Where are folks sourcing their matched 964/993 IMS Gear and crank timing gears?

[JonT]

Might be looking for a matched set or new possibly. Can non-matching set be used? Exploring my options here. Thanks for help.

[stanglife]

bump

[Walt Fricke]

Jon - I suspect a "non-matched" set isn't going to happen. When I wanted to go this route for a race motor I bought the set new. These don't wear like the aluminum IS gear does. And the motors are long lived.

The aluminum gears can be replaced without replacing the steel gear on the crank, so I suspect the same would be true for these steel gears, if they go separately on the used market.

You could post to this sites parts for sale/wanted list for a used pair.

[Catorce]

You can still buy a new IMS gear from Porsche as well as the matching crank gear. Depending on what motor you are building, this can be big bucks.

Tell us more about what you are doing, I may be able to get you a set but you'll pay some large dollars for it, larger than you think.

[stanglife]

If you buy a matched crank and IMS with visibly acceptable gears, are they generally good? No pitting or chips with a good contact patch. Building a motor and I need a crank...so I have to decide if I want to cannibalize the running engine that's in my car for the crank setup or just buy one somewhere else.

[rdimarco]

Pauter makes a straight cut steel gear set, less expensive than oem. I got mine from William Knight, KnightRace on the forum.

[Walt Fricke]

Rick - that's a turn around. Four or five years ago, when I got my OEM IS steel gear, that was a lot less than a straight cut set. Typically a used crank will have the steel IS gear on it, so you only need the IS gear. The steel gear from an '89 or earlier crank shouldn't show any wear, since the other gear is aluminum.

For a race motor, of course, straight cut is the way to go.

[rdimarco]

I thought the 964 steel IS gear had a different tooth count (60/35?) than the earlier cars, so you couldn't mix a 964 IS gear with the 89 and earlier crank gear. I could be wrong. My '78 had 48 teeth on Aluminum gear and 28 teeth on the crank gear. Hopefully somebody that knows or has a 964 gear handy can clarify.

[Walt Fricke]

Rick - I checked parts catalogs, and the cam sprocket and IS sprocket for the 1972 911 and the 964 version have the same 901 part number! So does the crank IS drive gear. So the IS steel gear has to have the same tooth count and tooth angles.

Since the total ratio of crank to cam is 2:1, and Porsche cleverly didn't divide this up evenly between crank to IS, and IS to cam (so that the chain kept mating with different teeth every revolution), that ratio is fixed.

I can't say I ever thought about this (though it is easy enough to find a reference to these tooth counts), but the 964 steel IS gear I bought for use on a 66mm crank with its IS gear in place works fine.

The PDF parts manuals (free download from Porsche) are really useful to have.

[MBEngineering]

HI

I think you may need to look again at the parts listing for the 964/930 turbo? and check the application code's for the parts

the 964 inter-gear SET, with matching No's

for a "0" 993 105 911 56 £935.55 + vat uk prices

for a "1" 993 105 911 57 £804.84 + vat

a early car + 911 and 964 Turbo, crank gear,

for a "0" 901 102 111 02 £293.78 +vat

for a "1" 901 102 111 20 £192.61 +vat

now the GT3 has a steel gear set with the old large gear cut and the shaft and gear is made out of the one piece,

[Walt Fricke]

Well, the PET shows, in the crankshaft portion, the crank small IS gear as the 901 part for the M30.69 model for the 0 and 1 gear. For the other models it references "see group 1/23/15, for models M64.01, 02, 03, and 50.

In the IS section, it shows the intermediate shaft with the big gear, and as part of the assembly the crank gear, with 964 part numbers. It appears that there was some change for both the 0 and the 1 gear "sizes" between 1989 and 1990.

The 993 crank diagram refers to group 1/03/15, which has 993 part numbers for the IS/timing gear as a single item.

But the chain sprockets are still the good old 901 parts (one of the 993 sprockets is a 993 number, but the other is the good old 901 still), so at least the ratio of crank to IS can't have changed.

Maybe Porsche was no longer stocking the older parts? Only selling a set? Maybe in '90 they did what you say the GT3 got later - gear cut on the shaft itself, all one piece?

But at those prices, straight cut from Pauter or maybe even elsewhere might look pretty good. With a race exhaust you can't hear the extra noise anyway.

And my PET PDF is from August 2006, so there may have been some change there.

None of this quite answers the question of whether all the crank drive gears will drive all of the intermediate shaft gears for the air cooled cars, regardless of part numbers.

Perhaps this question should have been addressed to the 911 engine forum? There are more experienced engine guys there.