Just bought my cummins donor vehicle

[outofcontrol]

I have studied all the pictures and re-read this whole thread 5+ times. it's awesome; thanks for sharing. I've even been looking around for a donor vehicle. check this one out: http://orangecounty.craigslist.org/rvs/579298112.html

I know it's a little late to ask, but did you consider an Allison tranny?

What I need to do now is get my 454 to fail so I have a good reason to replace it. It really makes more sense to sell the 454 as a working unit, but my wife would kill me if I started this project now. Maybe I can fake it, and make it look like the motor blew up...

-Kevin

[safari57]

Kevin

Pull a couple of vacuum hoses and it will run like crap

Been there and ain't admitting I done that

That swap from an LS5 to an LS7 was phenomenal

Barry

[gwbaker]

Originally Posted by outofcontrol

I have studied all the pictures and re-read this whole thread 5+ times. it's awesome; thanks for sharing. I've even been looking around for a donor vehicle. check this one out: http://orangecounty.craigslist.org/rvs/579298112.html

I know it's a little late to ask, but did you consider an Allison tranny?

What I need to do now is get my 454 to fail so I have a good reason to replace it. It really makes more sense to sell the 454 as a working unit, but my wife would kill me if I started this project now. Maybe I can fake it, and make it look like the motor blew up...

-Kevin

Yes, the allison is a great tranny. Reasons why I didnt go with it: 545 ally does not have lock up converter, also allys are big and heavy. they also do not have "park", they have that big brake on the output shaft that i would have to rig up. The 47rh has the perfect gear ratio, lock up etc..

[bkahler]

Originally Posted by gwbaker

The 47rh has the perfect gear ratio, lock up etc..

Ok, you've got my attention. What is a 47rh transmission? Who made it, what models did it come one, etc !

Thanks,

Brad

[outofcontrol]

I have some of the same questions. I'm trying to figure out a good place to learn about these trannys, but once you have gone out and tested this set-up, I might just trust all your research. it seems pretty spot on so far.

Are there 47RH trannys form dodge that don't have the lock-up? obviously the 91 doesn't. how do you know?

Is this where you bought the Tranny from? Phoenix
it looks like they include their own CNC HD Tq converter with the tranny, is that right?

Sorry I'm such a novice at this, but how do I find out what the final gear ratio is in my rig? (besides opening it up and counting teeth).

-Kevin

[gwbaker]

Originally Posted by bkahler

Ok, you've got my attention. What is a 47rh transmission? Who made it, what models did it come one, etc !

Thanks,

Brad

Wikipedia has a great write up on these trannys, but in a nutshell, the 89-93 dodge came with the Torque Flight 46rh also called the chrysler 518 (4 speed, overdrive, non lock up, hydraulic controlled). From 94-95 they had the 47rh or 618 (beefier version, still 4 speed with overdrive, but this one has lockup trq converter) After 95 they made the 47 and 48 RE (same as above but electronically controlled. Now you have to buy a box from somebody to control the tranny. no big deal, just 500$ or more for this box. These are all based on the 727 3 speed that dodge has used for years. The 47 RH is best in my opinion for guys like us because it gives us almost all the great attributes of the big 6speed electronic allison trannys but at a fraction of the cost. The 47RH also has the .69 overdrive which is taller than any other overdrive than I can find. If you do the math on this, it equates to about 1800 RPMs at 57 MPH if you have 4.56 rear end and 8R19.5 tires. You just cant get a better more economic combo than this. (By the way, most of us have this same rear end ratio). If you are cruising at just under 3000rpms at at about 60mph once the tranny warms up, 4.56 is what I suspect you have. If you are unsure,, It should be stamped somewhere on the diff.

Downsides of this tranny:

1. In its stock configuration, this tranny will not handle much more than 400lbs of trq. For a few bucks it can be modded to handle 800 or more. In our world, we just need a larger, good aftermarket trq converter with a rebuilt tranny. I'm using a single disk beefed up version. You can get a triple disk billet for more money.

2. It wasnt set up to run cool enough in the dodge. This is why it has such a bad reputation for breaking down. the tranny cooler in the dodge is very small. In our world, we need a large tranny cooler and a tranny temp gauge. If you keep the temps down on this or any other tranny, you will be fine. If you run this tranny into the ground and improperly cool it, you will be one of the ones complaining about it. There are no fundamental problems with the actual tranny, just the way it has been installed over the years.

3. The gear ratio spread between 3rd gear and overdrive is a lot. from 1.0 to .69 is more than most. This has to managed by the driver so as not to run the tranny too hot. in the dodge, this is another reason for high temps and failure. the truck hunts for the right gear while locking and unlocking the trq converter. In our world, we run toggles to manually control the converter and the overdrive when climbing hills and pulling big loads. we also run pressure switches to automatically control the trq conv and OD when we are driving normally (that way you are not flipping switches the whole time). the stock computer is more concerned with a comfortable ride than the health of the tranny, so it gets chucked in the dumpster.

For more info on the pressure switches and all that, go here:

www.transmissioncenter.net/dodge.atm

Its all the way at the bottom

For more info on where I got my tranny, go here:

Rebuilt Transmission | Transmission Parts | Rebuilt Transmissions

These guys sold me a reman 47RH with the trq conv and they even took my 46RH as a core.

[gwbaker]

Originally Posted by outofcontrol

I have some of the same questions. I'm trying to figure out a good place to learn about these trannys, but once you have gone out and tested this set-up, I might just trust all your research. it seems pretty spot on so far.

Are there 47RH trannys form dodge that don't have the lock-up? obviously the 91 doesn't. how do you know?

Is this where you bought the Tranny from? Phoenix
it looks like they include their own CNC HD Tq converter with the tranny, is that right?

Sorry I'm such a novice at this, but how do I find out what the final gear ratio is in my rig? (besides opening it up and counting teeth).

-Kevin

Hope my last reply answered your questions. Yes that is where I bought my tranny, and yes the trq converter comes with it. Hope this helps

[bkahler]

gw, thanks for the reply. It sounds like a 94-95 dodge truck is the ideal donor as long as it has the cummins and the 47rh transmission.

Thanks!

Brad

[gwbaker]

Originally Posted by bkahler

gw, thanks for the reply. It sounds like a 94-95 dodge truck is the ideal donor as long as it has the cummins and the 47rh transmission.

Thanks!

Brad

Well, thats up for debate. The 94 thru 98 cummins has the p7100 inline injection pump. Its a great pump, but it is HUGE. You have to cut away some of the side firewall to make it it fit. This is why I bought a 91 so I could get the skinny motor, then I traded the 46RH in for a 47RH reman.

[bkahler]

Thanks for clarifying the year. What years had that particular arrangement for injection pumps?

Brad

[gwbaker]

Originally Posted by bkahler

Thanks for clarifying the year. What years had that particular arrangement for injection pumps?

Brad

89-93, but you have to go with the 91-93 if you want the intercooler.

[outofcontrol]

1994 is also the year that the Ram changed to the new body style. This is actually when I started paying attention to the Cummins. (I thought the new style was 10x better than the old.) The reason I bring it up is that the '94s demand more when you're looking for a donor. I can regularly find '91-93 Cummins 2WD trucks with less than 200k miles for 2,000-2,500, but the '94s seem to start at $4k.
I've heard the same thing about the dodge transmissions. So many guys started hot-rodding the Cummins and the tranny was the rumored weak point. too much heat or too much torque will burn them up. GW, I think you're right on the money with your choices.
Wikipedia.org has some great info for lots of stuff, including the Tranny history, and the injection pump history of the 6BT.
The dodge Cummins motors are basicly catagorized into 3 groups;
1st gen is the 12 valve(89-98.5), 2nd gen is the 24 valve (98.5-2002), and the 3rd gen is when it went Electronic. In my quest to find out more about these motors, i've spent some time here: DTR they even have a "conversions" forum that's pretty cool.
PATC looks like a great website. BTW your link has a typo: http://www.transmissioncenter.net/dodge.htm I know very little about automatic transmissions, but this seems doable. I always thought that a torque converter was a closed mechanical/hydraulic system that connected the engine to the tranny - I didn't know you could control it with a switch.
So do the 44psi and 52psi switches correspond to 44 and 52mph with our tire size and rear end ratios? Are you buying the tranny cooler and temp gauge from PATC?

You've definitely done your homework. I can't wait to hear about some road testing!

-Kevin

[gwbaker]

Originally Posted by outofcontrol

1994 is also the year that the Ram changed to the new body style. This is actually when I started paying attention to the Cummins. (I thought the new style was 10x better than the old.) The reason I bring it up is that the '94s demand more when you're looking for a donor. I can regularly find '91-93 Cummins 2WD trucks with less than 200k miles for 2,000-2,500, but the '94s seem to start at $4k.
I've heard the same thing about the dodge transmissions. So many guys started hot-rodding the Cummins and the tranny was the rumored weak point. too much heat or too much torque will burn them up. GW, I think you're right on the money with your choices.
Wikipedia.org has some great info for lots of stuff, including the Tranny history, and the injection pump history of the 6BT.
The dodge Cummins motors are basicly catagorized into 3 groups;
1st gen is the 12 valve(89-98.5), 2nd gen is the 24 valve (98.5-2002), and the 3rd gen is when it went Electronic. In my quest to find out more about these motors, i've spent some time here: DTR they even have a "conversions" forum that's pretty cool.
PATC looks like a great website. BTW your link has a typo: http://www.transmissioncenter.net/dodge.htm I know very little about automatic transmissions, but this seems doable. I always thought that a torque converter was a closed mechanical/hydraulic system that connected the engine to the tranny - I didn't know you could control it with a switch.
So do the 44psi and 52psi switches correspond to 44 and 52mph with our tire size and rear end ratios? Are you buying the tranny cooler and temp gauge from PATC?

You've definitely done your homework. I can't wait to hear about some road testing!

-Kevin

700R4, 700 Raptor Transmission from PATC, 700R4 4L60E 48RE 4L80E should yeild results. try hand jamming it in to the address bar. Its a great site with lots of info. I use it for info all the time. I am still waiting to get the drive shaft spliced. that is the last thing. as soon as its done, I'll test drive and post results. I am hoping that these 44 and 52 switches work, but if not, I'll fine tune and get it right. I got the Tach working this weekend. Dakota Digital is the ticket. Stock tach works great. I also dropped the front end down onto the suspension(its been up on blocks), and the front end sits exactly where it did with the 454.

[bkahler]

Originally Posted by gwbaker

I also dropped the front end down onto the suspension(its been up on blocks), and the front end sits exactly where it did with the 454.

I'm wondering if you won't get some settling once you get out and drive it around. Be nice if you can get away without changing the front springs. However I would watch carefully for front end tire wear.

How much longer before the driveshaft is complete?

Brad

[jjhypnotist]

Two thoughts before you change the springs out go get the front end weighed at a truck stop so that you put the right springs in.... also to really maximize the gas milage up instal a gear vendors behind the tranny they are expensive however I now drive 70 miles an hr at about 2000 rpm.... and I am staying well above the 15 mile per gallon mark....

The only problem I find with the whole 55 mile an hr thing is it is not practical unless you are in Oregon or another state that has 55 mile max speeds...

Justin
1982 280 turbo diesel turbo 400 hydromatic with alison converter and shift kit +gear vendor.

[outofcontrol]

454=750lbs
6BT=1100lbs
~350lbs difference.
When I go over the scales I'm about 4k on the front and 8k on the rears. I would imagine that 350lbs extra should make a difference, but really if my fresh water is full (50g x 7lbs = 350) and my wife and dog are in the front with me (200+125+50=375) that's more than the difference of the engines. If the ride is even close I wouldn't bother with the springs unless there were some real steering/braking problems. Furthermore, I think GW has stripped some additional weight out of this rig to lighten the loading that could compensate for the extra engine lbs. He's a helicopter pilot by trade, I'm sure he knows a thing or two about load balancing. But yea, a scale would be in order to know if the math works out. You could be right at the end of the spring's usable range, and they're gonna settle a little after being unloaded for weeks.

I happen to be in Oregon, but even on our 2 big hwys (I-5 and I-84) I drive 55 not 70. I might be a 36 yr old slow fart, but I usually set the cruise just under 60 and let the traffic work around me. Although, I've been to AZ and people drive 80mph everywhere there. People in Oregon do drive slow in comparison. Plus there's a lot of hills here, and I end up going 35 with the trailer. I get 8-9mpg at 60 and 6mpg at 70. I would love 15mpg and the power to go up hills with traffic.

jjhypnotist,
Is your diesel the Isuzu or Cummins? was it OEM? with the TH400 behind it? did you install the gear vendors? you really get 15+ mpg? what's the best you've gotten? how much does your rig weigh?

Sorry if I'm a bit wordy, I love this subject and this thread.
-Kevin

[jjhypnotist]

Hi Kevin, as for the springs I always think after you do major work like that to an RV you should get the front end weighed and I do not remember the Vendor however they are out of Grants Pass Ore and make heavy duty RV springs no air bags needed... Suspension on these is important to keep in line...

As for Me I have the Isuzu Motor currently it still only has 36,000 mile on it so not broken in... I drove it from texas to vegas pre tranny update and was maintaining 13+ miles an hour driving at 65 - 70 miles an hour the Tach was running as high as 3500-3700... The noise was horrible.......
Many of the speed limits across the country are 70 + at least where I am though I am up in your neck of the woods at least once a year and crawling through......

Personally it scares me to always have everyone passing me and not having the ability to pass or maintain speed in traffic... Here in vegas if you can not ride with traffic it can cause some dangerous situations... LA and Seattle as well....


Getting the Gear Vendor was a necessary evil... Unfortunately my transmission case was cracked when I went in to Camping world to get it installed and so I had to get the transmission re-cased That turned into a total rebuild so 1700.00 later I had a turbo 400 with straight cut gears a stage one shift kit and a Allison converter...
The Transmission for these RV's have straight cut gears same as tow trucks and what not... So is more costly.....

Pre Gear vendor I was running at 3000. RPM at 65 miles an hour and 3600 at 70..... The engine screamed..............

With the gear vendor installed I am now running about 2000 RPM at 65 miles an hour and 2500 at 70... if I am not careful it will hit 80 quickly..
Gas milage is staying above 15 and currently I am doing a lot in town driving ... I am hoping for better once I am cruising on the highway.....

total cost for me to get the Gear Vendor and Tranny was close to 7k once done.....

[jjhypnotist]

Hi Kevin, as for the springs I always think after you do major work like that to an RV you should get the front end weighed and I do not remember the Vendor however they are out of Grants Pass Ore and make heavy duty RV springs no air bags needed... Suspension on these is important to keep in line...

As for Me I have the Isuzu Motor currently it still only has 36,000 mile on it so not broken in... I drove it from texas to vegas pre tranny update and was maintaining 13+ miles an hour driving at 65 - 70 miles an hour the Tach was running as high as 3500-3700... The noise was horrible.......
Many of the speed limits across the country are 70 + at least where I am though I am up in your neck of the woods at least once a year and crawling through......

Personally it scares me to always have everyone passing me and not having the ability to pass or maintain speed in traffic... Here in vegas if you can not ride with traffic it can cause some dangerous situations... LA and Seattle as well....


Getting the Gear Vendor was a necessary evil... Unfortunately my transmission case was cracked when I went in to Camping world to get it installed and so I had to get the transmission re-cased That turned into a total rebuild so 1700.00 later I had a turbo 400 with straight cut gears a stage one shift kit and a Allison converter...
The Transmission for these RV's have straight cut gears same as tow trucks and what not... So is more costly.....

Pre Gear vendor I was running at 3000. RPM at 65 miles an hour and 3600 at 70..... The engine screamed..............

With the gear vendor installed I am now running about 2000 RPM at 65 miles an hour and 2500 at 70... if I am not careful it will hit 80 quickly..
Gas milage is staying above 15 and currently I am doing a lot in town driving ... I am hoping for better once I am cruising on the highway.....

total cost for me to get the Gear Vendor and Tranny was close to 7k once done.....

As for weight I have to go to the scales myself shortly I have been doing a lot of mods to the RV and No I did not instal the GV myself...

Justin

[outofcontrol]

My rig has air bags to assist the front end. I guess it adds some adjustability, but I'd rather just have the proper springs. If (when) I do this mod, I'll probably just get the correct springs - good to know the source is close! here in Orygun!

I see the problem you had. The 400 tranny has a 1:1 top gear. with a 4.56 rear end you would have had:
RPM = MPH
2000 = 41.77
2500 = 52.21
3000 = 62.66
3500 = 73.01
That Isuzu motor was screaming at 70mph and waaaaay above it's sweet spot. Your gear vendor decision was a wise one for your set-up. I don't know about the Isuzu motor, but the sweet spot is usually at the peak of the torque curve. For the 6BT I believe it's like 1820 or something.
With the 47RH .69 OD and a 4.56 rear end here are the numbers:
2000 = 60.54
2500 = 75.67
3000 = 90.81
3500 = 105.94
If you put an additional gear vendor with this set up you'd be ready for Bonniville, but way under target efficiency.
Formula: RPM = mph x tranny ratio x rear end x 336 / tire diameter.
Check out this site: 91 Ram engine specs
-Kevin

[jjhypnotist]

Yes the 400 had no overdrive.... till now and it is so much happier..

Justin