1998 Z28 with 4l60e with LS1. I have a PTC converter 3400-3600 stall. In checking clearances, we are finding .334 between the flexplate and converter pads. The only tolerance we have found says that min and max is .060 and .187. Which would mean we would need a .2105" shim between the torque converter and the flexplate, which would be center of the clearances given. Is our thinking correct?

 

correct

 

Stock Flex-Plate?

Good time now to replace with a new SFI certified Flex-Plate (should be slightly thicker as well).

 

Yes stock plate. on a time limit though as I'm using a friend's shop. It was sort of an on the whim deal so unfortunately I won't be upgrading that. Wouldn't machined washer (s) be the best? Doubling up or tripling up seems like it may not be perfectly square.

 

yes, I will bring a digital caliper to a hardware store and get 3 washers that a very close because even same washers vary in thickness bit

 

Perfect. What did you do for bolts?

 

Just bought a little longer grade 8 bolts from the hardware store. The bolts to flex plate is not a high stress point so you will be plenty good with bolts from the local hardware store.

 

The hardware store is fine... just stick to only using hardened fasteners though. Grade 8 (Bolts, Washers, and Nuts) preferably.
In your situation... Metric bolts should be marked as 8.8 , 10.9 , or 12.9 ...

Note: a quick way to establish that the spacing of the flex-plate and torque-converter mounting pads...
Is to grab a 1/16" drill-bit (minimum required spacing) and a 3/16" drill-bit (maximum required spacing) to stick in between the mounting pads.

1/8" is roughly ideal for the spacing... use washers as needed.

 

Sorry, I forgot to say...

Grab bolts that are 10.9 or 12.9 ideally.

 

This was my plan actually. Thank you.

Also, thank you to everyone else chiming in with tips. I appreciate it.

 

If you plan to space the converter that much make sure you are not spacing the converter out of the crank to where it is not engaged with the crank. Unless the converter is purpose built a certain way then usually an install requiring so much in spacers has another issue that needs to be addressed(ie: backwards flexplate, wrong flexplate, wrong conv setup, not setup correctly for the crank length being used etc.)

Just food for thought before you go stabbing that transmission up to the block again... If you want to double check pilot engagement with the converter try to hold the converter up to the flexplate(no trans) with the washers/spacers (or equivalent) and see if you can slide the converter around on the flexplate, if not then the converter is being held on center by pilot, if you can chances are you are pilot is not engaged.

 

Great info, thank you! Previous owner had to shim as well and it was in the same trans. I will definitely take your tips to verify all is well before running it.

 

Definitely double-check that the pilot of the torque-converter is both supported and centered by the crankshaft.
If not... then FTI can make you a converter that would solve the problem.

Adapters/ spacers do exist, but they are not always ideal depending on spacing and fitment concerns.
Many, many people give this zero thought at all...

Ignoring this, can cause horrible vibration and damage to occur.

I would say that the damage done from this would be similar to:
Removing the harmonic-damper and one piston from your engine... and running it that way! LOL!

 

That certainly wouldn't be ideal lol. I do know the previous owner shimmed with 3 washers because he needed just a hair over 1/4". I'm just under 1/4" so I should be OK (to be middle of the spec). But again I will definitely check it all very carefully when assembling it all back together.

 

Well everything seems to be working as intended. It really rips out of the hole.. however, after my third trip I got a p1870 code. I had the cruise set at roughly 58mph for a few miles and the code popped. I do have an Aeroforce Interceptor with a few options for TCC. Any advice on what to look for and what numbers I should be seeing? I'm pretty new to transmissions. It has a PID for TCC Slip and TCC Duty. Could be some others in there somewhere I could turn on, not really sure.

 

Also I had Frost tune it.

 

I cleared the code and it returns seemingly every other trip or so. Everything seems mechanically flawless. Runs fantastic.

 

Frost said its not the tune but that its a trans valve body issue. Which to be honest I didn't want to hear. The last 25K miles have been flawless and its still shifting flawlessly today. Theres no way installing the converter is just a coincidence IMO. Ive never seen that code in my life, and it just shows up right after the installation. Any experts please chime in on where to go next.

 

Common issue. There is a video also in that link to avoid having to drop the valve body. Messy but straight forward job.
https://www.fitzall.com/supportDetail.php?A74741Q-188

 

Wow thanks Cayenne. You've been such a huge help for me the last couple months. Is the car OK to be driven until I do this? With the code cleared, of course.