Interesting Torque Converter Measurements for 4R70W Converter

[MikeStang 247]

Came across all my old measurements from my stock converter to my new converter for my 4R70W after I wiped out a thrust bearing on my 408 and figured I would share them since the stock converter was deemed the problem.
The thrust failure was NOT a result of converter ballooning, but rather converter hub length and crank pilot hub depth "or lack there of"
Anyhow here are the measurements for comparison.

Abbreviations will be as follows

OC = Old Converter
NC = New Converter

1. Difference in over all height of converters measured from the tip of pilot hub to the end of the input on converter was .085 with the new converter being the shortest.

2. Overall depth of converters measured from inside of converter to outside lip of input shaft area... basically stuck a Dial caliper in the converter and extended it to the bottom inside of both converters and measured to the end of the input shaft area on each converter.
OC = 7.435
NC = 7.107
Delta = .328

3. Depth from the mounting pads to the edge of bell housing after converter was fully seated.
OC = .935
NC = 1.094
Delta = .159

4. Distance from mounting pads on converter to the tip of the converter pilot snout.
OC = .897
NC = .884
Delta = .013

5. Distance from Tip of Pilot Hub to edge of bell housing after seating both converters.
OC = .055
NC = .249
Delta = .194

6. Pilot hole depth for Old Crank that burnt the thrust was .600
Pilot hole depth on new crank is .590 so its a bit shallower and so far as I can tell all is going okay.

Anyhow not sure if these measurements will help anyone but there they are for future ref.

Basically if your going to run a stock converter behind a 302/351 Combo be sure that your converter seat depth from the mounting pads to the edge of the bell housing is at least 1", if not then you need to be sure you have the converter seated correctly and if so then your converter is probably not going to work without giving you problems...
Also if you have a rebuilt motor check the Pilot hub depth, and remember when you install the transmission that the converter should slide forward and backwards with ease and you should have about 3/8" of movement back and fourth... If you bolt it in and cant slide the converter your in for trouble.

[mwye0627 44]

What are the 2 different converters that you tried?

Do you have part numbers or application info?

 

Thanks,

Mike

[MikeStang 247]

Well the original converter was a Factory unit that came with the transmission so its a Ford unit.

The 2nd one I got was from PTC "Performance Torque Converters" over in Alabama if I recall... they sent me one that was WAY to loose, then built me another one that is still too loose IMHO, so when I remove it to send back this time they are building me a 13" unit LOL

[mwye0627 44]

So it was the factory unit that caused problems with the thrust bearing???

I have a 2001 V6 3.8L Converter, which is supposed to be higher stall behind a

higher horsepower, modified 5.0 HO...

I guess I'll really have to pay attention to those measurements to make sure

I don't do any damage to my thrust bearing!!!

[MikeStang 247]

Do a few things.

 

#1. Measure the Crankshaft Pilot Hole Depth..

#2. Measure Converter Pilot

If the Hole in crank is deeper than the length of the pilot hub on the Converter your probably Okay, but I would check a few more things.

 

Put converter up on to flywheel and see if the converter bottoms out before the mounting pads contact the flex plate...if it does don't use the converter LOL. You could possibly get another flywheel with a bit more offset to it that would hold the converter back and be okay but you would have to locate one.