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What does it mean for an A/t to shudder besides the vibration and feeling? Is it temp dependent? Is it fluid breakdown? Materials clogging up fluid lines.
What is a tq shudder?
- Thread starter proveitwithdata
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The torque convertor clutch is slipping as it tries to engage / lock up is the shutter you feel. Lots of different causes. My daughters 95 Camaro V6 shook when it went into overdrive. I thought for sure it was the TQ. Nope bad spark plug that wouldn't fire under load. Good Luck!!!
I believe this occurs when a certain part of the transmission fluid additive package is depleted or becomes ineffective through use.
What part gets depleted?
2015 to 2019 C7 Corvettes have somewhat of a history of transmission shudder. It is easily fixed in most cases with what is called a triple flush of the transmission and usually costs about $750.00. It's not a guaranteed fix however in most cases it works well in the A8 automatic transmission which is also used in many other GM vehicles.
I imagine the shudder is caused by external to the torque converter issues. Older transmissions don't have converter lock up per se other than their fluid dynamics. Newer transmission TC's have a lock up feature but I am thinking the lock up is controlled external to the TC through the hydraulic circuit. Worn out fluid is probably not a smoking gun unless the valving has been compromised by filth etc external to the converter. Need an auto tranny expert to chime in. When is it shuddering? May be compromised steels/friction discs in that gear drum. I remember a friend's Chevrolet compact in the early 1980's that had a weird shudder going into overdrive and locking into gear. It did it from brand new and was widely known by consumers. GM said it was normal at the time.
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This is how I understand it:
If the clamping force for a TC lockup clutch diminishes across it's life (usually due to TC clutch wear,) eventually there is insufficient clamping force to maintain static friction (lockup), and it will slip under acceleration/load. After it breaks static friction, the torque converter begins spinning differential speed and acting as a fluid coupling again, gradually taking load as it increases in differential speed. Once the TC starts bearing this load, the lockup clutch (which never disengaged any clamping force) eventually has sufficient force to regain static friction. Once it regains static friction, the TC slows to a stop, eventually putting full load on the clutch, and the cycle starts all over again. This cycle happens in fractions of a second, and feels like a vibration to the driver. Some software in ATs will recognize stick-slip shudder and disengage the lockup clutch for a duration, then reengage, just in case it was anomalous (ie, not due to insufficient clamping force) and to protect against clutch glazing and wear.
If the clamping force for a TC lockup clutch diminishes across it's life (usually due to TC clutch wear,) eventually there is insufficient clamping force to maintain static friction (lockup), and it will slip under acceleration/load. After it breaks static friction, the torque converter begins spinning differential speed and acting as a fluid coupling again, gradually taking load as it increases in differential speed. Once the TC starts bearing this load, the lockup clutch (which never disengaged any clamping force) eventually has sufficient force to regain static friction. Once it regains static friction, the TC slows to a stop, eventually putting full load on the clutch, and the cycle starts all over again. This cycle happens in fractions of a second, and feels like a vibration to the driver. Some software in ATs will recognize stick-slip shudder and disengage the lockup clutch for a duration, then reengage, just in case it was anomalous (ie, not due to insufficient clamping force) and to protect against clutch glazing and wear.
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So when a vehicle is in overdrive, going up a hill to the point of the where the engine is needs to downshift or risk inducing lugging, and it starts hesitating/bucking/shuddering is that the torque converter slipping thats being felt?
Its caused by clutch plate slipping due to worn transmission fluid, in worse case it would need a torque converter but if the oil is exchanged at early stage, then the issue usually goes away. The best way to find out is to do a drain and fill and add a tube of lube guard, if issue improves, thats good news and time to do a fluid exchange.
Probably not. Likely ignition related misfire
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