After testing and conferring the consensus is my truck needs a new torque convertor.  The truck is used 95% of the time towing a 8,000+ pound 5th wheel and the transmission is basically stock.    Which brand is good and which type, stock or billet?  Should it be a single or triple disk?  High or low stall speed?  Any thing else you can think of.

@IBMobile I had two billet singles (took some bad advice from a local shop, replaced it under warranty once), and slipped them both without trying @ 50 lbs of boost. I finally broke down and got a Goerend triple disk, 17SS. Also, for my first converters, I took some terrible advice that I should get a low stall. These trucks are absolute dogs with a low stall (especially when you have 35" tires and 3.54 gears). We need the RPM to spool the turbo, and in my case turbos. 

 

Since we have lockup converters, I think most negative effects of raising (or at least not lowering) stall speeds are moot. Efficiency of fluid coupling is more important. Once my truck boosts under WOT, I pretty much ride the rev limiter until lockup anyway.

 

To be honest, even the Goerend 17SS could stall a little higher for me. It's still a bit slow to build boost from a dead stop. I don't want this to turn into a debate about stall RPM, just outlining my personal experience. 

 

I would also make sure you have a well built valve body. And, you may not want to hear this, but depending on how many miles are on your trans, if it's worn enough for the converter to have issues, And you're pulling it anyway, it likely should have a full rebuild.

1 hour ago, kzimmer said:

@IBMobileAlso, for my first converters, I took some terrible advice that I should get a low stall.

You absolutely DO NOT want a high stall converter for a dedicated tow rig.  For a street truck looking for power that rarely tows...sure a higher stall might be a good idea.  But for a dedicated tow rig it would be "terrible advice". 

14 minutes ago, Bullet said:

You absolutely DO NOT want a high stall converter for a dedicated tow rig.  For a street truck looking for power that rarely tows...sure a higher stall might be a good idea.  But for a dedicated tow rig it would be "terrible advice". 

 

Well, I guess what you mean by "high stall". If your trans is capable of manual lockup in 2nd gear and 3rd gear, then I disagree. 200rpm or so over stock stall would perform just fine towing. You're going to spend most of your time in lockup, where stall means nothing.

 

I'm not saying you need to go higher, or that I recommend it. I'm just saying it would be fully functional. Stock stall is fine. I would strongly advise against a lower stall in a 24v Cummins. It turned mine into a complete dog.

8 minutes ago, kzimmer said:

 

Well, I guess what you mean by "high stall". If your trans is capable of manual lockup in 2nd gear and 3rd gear, then I disagree. 200rpm or so over stock stall would perform just fine towing. You're going to spend most of your time in lockup, where stall means nothing.

I agree...having a higher stall with lockup capability would be having the best of both worlds.  But the OP would need a modified valvebody, strong flexplate and a billet input shaft and possibly even billet intermediate and output shafts to do that...since he would be locking in 2nd and doing locked shifts while towing a load.  That's a pretty expensive route though. 

29 minutes ago, Bullet said:

I agree...having a higher stall with lockup capability would be having the best of both worlds.  But the OP would need a modified valvebody, strong flexplate and a billet input shaft and possibly even billet intermediate and output shafts to do that...since he would be locking in 2nd and doing locked shifts while towing a load.  That's a pretty expensive route though. 

You do not need billet flexplate or input shaft to use manual lockup if you are careful to not allow locked shifts. However, it's never a bad idea to get a billet flexplate and input with a triple disk regardless. To be honest, my triple disk doesn't feel like it locks up much harder than my single disk did. It just stays locked and doesn't slip! 

 

Edit: If I may backpedal a little bit, my factory flex plate broke with just a single disk converter 1000 lb ft of torque (usually tuned to run lower). Sometimes s**t just happens. The billet parts were definitely a good suggestion. I hate doing things twice, but that's how we learn. Now I have a BD Black flex plate and a TCS Products billet input to go with my Goerend converter.

Edited August 22, 20195 yr by kzimmer

5 minutes ago, kzimmer said:

You do not need billet flexplate or input shaft to use manual lockup if you are careful to not allow locked shifts. However, it's never a bad idea to get a billet flexplate and input with a triple disk regardless. To be honest, my triple disk doesn't feel like it locks up much harder than my single disk did. It just stays locked and doesn't slip! 

I love my triple too.  Mine definitely feels like it locks harder but I went from stock to triple.  I went with billet flex, input and intermediate just to be safe.  Kept the stock output but I won't have to pull the entire tranny to change it if it ever craps out on me.  Nothing puts the power down like a triple. 

1 hour ago, Bullet said:

Kept the stock output but I won't have to pull the entire tranny to change it if it ever craps out on me.

I did the same. It's nice to have a mechanical fuse, stock output shafts are pretty cheap. 

He wouldnt have to do locked shifts

I wonder if I could do input shaft myself.  My single isn't slipping but still I've had thoughts of upgrading to a triple. 

18 hours ago, Bullet said:

I love my triple too.  Mine definitely feels like it locks harder but I went from stock to triple.  I went with billet flex, input and intermediate just to be safe.  Kept the stock output but I won't have to pull the entire tranny to change it if it ever craps out on me.  Nothing puts the power down like a triple. 

For a normal built trans that is not abused is it better to have the billet intermediate?

2 hours ago, gipperkid said:

For a normal built trans that is not abused is it better to have the billet intermediate?

No it is not necessary in that scenario.   I would say that it becomes necessary when the transmission is getting abused behind a high hp engine.  And by abused I mean boosted 4x4 launches, locked shifts under full throttle, etc.  

350 horse with a triple can break input shaft under normal driving conditions. 

 

Ohh you said intermediate. ?

Edited August 24, 20195 yr by Evan

2 minutes ago, Evan said:

350 horse with a triple can break input shaft under normal driving conditions. 

I assumed by "normal built trans" that he doesn't have a triple disc. 

Lol yeah.

 

I kinda close my ears whenever I hear or see built 47re. Most people that seem to say it have no clue what's in it

11 hours ago, Evan said:

Lol yeah.

 

I kinda close my ears whenever I hear or see built 47re. Most people that seem to say it have no clue what's in it

I mean like a Dynamic or Firepunk built transmission. Just want to know if a billet intermediate should be added during a build.

6 hours ago, gipperkid said:

I mean like a Dynamic or Firepunk built transmission. Just want to know if a billet intermediate should be added during a build.

It depends on how much torque you are making and whether or not you are shocking the trans with all that torque...i.e. boosted launches, locked full throttle shifts with a triple disc.  Depends on your wallet as well...billet intermediate shafts are about $700.  Another factor would be whether you are willing to jerk the trans out and completely disassemble it again to fix it if it ever breaks the stocker.

 

It was the last reason that got me.  But I also feel better about locked throttle shifts and boosted launches now. 

I highly recommend and use ONLY triple disc converters in every Cummins application. You MIGHT be able to talk me into running a single behind, say, a BONE STOCK 12 valve, but only because of the line pressure I run. Beyond that, I will only run a triple.

 

The intermediate shaft would be the last of the 3 shafts I'd be worried about. The stock shaft will put up with pretty much anything most guys are going to throw at it in a 2nd Gen application.

 

Stall speed needs to be match to your turbo setup (and camshaft if you've got an aftermarket). Most stock (or near stock) singles like a little tighter converter; about 200 under stock. Anything over about 62 mm on the compressor size, or ANY compound setup should stick with a stock stall. I wouldn't really recommend anything higher than stock, unless you've got some kind of WAY radical setup. Even DDP's UCC transmission is running a stock stall DPC, behind a nearly 2200 hp setup. Same with Skyler Oestrich's (DDP employee and great customer) 1600 hp, 9 second Cummins truck...stock stall DPC.

 

The only locked shifts I, personally, will endorse are a 3-4 upshift and a 4-3 downshift. (A stock 47RE valve body will not allow a locked 4-3 downshift, FWIW.) Other than that, unless you're racing or something, there's no reason to put your gear train through that kind of abuse, especially a 47RE gear train.

I've had problems on and off with this transmission for the past year.  First it would either have a delayed or no 1-2, 2-3 shift which was fixed with a new governor solenoid and pressure transducer.  Now the torque convertor lock up won't work due to a bad convertor clutch.  If I replace just the torque convertor I still have a valve body that has insufficient stock line pressure along with it's other drawbacks and a transmission that has been overheated.

 

I call John @Dynamic transmissions and ordered a "Stage 2" transmission with a low stall speed Georend torque convertor.  I hope to have it in a week or two.  I've got another 1000 mile camping trip planed for October 2ed which will give it a good test drive..     

Keep us posted... talking with John couple years ago at his place, that's the route I was thinking about going also.  

 

1 hour ago, 015point9 said:

Keep us posted...

You can count on it.