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Old 03-02-2008, 08:10 PM   #71
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Quote:
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.
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Old 03-03-2008, 06:35 PM   #72
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Thanks for the schooling!

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
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Old 03-03-2008, 07:38 PM   #73
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1979 28' Airstream Excella 28
saluda , Virginia
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Quote:
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.
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Old 03-03-2008, 07:55 PM   #74
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Quote:
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
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Old 03-04-2008, 12:47 AM   #75
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Springs and gears

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.
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Old 03-04-2008, 02:26 AM   #76
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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
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Old 03-04-2008, 11:42 PM   #77
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1982 28' Airstream 280
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Springs and Things

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.....
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Old 03-04-2008, 11:44 PM   #78
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1982 28' Airstream 280
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Springs and Things

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
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Old 03-05-2008, 01:57 AM   #79
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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
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Old 03-05-2008, 11:25 PM   #80
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Lol...

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

Justin
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Old 03-07-2008, 04:25 PM   #81
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I drove it today

Well, I got the driveshaft back today, put it in and drove the motorhome. Good fun! The engine is loud, I've already ordered soundproofing from JC whitney. Also the tranny is shifting at weird points. i will have to check my wiring and also adjust the TV cable. It wont upshift unless I let up on the accelerator a little. It also shifts into overdrive and locks up at the same time, regardless of switch position. Probably some mistake I made, I'll keep you all posted. Also the tranny runs hot at idle. I think its because the engine runs so cool, that the big fan never comes on, so the tranny cooler is not getting enough airflow. maybe a small electric fan, maybe it doesnt matter. It will get to 210-230 at idle, measured at the output of the tranny on the way to the coolers. I dont really like that. Once I start moving, it goes below 180. Other than that, I was effortlessly going down the highway at below 2k RPM. Once this thing is in Overdrive, Holy crap, the RPMs drop to 1800-1900 and its like you are idling at 55-60 MPH. Up hills, the boost and EGT rise a little and I can hear the turbo spooling, but it just chugs along with no downshifting. Its pretty awesome. I am pretty happy. I cant wait till the 1st trip in April down to FL., then I can get some real data.
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Old 03-07-2008, 05:04 PM   #82
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That's so awesome. i can't wait to hear about the mpg. we need more pictures of your rig too. that polished oil burner is going to be Pimped!
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Old 03-07-2008, 06:26 PM   #83
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saluda , Virginia
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Quote:
Originally Posted by 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
I agree. A gear vendors for me would be overkill. The .69 overdrive in the 47RH is already taller than the .72 in the Gear vendors. The best thing I can do for efficiency is stay at 55MPH (best aerodynamic drag coefficient) which equates to 1800RPMs with my setup (best fuel efficiency RPM as posted by Cummins)
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Old 03-07-2008, 06:38 PM   #84
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I STAND CORRECTED. The gear vendors is a .78 overdrive, not .72
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