Torque Converter | Mercedes | 722.6 & 722.9 (272mm & 290mm), 5 Speed, MC-18, MC-19 | MC-18
Mercedes transmissions have frequently suffered from a shudder and cold-stall condition. Naturally this is blamed on the converter. The consensus, after a thorough investigation, is that there is no single cause. We list here some possible causes and fixes. The number one cause is using the wrong transmission fluid. Mercedes supplies different (costly) fluids for each type of unit. Trying to cut costs by substituting with conventional fluids will definitely affect the shudder condition among other symptoms. Leakage of anti-freeze into the transmission via the radiator will definitely cause the problem. Vehicle manufacturers require triple flushing of the transmission to assure thorough removal of the antifreeze. This is necessary to assure complete removal of the contaminant. Some rebuilders replace the lockup solenoid with every converter replacement. Correction of the condition may merely be anecdotal. In an extreme case, replacement of the solenoid block and all the solenoids is the fix. The block is made of plastic and can easily cause the problem. This is the factory approach and it is very costly. Complete factory valve bodies are also a way of dealing with stubborn cases. If the problem is isolated to the converter, first to be blamed is the type of friction plate used. Experienced rebuilders know that the particular brand or make is not the root cause of shudder, various rebuilders attribute the condition to internal leakages and have applied leak fixes in different locations in the converter. Maybe the condition is corrected by one or more of them. No one can be quite certain of the exact cause. At present, the most successful correction is the installation of Tri's. Spring loaded, space steel plate kit, intended to deal with shudder and cold stalling. The concept is to "bypass" the various conceived issues. Major rebuilders install them in all rebuilds successfully. This is the simplest "drop in" fix, highly recommended and accepted. An added benefit is the cost-effectiveness. Relevant part numbers are: HX-23-13K, containing one notched steel plate and ten 0.310“ long springs”, and HX-23-15K containing two notched steel plates and ten 0.510“ long springs”. Genuine Tri-component friction plates have long been a proven companion, favorite among rebuilders.