What causes Torque Converter Shudder

Torque converter shudder is usually caused when there is a buildup of contaminants in your automatic transmission fluid. This is the way it happens: let’s say there’s a buildup of deposits somewhere in the transmission that is freed up by the detergent properties of the automatic transmission fluid. And, let’s say further that the contaminants begin recirculating throughout your transmission as they are likely to be microscopic to small in size so they will easily get through things like the valve body and they will likely get by the filters because they are too small, at this point.

As time passes on and the contaminants continue to circulate they begin to fall out of the transmission fluid again, this time on other parts of the transmission, say a gear or a clutch pack or, perhaps, on an impeller turbo vane. Over time, other contaminants are attracted to the new buildup like metal is attracted to a magnet (look at the magnetized screw in your transmission pan for confirmation the next time you change fluid. If there are small shards on it, the plug is doing its job of taking metal out of the fluid and holding it safely out of the way).

Now, let’s say there’s enough contaminant buildup on one of the parts mentioned earlier, let’s further say, it’s an impeller van, and so what happens when the buildup becomes large enough to effect the part? The part slips briefly causing a shudder through the whole transmission. It is easy to feel as the vibration goes through the entire structure of your car. (The reason this happens is the way cars are built today. Car frame members are attached to one another throughout the body of the vehicle. This increases tortional strength or resistance to breaking and shearing. It also increases intrusion protection. The downside is that if there’s a resonant vibration anywhere in the frame, it is felt in all parts of the frame equally.)

The funny thing about transmission shudder (torque converter shudder) is the quick nature of the whole thing. Usually, the buildup, when it reaches the stage where it can become a nuisance in the transmission, breaks down and goes away as quickly as it appears. It may take several driving cycles as the problem breaks down for it to go away fully, but it usually does. Note that this type of problem can happen anywhere in the transmission. Sometimes, buildups can become troublesome. In that case, you’ll have to employ a quick fix.

The fix is relatively easy. Swap the old transmission fluid and filter. (Don’t rely on a drainage and replacement; you will have to drop the transmission pan to get all of the automatic transmission fluid out as well as to access to filter). Then, replace it with fresh fluid and a fresh filter. If the problem repeats, repeat the process. Yes, it is costly in terms of transmission fluid and filters, but, think of it this way. By paying $30 to $50 for the proper fluid and another $35 for the filter, you are ultimately saving because, even if you invest $200 in new fluid and filters, you are saving yourself about $2,800 in major work to the transmission.

Here’s an important thing to note: while some authorities say it’s best to remove all the fluid by using a blast of compressed air on one side of the transmission and draining things off, it actually can cause damage. If a part is dislodged or a major clump of something breaks off and travels through your transmission along with the rest of the evacuating fluid, it may cause damage downstream. All it takes to remove the total amount of fluid is patience. First drain the fluid, let the vehicle rest as all of the fluid will drip down to the pan and second remove the pan over a bucket to keep the floor clean. That’s it and your transmission is safe.

Read more: How a reader fixed shudder himself