Circle d torque converter in a 4l80e/lq4

[Slowguy]

So I’m ready to plop the 6.0 onto the frame. The only thing that’s holding me up now is that I can’t get a straight answer from circle d (or I’m just too ignorant to comprehend what they are telling me).

I bought this converter: http://www.circledspecialties.com/4l80-hp-series-278mm

After I get it they tell me I can’t use my stock flex plate and that “any” plate from a 4l60 will work. I ask the specifically and they continually point me to new aftermarket $240-500 options. Had I known I’d need a $250 flex plate i’d Probably not done the converter.

Can anyone tell me specifically if there is a used plate I can buy? 5.3/4l60 plates are a dime a dozen on eBay but I want to make sure I’m getting something that’s compatible with both this circle d converter and my lq4 crank. Also, aren’t the plate balanced with the rotating assembly at the factory? If my engine is done, how would a used plate affect the balance?

[ls1nova71]

I had an identical set up in my Blazer, 6.0/4l80e with a Circle D converter , not sure if its the exact same one, but the price seems close, and I had to use a 4l60e flexplate. Worked fine, they aren't balanced by the flexplate as far as I know.

[1971Stepside]

I'm curious now myself. When I spoke to Brian Tooley they told me that the Circle-D would bolt to my existing flex plate. I know there are some on Summit that are reasonably priced.

https://www.summitracing.com/parts/atp-z270

My stock flex plate is for a 4L60, so hopefully this isn't a surprise. Keep us posted on what you come up with.

[Slowguy]

Maybe my ocd is kicking in again but I tend to overthink everything. The only reason I ask about the balancing in because I think the aftermarket ones are typically unweighted. And, correct me if I’m wrong, stock plates usually have a little weight added to them when the rotating assembly is balanced. My logic then tells me it might be better to remove that weight when using a used plate from engine A to install on used engine B?

[mongocanfly]

I've got a 5.3/4l60 flexplate I just pulled off...there's no counterweights...
I've also got a 6.0/4l65 flexplate....no counterweights.
There's no difference between them..
Except
The 5.3/4l60 has 3 small holes drilled around the outer edge...

[Rickysnickers]

Seems odd that it wouldn't work with a stock flexplate when it says this on the website, "ONLY fits the dished LS style flexplate."

[ls1nova71]

This is being made way harder than it needs to be. You just need a 4l60e flexplate.

[1971Stepside]

Here is the response I received from Circle-D when asking about my flex plate.

You can use the stock, 4L60, flexplate when you install one of our 278mm HP Series converters. For Pro Series, it will depend on which bolt pattern the converter was built with.

[Dustytrix]

True just use the 4l60 plate, I have same setup and love it.

[indymachinist]

Use stock 4l60 flex plate. They are cheap if you dont have one. No, they are not balanced with the engine.

No problems here... only over thinking.

[RedRider]

Great info, just bought the same converter and was wrestling with the same issue. Thanks!

[Slowguy]

It looks like the flywheel mates with the holes in the crank just fine (as was expected) but what did you do about bolts? I assume I need to purchase some 4l60e flywheel bolts because the 80e bolts are too long. There is a spacer/shim in the 80e flywheel that the 60e does not have.

[ls1nova71]

Just get some 4l60e bolts, you wont need the spacer.