schmendog

iTrader: (10)

So I thought I ordered the wrong TCI flexplate (PN 399754). After it was already shipped, I read in several places that what I should have needed was PN 399753 for my th400 from FTI, and engine. I recieved it today, and just to see what would happen I bolted the converter to it. It fits fine. According to the TCI website this one I ordered is actually supposed to be for a 4L80?

Any reason I can't run it? Not sure if the pilot hole in the center is different or anything?

forcd ind

iTrader: (7)

The diff used to be one came with just the FW, the other came with FW, bolts, and spacer-now it looks like they both come with everything, just one has a smaller(or dual) bolt pattern-I have been meaning to call them about this

Circle-D_Brian

399754 flexplate is 6 on the 11.5" pattern. This is the 4l80 pattern. TH400 pattern is usually 3 on the 11.5. So that's why it fits. The pilot is most likely standard GM length on your converter so you would use the extender to engage the crank. The 399753 is a dual pattern flexplate with 3 on the 11.066" (LS) and 3 on the 10.75" (LT). Something we have learned along we way is to grind the powder coat off the mounting surface of the flexplate. This can cause loose converter bolts over time if you don't.

-Brian

schmendog

iTrader: (10)

Thanks for the help Brian. So there's no issue running the 4L80 flexplate with only 3 of the mount holes being used I assume (bolting up my th400). My converter has two sets of bolt holes, one must be the 11.5 since it fits this flexplate, the smaller set of bolt holes must be the 11.066"

Ive got everything back together on the car, but didn't use the spacer. I need to determine if I need to use it or not, based on what your saying. With the trans in the car and converter bolted to the flexplate, I can visually see that the pilot is into the flywheel, but I cant tell how far into the crank it is. I didn't measure before hand, but I did lay the converter on the flexplate on my workbench, and the pilot extended all the way through the flexplate, and about 1/4" out of the backside. I assumed that was normal, but hopefully I wasn't wrong. How can I determine if I need to use that spacer or not?

Circle-D_Brian

You may have the LS pilot on there and may not need the extender. Verify it engages the crank and you'll be good to roll.

-Brian