Automatic Transmissions

[Dwey]

1990/93 Dodge Automatic Transmissions

Hi there TDR friends,I am wondering if some one can shead some light on jest how reliable these 1990 to 93 (dodge cummins),three and four speed over drive transmissions really are? From my knowledge (Four Wheel Drive Mags... and local friends),once they let go,and are rebuilt properly with the right tork ,shift kit and proper maintainance,they can be pretty much bullet prof. Any comments or mecanical sudjestions out there that may help me out,especaly when one of these need rebuilding?THANKS!. DWEY.

 

[TWorline]

If you look at some of the signatures on this forum there are alot of guys making serious HP with an auto. Heat is the killer on an auto. So build it up and keep it cool they will take the punishment.

 

[cerberusiam]

Best advice is find a builder that understands the challenges of building for a diesel. From the 727 to the 48RE a lot of parts will interchange and there are a lot of little things that make a trans for a decent one into a really good one.

 

[DBF]

Hi there TDR friends,I am wondering if some one can shead some light on jest how reliable these 1990 to 93 (dodge cummins),three and four speed over drive transmissions really are? From my knowledge (Four Wheel Drive Mags... and local friends),once they let go,and are rebuilt properly with the right tork ,shift kit and proper maintainance,they can be pretty much bullet prof. Any comments or mecanical sudjestions out there that may help me out,especaly when one of these need rebuilding?THANKS!. DWEY.

I've towed the 5er all over Canada & Alaska. My mods were done with the intent to keep up with urban traffic while towing the 5er as well as any hill-climbing needed.



So far, so good, with 60,000 miles towed and 130,000 on the truck since.



Of course, I've added a mess of transmission fluid coolers (it's hot down here in the summer). Heat kills transmissions.



Regards, DBF

 

[boatpuller]

Of course, I've added a mess of transmission fluid coolers (it's hot down here in the summer). Heat kills transmissions.



Regards, DBF

I've got the factory underbed cooler, was wondering about adding more, what extra coolers have you added, and which one helped the most?



Thanks,

Caleb

 

[dpuckett]

I'd think replacing that cheesy factory cooler in front of the AC condensor would help more than any others. Of course you'd want the biggest you could stuff in there.



DP

 

[DBF]

I've got the factory underbed cooler, was wondering about adding more, what extra coolers have you added, and which one helped the most?

This gets to be a long saga. The primary concern was overheating the transmission fluid while towing my 5er in a hot climate.



First, I had to buy & install the Superduty cooler you have as the "factory underbed cooler"; I got one of the last ten DC had in stock. That helped a bunch - probably the best of the lot. But I still had issues - the engine temp would soar towing up a long hill and that would be coupled over to the transmission fluid thru that cannister heat exchanger on the passenger side of the engine.



I had the radiator re-cored, which helped that problem but didn't completely eliminate it.



Then I lost the cannister-type heat exchanger due to a leak between engine coolant and transmission fluid. I removed all the plumbing to that thing. Then I put a big plate-and-fin, fan-cooled cooler that looks a lot like the Superduty cooler in the same spot on the passenger side underbed.



I added 1/2" tubing (2 pcs) across the bottom of the bed from near the factory under-the-bed cooler and used short hoses between the tubing and coolers. I installed some heat-sensors & relays to turn on one fan or the other, or both.



That pretty much did the trick. I can drive (towing) trans fluid temp up to 220* on a long hill in 90+* weather, but not much more than that. And if engine temp does go up a bit, it doesn't affect trans fluid temp with that cannister gone - I don't need it for the cold-weather benefits here in Florida.



Next, I'm going to replace the dinky thing in front with something more substantial - it's time to replace the hoses up front anyway.



Regards, DBF

 

[sdstriper]

Under bed cooler source

I found a site that sells an underbed transmission cooler kit. Looks like a great kit but it's a little pricey for me, I'm cheap...



http://proweldperformanceparts.com/Supercoolers/SuperCoolerStory.html

 

[DBF]

First comment is that those kits are for 1994-2001 pickups, not ours.



Second comment is that those kits are real Cadillacs - they have special mounts attached for mounting under the cab (not the bed) and a lot of protection from flying rocks, etc. They have all the hoses & bolts for installation, with instructions.



So, can we do better in terms of price? Sure.

Capability? No, they have a pretty good cooler in that package.

Installation? Most of us have access to everything needed.



You're welcome to look in my "gallery" for pictures of the Superduty installation. I'll try to upgrade it soon to reflect the addition of the second fan-driven cooler.



Regards, DBF

 

[sdstriper]

First comment is that those kits are for 1994-2001 pickups, not ours.



Second comment is that those kits are real Cadillacs - they have special mounts attached for mounting under the cab (not the bed) and a lot of protection from flying rocks, etc. They have all the hoses & bolts for installation, with instructions.



So, can we do better in terms of price? Sure.

Capability? No, they have a pretty good cooler in that package.

Installation? Most of us have access to everything needed.



You're welcome to look in my "gallery" for pictures of the Superduty installation. I'll try to upgrade it soon to reflect the addition of the second fan-driven cooler.



Regards, DBF

It is a nice kit. And they do sell the components seperate also I believe. What would be the big difference, if any, for a 2nd gen application?

 

[DBF]

It is a nice kit. And they do sell the components seperate also I believe. What would be the big difference, if any, for a 2nd gen application?

I don't own a second-gen, so I can't tell you exactly. If you have one, read the instructions, measure 29. 5" back from the return line input to the transmission, and calculate where that mount would fit.



I *think* it has to do with mounting under the *cab*, not in the recesses under the bed on the sides.



Regards, DBF

 

[sdstriper]

I don't have one (2nd Gen). This is one of those deals where I thought the kit was really nice and I doubted there would be anything to prevent someone from putting one on the 1st Gen truck. Hose length maybe, and location other than the transfer case bracket (2wd).



I myself would piece together something similar. Possibly the B&M with fan and replace the factory air to air cooler at the radiator with a TruCool HB7 if it fits there.

 

[CBottomley]

Hello DBF

I have a few questions I'd like to hear when you have time.

What is a PDR Ve Pump @ 15* ? Cost?

Borgeston steer shaft? was the old worn out?

Front Springs? Your old old ones worn out?

radiator recored? Rebuilt for better cooling?

You stated 220 degree on transmission. Is this hot-line coming out of transmission or pan temp?



I have experienced the high heat from the transmission also while going to Alaska and Canada, Montana. I have a 1991 early 3/4 ton cummins with a rebuilt A727 transmission stock but with a Hughes Performance Tow-master torque convertor. Also have a gear vendor. I love it. I have my transmission temp reading coming out of the transmission (hot-line). I also did what you did because of high heat put two transmission coolers. I used Derale. My question is did you do 1/2 inch tubing every where? I did half 3/8 and other half 1/2. I haven't had problems but I would like if going all 1/2 inch is best? I don't know how important size matter in the cooling circuit? I'm thinking seriously doing what you did pull the heat exchanger out out before I have a problem. the coolant/transmission exchanger that is. Thank you for your time.

 

[boatpuller]

Hello DBF

I have a few questions I'd like to hear when you have time.

What is a PDR Ve Pump @ 15* ? Cost?

Not DBF, but some of these are common things, Piers Diesel Research rebuilt fuel pump installed at 15 degrees advance. See www.piersdiesel.com

Borgeston steer shaft? was the old worn out?

Borgeson Steering shaft is an upgraded shaft that has an actual U-Joint rather than the factory joint at the steering box that doesn't last long and has a tendancy to allow our trucks to wander. A very common upgrade to a 1st gen Dodge truck.

Front Springs? Your old old ones worn out?

I believe that the partnumber he has listed for his new front springs is for the heavy duty replacements that are strong enough to keep the weight of a mighty Cummins from bottoming out the front suspension on a 2 wheel drive truck.

radiator recored? Rebuilt for better cooling?

You stated 220 degree on transmission. Is this hot-line coming out of transmission or pan temp?

Can't say why he had his radiator recored , I was going to guess that his trans temp was in the Hot line but after looking at his pictures the pickup for his transmission temp is in the pan, for the pan to get to 220 degrees the transmission is very hot, I used to have my sensor in the pan and rarely would it get over 200 degrees, now with the pick up in the hot line from the trans my temp gets to 220 easily, that's why I'm looking to add more cooling, I have to back out of the throttle on hot days, long climbs to keep transmission temp in check, never thought I had a problem when the sensor was in the pan.



Thanks for the info DBF, I'm going to add another cooler on the passenger side of the truck like you did.



Caleb

 

[sdstriper]

CBottomley, I would change those 3/8 lines out to 1/2 I. D. if I were you. With heat being the number one killer of automatic transmissions there is no sense in keeping hoses with a 25% reduction in flow, 3/8 inside diameter is 25% reduction. Your right on track with the temp gauge in the fluid out port (pressure out) as opposed to having one in the pan. Pan temperature sensor locations give fluid temp. readings after fluid has gone thru the coolers.



If I am not mistaken I believe DBF had temp sensors both before and after cooler circuits, on a switch. I saw this in his gallery some time ago I believe. Is this correct DBF? Could have been someone else...

 

[cerberusiam]

CBottomley, I would change those 3/8 lines out to 1/2 I. D. if I were you. With heat being the number one killer of automatic transmissions there is no sense in keeping hoses with a 25% reduction in flow, 3/8 inside diameter is 25% reduction.

First, do NOT swap to 1/2 inch lines. Keep the factory size between the trans and the coolers. You can run 1/2 between coolers but you would be better off with 3/8. This has been tried and it was not a success. The air-to-fluid coolers are not efficient enough to cool the fluid with a higher flow rate. What will happen is the temps will go up not down under the same circumstances.



Second, the 2nd gen coolers or a universal will work quite well as long as you maintain the factory lines and do not run excessive lengths of hose to get to the coolers. Both length and size of line will have an impact.

 

[sdstriper]

First, do NOT swap to 1/2 inch lines. Keep the factory size between the trans and the coolers.

The factory size for our diesel truck transmission cooler lines is 5/8 steel tubing, which is pretty close to 1/2 inside diameter. I recommended he NOT keep reduced size hose on there just as any big name transmission builder or cooler manufacturer would recommend.



If a guy chooses hose because it is more readily available etc, Hose is sold/measured with ID measurement. Tube is sold/measured OD.

 

[Madurski]

I have almost 320K miles on the original auto in my 92 and it is still going strong. It slips a little when cold and I want to replace/rebuild it but I haven't had teh time to do so.



Fluid changes every 50K since I bought it 7 years and about 150K miles ago.

 

[DBF]

I believe that the partnumber he has listed for his new front springs is for the heavy duty replacements that are strong enough to keep the weight of a mighty Cummins from bottoming out the front suspension on a 2 wheel drive truck.



Can't say why he had his radiator recored , I was going to guess that his trans temp was in the Hot line but after looking at his pictures the pickup for his transmission temp is in the pan, for the pan to get to 220 degrees the transmission is very hot, I used to have my sensor in the pan and rarely would it get over 200 degrees, now with the pick up in the hot line from the trans my temp gets to 220 easily, that's why I'm looking to add more cooling, I have to back out of the throttle on hot days, long climbs to keep transmission temp in check, never thought I had a problem when the sensor was in the pan.



Thanks for the info DBF, I'm going to add another cooler on the passenger side of the truck like you did.



Caleb

You did well in explaining my mods. The spring thing just replaces my old crushed down springs & thus lifted the front end a little. No change in ride.



The radiator deal was that it was so clogged that engine coolant temperature would go way up, almost to the top of the gage. That warmed the trans fluid until it got really warm. Only remedy was to downshift & get engine temps under control. Recoring helped by keeping engine temps in the more normal range.



I've a good start on uploading the pictures - see Auto Trans Cooling 2 in my gallery.



Regards, DBF

 

[DBF]

If I am not mistaken I believe DBF had temp sensors both before and after cooler circuits, on a switch. I saw this in his gallery some time ago I believe. Is this correct DBF? Could have been someone else...

Temp sensors at (1) trans output, (2) after first fan-cooler, (3) after second fan-cooler. Two gages, one always showing trans out, the other switched between (2) and (3).



Temps-sensing switches to turn fans on automatically at the output of each cooler. Switches to turn them on manually. Two LED indicators to show fan(s) running.



More later, DBF