Attention: TDR Forum Junkies Many of you have e-mailed me about this upgrade after seeing my signiture. I've finally got it sorted out enough to post my experiences so far.
For those how don't know, the 47RH is the 4-speed auto trans used in the second gen trucks from 1994 thru early 1996 model years. It is equipped with lockup and is also refered to as the A618.
I will begin this explaination at the engine and work to the rear of the truck and then deal with control and operation.
My truck is a 4x4. Those of you with 2x's only need to skip the t/case and exhaust paragraph.
Do to the fact that the torque converter sticks out past face of the bellhousing on the 47RH and is flush on the 727 the engine adapter plate needs to be replaced with one from a 1994 or newer Ram. This requires the starter to be changed also as the bolt pattern was changed and there isn't enough material in the location of the one relocated hole to drill and tap the adapter plate to make it duel pattern. Installation of the new starter requires minor relocation of the fuel lines on the frame for clearance. Also the draft tube is better routed over the starter instead of it's original location between the starter and block as this is now a much tighter space.
The pivot point for the shift linkage on the frame rail also needs to be extended back 1"
so it will line up with the pivot on the trans.
The NP205 t/case will bolt up to the back of the 47RH with some minor adjustments. The locating dowel needs to be removed from the t/case mounting flange as there is no longer a corresponding hole in the trans mounting flange. The seal needs to be removed from the back of the trans to allow clearance for the input coupler on the t/case. There is a weep hole passage ground in the mounting flange on the trans, this needs to be plugged. I applied a bead of RTV to the passage just before installing the t/case gasket-4 months later and still know leaks.
The t/case shifter bracket and linkage need to be modified. The bracket is S-shaped, cut it at the peak of both pends and discard the the center piece. Weld the two remaining pieces back together so they are straight and flat, the weld will need to be ground flush for clearance. The linkage rod needs to be lengthened about 4", I used a piece of pipe that would slip over the rod after I cut it in the center. Do this after the t/case is installed as a 1/2" error in measurement is the difference between hitting the dash and the seat(I learned the hard way). A 5" piece of exhaust pipe will have to be cut out in front of the muffler and be reinstalled in front of the trans crossmember to put the bump out in the proper place.
I built a new trans mount from scratch to bolt to the muonting plate frome the 727. Others who have posted about doing this conversion have moved the crossmember back to line up with the cast steel mount used on the 91. 5 to 93 trucks. I did not do this for three reasons:
1)This creates extra hole in an already stressed frame.
2)This mount has been out of production for 3 years and is no longer available.
3)Leaving the crossmember in place produces much more room for the future 4" exhaust installation
#ad
.
I space the mount so I had 1" clearance between the top of the t/case and the floor pan of the cab. This maintains original engine cant and provides sufficient clearance for the front driveshaft even at full front axle droop.
The rear drive shaft was pretty straight forward. I had a friend cut it down 5 1/8" on his lathe and I welded it back together.
The front driveshaft is a little more interesting. The 95 Ram driveshaft I had on the shelf was exactly the right length. The problem is the front joint. The second gen Rams all use standard 7290 chrysler joints and no one makes a converion joint to match this with joint on the first gens front axle.
I built one using a 7260x7290 conversion joint and two 7290 caps. It has lasted through some tuff trail rides so far but will be replaced soon with a 7290 and a new yoke for the front axle.
I am currently controlling O/D and lockup with two lighted toggle switches on the dash.
I had a stand alone controller design in the works, but this has been put on hold until I do a valvebody and torque convertor upgrade as this will drastically change the shift schedule programming. The connector on the trans is a 3-way connector with the center pin being a common power feed (12V 15A). The outer pins are grounded to engage overdrive or lock-up.
Operation has been good so far. I have seen at least a 2MPG increase in fuel economy. This will probably increase when the stations up here quit pumping winter blend as my baseline with the 727 was set on straight #2.
My current shift schedule is as follows:
Once trans is in 3rd gear engage lockup when speed reaches 30mph if empty, 45mph if loaded(4 cords of green maple on 1200lb trailer).
Engage O/D at 45mph with less than 1/3 throttle if empty(this is done with trans locked up-REALLY gives her a kick in the pants if over 1/4 throttle#ad
). If loaded I take it up to cruising speed in third lockup and engage O/D with foot off of fuel.
I have found that the stock converter in this trans is extremely sloppy and hopefully will be able to save up enough money to replace it with one of Bill K's units by this time next year. Also I will be changing the gears from the stock 3. 07's to either a 3. 55 or a 3. 73 to compensate for 36" Buckshots that need to go on this summer.
The 3. 07's would be okay with stock tires, but even with the 33's the gearing is too high to use overdrive effectively for the daily commute.
Those of you who I have e-mailed this info to please e-mail me if I left anything out.
Any of you who have questions feel free to e-mail me.
Happy Bombing.
------------------
89 w250, 47rh trans, cleaned up exhaust, Dynomax bullet muffer, 3" lift
For those how don't know, the 47RH is the 4-speed auto trans used in the second gen trucks from 1994 thru early 1996 model years. It is equipped with lockup and is also refered to as the A618.
I will begin this explaination at the engine and work to the rear of the truck and then deal with control and operation.
My truck is a 4x4. Those of you with 2x's only need to skip the t/case and exhaust paragraph.
Do to the fact that the torque converter sticks out past face of the bellhousing on the 47RH and is flush on the 727 the engine adapter plate needs to be replaced with one from a 1994 or newer Ram. This requires the starter to be changed also as the bolt pattern was changed and there isn't enough material in the location of the one relocated hole to drill and tap the adapter plate to make it duel pattern. Installation of the new starter requires minor relocation of the fuel lines on the frame for clearance. Also the draft tube is better routed over the starter instead of it's original location between the starter and block as this is now a much tighter space.
The pivot point for the shift linkage on the frame rail also needs to be extended back 1"
so it will line up with the pivot on the trans.
The NP205 t/case will bolt up to the back of the 47RH with some minor adjustments. The locating dowel needs to be removed from the t/case mounting flange as there is no longer a corresponding hole in the trans mounting flange. The seal needs to be removed from the back of the trans to allow clearance for the input coupler on the t/case. There is a weep hole passage ground in the mounting flange on the trans, this needs to be plugged. I applied a bead of RTV to the passage just before installing the t/case gasket-4 months later and still know leaks.
The t/case shifter bracket and linkage need to be modified. The bracket is S-shaped, cut it at the peak of both pends and discard the the center piece. Weld the two remaining pieces back together so they are straight and flat, the weld will need to be ground flush for clearance. The linkage rod needs to be lengthened about 4", I used a piece of pipe that would slip over the rod after I cut it in the center. Do this after the t/case is installed as a 1/2" error in measurement is the difference between hitting the dash and the seat(I learned the hard way). A 5" piece of exhaust pipe will have to be cut out in front of the muffler and be reinstalled in front of the trans crossmember to put the bump out in the proper place.
I built a new trans mount from scratch to bolt to the muonting plate frome the 727. Others who have posted about doing this conversion have moved the crossmember back to line up with the cast steel mount used on the 91. 5 to 93 trucks. I did not do this for three reasons:
1)This creates extra hole in an already stressed frame.
2)This mount has been out of production for 3 years and is no longer available.
3)Leaving the crossmember in place produces much more room for the future 4" exhaust installation
#ad.
I space the mount so I had 1" clearance between the top of the t/case and the floor pan of the cab. This maintains original engine cant and provides sufficient clearance for the front driveshaft even at full front axle droop.
The rear drive shaft was pretty straight forward. I had a friend cut it down 5 1/8" on his lathe and I welded it back together.
The front driveshaft is a little more interesting. The 95 Ram driveshaft I had on the shelf was exactly the right length. The problem is the front joint. The second gen Rams all use standard 7290 chrysler joints and no one makes a converion joint to match this with joint on the first gens front axle.
I built one using a 7260x7290 conversion joint and two 7290 caps. It has lasted through some tuff trail rides so far but will be replaced soon with a 7290 and a new yoke for the front axle.
I am currently controlling O/D and lockup with two lighted toggle switches on the dash.
I had a stand alone controller design in the works, but this has been put on hold until I do a valvebody and torque convertor upgrade as this will drastically change the shift schedule programming. The connector on the trans is a 3-way connector with the center pin being a common power feed (12V 15A). The outer pins are grounded to engage overdrive or lock-up.
Operation has been good so far. I have seen at least a 2MPG increase in fuel economy. This will probably increase when the stations up here quit pumping winter blend as my baseline with the 727 was set on straight #2.
My current shift schedule is as follows:
Once trans is in 3rd gear engage lockup when speed reaches 30mph if empty, 45mph if loaded(4 cords of green maple on 1200lb trailer).
Engage O/D at 45mph with less than 1/3 throttle if empty(this is done with trans locked up-REALLY gives her a kick in the pants if over 1/4 throttle
#ad). If loaded I take it up to cruising speed in third lockup and engage O/D with foot off of fuel.
I have found that the stock converter in this trans is extremely sloppy and hopefully will be able to save up enough money to replace it with one of Bill K's units by this time next year. Also I will be changing the gears from the stock 3. 07's to either a 3. 55 or a 3. 73 to compensate for 36" Buckshots that need to go on this summer.
The 3. 07's would be okay with stock tires, but even with the 33's the gearing is too high to use overdrive effectively for the daily commute.
Those of you who I have e-mailed this info to please e-mail me if I left anything out.
Any of you who have questions feel free to e-mail me.
Happy Bombing.
------------------
89 w250, 47rh trans, cleaned up exhaust, Dynomax bullet muffer, 3" lift
