch. But applying the band in normal drive gives a terrible 1-2 shift. That’s why Chrysler does not apply the band in normal drive.
The roller clutch is designed to be able to withstand normal everyday driving.
But the trans was not designed to withstand a neutral drop at 5000 rpm.

 

[Bakerlite]

Totally agree. Bolt in is better, but the better sprags also increase the roller count as well.
My point was on any torqueflite it is a common practice to upgrade the roller clutch.
The 904, because it is riveted into the case,
Was a better design, but there is now an upgrade as well for the 904.

I hate to tell you this, but it's not as common upgrade as you might think. Most of the bolt in sprags are just stock ones which have been drilled and tapped. They have same element count. They may not turn in the housing , but the gut's will fall out, which is usually what happens when they fail, just like a stock one.
The extra element count sprags are more robust, but will still fail if abused. They are not a problem solver solution.

 

[Bakerlite]

If you want to sweat details to give the illusion that I don’t know what I talking about, that’s your choice. You thought I didn’t know how a transbrake releases.
I think you are not looking at your own posted chart. It clearly shows that the rear band is on in manual low. It clearly shows the low band is off in second gear and that the front band is on in second gear. In order to get a clean 1-2 shift the low reverse band on a transbrake must release fully before the front band comes on. All transbrakes, all of them apply the low band when the brake is on. You have to or you would break the sprag. How and when that band is released varies by manufacturer. Thats all I am saying. Because of this variation, it is still possible to hurt the roller clutch if the slicks lose traction and then regain it again after you have left the line if the car is still in first gear because the low band may have already released.
A better stronger roller clutch might prevent
A failure in that scenario. To prevent this, manufacturers try to leave the low band on as long as possible, but leaving it on too long can mess up the 1-2 shift with band overlap.
Drive any bone stock torqueflite in manual low (when the band is on) and quickly throw the shifter to 2nd gear and tell me what kind of shift quality you get. The shift is crap because the band doesn’t release fast enough.
I build all my own trannys too. Look at the photos in my signature. John cope is not some guy and neither is Paul Forte of turbo action.
These guys are premiere torqueflite valve body designers. I learned something too when they explained it to me.
Trans act used to have 2-3 different transbrake versions.
Since all brakes apply the band when the brake is on, what do you think the low band apply option is in his other models ? It refers to when it shuts off and the billet models deal with that better with enlarged and rerouted oil circuits.

First of all, I know John Cope, I buy HP parts through John.
Second, your posts are jumbled and meander all over the place.
You seem to be confusing releasing the transbrake with the 1-2 shift, they are not related.
Transbrake on:
Rear band , Rear clutch, Front clutch on.
(Trans is now in 1st and Reverse gear at the same time)
Transbrake Off and launching in 1st gear:
Rear band, Rear clutch on.
(Front clutch was dumped via Transbrake switch to release Reverse gear and unlock the trans)
Second gear:
Front band, Rear clutch on.
(Rear band dumped, front band applied)

What full manual VB designers have been trying to do is cut down the overlap time between releasing the Rear band ( dumping 1st gear) and applying the front band ( applying second gear). That's obviously easier to do with a billet VB.
And they seem to have done a good job of it.
The only manual VB's I use, have rear band apply in 1st. Doesn't matter if it has a transbrake of not.
From what I can see, all of Johns VB's ( either just Manual or with a Transbrake) have the rear band apply until the trans shift into second gear.
To be honest, I'm not really sure what your trying to get at?

 

[Bakerlite]

A bone stock torqueflite is designed primarily to be driven in drive, not manual low.
An educated driver may select manual low perhaps if pulling a heavy trailer up a hill or descending a steep hill and needed engine braking and wanted to protect the roller clutch. But applying the band in normal drive gives a terrible 1-2 shift. That’s why Chrysler does not apply the band in normal drive.
The roller clutch is designed to be able to withstand normal everyday driving.
But the trans was not designed to withstand a neutral drop at 5000 rpm.

Yes, I know all that. Joe Average want a silky smooth, slippy, sloppy shift, thus not using the rear band in 1st (Drive).
Racers want a robust trans, thus applying the rear band in 1st.
What's your actual point?
You can get Full manual VB's that don't apply the rear band in 1st, but they are not the safest to use, and you can lose your toes..

 

[Duane]

First of all, I know John Cope, I buy HP parts through John.
Second, your posts are jumbled and meander all over the place.
You seem to be confusing releasing the transbrake with the 1-2 shift, they are not related.
Transbrake on:
Rear band , Rear clutch, Front clutch on.
(Trans is now in 1st and Reverse gear at the same time)
Transbrake Off and launching in 1st gear:
Rear band, Rear clutch on.
(Front clutch was dumped via Transbrake switch to release Reverse gear and unlock the trans)
Second gear:
Front band, Rear clutch on.
(Rear band dumped, front band applied)

What full manual VB designers have been trying to do is cut down the overlap time between releasing the Rear band ( dumping 1st gear) and applying the front band ( applying second gear). That's obviously easier to do with a billet VB.
And they seem to have done a good job of it.
The only manual VB's I use, have rear band apply in 1st. Doesn't matter if it has a transbrake of not.
From what I can see, all of Johns VB's ( either just Manual or with a Transbrake) have the rear band apply until the trans shift into second gear.
To be honest, I'm not really sure what your trying to get at?

Everything in this post is what I have said all along. I never brought the release of the brake into the conversation, you did. You assumed I did not know how the brake releases. The release of the brake releases the front clutch but in some trans brakes, it also releases the low band. All I have said is that some brakes do not release the band right away. The ones that do can potentially still hurt the sprag.

 

[Duane]

Yes, I know all that. Joe Average want a silky smooth, slippy, sloppy shift, thus not using the rear band in 1st (Drive).
Racers want a robust trans, thus applying the rear band in 1st.
What's your actual point?
You can get Full manual VB's that don't apply the rear band in 1st, but they are not the safest to use, and you can lose your toes..

My point, I have no point, you asked why buy a better sprag, and I have tried to explain the reason for it. Because in some situations, poorly prepped track, it is still possible to hurt the sprag. I understand how the release of the brake works by releasing the front clutch, even that varies by manufacturer. Some release much faster than others. The griner brake and it’s derivatives are very popular because of the speed of there release. I have met many racers of the 904 who switched to a power glide because they claim they could not keep the roller clutch from breaking. For some applications there is a need for a stronger roller clutch. That’s all I was trying to say.

 

[Bakerlite]

I think this is where the confusion started;

if the band is on during transbrake, after the launch, and depending on the valve body design, if the slicks were to hook, slip, and rehook while still in first gear, you would be on the sprag without the band on to help.

First your saying the band is on, then your saying it's not on, it's a little confusing.
That's why I made the comment about the non band apply VB's.