Flyer97

I haven't seen this specific issue in the forums and the shop that just rebuilt the trans is scratching their head too. When accelerating thru the gears, which is normal, from 3 to OD the truck shudders and shakes. If I hold the throttle at the same rpm the shake gets worse, if I accelerate or back off the shake stops. I've seen the OD drop out thread and installed new TPS prior to rebuild. Saw the manual lock up posts, could that be a solution?
I've been referring to this site for years and have used info posted successfully. Got a new rust solution suggested, coal oil driveway coating on the frame. I have used chain bar oil 60/40 with mineral spirits through a small compressor. Which would be more effective?

Thanks


94 Ram 2500 CTD, 4x4, 47rh, 235k K&N, 4"

cougar

In my experience, it's been hard to find a good transmission mechanic that knows what they are doing and puts their best effort into the job. My 47RH story is a prime example.
My guess is solenoids and/or throttle body to start with. Leakage in the feeds to the OD unit can also be a cause.
Was this an exchange transmission or yours overhauled?

AlpineRAM

Hard to say from the description- is it the OD that shudders or is it the torque converter lock.

What happens if you drive with OD off- does it shudder when locking up the TC?

Flyer97

Cougar,
The shop is Sworens in Bushkill PA, they are very experienced in HD rebuilds, mine was a rebuild, and they have done work for me in the past. I was told by the owner the inside of the trans is not the issue and they haven't seen anything similar.

Alpine,
Good point I will drive with the OD off and see if the shudder happens on lock up.

This seems to be intermittent, once the trans warms I expect the shudder when reaching 45mph or so and the trans shifts from 3rd to OD, sometimes its a shake sometimes the whole truck feels like all four wheels are seriously out of balance.
I will try to video the shake as it happens.

Thanks so much for responding.

Angry Johnny

It's not going to lock up if it's not in O/D. 45 MPH is about where the converter should lock up on normal acceleration. Did they replace the torque converter? If they didn't they should have. Is this the reason why you had it rebuilt or was it something else? Either way was this condition present before it was rebuilt?

Flyer97

Yes the TC was replaced, yes this was one of the reasons for the rebuild. There were some up shift & down shift issues that are resolved. The shudder was my main concern. I took the truck to NJ on Rt 80 yesterday, it seemed to shift from 3rd to OD but shuddered right after, might be problem in TC when locking up ?

AlpineRAM

In OD off the TC will lock in 3rd...

cougar

Bypass the PCM by putting switches on the OD and Lockup solenoids. That will tell you for certain weather it is the transmission or the truck.

Flyer97

Thanks Cougar,
That makes sense so I ran this past the trans shop owner and he wants to replace the wiring harness and plugs connecting the PCM and trans. Does this sound like a good place to start?

Angry Johnny

Only under certain conditions and it won't do it at the normal 45 MPH.

AlpineRAM

It should lockup under light to medium throttle at a little lower speed- that's why I recommended it for testing. Resonance from eg unbalanced tires or other rotating parts like driveshaft etc should be out of the range where he experiences the shakes.
Had a customer's truck that had a combo - bad wheel balance + rear transmission mount rubber torn off- when going to lockup in OD the engine started to shudder in the mounts, therby moving the throttle, this causing lock/unlock cycling. Took me some time to find the root causes...

cougar

No, because your just replacing parts without knowing their bad. You can buy the connector from the transmission center, a couple switches and some wire from your local auto parts store and you have a simple bypass setup for troubleshooting. I'm surprised (not really) that the transmission shop hasn't already tried this.

Angry Johnny

I would also be looking at the crankshaft end play.

1workinman

I have a 95 that has 214 k on ir . First off I don't care for automatics except for equipment like power shift . I have had problems in the past and I installed lock up switch and made it work . Now once I had a problem with my brake peddle that would bounce a bit and cause unlock and off over drive . A stiffer spring fixed that . A couple of weeks ago it finally gave up and stopped working . So I done with automatics and its going to have a g56 installed a twin disc clutch ect . I could have had a custom built 47 built with 48 parts but I still have 4 gears and that would not change . I never have liked the pitiful fluid coupling and the 750 rpm gear splits . Good luck

Osam

If you are still dealing with this issue, look into W-T ground wiring mod.
https://mopar1973man.com/cummins/art...mplified-r574/