Cutting A833 Input Shaft Question

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E Satterfield

E Satterfield

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Hello. I’m changing from a 727 to an A833 in my 440 Roadrunner. I’ve read the many posts here on cutting vs drilling the crank for transmission main shaft pilot bearing clearance. Drilling the crank is not really an option for me. I have an auto crankshaft and I’ve installed the large late model pilot bearing in the convertor register It appears about 1-1/4” will need to be removed from the shaft. Has anyone else had to cut one of these that much? Not worried about ever using the transmission in another car and the engine itself is fresh so a new crank isn’t in the equation either. Thanks!
 
The pilot bearing area may not be finish reamed for a pilot bushing but is it at least counter bored for one beyond the torque converter register? If it is you won't have to cut a thing.
 
Unless I measured wrong ( and I very well may have and will check again). But it looks like 1-1/4. I have read multiple posts on this and haven’t seen anyone else need to remove this much material. Thanks
 
Measure from the trans surface of the bell to the depth of the crank hole. Then measure from the face of the trans to the end of the shaft. Give yourself at least 1/16 difference so the shaft doesn't bottom in the hole and cut off what is not needed . Slide and old bushing or pipe on the shaft cut to the amount you want to keep. Put the trans in gear and have someone spin the output using a driveshaft yoke while you cut the shaft with a cut off wheel. This will keep it true to length. You can use this same method to taper the end after taking the Bushing /pipe off. They cut down mopar Hemi trans inputs all the time to install in GM's

106_0626.JPG


106_0627.JPG
 
i didn’t build the engine It’s a six barrel 440 and internally balanced. I have all the particulars on the rebuild. But it wasn’t stated cast/forged when I bought the car and I failed to ask the guy (69 Roadrunner..A12 clone/copy) a couple years ago.
 
volaredon said:
The pilot bearing area may not be finish reamed for a pilot bushing but is it at least counter bored for one beyond the torque converter register? If it is you won't have to cut a thing.
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Not necessarily true. I once got ahold of a factory untouched 67 440 complete with the "golden" heads back then. Automatic, it was forged crank and drilled but TOO SHORT and TOO small diameter. I had that one finished in a lathe, but you would have had to but an undersize bushing and cut 3/8 or so off the shaft otherwise.
 
Before you install the bearing mount the bell housing and stick the transmission in. Do not install the clutch or pressure plate. If the face of the transmission meets the bell housing there is no need to cut anything. If there is a gap then measure it and add a quarter inch to it and cut the shaft.
 
" I have read multiple posts on this and haven’t seen anyone else need to remove this much material. Thanks"


That's likely because of differing bore depths through the years.
Here's a '68 440 auto crank. It has the depth but not the standard bushing diameter....

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1670288147510.png


Some only have a center where the bushing would be (picture from BBD).....

1670289063551.png
 
I had figured on having to cut the shaft before I started the project so I have already installed the Clutch/Flywheel/Bellhousing. The crankshaft in my car looks like the bottom picture in Daves69 photos .
Thanks Everybody for the help!
 
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The best I can get with what I have here to measure with (ruler straight edge). The total depth of the hole measured to the trans mounting surface on bellhousing is. 7-1/2”. The length of the input shaft from mounting surface on the case to the tapered tip is. 8-5/8”. Thanks Again.
 
mcodecuda said:
Before you install the bearing mount the bell housing and stick the transmission in. Do not install the clutch or pressure plate. If the face of the transmission meets the bell housing there is no need to cut anything. If there is a gap then measure it and add a quarter inch to it and cut the shaft.
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I'll never advocate cutting an input shaft, but if you insist, this is the way
 
Im new to Mopars and this is all new to me. I have two now 72 Duster /69 Roadrunner . I’ve always liked them but they’re scarce in the area I live in. I’ve been building and working on Chevys for over 40 years.
How deep can I safely go on the drilling? I’m afraid if I don’t drill this somewhat. It’s going to put the pilot bearing forced against the taper on the shaft at the clutch splines. I figured if I added even a 1/2” more depth will lessen the amount of cut required.
 
Measure twice before you cut. You want the input taper beyond the bearing but not bottoming on the crank, maybe .125" clearance.

If it helps, this is what I found on a 440 crank in a block. The depths were measured with my Starett as best I could from the END of the crank.
Use at your own risk.

Concerning the diagram below, in a Brewers Performance diagram I've seen, I believe the 2.225 " depth is all the way to the drill point. It may well be the better dimension to use as they have had more experience with this. Drilling too deep gets you into a journal oil passage.

The trans input/bell should be typical of the un-cut input shaft IMO. So the input would be 2.120 into the crank.

1670339170032.png
 
Thanks again for the diagram and all others input. With my somewhat crude measurements. It looks like if I were to remove the seemingly needed 1-1/4” from the input shaft. I would have roughly 1/16 to maybe 1/8 “ of an inch to play with before the taper after the splines is forced into the start of the bearing cage which I feel is too close for comfort.I don’t plan to drill the full depth just enough to get some wiggle room to prevent any binding of the bearing or shaft. Do I understand correctly that there is better than 2” of material in the register before I reach oil? And if that being so. I thought of going somewhere less than one inch of extra depth. All I have to drill this with is a hand drill and what bit size would be recommended maybe an 1”? Thanks again
 
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jos51700 said:
I'll never advocate cutting an input shaft, but if you insist, this is the way
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Me skeeter beaters... I envision a future world with a bunch of A 833s with hacked input shafts for the masses...you fdont use a hand drill you take to a machine shop with a huge drill press...
 
I didn’t plan to try and bore the center of the crank to hold a pilot bearing with a hand drill. All I was going to try and do was deepen the existing pocket a little deeper so that not as much material would need to be cut from the shaft. The shaft measures at 3/4” and it seems to me that anything on the unsupported side of the pilot bearing could be the same or any size larger than the the shaft as it’s only providing it room to rotate nothing else. The thought of slightly larger would provide a little room if the hole is not perfectly straight and I highly doubt that it would be
There is 1 so called machine shop in the area that I live in. I would Not trust them to do any kind of work for me from past experience and I don’t plan to remove the engine from the car or the crank.

As far as cutting shafts. I will have this car until I’m dead and if a future owner or generation doesn’t like it that the shaft has been cut then they can purchase a new one like I did. Thanks again for the input
 
I've done some homework on this topic as well, as I am switching from a 727 to an 833 and do not know if my 440 crank is drilled yet.

Here are a couple photos I have saved from other discussions about this, there are quite a few if you do a search.

Based on these pics, your measurement of ~1.25" doesn't seem out of line, eventhough most people seem to say it only needs ~5/8" removed.

CRANK PILOT-MIN DIMENSIONS.jpg


PILOT BUSHING DRAWING.jpg
 
My main concern is enough material remaining on the shaft that it doesn’t force the taper into the bearing. Naturally the further back the input shaft has to be cut the further towards the splines and taper the pilot is going to ride. If the measurements were 1/ 2to 3/4 needed cut I would not be concerned . The engine is this car was built by a shop in Colorado and dyno tuned before it went into the car. I’m not touching it if I don’t have to as it’s been as close to perfection as I could expect

EE501582-3F84-4DB5-ABB4-0CC0115BB81C.jpeg
 
E Satterfield said:
My main concern is enough material remaining on the shaft that it doesn’t force the taper into the bearing. Naturally the further back the input shaft has to be cut the further towards the splines and taper the pilot is going to ride. If the measurements were 1/ 2to 3/4 needed cut I would not be concerned . The engine is this car was built by a shop in Colorado and dyno tuned before it went into the car. I’m not touching it if I don’t have to as it’s been as close to perfection as I could expect

View attachment 1716019209
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Regardless of where you cut it, the distance the to the splines the bearing rides is not going to change. The face of the trans to the roller bearing in the crank is a fixed distance of 6.525" regardless of input shaft length. You are cutting off excess input shaft length that would protrude beyond the roller bearing into the crank, not the part between the bearing and the trans.
 
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