Steel geared intermediate shaft in 930

mppickett · 05:38 AM

I'm starting to assemble my 930 engine and wanted to run something past the group. I bought some replacement parts including a crankshaft and intermediate shaft assembly. The large gear on the intermediate shaft is made of steel rather than aluminum and has more teeth than the aluminum gear. The crankshaft has a matching gear that has the finer teeth to match. I think I remember that the intermediate shaft came from a 964???. Can anyone think of a reason not to use it instead of the aluminum geared stock intermediate gear? It is in great shape and obviously should be stronger but thought I'd check before proceeding.

Many thanks,
Mike

mppickett · 12-17-2005, 05:42 AM

Any wisdom on switching from the aluminum gear to the steel gear? Thanks. mpp

mppickett · 12-18-2005, 05:41 PM

bump

Eagledriver · 12-18-2005, 09:18 PM

I don't know for sure but since no one else has answered I'll take a stab at it. I think steel gears would be better. I've seen quite abit of wear on the aluminum gears. The two things I'd check are that the ratio is the same (number of teeth give same ratio as the old set ie: 40:10 and 44:11) and the new gears fit into the case with a good mesh and the correct backlash (very little backlash).

The ratio of the gears is important because it goes with the ratio of the sprokets to turn the cams at half the speed of the crankshaft. If your new shaft has different sprokets you'll have to do some counting of teeth and some math to make sure it all works out.

-Andy

mppickett · 12-19-2005, 04:18 AM

It does have a different sprocket. Good tip, Andy. I'll count the teeth to make sure it doesn't change the ratio.
Thanks

Henry Schmidt · Henry Schmidt's Garage

The 964 intermediate shaft will fit any of the early engines except the aluminum 2.0.
The steel gear is quieter so enjoy the update.
Make certain that the crank gear matches the intermediate gear. There is a number etched in both and the number should match. If they don't, you could get noise.

mppickett · 12-19-2005, 05:20 PM

Thanks so much, Henry!
Mike

mppickett · 01-11-2006, 03:50 PM

Just an update on this to document what I found for future Pelicans who are considering this option:

1978 930 aluminum intermediate shaft gear has 48 teeth - the matching steel gear on the crank has 28 teeth

The 964 steel intermediate shaft gear has 60 teeth - the matching steel gear on the crank has 35 teeth

The ratio of both gear sets are the same 1.714285714 to 1.

Mike

kenikh · 09-10-2009, 07:47 PM

My steel 964 (60 tooth) intermediate shaft has "52" stamped on it and cannot figure where to get a matching gear for my crank (66mm). There is no '0' or '1'.

The part numbers I find are totally confusing, too. The part nubmer listed for the 964 is a 901 number which makes no sense.

Am I missing something? How do I get a timing gear for my crank that will mate to my 60 tooth i-shaft???

Henry Schmidt · Henry Schmidt's Garage

The steel gears sets are sold as a matched set.
Very much like a set of transmission gears they are matched to prevent noise and excessive wear.
If the gears get separated you're screwed.
What usually happens is the engine comes apart and the crank is sold with the drive gear still installed.
I have two or three steel intermediate shafts with no drive gear. I have often thought of mismatching gears to see what might happen but the labor to rebuild a 911 engine makes the gamble kind of crazy.

kenikh · 06:57 AM

Quote:

Originally Posted by Henry Schmidt

What usually happens is the engine comes apart and the crank is sold with the drive gear still installed.

On the nose...wish I'd known when I'd sold the crank. Good news is the guy I sold the crank to is a friend who has yet to assemble the motor using the crank. Will check with him ASAP.