In automatic vehicle, there is a metal disc connecting crankshaft with torque converter, which is called flexplate. Thus, flexplate proves to be flex-shock device, between engine crankshaft and torque converter.
Flexplate is a steel circular disk with holes. It should be balanced to improve and smooth running. Hence, flexing allows it to respond to tiny differences of alignment, between engine and transmission.
In fact, flexplate has two components. Flexplate and ring gear, which is installed to the outside edge of the plate.
The starter motor engages the ring gear to start the engine. You usually need to remove it. However, if you need to remove the flexplate, it must go back in same way, since balancing is vital.
What can make flexplate fail
1. Engine or torque converter is not balanced.
2. Starter drives badly, which can make teeth or ring gear wear quickly or even break off.
3. When engine is running and starter is engaged, teeth can break as well.
4. It is failed to torque the bolts, as proper specifications and sequence.
5. It is failed to use required starter shims.
6. The parts’ quality is not good.
7. Dowel pins miss.
A loose bolt on flexplate or crank between bolt holes can lead to ratting or knocking sound, which is similar to bad connecting rod and is misdiagnosed.
As time goes by, flexplate will crack, which will lead to its swing. Hence when engine is running, there can be rhythmic clunking or grinding noise.
In fact, a misaligned flexplate can make engine run smoothly as well. Thus, if you suppose there is a flexplate issue, you need to inspect carefully.
If you hear any sound from transmission bell housing when engine is idling, the sound illustrates flexplate issues. Some bell housings have inspection port. If there is, please remove the inspection port and use light to inspect the flexplate visually.
A warped flexplate can not engage with starter motor properly. Hence when starting the engine, you can listen rhythmic bogging down of the engine. As a result, ring gear’s teeth can be damaged, which would lead to grinding sound.
Ring gear issues can also damage starter motor. Thus, if you would like to replace your flexplate, you’d better inspect starter as well.
Cracked flexplate can also indicate other issues. Hence, if misdiagnosed, it will take place again and even damage the transmission. The factors which can cause flexplate to crack, can lead to transmission issues as well. What’s more, damaged and leaking front seals as well as front transmission pumps are frequent symptoms.
If engine makes noise when starting, this illustrates starter failure or flexplate’s broken teeth.
In a word, if you need a new flexplate, that is a big issue, since transmission must come out to replace flexplate. For example, you need to pay $1500 or more for flexplate replacement.
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