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Dual feeding directs.... or modified direct drum with extra clutches?

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Blazer406

Mechanical Engineer
Joined
May 2, 2002
Messages
5,068
I read alot on here... and there are many different ways to accomplish goals.... each having it's own merrits....

On the subject of dual feeding the direct clutches/drum....

Dual feeding has been done by many on here with alot of success. The steps you need to do to dual feed are documented.....

I have also read a thread where CK has modified a direct drum to accomidate 8-9 frictions and full thickness steels in the direct drum....

hmmmm

I understand if you dual feed.... it is highly recommended you have a billet forward drum (IIRC)

Does the modified drum (with 8-9 frictions and full thickness steels) mentioned above work "as-well-as" dual feeding? Or.... almost as good?

What are the pro's and con's of either?

Has anyone here done both that can weigh in on there merrits?

I am hoping someone can give me a quantitative answer... that dual feeding provides xx percent better holding power than stock..... and 9 frictions provides xx percent better holding power over stock....

I am looking for how close the two modifications are in their ability to hold the clutches w/o slipping...... are they even on the same order of magnitude?
 
Upon further investigation, Alto has a "PowerPack" that includes .061" frictions (8), .060" steels(7), .078" steel (1) and a .170" Backing plate.

Stackup is .078 steel then alternating .061 frictions/.060 steels until all 8 clutches are in... then the .170" BP.

If I did my math correctly.... stackup should be 1.156" + the .040" clearance everyone seems to run....

Does this fall inline with what Chris was talking about?
 
good ?

And I don't have an answer but, I would like to try one of my welded forward drums in a DF application but it would need to be a 10.50 or slower car.Why don't you try one and let us know?
I don't know about 8-9 clutch packs--looks like 6-7 if done right would work for 99 percent of the people. Keep in mind I have limited experience.
 
considering that dual feeding is basically a free mod (if you need dual feeding you should already plan on a billet forward drum) Maybe I'm wrong here but i think dual feeding with the 8-9 clutches in the modified drum would work great. It doesn't have to be one or the other. Ive run 6 clutches and stock thicker steels and run 7 clutches with some thinner steels thrown in (played with backing plates as well) and both work well for me in 500 rwhp car (124mph)
 
I think dual feeding with 9 clutches is a little overkill for most of us. Of course like anything else it depends on your power level. I ran dual feed with 8 clutches for a while and it was too abusive at wide open throttle shifts. Backed it off to 6 clutches and it had much better manners. I'm also curious on how 9 clutches would work with the thick steels without dual feed. :rolleyes:
 
9 clutches should be 9/6 or 1.5 ...... so 50% more holding power
8 clutches should be 8/6 or 1.333.... so 33% more holding power
7 clutches should be 7/6 or 1.167 ... so 16.7% more holding power

Assuming the hydraulic pressure on the piston is the same... and the piston area is the same.

If I understand "dual" feeding.... the whole area of the piston is used to apply the clutches.... which is a much greater area than when you subtract the hole..... I don't know these dimensions... so I can't calculate that theoretical difference in holding power....

Someone throw me a life preserver and chime in if I fell overboard...
 
I did the math a few years ago. Dual feeding slightly more than doubles the clamping force. I don't remember the numbers exactly but I think the inner piston area was in the 5-6 sq. in. range and the outer piston area is in the 7 sq. in range. So going from a standard feed setup to dual feed you are going from 5-6 sq. in. to 12 sq. in of surface area. That equates to a very large difference in clamping pressure.
 
And I don't have an answer but, I would like to try one of my welded forward drums in a DF application but it would need to be a 10.50 or slower car.Why don't you try one and let us know?
I don't know about 8-9 clutch packs--looks like 6-7 if done right would work for 99 percent of the people. Keep in mind I have limited experience.

Lee,
We did a couple running welded drums that we dual fed YEARS ago just to test the strength. Both units were run in my low 11 GN at the time, and we did not break anything. 1 lock up, 1 non lu. 7 clutches in the directs, and one of our old custom servos.
It shifted like a sledgehammer smashing you on the back and did not break.(no accumulators) But, those were late model (somewhat better metal IMO), low mile, unabused pieces to start with before the welding.
Fatigue and age seem to be a strong contributor of the issue with breakage. Butthe metal was definatly junk that GM originally used.

Brian
 
I disagree that adding steels will increase the the amount of friction during a ratio change in most instances if the steels are swapped out for thinner ones. It may have more holding power but we need to be able to apply the clutch effectively under high toque. Holding it is not the problem. Adding clutches is great if you have a modified drum and and backing plate and the steel thickness is not compromised. If the thinner steels are used they will quickly hot spot in a 10 second application. Chris has a nice product available soon that accomplishes this. IMO there is no replacement for dual feeding. You are increasing the hydraulic apply area substantially with a dual feed. Which is what the trans needs. Fwiw i have 3 welded and cryoed frorward shafts that i dont have to the balls to put in anyones transmission. I dont think its worth with the availability and cheap price of the new shafts today.
 
Lee,
We did a couple running welded drums that we dual fed YEARS ago just to test the strength. Both units were run in my low 11 GN at the time, and we did not break anything. 1 lock up, 1 non lu. 7 clutches in the directs, and one of our old custom servos.
It shifted like a sledgehammer smashing you on the back and did not break.(no accumulators) But, those were late model (somewhat better metal IMO), low mile, unabused pieces to start with before the welding.
Fatigue and age seem to be a strong contributor of the issue with breakage. Butthe metal was definatly junk that GM originally used.

Brian


What welding process did you choose? What "else" was done besides the actual weld bead around the base of the shaft?

bison said:
......Fwiw i have 3 welded and cryoed frorward shafts that i dont have to the balls to put in anyones transmission.

I am going to tackle this build-up myself....so when it breaks I can fix it.... and I am going to try one of Lee's welded forward drums...My combo should be good for mid to upper 10's..... and I am dual feeding as well..... with a 5-disk Vigilante lockup converter...going to lock it at the strip..... Sound daring?
 
What welding process did you choose? What "else" was done besides the actual weld bead around the base of the shaft?


There was nothing else done to these drums. No heat treating, or annealing.
The one thing we did was to make every attempt to match the metal of the drum, with the TIG welding rod being used.
This made a big differnce.

Some of the old nickle welded and cryoed drums failed under or over the actual weld area.
We also found this to be true when we used to use "hard" TIG material. It would fail before or after the weld.
The material matching made the biggest differnce in the part surviving.
 
I would like to respectfully disagree with the thinner steels hot spotting quickly in a 10 second application. This is just simply not the case.
My partner and I have been using this method since the EARLY 90`s in literally 100`s of units. The above has NEVER been true in a properly prepared unit.

Now... We have seen the issue you point out with extra clutches from other builders (always improperly set up). It is usually in a trans that is set up with loose tolerances that have no business in daily driver, let alone in a high performance application.
Also, "boxed" shift kits are not the answer.
By this I do not mean the CK (very nice kit for the $$$ spent) or PTS kits. Trans-Go, B&M, and TCI are what I am speaking of.

I firmly believe the biggest need for dual feeding is guys that use lower pressures.(250ish) The .500 booster is a great upgrade from stock to maybe mid-high 11`s (non dual fed, maybe a little faster with D.F.). But after that, larger boosters, wether .521 (minimum), .550, or .570 are very important to keep up with the torque curve of these Buicks. ***The line pressure needs to rise much faster at lower throttle angles to keep up. V8`s are typically not as critical as they have a more linear torque curve, not a spike like the turbo V6. With higher line pressures, and quicker rise, dual feeding is not needed.

Bruce (not to drag him into this) and I talked about dual feeding long ago. We both feel this to be unnecessary modification. Proper hydraulic control (mainly line pressure rise) offsets the need for this.
We have never sold a unit that has been dual fed.
Also, you do not need a shift that breaks your neck to have a trans live a long service life. Nothing sucks worse than getting in a car with a built trans and having a sore neck for a week after your ride.

One of our earliest local customers has Stage 1 4.1, a BQ v-b, with an old Art Carr drum and input shaft (READ, NO BILLET) and 9in n/l conv, 8 clutch directs (not the thin Alto kit), 694 servo, and a 500 booster as we weren`t doing the 550 yet. That trans unfreshened (of course, not dual fed), ran 10.2x`s- 9.8x`s for 6 years driven to and from the track over an hour each way. This trans was built 10 years ago, and is now in another low 11sec car. But this trans runs higher pressures than the 250ish many look for.
Another customer, John Plog, has over 600 mid to low 10 second transbrake passes in 2 years. Built similar as above, again.... NO DUAL FEED.

Bottom line. Dual feed is not needed if you have a higher line pressure and faster pressure rise, along with proper hydraulic control (shift cal).
But, with low pressures, and .500 boosters... you better D.F. :smile:

The above is not opinion, but fact. From real world experience.
I know some other builders will say, I have tested this or that. And X, Y, Z is the answer and the best. Whatever! Our builds have been nearly the same for 15+ years, and we see no benefit to changing.

CK`s new 8-9 pack drum sounds like the answer most have long been waiting for. Hopefully after this hits the market, this whole dual feed topic will die a painful death!!!!:eek: :wink:

Take care, and death to dual feeding!:D

Brian
 
I've heard from 2 different people (one via a phone conversation) that the directs wear out from slow application.... and that in their opinion it wasn't "holding power" that was toasting the clutches.

What is your opinion on that Brian? .... Chris? ....... Bruce? ..... Lonnie......Russ?

All you guys I consider guru's of the 2004R..... maybe this can shed some more light on dual feeding....

This thread is getting more educational with every post.... keep it coming guys....
 
I've heard from 2 different people (one via a phone conversation) that the directs wear out from slow application.... and that in their opinion it wasn't "holding power" that was toasting the clutches.

What is your opinion on that Brian? .... Chris? ....... Bruce? ..... Lonnie......Russ?

All you guys I consider guru's of the 2004R..... maybe this can shed some more light on dual feeding....

This thread is getting more educational with every post.... keep it coming guys....

Definatly true.

Slow application, low line rise/pressure, or slipping will kill the clutches in short order.
You need to get the clutches on right now. This is where your shift calibration (kit) comes in.
Not as much to do with holding power, but application.

You know when you mod your stock motor. The more power you make after mods or turning up the boost, you eventually start to get a flair on the 2-3 shift. You need to improve shift timing and internal pressures.
It will hold after the shift... It is just getting it there.
 
Playing devil's advocate..... the people touting direct feeding say that after they direct fed their tranny they quit toasting direct clutches..... so what was the solution?

Was it the increased pressure applied that made the clutches "hold" better.... or was it the direct feed mod "applied" the clutches faster..... or is it a combination of both?

I will agree there is probably more than one way to skin a cat.....

I see two basic schools of thought.

Seems that if you direct feed.... line pressure or line pressure rise isn't as critical to clutch life.... at least for the directs....​

Seems if you have your line pressure high enough.... and the rate of pressure rise right....the direct clutches live just fine​

Now the question would be what boost valve pressure regulator spring combination will yield the best results if you don't dual feed? Is there any other key players in this situation?
 
As one begins to understand hydraulics the mind, thru understanding generates a picture or table of what the hydraulic demands and the effects of a given line pressure,apply area ,friction pack(its type, dimensions,held and driven load,etc),have on performance and the mechanical and structual limitations of internal components.It is evident to me that a minimum line of 90 psi and a maximum of 250 to 280 psi ,that rises and falls in a manner synchronized to throttle angle(which mechanically thru the tv cable and hydraulically thru the tv system creates an engine load signal)with the proper size servo apply area and dual feed direct utilizing the inner and outer area of the direct clutch apply piston area ,will produce better shift quality throughout the engines operating range than any other methods.High line pressures such as those generated by boost valves over .530" introduce internal components failures to the 2004r transmission .First is the amount of pressure required to open the pr valve transitions from cruise to WOT operation.This extra stress is a one of the direct causes of pump rotor and slide breakage.Second ,this causes most band anchor pin failures.Third,this extra pressure causes excessive amounts of oil to bleed out between sealing areas such as the valve body and seal ring to bore surfaces.The larger apply areas ,such as from dual feed direct and the oversize servo
aways beat out the power robbing pumping losses,loss of low speed shift quality,clunk 3/2 backshifts ,and parts breakage of operating psi ramped beyond the hydraulic systems original design parameters.Our new seperator plate is producing excellent results even with small feed holes and dual fed direct clutch pack assemblies.We will be including stock 1/2 accumulator spring as well for even more control over the shift quality in the near future.The drum will be released soon .As for the inquiry into "dual feeding verses extra clutches " the dual feed still is needed and Ill get into that a little later.
 
I always forget this one important thing...
The biggest benefit is probably that it is a free mod. Most things that are free are hard to pass up or not try. The nice thing is that you are going to venture on your own, as you have pointed out, and build you own unit. That is a big achievement to build your own trans. You will get an intimate view on what it takes to make it happen. Also, if you do not like whichever path you follow. You can always go another direction.

I will agree that the internals are slightly more stressed by raising the pressures. But not enough to stop building this way. We get a little over the 280 mark.(but not much) Now that both of the "big guns" in the game are making billet anchor pins, we do not have to worry about that failure any longer. That was an issue until we made our own as well. I think the pin rocking in the bore as well as fatigue caused many failures in the pins. The pump rotor breakage I have always believed to be and have seen, is to be related to the converter engagement or lack there of.

Some have felt that if you went this direction with D.F. you needed to look at other areas. There are always different ways to end up at the same result. Somethings work better for others. Niether is wrong, just what works for an each person. Eventually we MAY give it a try in a sub 9.5 car. Just waiting for someone to step up with a test car.;) :smile:

Chris has made by far the biggest time investment to bring this mod along and bring it to the masses. And has shown the willingness to support this with his technical ability, as well as product devolopement. Anyone who spends as much time as he has to develope new ideas deserves respect and consideration.

Brian... OUT:cool:
I wont be back:rolleyes:
 
I've heard from 2 different people (one via a phone conversation) that the directs wear out from slow application.... and that in their opinion it wasn't "holding power" that was toasting the clutches.

What is your opinion on that Brian? .... Chris? ....... Bruce? ..... Lonnie......Russ?

All you guys I consider guru's of the 2004R..... maybe this can shed some more light on dual feeding....

This thread is getting more educational with every post.... keep it coming guys....

On a mid/low 11 car, not really an issue to make a 2004R work pretty easily.

My take on the 2/3 shift on a fast car? The job def needs to get done quickly! I do it with the dual feed method.

Well, if we're at the track racing, the 2/3 happens a little after the 330'. Long after we've been at full TV, the pressures are at where your pump has been set up to. If you have fluid control in the pan and it isn't suckin air, all should be well and your shift kit is in control. 250-280 line will get the job done (right from the Brucehorses mouth) and a .500 valve is all that's needed. I use the Sonnax O-ring valves without any issue. I don't see any need for bigger unless perhaps you have some bore leakage which when wet testing the pump on the bench can be pretty interesting :). I'm a dual feed guy, and extra clutches and thin steels (Art Carr type set up) are not the answer in my opinion. I have my own stack up of 6 clutches and steels that has worked flawless and is pretty unique. I've watched Bruce build/test em, the man runs 330+ line @ full TV and doesn't dual feed. I personally haven't seen too many 2004Rs with pressures that high, from anyone. You def don't need it like that to get the job done.... We all have our own idea of the "perfect" trans, I know I have mine.....

Transmissions are like little people, they all have a personality. One thing needed to be cleared up (incase some took it wrong) is dual feeding doesn't make the part throttle shift/drivability any more violent than non dual feeding. WOT, dual feed is awesome and I'm stayin......;)

A Sonnax rep called over the summer askin me a couple questions about their products I use. In the middle of the conversation he asked if I wanted to know how to increase the direct clutch apply/hold power by 5 times over stock. I listened to him and basically he wanted me to reinvent the wheel with modding the center support, reversing the piston apply for direct and reverse......I'm like why don't I leave off two seals, and block a hole and get 8 times the power? He didn't have an answer...... I'm like, your servo and boost valves work pretty good dude.......Thanks man ;)
 
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