Diesel Truck TransmissionRepair in San Diego
Automatic and manual transmission diagnostics, clutch work, and full rebuilds for Allison, Eaton Fuller, Volvo I-Shift, and Detroit DT12 transmissions. Every job starts with an ECM scan — we identify the exact failure before recommending repairs.
Serving San Diego's owner-operators and fleets from our Otay Mesa shop. 1-year warranty on all transmission work.
Automatic. Manual.Automated Manual.
Different transmission types have different failure modes. We service all three — and know the quirks of each platform.
Automatic
Allison 3000 and 4000 series are the most common automatic transmissions in commercial diesel trucks. Torque converter issues, solenoid failures, valve body problems, and overheating are the typical failure points. We read TCM fault codes and test shift patterns before recommending repairs.
Manual
Eaton Fuller transmissions — 10, 13, and 18 speeds — are built tough but wear out over miles. Clutch wear, synchronizer failure, bearing noise, and hard shifting are the most common complaints. We inspect and test before recommending clutch replacement or a full rebuild.
Automated Manual
Volvo I-Shift, Detroit DT12, and Mack mDRIVE are computer-controlled manuals that shift themselves. Actuator failures, clutch wear adaptation issues, and software faults require specialized diagnostic tools — which we have. These aren't transmissions you can fix at a general shop.
Transmission Issues We Fix Daily
Hard or Delayed Shifting
Slow shifts, harsh engagement, or refusal to shift into certain gears. Could be low fluid, worn clutch packs, solenoid failures, or actuator issues on automated transmissions.
Slipping & Power Loss
RPMs climbing but no acceleration. Torque converter issues on Allisons, worn clutch on manuals, or clutch adaptation failure on I-Shift and DT12 platforms.
Transmission Overheating
Fluid breakdown, clogged cooler lines, or internal friction from worn components. Overheating causes cascading damage if not caught early.
Clutch Wear & Failure
Glazing, hot spots, and worn friction surfaces. We measure remaining clutch life via ECM data on automated transmissions and physical inspection on manuals.
Noise, Vibration & Grinding
Bearing wear, gear tooth damage, synchronizer issues, and input shaft problems. We identify the source before opening the case.
Check Trans Light / Fault Codes
TCM fault codes across Allison, Eaton, I-Shift, and DT12 platforms. We read and interpret transmission module codes alongside engine ECM data for complete diagnosis.
Common Questions
How much does a diesel transmission rebuild cost in San Diego?+
Transmission rebuild costs vary by platform and extent of damage. An Allison rebuild is different from an Eaton Fuller rebuild. Call us at (619) 848-0459 for a diagnostic — we'll identify the issue and provide an accurate estimate.
Can you service Volvo I-Shift and Detroit DT12 transmissions?+
Yes. I-Shift and DT12 require specialized diagnostic software and calibration tools that most shops don't have. We diagnose actuator failures, clutch adaptation issues, and software faults on both platforms.
How do I know if my clutch needs replacing?+
Symptoms include slipping under load, difficulty engaging gears, shuddering, and a burning smell. On automated manual transmissions, the ECM tracks clutch wear percentage — we can read this during a diagnostic to tell you exactly how much life is left.
Do you rebuild Allison transmissions?+
Yes. We rebuild Allison 3000 and 4000 series transmissions including clutch pack replacement, valve body service, torque converter rebuilds, and full unit overhauls. Every rebuild comes with our 1-year workmanship warranty.
Should I rebuild or replace my transmission?+
In most cases, a rebuild is more cost-effective than a full replacement. We'll assess the damage during diagnostics and recommend the option that makes the most sense for your truck and budget.
