While building a 727 trans, I noticed the small hole in the face of the reaction shaft support was larger then any others I have seen.
So, I searched the internet and found a B&M modification that drills this hole to 9/64" and they call this a "Track Only Modification".
I checked the hole and it is 9/64".
My questions are, is this shaft stock from Chrysler like this on some models?
And is this OK to use on the street in a stock type transmission?
Or should I look for another reaction shaft support?
Any help would be appreciated.
Thank, Jeff

ebay seller Pat Blais probably knows unless someone on moparts does. I've done that modification decades ago on street cars and wouldn't think twice about using it.

The purpose of enlarging the hole is to provide additional lube to the front clutches. 9/64" (.140") is pretty large, I normally drill them .094" for the street. (the original hole is tiny)

Since this hole is a wide open pressure leak from the converter pressure circuit it would seem to be counterintuitive but the converter pressure is regulated to below line pressure so it's not that big of a pressure loss.

Thanks for the replies.
So, this is probably taking some fluid away from the converter.
And on a race car, which runs at a higher line pressure, there is still enough fluid to feed the converter?
As to why B&M refers to this as a "Track Only Mod."
But, on a street car this large of an opening could starve the converter during daily driving use?
The original hole seems slightly smaller then 1/16".
.140 is quite a bit larger then .062.
I guess I could drill and tap the hole for a set screw that has been drilled closer to stock size or even .094.
Just thinking out loud, and thanks again for the replies.

The way the 727 is designed, the front drum and the released clutches spin the opposite direction from the input shaft by .80 in 1st gear....IOW, the actual surface speed of the drum and clutches is 180% of input shaft speed in the opposite direction; this causes a lot of parasitic loss from the drag of the released clutches, thus the increase in fluid to lube them.

The idea of increasing the orifice size to send more lube to the front clutches sounds good until you realize that the extra fluid has nowhere to go, it just deadheads in the front drum. That's why I like to drill the outer periphery of the drum to give the fluid an escape path.

Thanks John Kunkel.
I see you have spent a little time inside a 727.
I think I might be over thinking this.
So, it should probably be OK to use this shaft as is?
My concern is that I would be taking oil away from the converter as this car will probably never see any racing.
Thanks, Jeff

By the way, This trans I'm working on is a restoration project of an original six barrel car,
Thanks again

As I stated earlier, the converter has its own separate pressure regulator valve which regulates the converter pressure well below line pressure. If the trans is healthy, any excess leakage in the converter/lube circuit will be compensated by allowing more flow into the converter circuit.

I'd run it.

I'll do that John.
Thanks for your help, I really appreciate it.
Jeff

Does anyone have a picture of this holes location in the reaction support?Is it both in the early and 1971 up support? John,what size are the bleed holes in the direct drum in your photo, and how many are there? Any info would be appreciated!

If you are that concerned why not just replace the shaft, it's not like it has a VIN stamped in it ...

Pic below shows the hole's location, this one is enlarged. The lube hole was discontinued in '74.





The holes are 3/16" 12 holes total in 3 staggered rows.