Tighter Converter & Tow Box

[KSHall]

I've got a 05 4x4 with a 48re automatic. Ok I would like to add a Quad tow box or Flashpac or whatever mild box to add a little more umph. I also want to add a better / tighter converter so that the truck will not stall so much when driving or towing. Ok here we go, some say when you change converters you gotta change your VB, then some will say you gotta change your flex plate, then some say you gotta change your input shaft, then some will say you gotta change your output shaft... ... give me a break! Are these things that close to being a peice of junk straight from the factory or are the after market companys blowing smoke. I know that alit of you guys are making a BUNCH of power and "need" all of that stuff so your trannys will live but does the average smowe like me with that small of power need it too? I'm not racing or sled pulling just driving and towing like most folks do. Help!!!! :{

 

[Diesel Power]

no, the average person thats just out to tow and get aliitle more power really does not need any more than a converter--because it is the weakest link, but a valve body is a good idea, because they will work together to give you a more positive shift and holding power for no slipage and much better reliability. or you could just by a fully built transmission and just forget about it, thats what i have done and im very glad i did. good luck :-laf

 

[cerberusiam]

Yeah, its pretty easy to get caught up in all the hoopla about cool products and what you need to handle the power. A lot depends on how much piece of mind you want. If you have the dollars and you wwant a top quality piece that will allow you to forget restraint then go for it. If you want 50-60 HP and a better fluid coupling to hold it and you realize what the restrictions are a converter will do just fine. A VB will allow you to add some more HP and use a little less restraint. The 48RE is a pretty stout piece in stock form. A better fluid coupling and a little more line pressure and it will handle a lot of work and abuse. Spend what you can afford and enjoy it. Cheers.

 

[BHolm]

There is a reason "people" say you should do the Vb and TC together. As mentioned one works directly with the other. If you just do the TC you will drop the stall speed but you need the VB to apply extra pressure to the lock-up clutch in the TC. This gives you the extra holding you need for the increased power. I am also considering the Quad tow box, even that mild mod adds about 150 lb/ft of torque. That is a pretty substantial amount above stock. When towing with the box you will need the extra pressure a VB gives you to reliably pull a load with that extra power. You do not need shafts or a completely new trans though.

 

[KSHall]

You know it just seems that with a greater amount of clutch surface that it would require less pressure to achieve the same amount of holding power. My thought is that with less stall speed that would be were the big difference would be noticed. Am I thinking right or wrong about this? A standard transmission's clutch that is 10" in diamater would require a bunch more presure to match a clutch 12" in diamater that has less pressure, right?

 

[fox]

KSHall, the purpose is to protect all the other clutches on the trans. More than one link in this chain.

 

[ASchuerg]

I went through the same problem

I changed my turbo added power pac, exhaust to the tune of around $6K. The trans was the problem I wasa towing a 19,000 # 5th wheel w/a 24 valve auto shortbed 98 dodge.

Change converter to a high performance BD and valve body. My first trip out climbing a grade into Laughlin Nevada transmission hot light came on. Come to fing out that the transmission fluid capacity was not enough to handel the strain changed out the pan to add an additional 6 quarts of syn trans fluid heat problem disappeared I am gettting 13 mi per gal. Got rid of the 5th wheel a year later and a new trans problem occured would not lock up between 45 to 70 mph. Carried back to dealer $ 275. 00 later told me was cured drove out and came back in 15 min. Dealer told me was my add on power unit needed reflashed. I took it to a Cummings shop they had seen the problem and were stumped. carried to a different dealer who sells alot of trucks took it for a test drive gave me back the truck in an hour and half with a bill of $65. 00 and the problem was cured They reflashed the Transmission and engine. RUNS LIKE A CLOCK Getting average 21 mpg.

 

[zstroken]

You can call Dave Goerend for some transmission advise 563 778 2719. He has some solutions for right around $1000 I think( maybe $1200). Single disk, with Valve Body

 

[cerberusiam]

You know it just seems that with a greater amount of clutch surface that it would require less pressure to achieve the same amount of holding power. My thought is that with less stall speed that would be were the big difference would be noticed. Am I thinking right or wrong about this? A standard transmission's clutch that is 10" in diamater would require a bunch more presure to match a clutch 12" in diamater that has less pressure, right?

Your essentially right. More disc surface will hold more at the same pressures. The problem then transfers to the next weakest link, the clutch packs. Raise the pressure a bit there also and you have better holding power. The lower stall speed translates to lower pressures because of the revs. Tighter converter plus less pressure plus a heavy load will cause the clutch packs to take the load and possibly slip. You have to balance what you want to do with the upgrades.

 

[Matt400]

The lower stall speed translates to lower pressures because of the revs.

All to often that is the thing with mods, the domino effect. . change something here and it effects something we might forget about. Thanks for the reminder

 

[KSHall]

Your essentially right. More disc surface will hold more at the same pressures. The problem then transfers to the next weakest link, the clutch packs. Raise the pressure a bit there also and you have better holding power. The lower stall speed translates to lower pressures because of the revs. Tighter converter plus less pressure plus a heavy load will cause the clutch packs to take the load and possibly slip. You have to balance what you want to do with the upgrades.

Well, I guess that makes sense. Darn it ! I see what you mean about less RPM's = less pressure on the clutchs. Ok with less pressure how does the VB make more pressure for the clutchs ? Man I was hoping to make this simple. Darn it, DARN IT!!!!! :{

 

[bmoeller]

Ok with less pressure how does the VB make more pressure for the clutchs ?

http://www.dieseltrans.com/phpBB/viewtopic.php?t=51

 

[cerberusiam]

Well, I guess that makes sense. Darn it ! I see what you mean about less RPM's = less pressure on the clutchs. Ok with less pressure how does the VB make more pressure for the clutchs ? Man I was hoping to make this simple. Darn it, DARN IT!!!!! :{

Ahhh, and that is the $64 question, "How does it do that?". Which, as you can see from the posted link will not get answered directly because thats giving away business secrets. Beginning to see the pattern?



It's quite simple really, buy a built transmission from whom ever YOU deem to be the most knowledgable source YOU can find. Simple yes? Cheap? No. Absolutely needed? Weellll, now we get into the personal opinion and experience thing that is hard to quantify. Of course the next step is "my idea is better than yours" and ultimately ending with "I am right and everyone else is full of crap" type discussions where nothing gets answered.



What we do know for sure is:



1. The 48RE is a relatively tough piece of machinery



2. It has the potential to be a lot better.



3. In stock form its not bad, but, when you push the performance envelope you run the chance of having problems.



4. Upgrading one part will move the weak spot to the next one.



5. The next step is a personal choice. Period.





If it was "easy" this wouldn't be so much FUN, huh? :-laf :-laf Cheers.

 

[Matt400]

The OEM spec on the 48re line pressure is 54 to 60 lbs.

Adjusting it too high could damage seals but I would feel more comfortable with 62 lbs vs 54.



Anyone change the pressure themselves, and if so what to?

 

[PHeadings]

I've got a 05 4x4 with a 48re automatic. Ok I would like to add a Quad tow box or Flashpac or whatever mild box to add a little more umph. I also want to add a better / tighter converter so that the truck will not stall so much when driving or towing. Ok here we go, some say when you change converters you gotta change your VB, then some will say you gotta change your flex plate, then some say you gotta change your input shaft, then some will say you gotta change your output shaft... ... give me a break! Are these things that close to being a peice of junk straight from the factory or are the after market companys blowing smoke. I know that alit of you guys are making a BUNCH of power and "need" all of that stuff so your trannys will live but does the average smowe like me with that small of power need it too? I'm not racing or sled pulling just driving and towing like most folks do. Help!!!! :{

As it was said earlier It Is only as good as the next weekest link.



I would guess the chain carries something like this T-Converter, VB, Clutch Pack, Flexplate, Input shaft, Inter Shaft, Out Shaft, Drive line, Rear End.

 

[fox]

The OEM spec on the 48re line pressure is 54 to 60 lbs.

Adjusting it too high could damage seals but I would feel more comfortable with 62 lbs vs 54.



Anyone change the pressure themselves, and if so what to?

Matt, In my opinion, most of these trans can safely go to 70 psi. This will be about 3- 3 1/2 turns counterclockwise.

Do you understand that IF it has a weak seal, it can fail and then you MUST do a complete rebuild? On some models, the increased pressure will raise the shift points beyond the range on the Cummins governed speed.

Do it at your own risk.

 

[cerberusiam]

Matt, In my opinion, most of these trans can safely go to 70 psi. This will be about 3- 3 1/2 turns counterclockwise.

Do you understand that IF it has a weak seal, it can fail and then you MUST do a complete rebuild? On some models, the increased pressure will raise the shift points beyond the range on the Cummins governed speed.

Do it at your own risk.

Exactly!! And double ditto on the 05's and up. If you do not get the adjustments within a range that is acceptable to the ECU it will throw codes and go to limp mode. The TV pressure is now electronically controlled and if it sees a range of movement or voltage outside of its paramters it throws a fit. When the VB work is done the builder really needs to know what th eeffects of the changes are and counter them. It makes no difference if you have great pressures and the trans goes to limp mode every time you hammer the throttle. Gone are the days of throwing a shift kit at it and calling it good.

 

[Matt400]

Matt, In my opinion, most of these trans can safely go to 70 psi. This will be about 3- 3 1/2 turns counterclockwise.

I was thinking that too. . 8 to 10 lbs past OEM. The thing is if it was set at 54 from the factory and acceptable as within the spec then adjusting up another 10 lbs from there shouldn't hurt and only add to the longevity.

On some models, the increased pressure will raise the shift points beyond the range on the Cummins governed speed.

Its important to also adjust the throttle pressure which is going to effect shifting and that setting needs to be done "after" a change to line pressure is made according to the manual. I could see someone skipping that procedure or simply not aware of it.

 

[Tryingit]

If you do a search, it would appear many on this site and other sites have done a Convertor and VB. Many have added a whole lot of power and seem to be fine. Even Banks believes that a convertor alone will solve some of the problems. I'm in the same boat and just as confused. I guess it will depend on how you use and abuse your transmission. Since I have 30K on my truck I'm afraid to to basic stuff in case I already some internal wear and tear. Maybe I'll just wait to 85K when my extended warranty runs out then do it once right, for once (Make sense?) :-laf

 

[KSHall]

54-60 psi seems low to me. I've been told that a 47re with a aftermarket VB can have over 150 psi, is that right? If 70 psi is the "hot-rod" pressure for this transmission then it sounds like seal failure would not be a big factor, but this "limp home" mode thing would be a real pain. Where do you check the line pressure and how do you do it? How do you adjust it? How do you check the "throttle pressure" and adjust it? Boy a six speed would solve all of this delima!