14 GEARS October/November 2011

Lately we’ve been getting more calls about lockup problems on the early KM-series transaxles

found in Mitsubishi and Chrysler vehi-cles (figure 1). It seems like these units have been around forever and they’re still quite popular among the younger crowd. You know the ones: With the loud, annoying exhausts and stereos

you can hear from a block away.I’m not even sure it’s possible for

those customers to feel a converter clutch shudder; most of the time they bring their cars in because the warning light on the dash started flashing.

The complaint may be a chatter, or the engine may start lugging while coming to a stop. Or maybe it’ll just

involve a TCC code. Whatever the complaint, the solution is old news to some; to others, it may be brand new.

The way the call usually goes on the HotLine is something like this: The technician explains the problem. We listen patiently, and then ask whether he replaced the O-ring on the stator sup-port. Then there’s usually a moment of

Figure 1

by Mike Souzamembers.atra.com

www.atra.com

KM Lockup Problems Caused by a Hidden O-RingAn old problemthat continues to rear its ugly head in shops across the country.

8tech1011.indd 14 9/30/11 12:55 AM

72 72

www.wittrans.com

45RFE / 5-45RFE RWD 4 & 5 Speed

© Whatever It Takes Transmission Parts, Inc.

510

Body

899

500

898

311B311

070 519

Front Cover Plate

777

530

544 528 036 520

778Stator

179037

211

PumpParts

507

381 554336341961051971879480 880

337 862334A

334B574670

Input Clutch Hub

877960970980875

560

050

047378

177

O.Dr. / ReversePiston

Input ClutchRetainer

Input Shaft

561

860

876102122 142*

O.Dr. Clutch

100 120 861 140 891 130110

Reverse Clutch

150 892*

Underdrive Clutch

232 571052

220 884331330

558883234576214570

Underdrive Hub O.Dr. Hub Reverse Hub2nd / 4th Retainer

482

054

121 101

4th Clutch

141 863*

2nd Clutch

124104

865968568 333332

962562

874

144*227*

226

852978

596 873 238 584 244 612 247 582

Input Planet

251 592235* 616 241

Reverse Planet

583586

Reaction Planet

053 058

Input RingGear

886 285887 885* 154134

114

Low/Rev Clutch

664888 654

Low RollerClutch

644

577 893 987 977 967567

338 339 061 557 690 895

Low / ReverseHousing

ParkGear

480

013

074

781770760 897

271

Ext. Housing

429

996

M304317B

317

438370

370436

846540

CaseParts

761

Case

782

740

420342

347

746

V.B.Parts

741

740

Valve Body

765

300

779

010

379

950

926B

926352

927

352

371

494493

Park Pawl Assy.

995995-2995-3995-1

991-4

994991-6

991-5

761-4072

991

Linkage

E

D

C

B

A

E

D

C

B

A

800-940-0197sales@wittrans.com

or buy online atwww.wittrans.com

Automatic Transmission PartsHard Parts•OEManufacturer,AftermarketNew,

Remanufactured,&Used•ClutchDrums•Shafts•FrontPumps•Planets•ValveBodies•CompleteLineof MiscellaneouspartsTorqueConverters•Completelineof CVCRemanufacturedConverters

SoftParts•MasterKits•BannerKits(LessSteels)•OverhaulKits•Paper/RubberKits•Filters&Kits•Frictions•Steels•Bushing•Modulators•Washers•Bearings•Gaskets•Bands•FlexPlates&Flywheels•SpeedoGears•Mounts•Coolers•TeckPakConversionKits•SuperiorShiftCorrectionPackages•DetentCables•TransgoReprogrammingKits•TransgoShiftKits

StandardTransmissionParts•RebuildKits•BearingKitswithSyncroRings•GasketSets•Gears&ShaftsRebuilt Transmissions•StandardsClutchParts•Sach’s&ValeoClutchKits(New)•Forks•PilotBushings&Bearings•ClutchAlignmentToolsTransferCaseParts•Gasket&SealsKits•OverhaulKits•Chains

ShopSupplies&Tools•Additives•AssemblyLubricants•BuildersBenches•Lifts•PartsWasherSoap•RoughServiceLightBulbs•R.T.V.Black,Blue,Clear•TechnicalManuals•Tools&Equipment•Threadlock

Remember that Old-Time Service?

Whatever It Takes Does!!!wit-AD1.indd 2 10/4/11 3:32 AM

16 GEARS October/November 2011

silence, and finally the technician asks, “What O-ring?”

It’s not surprising that someone might have missed this O-ring; in fact, it’s probably the most commonly over-looked part during the rebuild on early Mitsubishi-type transmissions. That’s because it’s located inside the pump stator support, in a groove on the shaft. You can’t see it; you have to know it’s there. That’s why many technicians miss replacing it during a rebuild.

The O-ring is extremely thin and, over time, becomes very hard and brit-tle, which creates a leak in the torque converter release oil circuit. This may only cause an intermittent lockup code that won’t go away. Or there may be symptoms of a converter shudder, surge, or engine lugging at a stop.

The only way to replace the O-ring is to press the stator support shaft part way out of the housing from the sealing ring side (figure 2). It isn’t necessary to remove the entire shaft.

Be careful not to damage the seal-ing ring side of the support while pressing the shaft out: Use a driver that fits just inside the outer diameter of the shaft (figure 3). Using a driver that’s too large will damage the stator support.

Make sure you support the pump side of the stator support housing while pressing the shaft out. The support isn’t very thick and can easily crack.

The next trick is getting the O-ring out: Very often, the seal becomes extremely brittle and will break apart from the pick or scribe (figure 4). You’ll need to make sure you’ve removed all the pieces before installing the new seal.

Once you see the O-ring, you’ll probably remember that very thin O-ring you saw in the overhaul kit, but never saw where it belonged. Suddenly it’ll all become clear…

Use a GaugeIntermittent lockup codes can be

difficult to diagnose. One thing that can

make them easier is a pressure gauge. Not all vehicles will have a converter clutch pressure tap or apply and release pressure information available. Not so with Mitsubishi and Chrysler vehicles equipped with a KM-type transaxle: Figure 5 shows the pressure tap loca-tions.

Figure 3

Figure 2

The only way to replace the O-ring

is to press the stator support

shaft part way out of the housing

from the sealing ring side.

KM Lockup Problems Caused by a Hidden O-Ring

8tech1011.indd 16 10/4/11 2:57 AM

Precision transmission repair kits.Because your customers have other things to worry about.

The road to successSo keep your customers humming along. Spec only transmissionparts and repair kits from Precision International and give them thequality and reliability they expect plus the peace of mind you bothdeserve. For more information, call or visit us online.

What are you really selling your customers? Performance? Reliability?Peace of mind? The truth is, when someone comes to you with atransmission problem, they want it fixed quickly and cost effectivelywith as few worries and hassles as possible. That’s exactly whatPrecision International, the worldwide leader in quality-tested domesticand foreign transmissions, delivers.

State of the partWhatever make, model or year transmission you’re working on, we’ve gotthe best parts and kits to fix it. All are cross-checked against the latest OEMspecs (with changes noted and made). All are OE quality or better. And allare guaranteed to work. Plus, our huge inventory virtually assuresimmediate delivery.We also offer outstanding tech assistance and support, includingwww.transmissionkits.com – our informative website with videoseminars, question and answer forums, complete parts information andmuch more – that can help you troubleshoot and solve virtually anytransmission repair problem.

606-PRE-107 Gears Magazine Oct 2011 Ad Trim Size: 8.125” x 10.875” 4/C

www.transmissionkits.com

14 Todd Court Extension, Yaphank, NY 11980(631) 567-2000 • Fax (631) 567-2640Toll Free: 800-872-6649Florida Office:6790 Hillsdale Point, Boynton Beach, FL 33437(561) 734-2332 • Fax (561) 734-2375E-mail: sales@transmissionkits.comwww.transmissionkits.com

The Problem Solvers.

for the TF-70SC applications, with and without pistons.

K79900LOVERHAUL

KIT

NEWPrecision International K79900L Overhaul Kit

606PRE-8.125x10.875-4C-107:x 9/12/11 1:47 PM Page 1

precision hair.indd 2 10/2/11 1:31 AM

18 GEARS October/November 2011

Connect your pressure gauge to the torque converter pressure tap (fig-ure 5). Normal pressure should be about 50-70 PSI with the TCC released (29-34 PSI for 1985-86 models).

When the computer commands the TCC to apply, pressure should drop to 0-10 PSI. If this occurs, the system’s working correctly; the problem is in the torque converter itself. If pressure doesn’t drop when commanded, either the damper clutch control valve is stuck or the damper clutch control solenoid failed.

If the pressure’s low, you may have a leak at the O-ring on the stator sup-port shaft. The O-ring doesn’t appear in most parts catalogs or repair manuals; you have to know it’s there.

Other possible causes for torque converter-related codes could involve a worn stator shaft bushing (figure 6) or

the seal on the inner pump gear (figure 7). And don’t forget to check the seal-ing ring bore in the stator support for damage.

The KM stator support O-ring is an old, familiar problem for some; for others, not so much. And if you aren’t familiar with it, there’s no way you’re going to find it simply by looking around while the transmission’s on the bench. Of course, that’s why the ATRA HotLine is here: to put the experience of thousands of technicians right at your fingertips.

Figure 5

Figure 6 Figure 7

Figure 4

KM Lockup Problems Caused by a Hidden O-Ring

If the pressure’s low, you may

have a leak at the O-ring on the stator support

shaft.

8tech1011.indd 18 9/30/11 12:56 AM

N E W R E M A N

6 - S P E E D S .

Mop a r R e p a i rC o n n e c t i o n . c om

AS68RCFor Heavy Duty Ram Trucks with Cummins

6.7L Turbo Diesel62TEFor Minivans, Journeys, Sebrings and Avengers

At times it can be diffi cult to determine the authenticity of a part. But rest assured, Mopar’s new Remanufactured 6-Speed Transmissions don’t contain any aftermarket airbrushing or showy enhancements. Mopar® Reman 6-Speeds include these 100% Authentic features:

• New seals, gaskets, pump bushings and bearings

• Fully-validated and tested solenoids, valve bodies (with new covers) and balanced torque converters

• Mopar’s industry-leading 3-Year/100,000-Mile Nationwide Warranty, with competitive labor terms and hassle-free core returns

• Dedicated factory technical assistance (866-OE-PARTS)

• An extensive distribution network of over 2,300 Chrysler Group LLC dealers with same day/next day delivery capabilities

• True Blue Wholesale Rebates and Loyalty Rewards for installers, available through MoparRepairConnection.com

Quit fl ipping through pages of generic, salvage and rebuilt replacements. Contact your local Chrysler, Jeep®, Dodge or Ram dealer today for Authentic Reman Powertrain.

16000 0911 © 2011, Chrysler Group LLC. All rights reserved. Chrysler, Jeep, Dodge, Ram, SRT and Mopar are registered trademarks of Chrysler Group LLC. Printed in U.S.A.

68RFEFor Ram Trucks with Cummins®

6.7L Turbo Diesel

MORE QUALITY FEATURES THAN A CENTERFOLD.

16000_ATRA_GearsAd.indd 1 9/14/11 2:22 PMmopar.indd 2 10/2/11 1:33 AM