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Remanufactured GMC C3500 Transmissions 

Remanufactured GMC C3500 Transmissions 

From hauling heavy loads to pulling heavy trailers, the GMC C3500 is no stranger to hard work. However transmission problems with the 4L80E, 6L90 or Allison 1000 can bring things to a screeching halt. So let’s figure out if installing a remanufactured GMC C3500 transmission is your best option. 

Common GMC C3500 4L80 Transmission Problems  

Erratic Shifting 

Since this was an early electronically controlled transmission, many shift problems/Check Engine Lights can be attributed to a failed input/output speed sensor, or throttle position sensor. 

Slipping Between Gears/Failure to Shift 

The 4L80E uses a total of 8 solenoids to actuate gear changes, and activate the lockup torque converter. These little plungers are used to control the ATF fluid pressure, and they’re activated by an electric charge that passes through a coil of wire that’s wrapped around the plunger mechanism. If excessive vibrations or an electrical surge causes the solenoid to short out, you’ll start to experience serious problems. 

Overheating 

The primary function of automatic transmission fluid is to remove heat from the moving parts inside. If you’re towing/hauling a heavy load and the radiator cooler can’t properly cool the ATF, the transmission will overheat, causing significant damage to the valve body, seals, clutches, bands, and other parts. 

Common GMC C3500 6L90 Transmission Problems  

Reverse Fails to Engage

If you’ve selected Reverse and your vehicle still won’t move, then it’s possible the park prawl (the metal piece that stops your vehicle from rolling), or one of the clutches has become damaged. 

Slipping Between Gears

If you experience slipping in reverse, or between 2-3, then it’s very likely that the 1-2-3-3/5-R drum has developed a crack, which will require an entirely new drum and bearing. 

Slipping in First Gear

If you have difficulty getting your vehicle to move from a dead stop, then it’s possible that one of the solenoids is stuck in the ‘off’ position, or there’s a problem inside of the valve body. 

Common GMC C3500 Allison 1000 Transmission Problems  

The Allison 1000 works by the concept of adaptive learning. By comparing the average shift time against preprogrammed ideal benchmarks, the transmission can make shifting more efficient. However, rapid changes in speed or sporadic acceleration/deceleration prevent this process from occurring and the gear and valve assemblies cannot adapt to fluid pressure increases. 

Another key problem can be an improperly lubricated C3 clutch. The way the transmission is set up, this clutch does not get any fluid unless it’s done directly. It reduces performance due to wear on the clutch pad and can lead to failure. 

Five-speed Allison 1000 transmissions have problems with the C1 and C2 clutches. The pistons that cause these clutches to engage were designed slightly off center, leading to a lack of even pressure and in turn to uneven wear and early failure of the clutch plates. 

How to Solve GMC C3500 Transmission Problems 

Solution A: Buy a Used GMC C3500 Transmission  

Going to the local junkyard and picking up a used GMC C3500 transmission might seem like the cheapest and fastest option. But you need to consider the fact that you don’t know what the actual shape of the internal components are. It could very well be on the verge of transmission problems of its own, which would leave you in the exact same predicament that you’re in now. And that 30 – 90 day junkyard warranty probably won’t cover labor charges to install the replacement transmission if something goes wrong. 

Solution B: Buy a Rebuilt GMC C3500 Transmission 

Getting a rebuilt GMC C3500 transmission would probably seem like a better idea. However, a lot of mechanics and transmission shops will only rebuild your GMC C3500 transmission back to its original factory specifications. Which means that all of those factory design flaws are still going to be in–play. And that rebuilt transmission warranty might only be good at certain shops, which could do you no good if you have transmission problems while you’re traveling. 

Solution C: Buy a Remanufactured GMC C3500 Transmission 

If you want to get the most service life out of your little luxury SUV as possible, then you really should consider a remanufactured GMC C3500 transmission from Street Smart Transmission. Each one is completely disassembled and re-remanufactured, so nothing is left to chance. They’re also modified to correct the factory design flaws, which will greatly extend the service life. Plus, you get a 3-Year/Unlimited Mile Nationwide Warranty. This will cover parts and labor charges at any licensed repair shop in the Continental United States, giving you a lot more flexibility and coverage.