48RE Transmission slipping 1st gear and 2nd gear

[JRam]

Hi, I have a transmission issue with my 2005 ram 2500 5.9 diesel automatic 48re 2x4 truck with 200k. Got the truck used and don't know if trans is original or not. I have done a lot of reading on this forum and have not found an issue exactly like mine. I have noticed Cerberusiam seems to be the local expert and was hoping he would chime in.

Truck sometimes seems to slip a bit on the 1 to 2 shift in D. Its like it gets to the top of first and overrevs a bit then rpms lower and slips sloppily into 2nd. This only happens in D and does not happen in manual 1 shifting to manual 2. Once it shifts into 3rd and overdrive every thing seems normal.
This problem is not my primary concern.

My primary concern is a slip then harsh gear engagement that happens when you are for example approaching a red light and you are almost completely stopped then the light turns green so you accelerate, the truck revs (like its in neutral) to about 3k rpms then violently bangs into gear. This also occurs when you are cruising say at 50mph and traffic in front of you slows to say 25mph and then you start to accelerate again, it will rev up like its not catching then bang into gear. This condition will not happen if truck is manually shifted.

So far I have replaced the front band with a new slip in band (old band looked well used but not terrible or worn to bare metal or anything), sonnax band strut, HD band anchor. And installed the upgraded borg warner governor pressure solenoid and transducer. With no change. Transmission fluid and filter also changed. Old fluid was still red but had a grayish or black cover when touched with paper towel (not sure when last service of it was). Magnet had metal on it but not really any more than I've seen with other trucks in the past.

If anyone has any advice it would be greatly appreciated. The only thing I can come up with after researching is possibly a bad overrunning clutch. Which is a part that doesn't seemed to get mentioned very often. I'm not sure if there is another more common name for it or not.

Thanks

 

[cerberusiam]

Does it always exhibit the runaway upshift to 2nd when starting from a stop even under moderate throttle? Do you have to push the rpms high to just get it to shift from 1 to 2?

If you manually shift gears does it engage firmly even under light throttle 2nd and drive?

Have checked for codes, especially anything about the TTVA motor? Both symptoms of the slam shift sound like it is running too high of TV pressure or too low gov pressure for the wheel speed. First thing I would do is change the output shaft speed sensor as it somewhat governs how the TV and gov pressure react with each other. They cna go bad with age but they can also get a build up of crud on them that totally fouls up the auto shifting patterns.

What metal did you see in the pan? Silvery pieces or the typical black sludge on the magnet?

 

[JRam]

Thanks for the reply Cerberusiam. I forgot to mention in my original post that I also installed a new output shaft speed sensor in an attempt to fix this problem with no luck.

Under moderate throttle the 1-2 shift issue is less noticable, the best I can describe it is that you cant feel the truck shifting when using moderate throttle. Even though I think it is shifting its just that the 1-2 shift is not pronounced.

If I manually shift gears it does engage firmly even under light throttle 2nd and drive.

I have checked for codes. Only thing I'm getting is an intermittent ABS Code #35 "APS RELAY OUTPUT CIRCUIT OPEN" and Code #65 "Power relay open"
ABS and BRAKE light are intermittently illuminated on dash. But transmission problem exists whether lights are on or not.
I was curious if since these codes are ABS related which is related to wheel speed sensors and such if this could be the cause of the issue. Or if the truck only relies on the output speed sensor for transmission related info.

Pan had typical black sludge on magnet.

What about the second gear apply servo? Could this be an issue? or does proper operation when shifting manually rule this out?
I have seen a "super hold servo" form sonnax and a couple other manufactures, would this be your next step? or new ttva motor?

 

[cerberusiam]

If it is holding in manual 2nd it is probably not the front servo. If you can nail the throttle in manual 2nd and you don't feel obvious slip then it is holding. FYI, do NOT do a Sonnax super servo without changing the apply lever, that will totally screw up shifting. If wont or need to change the servo use the TCS no leak billet servo, addresses the leaks and doesn't change the size of the servo that messes with shift timing.

The trans doesn't use the ABS sensors, it is all output shaft speed sensor and throttle position to determine shifting.

It sounds like you have a TTVA motor that is advancing too far, probably because someone tampered with it and advanced the gear a couple teeth in it, or it is going bad. It is entirely possible it is something on the VB circuits causing that also. Since you do not now what was done before you could just change the TTVA and see if it fixes it, or, get some gauges hooked up to the gov pressure port and the TV pressure port to see what is happening.

Had somewhat the same issues and after a rebuild the problem went away, we never figured out exactly what was causing that other than maybe clearances too loose or some FOD in a circuit somewhere that was washed out when it was cleaned.

 

[JRam]

It has held in manual 2nd during all of my testing including yesterday. But I will test drive again tomorrow to verify.

I will try swapping the TTVA motor and see if that changes anything.

As far as gauges go do I have to use manual gauges?
I think I can monitor gov pressure actual and desired with datastream on scanner. But not sure if tv pressure would be called something else or not in scanner.

I have noticed every now and then the square box that indicates what gear you are in doesn't immediately appear around P when I place truck in park. Does the range sensor on these trucks give any data to computer for shifting or anything?
Or is it simply used to mark the display and as a neutral safety switch?

 

[cerberusiam]

Yes, you have to use a manual gauge to get TV pressure, what is being applied to offset the gov pressure. That is the middle port on the lower part of the passenger side of the trans. Gov pressure is on the rear high side of the passenger side of trans. You can them compare actual gov to read gov and see if they are close then what TV pressure is doing. If gov is reading high on manual gauge it doesn't matter what the senor sees, it will hang and slam shift.

TV pressure is not monitored by the TCM so no way to get it other than a gauge.

The missing box on park is probably the lower mount being pulled back over time. You can bend that mount with a hammer, adjust cable length under the dash to get all the boxes to show on the dash, sometimes it take sboth to get it right. Aside from the range senor being a POS at times the ramp on th erooster cob top of VB wears and it won't ever align correctly. As long as it reads around D it should shift correctly, only time I have seen an issue is OD quits working when it is reading 1 or 2.

 

[JRam]

I tested again in manual 2nd and truck holds fine under even very heavy acceleration. So I guess servo is ok.

I changed ttva motor with one off of friends truck and went for a 45 minute test drive.

I thought the problem may have been solved. Truck shifted normal under light and heavy acceleration. I purposely did a lot of slowing down and then accelerating between 5mph and 25 mph to see if it would slip. It didn't at all... Until about 30 minutes in.

For some reason the 1-2 shift seemed to be fine, maybe a tiny bit of slip or soft shifting but ok.

Unfortunately the flairing issue returned. For example letting off the accelerator and making a tight right turn then when I would press accelerator acted like it's in neutral rpms shot up then bang! Gear catches and truck accelrates fine through the rest of gears.

Same thing coming to an almost complete stop then accelerating, truck revs like in neutral and then slams into gear.

It seems this slipping only occurred when trans reached between 200 and 210degrees f.
With 210 degrees being the hottest it got during test drive.

Are these temps too hot or normal?

Like I mentioned test drive was a lot of stop and go and some heavy accelerating.
Is trans overheating due to friction caused by failing part or some other reason? Ambient temp was about 80 degrees f.

Is there anything else I should do or check before hooking up manual gauges?

When I do hook up manual gauges do I need to drive on road and get truck to slip while watching gauges?
Or is there a test procedure like psi at idle in P, in R , manual 1 etc etc etc?


Thank you for all the help and advice

 

[cerberusiam]

Those temps are normal when doing what you were doing. If you go out the highway and cruise in lockup and the temps go back down to 180-190 it is all good.

If you can reproduce the flare shifting by getting the transmission warm, it keeps doing it when warm, and will work decently until trans gets to operating temp 2 things come to mind. The transducer is giving bad info when it gets warm (not unusual and have seen them bad out of the box), or, the forward clutch pack seals are compromised.

 

[JRam]

Should my next step be changing the transducer again? (Already replaced last week attempting to remedy problem)

Is there any grounds related to the transducer that I should check and clean?

Anything else that can affect the transducer?

Is the valve body ruled out at this point because condition seems to be only when truck is warmed up?

 

[cerberusiam]

I would say it is a good change it isn't the VB if it works cold. It is something that is being affected by the warmed fluid, most often that is the electronics or the clutch pack seals. Really need to get some pressure readings cold and hot to see what it may be.

 

[JRam]

When hook up manual gauges do I need to drive on road and get truck to slip while watching gauges?
Or is there a test procedure like psi at idle in P, in R , manual 1 etc etc etc?

I will perform test both cold and hot and get readings. Just need to know the procedure.

 

[cerberusiam]

There is but it won't tell you what you want to know with this problem. Monitor the TV pressure with one gauge and the gov pressure with another gauge and the demanded\read on the electronics to see if there are discrepancies.

 

[wolff098]

JRam
What was the problem with your transmission?
I'm having the same problem with my brother in laws . Operating fine when cold but as soon as it's up to operating temps, all foward gears slip but reverse works fine.
Just rebuilt. .

 

[cerberusiam]

Probably tore the lip seal on the forward clutch pack assembling it. Slipping when it is warm is almost a seal and if it is forward gears affected and not reverse it will be a forward clutch pack issue, seal or broke the Bellville spring.

 

[wolff098]

Probably tore the lip seal on the forward clutch pack assembling it. Slipping when it is warm is almost a seal and if it is forward gears affected and not reverse it will be a forward clutch pack issue, seal or broke the Bellville spring.

 

[wolff098]

Thanks for the reply
I just replaced the forward seals with a new suncoast billet apply piston .840 to take out slop from apply piston to bellville, new Bellville spring also. Air checked everything worked great. Was operating great on maiden voyage as soon as it warmed up started to slip taking off . So I changed the governor pressure solenoid, had I new one, test drove the truck, once it wormed up started to slip by time we made it back lost all foward gears.
My sister moved truck this morning , all foward gears slipping cold.
I will pull it tomorrow and see what broke.
Do you think the foward clutch housing or direct clutch housing could have a hairline crack that's opening up when warm ? Hopefully what ever the issue is has broken .

 

[cerberusiam]

Cracks are possible just not likely unless it has been abused. Usually the seal is the culprit unless you have a cracked VB housing.