TCC Vibration, Judder or Shudder Misdiagnosed - Transmission Digest

TCC Vibration, Judder or Shudder Misdiagnosed

Malfunctioning mounts are notorious for causing a wide variety of vibration complaints including what is often thought of as a converter clutch vibration, judder or shudder; particularly so with vehicles that perform cylinder deactivation for fuel economy.

TCC Vibration, Judder or Shudder Misdiagnosed

Shift Pointers

Author: Wayne Colonna
Subject Matter: Vibration
Issue: Mounts could be cause

Shift Pointers

  • Author: Wayne Colonna
  • Subject Matter: Vibration
  • Issue: Mounts could be cause

Malfunctioning mounts are notorious for causing a wide variety of vibration complaints including what is often thought of as a converter clutch vibration, judder or shudder; particularly so with vehicles that perform cylinder deactivation for fuel economy.

The mounts used can be liquid filled that are either electrically (figures 1 and 2)

or vacuum controlled (Figure 3) to dampen the effects of an engine not running on all of its cylinders.

When these mounts soften or lose their liquid and collapse (figures 4 and 5), they transmit the cylinder deactivation through the vehicle. This of course gets misinterpreted as a converter clutch problem as deactivation occurs near the time a converter clutch may apply.

With a wide variety of car manufacturers utilizing this type of strategy, it is good to keep this in mind when fighting what is thought to be a TCC issue when it is not. What can be a tip-off that the mounts are the problem and not a torque-converter clutch issue is the shudder occurs at the same time deactivation is taking place. Some manufacturers inform the driver that deactivation is taking place by way of an indicator light. An ECO light in a Honda is one such example. This too can aid in a quicker diagnosis if one pays attention to this detail.

This does not eliminate non-liquid filled mounts as being problematic. Non-liquid filled mounts malfunctioning in vehicles that do not perform cylinder deactivation are also prone to being misdiagnosed as a converter clutch shudder. An excellent example is 2006-and-later Dodge Chargers using the NAG1 behind a Hemi in police packages. A complaint of a driveline vibration or a shudder is felt coming to a stop. But when Autostick is enabled the vibration goes away. This immediately causes one to think TCC issues because when Autostick is not enabled, the TCM provides a “partial” electronic modulated converter clutch (EMCC) strategy on the downshift. When Autostick is activated, it delays EMCC strategy and no longer partially applies the clutch on downshift. For this reason the converter clutch is blamed. But what is really happening is the bad spongy mounts are transmitting the partial EMCC strategy through the vehicle.

Although only a couple of examples were cited in this article, the idea is to remain mindful that mounts are one possibility to what may be thought of as a TCC shudder problem. It’s always good to start simple before getting overly invested in time and money chasing after the wrong cause to a problem.

You May Also Like

Trying to Stop the Wheel Hop on Ford Edge with 6F50 Transmission

The 2014 Ford Edge SEL with a 3.5L engine (figure 1) and a 6F50 transmission can also be equipped with an AWD system. This would include a Power Transfer Unit (PTU) attached to the transmission with a rear driveshaft going to the Read Differential Unit (RDU). The RDU comprises a differential assembly along with a

The 2014 Ford Edge SEL with a 3.5L engine (figure 1) and a 6F50 transmission can also be equipped with an AWD system. This would include a Power Transfer Unit (PTU) attached to the transmission with a rear driveshaft going to the Read Differential Unit (RDU). The RDU comprises a differential assembly along with a viscous coupling assembly controlled by an Active Torque Control (ATC) coupling solenoid. The system is designed to monitor vehicle conditions continuously and seamlessly adjust torque distribution between the front and rear wheels. When it is functioning correctly, there should be no perception of this taking place when launching or driving the vehicle. 

Sherlock Holmes Approach to an AB60 No-Move Situation

The effectiveness in diagnosing automatic transmission malfunctions is an art form. Although there are similarities among the wide varieties of transmissions on the road, each transmission has its own peculiarities. Aside from having mechanical, hydraulic, and electrical hardware systems to contend with, software/programming issues and various vehicle platforms make diagnostics much more difficult.  Related Articles –

ab60
GM 6T40 Pump Identification Guide

The 6T40 was introduced in 2008 for General Motors front-wheel-drive cars in the Chevrolet Malibu and has gone through several changes throughout its three generations, specifically in the pump area. The 6T40 is closely related to the more lightweight 6T30 and the heavier duty 6T45 and 6T50. Generation one started phasing out during the 2012

Seeing the Forest AND the Trees

They say that the proverbial phrase “I couldn’t see the forest for the trees” means that a person or organization cannot see the big picture because it focuses too much on the details. Related Articles – TASC Force Tips: Hydraulics Fundamentals: Check Valves – Shift Pointers: Mazda Sensitive to Pressure – Transmission Testing & Repairs:

The Manifold Pipeway

The Honda six-speed transmission has been on the bench of many specialty shops for one reason or another (figure 1). But, for those of you who have yet to lay your hands on one, mounted on the upper side of the unit is one of the largest, if not the largest solenoid and pressure switch

Other Posts

Shift Pointers: Where’s that fluid leak coming from?

A 2016 Honda CRV 2.4L (Figure 1), using a BLJA CVT 4WD transmission (Figure 2) comes in to a shop with a customer complaint of a leak. Related Articles – The powertrain aftermarket: Growing and global – 6R80 whirring noise: TCC slip or engine surge? – The torque converter can of worms: Lockup and aftermarket

Ford 8F35 maintenance tips: Planetary failure and no-pressure conditions

Our shop has had several vehicles come in with the Ford 8F35 transmission having planetary failure. Apparently, there was a run where the pinion needle bearings had a hardness problem (see Figure 1). Related Articles – The Subaru mystery burn – Multitasking: Sorting out multiple issues with the same vehicle – Chrysler RH/RE late shifts and

Figure 12.
Shift Pointers: A Chrysler 300 no-shift complaint

The case study has to do with a 2009 Chrysler 300 C 5.7L Nag1 RWD with 71,923 miles on it (see Figure 1, above). Related Articles – Ford 6R80 shift solenoid ‘E’ resistance change: How to tell the difference – Allison 1000 geartrain bind-up – How to get around non-serviceable GM 6T70/75 self-tapping pump screws

Shift Pointers: What to do when the 62TE TRS tab breaks

How frustrating it is when on a hot summer day, as you go to open a nice cold can of your drink of choice, and the tab breaks off? You are outside, away from any tools to remedy the problem quickly. It now requires a MacGyver mentality looking around at the resources available to get