RDU clutch stuck engaged? Shudder from torque converter?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Adam F

New Member
Joined
Nov 9, 2023
Messages
6
Reaction score
2
Location
cincinnati ohio
Trying to narrow down some issues with an 11 SHO I picked up.

2 main issues.

First, is a binding of the tires when turning. Like I was in my 4wd truck with 4wd engaged and trying to turn on dry pavement. Also, sometimes I fell a slight drag when going straight. Also, when stabbing the throttle while already moving, the car feels like its crab walking a bit to the side, like something is wrong in the rear suspension. Could this be a locked up RDU clutch pack? I unplugged the electrical connector to the RDU and it did not change anything, still binding. With all 4 wheels off the ground, engine off, car in neutral, I can spin the fronts and the rears turn and spin the rears and the fronts turn. Do I have a problem with the differential in the transaxle, or RDU? Can I safely remove the rear drive shaft and drive around to see if the problem is still there?

Second, I have a horrible shuddering on partial acceleration, mainly 30-40mph. Shakes the motor back and forth badly (I also have worn out motor mounts and lower control arm bushings which makes it worse) Research tells me its a common problem with the torque converter? Does this sound like the issue? Shifts gears great, no slip. Also, RPM's flutter a tiny bit. Fluid was dirty looking, so I drained and filled 1.5 gallons. Still shudders. I'm going to add some lubegard shudder fixx and see if that helps.

I inspected the PTU/fluid. Exterior looks perfectly fine. No leaks. I drained the dirty black fluid with some fresh fluid. Didn't help the situation. Although I don't think it could cause the binding that I'm seeing since its just a straight gear set with no clutches.
 

kryptto

The Best Thing About Cars... ones in my mirror.
Supporting Member
Joined
Mar 24, 2023
Messages
1,757
Reaction score
953
Location
South East, Florida
Yeah - clean fluids in the rdu and ptu - you said black, or graphite grey? Did that ptu come with a magnetic plug? Get a code checker - Forscan is like $14 a year amd odbi cable. What if any codes?

Get the rdu changed too, analyze the oil. Too bad you didn't get how many oz drained from the ptu.

We can assume the wheel bearings all around need to be replaced at and shudder can be the joints in the front axles.

Before you go amadd an additive to the transmission, I would bet it could be this.

Slow down a bit, change fluids take pics, get any codes. If the transmission shifts fine, it could be all problems with bearings or PTU, you hearing a whine?

Plus how many miles?
 

Adam F

New Member
Joined
Nov 9, 2023
Messages
6
Reaction score
2
Location
cincinnati ohio
Good info. I actually have a professional grade scanner and there are no codes on engine or trans or 4wd besides an alternator code, but the battery is charging fine. I can see the torque converter data commanded vs actual but its hard to read without someone else in the car, and also I'm not sure what its supposed to be. Reads in RPM. I didn't really closely inspect the PTU fluid, used a mightyvac unit and it looked black but could very well be grey. There was no metal on the fill plug, but I don't know if it was magnetic or not. No whine or otherwise abnormal noises besides the drivetrain shaking. I watched the video and it could very well be the issue. I suppose I could pull the axle shafts and inspect them. Would be a cheap/easy fix. I'll also try to mount a camera like the guy did so I can see whats going on. Thank you so much for the help. I'll report back.
 

kryptto

The Best Thing About Cars... ones in my mirror.
Supporting Member
Joined
Mar 24, 2023
Messages
1,757
Reaction score
953
Location
South East, Florida
Axle shafts and bearings in the hubs.... could be causing this, ALSO missing weights off the AWD drive shaft. Look closely for any missing weights.

What miles?

PS what about your transmission mounts, one under the battery tray can cause vibrations and degrades around 100K+
 

Attachments

  • Screenshot_20231226_165130_Chrome.jpg
    Screenshot_20231226_165130_Chrome.jpg
    152.6 KB · Views: 7
  • Screenshot_20231226_165034_Chrome.jpg
    Screenshot_20231226_165034_Chrome.jpg
    93.6 KB · Views: 7
Last edited:

Adam F

New Member
Joined
Nov 9, 2023
Messages
6
Reaction score
2
Location
cincinnati ohio
Axle shafts and bearings in the hubs.... could be causing this, ALSO missing weights off the AWD drive shaft. Look closely for any missing weights.

What miles?

Nearly 200k :( Was involved in a front end collision and poorly repaired. I got it from a police impound so no history. I replaced the core support, radiator, condenser, and intercooler. I'll try to get someone to run it on the lift and see if I can find anything.
 
Back
Top