May 26, 2010

Converter Conundrums

Bob Warnke

Conundrum = A riddle involving a pun

The Top 3 Converter vs. Transmission Issues of 2010


Conundrum 1

Applications:
  • Mercedes ’00 to 2012
  • Sprinter
  • Dodge
  • Jeep
  • Freightliner
Complaints:
  • Engine stumble at cool temperatures (gas or diesel)
  • Rough idle when cool
  • Driveline vibration ( NVH) during TCC modulation
  • TCC shudder or drone between 35-48 mph
Cause:
Transmission Related:
  • Leakage of converter pressure into the TCC piston area
  • Low converter apply pressure, due to valve bore wear
  • Defective TCC solenoid
Converter Related:
  • TCC lining flake, due to water or Glycol
  • TCC clutch clearance and friction material
Correction:
  1. Air test the transmission and valve body circuits (see details on following pages).
  2. Visual or vacuum test the working pressure regulator, the lube/converter limit, the torque converter control and the TCC damper piston.
  3. Test, replace Y3 lockup solenoid.
  4. Refer to Glycol test kit.
  5. The TCC piston must return to release the converter clutch. A problem arises when centrifugal force reacts on fluid trapped behind the clutch piston. The residual pressure plus the force walks the piston toward the clutch. Within the 722.6 converter, oil trapped behind the TCC piston cannot be vented. This problem is increased by charge pressure of 50-100 psi. working its way into the low pressure TCC circuit. Fluid from the valve body to pump stator can exhaust at the control valve, but fluid trapped behind the piston loads it toward the clutch.
Alternatives:
  • Force the piston to release
  • Use higher flow friction plates

Air Testing
1. The TCC apply circuit can be air tested, (30-60 psi.) with the unit in the vehicle and the valve body in place. Charge the exhaust hole. The air supplied will push remaining fluid into the converter TCC piston. Minimal leakage should come out cooler lines or other valve body locations.
If the valve body is removed, the three converter circuits can be isolated. Any leakage from converter charge or converter out, is from cross leak at the pump or within the converter.
Note: Teflon®-type of sealing rings require fluid to lift. If air testing with a dry circuit, they will cross leak. Turbine shaft sealing rings should be the OE overlap design. Valve body must be flat and the pump stator or converter cross leaks should be eliminated. Internal transmission bushings insure the turbine shaft runs true, a requirement for the rings to seal.
The turbine shaft can also be installed into the converter and the clutch tested as well.



2. Low converter apply pressure extends from the main/working pressure regulator bore and the Lube/converter limit valve. Wear at either area affects TCC and converter charge psi. Critical wear points within circles (shown in photos below.) The TC control valve must stroke for full apply. Bore wear at either location reduces the TCC solenoid's ability to stroke the valves.



3. The normally closed, Y3/ 6y6, TCC solenoid strokes the torque converter lockup valve. If the Y3 solenoid leaks into the control valve circuit, the valve may rest in a partial apply position.


Converter Related:
4. Test for water or antifreeze in ATF. In some applications, one drop is sufficient to degrade clutch linings.

Mercedes kit # 000-989-009 and 000-989-0014
ESP Chemicals Inc. Ph; 520-622-4087 #HI 3859 @ $75.00
Chrysler cannot cross reference this number.
An alternative is to use a hot plate and check for a sizzle noise as the water burns off.


5. Aggressive converter friction plates, poor turbine shaft pilot and/or lack of piston return can create the condition.


Conundrum 2

Applications:
  • Odyssey
  • Similarities to other 4-speed designs
Complaint:
  • TCC slip codes
  • No TCC apply
  • Overheated converters
Cause:
  • Valve body bore wear
  • Restricted Coolers
  • Defective linear solenoid
  • Converter hub O-rings too small
Correction:
1. Main control body bore wear (critical points at circles).
Control valve body worn at the converter relief bore. To isolate prior to removal, compare scanner data to the cooler flow. You should see the TCC command and amperage change in parallel to a cooler flow change on a SonnaFlow®.

Loss of TCC or TCC slip: Created by end plug loose at the TCC control valve. A cross leak of converter charge oil into TCC control negatively affects TCC control. Inspect the stator for cross leakage at the finished area, where it passes through the casting.


2. Restricted coolers create back pressure on the hydraulics and either slow the stroke of the valve or cause it to stop midstroke.
Other 4-speed Hondas have similar cooler flow charts.


Conundrum 3

  • Aisin Warner 6-speed, front wheel drive
Applications:
Complaint:
  • Harsh shift (relative to converter release)
  • Overheated fluid
  • TCC cycling, RPM fluctuation
  • No move, no power
Cause:
  • TCC control valve bore wear. The converter is opened briefly during upshifts and some downshifts. If the clutch does not release, the shifts are very firm. The lack of release can be valve, solenoid or converter related.
  • Primary and secondary regulator valve bore wear. The feed for converter apply and release starts at the main regulator which then feeds the secondary regulator valve. Both of these bores are known to wear. This wear positions the valve in a low flow state, reducing converter feed and lube.
In-Vehicle testing:
It is possible to isolate the Electro-Hydraulic control over the converter clutch.
With a scanner; monitor the TCC solenoid. You should see amperage change as it’s modulated briefly to open the converter.
With pressure gauge; tap into TCC release. You should see the control valve stroke at the same time the scanner identifies the amperage command.


TF-60SN / 09G
Correction:
1. Visual inspection, WAT or vacuum test the TCC control bore at the inboard end and the outboard sleeve. If worn, ream or replace the valve body. Aftermarket valve body rebuilders generally have these in stock.




TF-80SC / AF 40/AM6




TF-81SC / AF21




TF-60SN / 09G



What’s Coming:

722.9 8-Speed:
OE information notes:
  • The torque converter is the same as the 722.6 with the addition of a turbine damper.
  • The 722.6, in some Dodge applications (300 Magnum) had a damper assembly.
  • 722.9, is noted to have an open, high flow converter. During TCC slip, flow will be reduced. We presume this is due to the position of the TCC control valve.
  • It can/ will be slipped in all 7 gears, with the intention not to go 1:1. It will generally be open in 1st and 2nd gear.
  • The last year of the 722.6 will be 2012.
  • 722.9 requires special fluid is required; Shell or Fuch’s, ATF 3353, MB# AOO1 989 45 03 10.
Ford 6R140:
  • F-350 trucks. 6.7 dsl, 6.2 ltr gas
  • This 6-speed unit has a PTO, which is driven off the inner pump gear. The inner gear drives the PTO idler, which is supported by the pump stator bearings.
  • Ford noted the design requires a close tolerance control over converter hub runout.
  • The converter has a closed piston converter clutch, comparable to a disc-shaped piston within a transmission housing.
ZF 8:
OE information notes:
  • TCC apply after second gear and remaining on. Generally these clutches are modulated open briefly during upshifts. In some instances they are not modulated/opened in order to reduce duration of the shift and improve drivability and economy.
  • Appears ZF continues the use of tabbed multi-plate with two-circuit fluid path and the release oil exiting from the turbine shaft.
DCT:
  • Dry clutch, dual dampened input clutch
  • Replaces torque converter and/or wet clutch
  • Ford will have a substantial production number of these dry clutch transmissions.
Honda 6-Speed:
  • Multi-plate converter clutch for expanded torque capacity and lower speed modulation. TCC can be applied from 20 kmh / 12 mph upward.
  • The cover has a separate floating piston with multi-plate slotted frictions.
  • The operation could be compared to the RE5R05A or 722.6.

Bob Warnke is vice president of technical development and a member of the TASC Force (Technical Automotive Specialties Committee), a group of recognized industry technical specialists, transmission rebuilders and Sonnax Industries Inc. technicians.

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Default Title: Converter Conundrums

Default Description: Conundrum = A riddle involving a punThe Top 3 Converter vs. Transmission Issues of 2010Conundrum 1- 722.6 Engine stumble, TCC shudder/droneConundrum 2- Honda B7