Rattling is driving me insane

[silverscottsk10]

Same thing
Terminology is not my priority lol

 

[79merriss]

Mine has cracked in the same spot 3 times. How many times has it happened? I'm going on my 4th and need to find a permanent solution.

 

[1low4x4]

I had never even heard of "flexplate" until I was like 27 years old and been around cars my entire life. Everyone calls them flywheel

 

[DoubleDingo]

I was corrected about it when I was 15 because I too used the term interchangably and didn't know any better.

Nowadays, in my current line of work we have to say the right terminology or it could cost us lots of money because the contractors use incorrect information on the plans or specifications to their advantage to rake in money.

Was only trying to point it out to him in case he went to get a new one and ended up with a flywheel instead of a flexplate. No harm, no foul.

 

[silverscottsk10]

I was corrected about it when I was 15 because I too used the term interchangably and didn't know any better.



Nowadays, in my current line of work we have to say the right terminology or it could cost us lots of money because the contractors use incorrect information on the plans or specifications to their advantage to rake in money.



Was only trying to point it out to him in case he went to get a new one and ended up with a flywheel instead of a flexplate. No harm, no foul.

I've spent last two years working on over the road diesels, they don't have flex plates lol

 

[DoubleDingo]

No they don't.

 

[Jarhead79]

Anyhow, if it isn't the flex plate, check the heat shield just under the cab, or if you have an automatic, make sure the speedo cable isn't hitting it, mine was tapping it while driving and bugged me, also had my rear parking brake cable hitting my exhaust, which was most annoying, now only rattle I have is the slider window because my exhaust is making it rattle! Lmao

 

[Georgeb]

I am interested to know the cause of the flexplate failures. It seems to me that flexing is causing it but why is there so much flex as to fatigue it to the point of cracking. Is there an alignment issue or balance issue that causes it? There must be a cause. And I have seen where several guys on here have had several failures on the same vehicle. Perhaps this has been discussed or should be a separate thread........

 

[chengny]

Mine has cracked in the same spot 3 times. How many times has it happened? I'm going on my 4th and need to find a permanent solution.

Are all your engine-to-transmission dowel pins in place?

The flexplate takes the place of the flywheel on automatic transmission vehicles. It bolts to the end of the crankshaft (near the center) and also bolts to the torque converter (close to the outer diameter).

Because perfect alignment of the engine and transmission are not possible, the flexplate is designed to absorb a certain degree of misalignment.


But as misalignment increases, the flexplate flexes more. Finally - at some point - this continued flexing eventually causes the metal in the flexplate to fatigue until it cracks (generally in the area of the crankshaft bolt circle).

Misalignment should be less than .008 of an inch and the less the better.

When the engine is manufactured, the back of the block is drilled and tapped to accept bolts. Holes are also drilled in the transmission bell housing that the bolts can pass through. These bolts allow the engine/transmission to be coupled together. But, because the bolt holes in the bell housing are larger than the attaching bolts, this bolting arrangement does not precisely align the two components.

To provide a better degree of alignment, the engine block is fitted with precision dowel pins. Corresponding holes are also drilled in the transmission bellhousing that accept the pins, and are sized to fit to them very tightly.

This series of dowel pins and precisely drilled holes are what hold the engine and transmission in alignment.

Bottom line: The dowel pins must be present to assure proper engine/transmission alignment - during assembly - and also to maintain that alignment while the vehicle is driven.

Next time it happens- and the transmission is out, check the crankshaft mounting hub for excessive run-out.

Check that all motor and transmission mounting points are solid and secure.