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Discussion Starter · #1 ·
I am having an issue with my transmission. When my truck is in o/d and I press lightly on the accelerator and the truck downshifts I get a slight bumping and almost like a light shudder. If I press harder and get it to drop another gear it goes away. No DTC's and no drivability problems. This is the only situation when I notice this. I can pull a trailer or camper or just stomp it and I have no issues and it pulls like a beast. But if I just need to drop one gear for just a little extra power it starts to bump. Any ideas? Fluid and filters were just changed within last 2000 miles no issues with old fluid being dark or burnt smelling. Current fluid level is good and color is good. No leaks, drive line is good and tight, carrier bearing is tight. U-joints were replaced about a year and three months ago and I have been keeping grease in them. Slip shaft moves in and out nice and smooth. No issues when in 4WD low or high.
 

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If what you feel is like a brief shudder, during the shift, then you are probably noticing what we call "bumpalong." To make a 5-4 downshift, the trans releases the 2C clutch and applies the 4C clutch. In theory, the shift goes like this: The PCM knows how long it takes to apply the 4C clutch. This is based on the 4C Clutch Volume Index (CVI), which is a measure of how much oil (volume) it takes to apply the clutch. The PCM can calculate how long it takes to flow that much oil into the 4C clutch, based on the current line pressure level.

So, to make the shift, the PCM first releases the 2C clutch. This allows the engine speed to increase (since basically the trans is going into Neutral). As the engine speed rises, the PCM turns on the 4C clutch at the correct moment of time, so that the 4C clutch will apply at the same instant that the engine speed reaches its new target (i.e. the speed it will need to be at in 4th gear). As the engine speed reaches the target, 4C gains capacity and the shift completes.

That's the ideal situation. But let's suppose your 4C CVI is too low. Then, the engine speed will reach the target, but 4C won't be fully applied yet, so engine speed will keep increasing. If this happens, the PCM will re-apply the 2C clutch for a moment (to stop the engine from running away). I had said (above) that 2C was released, but in reality the PCM only partially releases it, so it can be quickly re-applied if necessary. Anyway, after re-applying 2C for a moment, the PCM releases 2C again and sees if the engine speed stays at target. If the engine starts to run away again, the PCM will re-apply 2C again. It keeps on doing this until 4C finally gets applied and the shift completes.

This re-application of the releasing clutch is called "bumpalong" and it feels like a brief shudder during the shift. If the PCM sees that bumpalong is required, it will adjust ("learn") the 4C CVI up to a higher value (to reduce or eliminate bumpalong on future shifts). So I'd think that after a while, your trans (PCM) should re-learn the 4C CVI and things will smooth out for you.

If not, have your dealer check your CVI readings to see if the 4C CVI is reasonable. If the CVI is way off, you may have a hardware problem internally (like a cut 4C piston seal). But before tearing into the trans, have them try a "quick-learn" on the trans. They do this with a scan tool (it takes only a few seconds). The quicklearn resets all the trans adaptives to "factory" spec, and then re-learns all the CVIs at once. So if your CVI is way off (due to some glitch) this can correct it. If your bad CVI was due to an internal problem, then it will either learn back like it was (over time), or you will still have the same issue (or worse) after the quicklearn. In that case, have them drop the valve body and air check the 4C clutch (to see if the piston seals are leaking). Also check the conical "tower seal" on top of the valve body that feeds the 4C clutch. If the piston seals are leaking, then you have to pull the trans and tear it down to replace them.
 

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Discussion Starter · #4 ·
Just an update on the Tranny issue. Took it to the local dealer and had them do a re-learn on the transmission and I have not experinced the problem since. Thanks again!:smileup:
 

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Ok, I'm impressed with this post. I'm so glad we have members like this on the Z, because even though I can tear down an engine or rewire the entire truck... the tranny is still voodoo and black magic to me. :rep: to you my new transmission guru.

Glad to hear the problem was fixed :smileup:
 

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I have an 06 2500 w a 5.7 Hemi with the 545rfe and its doing the slight shuddering only when I take off from a stop with a trailer or a rapid take off ( I don't floor it is what I am trying to say but I don't grand pa it either ). Is this the same issue , do i need to go to dealer as well?
 

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I have an 06 2500 w a 5.7 Hemi with the 545rfe and its doing the slight shuddering only when I take off from a stop with a trailer or a rapid take off ( I don't floor it is what I am trying to say but I don't grand pa it either ). Is this the same issue , do i need to go to dealer as well?
If you're talking about a shudder right when you take off from a stop (trans is in 1st gear and is not shifting), then no, you are talking about a different issue.

For shudder during launch with a trailer, I would first check your U-joints to make sure they are not worn / loose. If the U-joints are OK, then you may be experiencing "launch shudder" which is apparently a normal phenomenon and exists (to some extent) on most or all trucks, but is greatly affected by driveline angles. Do you have a two-piece driveshaft? You might try shimming the center bearing slightly (to change the driveline angle) and see if that helps.
 

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5.7 hemi 545rfe. 50 000 miles
Dryving style: Active driving in 1-2 gear. Often kickdowns from 3-4-5 gears.

Transmission fluid changed 10 000 -12 000 miles ago (Mopar ATF 4+)
New filters installed: 05179267AC, 05013470AD
When changing atf, some friction powder was in pan

Earlier problems:
Delay when shifting (all gears) VIDEO in attach
Leaking hose of cooling ATF (solved)
Often appear error Transmission Over Temp when staying on "P"(Parking). (img in attach)

First become P0734 , next day P0733 + p1790.
Atf become smell a bit burned.

I replaced solenoid pack, atf and filters, Quick learn done, but no difference.

Shifting 1 to 2 gear are great(but as usually with some delay).
Stall test - great. 2300-2400 rpm in full acceleration.

Transmission is slipping i 3rd gear, but temperature not increasing. In 3rd gear car pulling forward only after 4000 rpm.

http://www.youtube.com/watch?v=q8GM6EQjO_U

Sliping 3rd gear

Clutch test(no errors)

Solenoids test(no errors)

Ican get more information, because having access to starscan
 

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No, I doubt it's a valve body problem. If you had no pressure going to the OD clutch, you would blow a P0871 (OD Pressure Switch Rationality) fault.

Fourth gear is the gear in default (limp-in), so as soon as it slips it puts you in limp-in. Actually, in "logical limp-in", where it will launch in 1st gear and then shift directly to 4th. However, if your OD clutch is gone, 4th gear will feel just like 1st gear. So if you have to drive it, drive it in "3" to avoid getting limp-in.
 

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No, I doubt it's a valve body problem. If you had no pressure going to the OD clutch, you would blow a P0871 (OD Pressure Switch Rationality) fault.

Fourth gear is the gear in default (limp-in), so as soon as it slips it puts you in limp-in. Actually, in "logical limp-in", where it will launch in 1st gear and then shift directly to 4th. However, if your OD clutch is gone, 4th gear will feel just like 1st gear. So if you have to drive it, drive it in "3" to avoid getting limp-in.
3rd gear not working even in manual shifting mode. It shifts into 4 gear immediately after 2nd gear. Third gear always passing

3rd gear enabled only one time, after i went to dealer and them cleared dtc by witech(but i think it was fortuitously, because i cleared dtc's by starscan many time). But when it's time to shift to 4 gear, transmission again started to slip.
Then third gear not enabled again...
 

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Oh, sorry, you've got an older truck. In newer trucks they enable 2nd Prime gear when in ERS mode (so ERS "3" is actually 2nd prime, which would still work), but apparently in your truck ERS "3" is actual 3rd (direct) gear. And you are correct; if your OD clutch is gone then it will slip in 3rd also. Sorry for the misinformation!
 

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Oh, sorry, you've got an older truck. In newer trucks they enable 2nd Prime gear when in ERS mode (so ERS "3" is actually 2nd prime, which would still work), but apparently in your truck ERS "3" is actual 3rd (direct) gear. And you are correct; if your OD clutch is gone then it will slip in 3rd also. Sorry for the misinformation!
No, it's not 2nd prime(starscan info). Engine rpms so high when it shift 2 -> 4.
In 4th gear rpms about 5000/35mph(as in 1 gear). But this there is no feedback with engine in 4th gear. The car does not slow down via engine from high rpms, as it does on the 1st and 2nd gear.

Also i noticed difference of pressures on idle rpms. (desired/actual)

http://www.youtube.com/watch?v=LDM5PlutlW8
 

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Yes, if your OD clutch is gone and the PCM tries for direct gear (or puts you in full limp-in, which should be direct gear) it will behave like 1st gear.

Direct gear uses the UD and OD clutches. But since OD is gone, all you have is UD. When the engine runs away, it will spin the rear sun gear so fast that the rear annulus gear tries to turn backward, and this will cause the overrunning clutch (ORC) to lock. That will give you the normal 1st gear ratio, so the trans will behave like it's in 1st, even though it is trying to be in direct gear.
 

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HELLO,,
I have the P0750 code on my 2007 with the Hemi, With what I guess is the 545 RFE trans, My question is,, will the solenoid pack for the Cummins work in the gas job?
I found a so called "GOOD DEAL" for the same year 545 RFE Cummins but was not sure if the pack was any different ??

THANKS
Any Help Would Be A Help
 

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HELLO,,
I have the P0750 code on my 2007 with the Hemi, With what I guess is the 545 RFE trans, My question is,, will the solenoid pack for the Cummins work in the gas job?
I found a so called "GOOD DEAL" for the same year 545 RFE Cummins but was not sure if the pack was any different ??
The solenoid module (aka solenoid pack) is common between 545RFE and 68RFE, so the short answer is that a 68RFE solenoid module will work in a 545RFE (and vice versa). Note, however, that the solenoid module CHANGED for 2011 MY (OD solenoid was removed), so a 2011+ solenoid module will NOT work in a 2010 or earlier truck.

The service solenoid modules are all "old-style," since the older modules will work in all trucks (old or new). But if you're buying one where you're not sure of the origin, check the color of the electrical connector. The "old-style" solenoid module had a WHITE electrical connector. The 2011+ style solenoid module has a GRAY connector. So make sure yours is white.

I would also note that the REAL original solenoid module (used in 1999-2004 MY; there have actually been three different versions altogether) had a BLACK electrical connector. Those should also work in any MY truck. But the white connector would be preferred.
 

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545rfe trans Hemi/Cummins same ?? (2007)

Thanks for the help.
I've found one local it says part number 52119435AF (Mopar) for the Cummins,,!! Just wasn't sure if it would fine the Hemi.
I believe that is the same one for the Hemi,,!!!

Thanks
Cummins is white plug,,NOT sure what mine is as I've not got into it yet.
 

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Thanks for the help.
I've found one local it says part number 52119435AF (Mopar) for the Cummins,,!! Just wasn't sure if it would fine the Hemi.
I believe that is the same one for the Hemi,,!!!

Thanks
Cummins is white plug,,NOT sure what mine is as I've not got into it yet.
52119435AF is the white-connector solenoid module and will work on any RFE-series transmission.
 
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