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Discussion Starter #41
I gotta say... I am surprised this never made it to sticky status.
I am glad it helped out some guys. If it was sticky maybe it could have helped some more over the past few years.
As an update, a couple years later.... Dashboard is falling apart, leaks oil like a sieve, the instrument cluster looks like night club lighting with warning lights, cranks over slowly even with new battery cables, solenoid kit and good batteries so about to break down and buy a new starter, APPS just sh*t the bed the other day and had to get a tow home so need to get one of those too.. But the tranny is still working great. Shifts are nice and affirmative. I don't daily drive this rig anymore due to diesel being being almost 4 bucks a gallon and the length of my daily commute.. I use it when I need a REAL truck.. so when its fired off, its going to work. Its used to pull campers, equipment trailers, yanked stuck stuff thats stuck in the mud.. I leave it in OD even with 8-10,000 lbs on the hitch. Still holding up great...

For the guys with X tuner stacked on top of Y tuner which is stacked on Z tuner and making 800hp, the stuff in this thread may not be of much value. But for the guy with a mild 2nd gen that uses his truck to get things done and got sticker shock on the price of a rebuild, it can let you decide if you can handle the job.
 

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Funny! I've had this write up saved for over a year now. Guys like you are really helpful so thanks for all the time you put into the write up.
 

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Discussion Starter #43
I am going to try to bring this thread back to life. I tried to help a buddy do what we thought was a simple fix today. His truck is having trouble shifting into 4th, and overdrive. Quick searching pointed to a couple solenoids. That is what I tried to help with.

We dropped the pan and planned a quick swap of them. Once the pan was on the ground we found a spring about the diameter of a pencil, a little over an inch long, and when compressed it was just about a half inch.
No clue on what that spring does, or if the one you found is even that spring.

However, regarding 4th gear(OD) operation...
The OD is pretty much an external unit. On these transmissions the main transmission case is a 3 speed unit, and the 4th, or OD gear is an add-on unit in the tail section of the unit. What would normally be the output shaft of a 3 speed trans is the input of the OD unit. When OD is not activated, the power just transmits through it. When OD is activated, a planetary gear set takes over that speeds up the output shaft of the trans, and gives you OD.

In order to get overdrive, first the PCM(engine computer) must want(command) overdrive.. And the the transmission must respond appropriately.

So the first check is to see if the PCM is actually requesting overdrive. This is done by using a Volt meter on a pin at the PCM output. Its been years since I had to do it, but this was one of the first things I had to do as a cummins owner so a search should be pretty easy to determine the pin. But you monitor the voltage at the correct pin at the PCM. It will normally have 12V on the pin going through 1st, 2nd and 3rd. To get OD, the pin is grounded which energizes the OD solenoid. If you are cruising along at light throttle and 45-50mph and still have 12V on that pin, the problem is not in the trans... Its in the PCM(less likely) or its in the inputs to the PCM which leads it to think its not in an OD appropriate state. So if you are in a condition that should be giving OD an that pin is not dropping to ground, the PCM is not even asking for it so look to the VSS or something else...
However, if the pin goes from 12V to ground you should almost immediately feel the trans shift into overdrive. If you get the drop from 12V to 0V, the problem is either the solenoid or the OD unit itself...
At that point, you want to get a mechanical pressure gauge, a long length of high pressure tubing, and some adaptors.. Tap into the OD pressure port on the OD unit(see factory shop manual for location). Drive the truck. When the voltage on the pin goes from 12V to 0V, if you dont see a spike or raise in pressure(unlikely) the problem is likely the solenoid itself. If you see a little rise in pressure that drops off or a big spike that drops off, then the OD clutches are shot.
The good thing is that if you have the above problem but 1 2 3 works fine, then you dont have to pull the trans... Just rebuild the OD unit which can be done without removing the transmission.. You just have to rebuild the overdrive unit....OD unit rebuild
The bad side is the rest of the trans may not be far behind.
 

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I don't know if I'll ever use this but it's nice to see it is available if I decide to redo the tranny myself. Still weighing my options - and the various parts out there.
Thanks,
 

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Boosted great write up. I have to bookmark this.
 

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great write up.. good to know my money was well spent at RKL and that this is way over my head.
 

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that was great. thanks for sharing
 

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Great write up! Subscribing since I just got home from the lake and found atf dripping off the underside of my truck and my entire boat I guess it's about time to start collecting parts and roll the dice. I still can't afford to have it built for me so I don't really have any other choice but to try it!

Sent from AutoGuide.com Free App
 

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Discussion Starter #49
Glad people are still getting value out of this thread.

As an update, almost 3 years later the tranny is still operating flawlessly.
 

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too tight here and it will slam into reverse
correct me if I am reading this wrong...

first, the springs can be orientated in fashion that allows
(1) use of more springs
(2) or add 1 spring totaling 10, but grouped in pairs

these additions are for a faster / firmer 1-2 up shift ? correct ?

does the addition of springs cause a harsh reverse engagement as well ?

I was under the impression that an additional spring was a good thing, but I would not want a harsh reverse engagement ???
 

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Great job. The only real issue is not addressing input shaft end play. It is checked before removing or disassemble of trans. It gives you a ideal of wear in thrust washers, ect. Try and reduce end play by using thicker spacer between input and intermediate shaft. Also the spacer on output shaft will affect. Thickness of OD spacer riding on OD piston is for adjusting OD direct clutch release.
 

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The gear train thrust washers should always be replaced, especially in the 48RE. Gear train end play is very important and you'll be loose if you reuse the thrust washers. Sonnax makes shims to tighten the gear train on the 46's and 47's, but not the 48's.

The forward clutch Belleville spring (the plate that he couldn't remember the name of...) should always be replaced at overhaul.

Also, the write up says to install the low roller clutch dry. You'll definitely want to lube it (and the OD roller clutch, also) with ATF before you install it. They both should also be replaced at overhaul.

It's also very important to replace the direct drum bushing at overhaul. This bushing locates the drum on the stator support. Any unnecessary play here and you can run into sealing ring problems and and up leaking direct (3rd gear and reverse) oil.

I'm not being critical here. Heck, most guys wouldn't even attempt to go into their transmission... Hat's off for that...! I'm just trying to add a few pointers...
 

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Is there a way to remove overdrive or lockuyp control from the ecm? I have a 98 12 valve with a 47 re and I'm eleminating as much ecm/electronic control as possible.
 

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Is there a way to remove overdrive or lockuyp control from the ecm? I have a 98 12 valve with a 47 re and I'm eleminating as much ecm/electronic control as possible.
If you really want to you would need to back down to a 47rh, this would take the OSS input out. currently the tranny speed is measured by the OSS, which inputs to ecm, then ecm also take TPS, VSS, Tach signals along with pressure and temps from vb. Ecm then send info back to gov solenoid and modulates pressure.
In the RH version, the gov press modulation is performed by a mechanical fly weight ( gov) mounted on the overdrive output shaft. Both the RE and RH use same OD and LU solenoids, just that the electrical connection is different, the RH connector is smaller as it only controls the solenoids.
 

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I am going to try to bring this thread back to life. I tried to help a buddy do what we thought was a simple fix today. His truck is having trouble shifting into 4th, and overdrive. Quick searching pointed to a couple solenoids. That is what I tried to help with.

We dropped the pan and planned a quick swap of them. Once the pan was on the ground we found a spring about the diameter of a pencil, a little over an inch long, and when compressed it was just about a half inch.

Neither of us are transmission savvy. We searched for YouTube vidoes, photos, anything we could to possibly find where it belongs. We could only come up with one location that looked right. I couldn't find a photo to give a clear picture of the location, until now. We slid it over the piston type device.

Can anyone tell me what that thing does? Or where a spring about that size might go?

wll, the valve body is FULL of little springs, I'm sure that you figured out where the spring came from, check out this instructional video https://www.youtube.com/channel/UCXqufnwB1bb0QKnP2Owo3nA
I think #6 is VB rebuild.
 
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