What's the story on billet flex plates?

[Extended Power]

Only seem to have a choice of two places: ATS or ELite Diesel Engineering.

Heard stories that a flex plate has to have the ability to "flex"...or it can cause internal damage to the transmission.
Don't think a billet anything is supposed to flex...
Should I just install another stock flex plate? (Held up so far...)

 

[windrunner408]

FWIW, Suncoast also sells a flex plate. I'm not sure if it is the same one that Elite sells or not. Just saw it one day while perusing their site.

Interesting topic for sure.

 

[Extended Power]

The new SFI rating is 29.3 (for high hp diesels)
The ATS looks like its still the old SFI rating. 29.1
Elite has been approved on the new rating...which s a bonus.

 

[Extended Power]

Ordered one through JD at Elite Diesel Engineering this afternoon.

Thanks JD!

 

[Derkperk]

So billet is the way to go?

 

[Extended Power]

...idk...but I needed a new one, and I try to improve on anything I ever have to replace.
Moving the "weakest link" all the time.

 

[strokin6L]

You said the stock one held up so far... so why change?

 

[Extended Power]

Stock one.is.not SFI 29.3 approved.

 

[onebadcoastie]

What is its rating and what exactly are you doing that requires the 29.3 or is a a "feel good" thing?

 

[Extended Power]

Here is what Elite's add says about it...

...gonna have to ask about the free shipping for all items over $100.00

 

[onebadcoastie]

That's cool and all but I'm one of those who wants to know what 29.3 vs 29.1 means? I tried searching for it on SFI page but got bored after a few minutes trying to find it and detoured to the forum. It's cool Elite's product is at the top in terms of SFI safety but I don't know what 29.3 means compared to 29.1. lol. Maybe someone from Elite can jump in here and explain that??

 

[Mark Kovalsky]

Heard stories that a flex plate has to have the ability to "flex"...or it can cause internal damage to the transmission.
Don't think a billet anything is supposed to flex...
Should I just install another stock flex plate? (Held up so far...)

I've wondered the same thing.

A flex plate MUST flex because the torque converter will expand at higher RPM. It gets wider axially (i.e., it takes up more room between the engine and transmission.) If the flex plate is too stiff the converter will push outwards, creating thrust on the engine's crankshaft and the transmission's pump. The thrust bearings on the crankshaft will be destroyed, Usually this happens before the pump is destroyed, but you could destroy both.

Why a billet flex plate? You got me. I have wondered why such a thing exists and have not been able to come up with a reason, other than whoever makes them wants to make money.

 

[Derkperk]

Thanks Mark. Nothing better than a transmission question answered by you!!:thumbsup:

 

[Extended Power]

This is to Mark Kovalsky:

Since you are a former Ford transmission engineer, maybe you can answer this for me...

Why is it that when I coast up to a stop sign, traffic light, whatever...in neutral, why does the transmission slam so hard the rear tires shake just before the truck comes to a complete stop?