It takes a lot of money to develop a transmission from the ground up. That’s why General Motors and Ford teamed up in the early 2000’s to create a brand-new 6 speed automatic transmission that both companies could use in FWD and AWD vehicles. The GM 6T75 transmission is very similar in design to its Ford 6F counterpart, but each company used its own specific set of internal components. One part that is known to fail in the General Motors 6T75 are the wave plates, which can almost completely destroy the transmission and leave owners with a massive repair bill.
What Transmission Do I Have?
6T75 which waveplate fails?
6T75 wave plates are metal discs that are sandwiched between the clutch discs on a drum. There designed to act as both a cushion during gear changes, as well as give the friction material on the clutch discs something to grab onto. If one of them shatters, the fragments can completely destroy the clutch drum. The wave plates on the 6T75 3-5-R drum are the ones most commonly known to fail. When that happens, drivers will experience serious issues when the transmission shifts into 3rd, 5th or Reverse.
Symptoms of 6T75 transmission wave plate failure
Harsh 2-3 shift
3rd gear failure
Harsh 4-5 shift
5th gear failure
Harsh reverse shift
Reverse gear failure
P0776 diagnostic trouble code
What to do when 6T75 transmission waveplate fails
Unfortunately, knowing which 6T75 waveplate fails will not keep it from happening. Of course servicing your transmission at the recommended intervals, and being gentle in your driving can help extend the life a little bit. But that alone will not prevent the inevitable. The problem stems from a design flaw, and possibly a manufacturing flaw with the 3-5-R wave plates themselves. GM did update the design in 2009, however that didn’t entirely solve the problem.
When 6T75 wave plate failure occurs, the splines (or teeth) on the clutch drum will become damaged and sort of filed off. The drum itself may also crack as well. The metal shards from the broken waveplate can also get circulated throughout the transmission and cause catastrophic damage to other components. At this point, not only will the 6T75 3-5-R clutch drum need to be replaced, but all of the major components inside the transmission will need to be carefully inspected for signs of scoring, cracking and other associated damage. So you really only left with three logical options.
Buy a Used 6T75 Transmission
If you wanted to save some money, you could go down to the local junkyard and buy a used 6T75 transmission. But keep in mind, it’s coming out of a wrecked otherwise totaled vehicle. This means you don’t know how it was maintained, if it was abused or what the condition of the internal components really are. So you have no way of knowing if you are going to get 30 miles or 30,000 miles out of it. And that replacement warranty you get from the junkyard isn’t going to cover the labor cost that you’ll have to pay a mechanic to install a replacement transmission if the first used 6T75 breaks.
Buy a Rebuilt 6T75 Transmission
If you don’t want to risk future problems from a used transmission, then you might consider buying a rebuilt 6T75 transmission from a mechanic or transmission shop. In this scenario, they basically take your existing transmission and replace all of the main seals clutches and other “wear parts”. A rebuilt 6T75 transmission is obviously better than a used one. However, most mechanics and repair shops don’t have the experience and equipment to inspect every single component for signs of damage, warping and any other condition that might cause the parts to fall below the original manufacturer’s specifications. Plus that rebuilt transmission warranty may only be honored by a few local transmission shops.
Buy a Remanufactured 6T75 Transmission
Unlike a rebuilt 6T75 transmission, a remanufactured 6T75 transmission has been completely disassembled and then re-engineered on an assembly line. Each component is inspected, cleaned, and reconditioned by a technician that specializes in that particular stage of the process. All of the critical elements including the case, gears, valve body, shafts, pumps, and the torque converter are tested to ensure that they meet original equipment (OE) tolerances and standards. And any part that doesn’t meet the original specifications is either machined until it does or replaced with a brand new part.
Once all of the components meet specification, they’re sent down an assembly line and the transmission is reassembled. The reman 6T75 transmission is then put on a dyno machine which simulates real-world driving through a software program called C.A.R.S. This allows any leaks and imperfections to be discovered and dealt with before the transmission leaves the factory.
Another benefit of a remanufactured transmission are the updates and upgrades it receives. Once a certain vehicle model has been in production for a few years, small issues with the design are discovered and solutions are implemented. It may be more robust friction materials, stronger seals, stiffer springs, or number of other things. These changes are immediately applied to the new models still in production, and Technical Service Bulletins (TSB’s) are sent to dealers so they know how to deal with problems that may arise. Transmission remanufacturing companies like Street Smart Transmission also get these TSB’s, and implement the changes on their assembly line as well.
What Transmission Do I Have?
