Anyone know these two 108mm applications?

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Both (on the right) are 108mm course-spline flanges. But as the pic below shows, the center flange has the same dimensions as the 914 flange (left) on all turned surfaces.

The 108 flange on the right is the same dimensions (on turned surfaces) as the 100mm SC flanges I use with 944 cv's on my 914.

I can just barely make out what I think may be the part number on the rightmost flange.

915.332.209/01 but this may be incorrect. It's not very distinct.

Anyone run into both at some point? My guess is that the flange on the right is from the SC era and the center one is an earlier turbo, but I'm basing that on the SC dimension match, not from actual fact.

Ideas?

They did away with coarse splined flanges after 76 I believe so, the first year Turbo would have been the last. No SC's had them that I am aware of.

Check Sporto vs, Standard...

I'll look into that. I didn't think of the sporto because all of it's parts were so small compared to the 901/914 transaxle equivalents, that it was hard to imagine a 108mm cv with one. I'll report back if none of us knows the skinny up front. I've never even seen a 915 based sporto but I may have to cruise through the PET to find the answer.

I have a friend's 914 race box in for a seal installation and his 108's are the same as the pic on the right.

HI Ron,

I've been running an '78 930 trans in my 914 for 8 years on-track using standard
SC half-shafts. It was a pure plug & play deal with no mods. I picked up the 1/2 shafts at a Porsche swap meet for $85 and they are still good.

I happened to have the V8 & 930 "LUMP" out of the car and when I measured the output flanges found the measured 110 mm O.D. with the bolt center-line to the CV joints of 94mm. My output flanges are the later fine-splined version.

My Porsche 911 knowledge is not very deep, but I learned that the 930 box uses the 915 hub carrier as the Quaife TORSEN dif upgrade was the same for 930 & 915 boxes.

I'm guessing that you are also running a STRONG V8 as there is no other reason to put up with the 930,'s terrible gear ratios, except its ability to handle big power. I can atest to the fact that the 930 is bullet-proof handling my 383 Chevy 500+ HP & torque.

If you haven't been inside your 930, the gears are MONSTEROUS with a 9.5" ring gear and individual gears that remind me of a Muncie 4-Spd.

I hope this helps,

Terry

I'm still running the 914 trans and a GT LSD/100mm 944 cv's and a 3.6L engine. The turbo flanges won't be used until a big horsepower conversion is on the table. I'd rather put the money into driving experience, safety and suspension upgrades, and get more horsepower (for now) by lightening the car.

The turbo (axle) gear is so much heavier than the 944/911 gear that it didn't seem to make sense to convert to it yet.

I've always understood the 930 cv's to be 108's and you're right about the 110mm measurement on the flanges. But both of these flanges are identical in that respect.

The difference in the two flange pairs makes for about 1/4 in in total length, which will potentially make a difference in the axle length if I specify a custom axle.

I hear you about the 930. I don't have one sitting around but have a Quaffe diff ready to put into either a 915 (which I do have) or a 930. What I don't have are fine-splined 930 flanges. But that's another story.

I still want to find out what application the longer flange is for. Perhaps it's an aftermarket flange for off road. A man's gotta know what he's working with!

I thought sporto's were 923 part number.....

EDIT: 905 = 901 bases sportomatic, 923 = 915 based sportomatic.

The longer flanges have numbers but I can't read them enough to tell if they are even Porsche parts.

Question answered by GT's Matt Monson. The longer ones are for the factory ZF LSD's and the shorter ones are for the open diff's. In a post on another board he stated the following on a different but related topic...
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The mag case 911 gearboxes (which includes the 1969 type 901s) use the same differential as the 914. The very early 915 gearboxes also use that same differential.

If one were to acquire a factory ZF LSD for the 911/914 be sure to get the proper LSD stub axles flanges to go with it. The length is greater and the open diff flanges will be too short.

... The length to the step on a standard open diff flange is 56mm. The length to the step on the LSD version is 61mm...

Our (GT) LSD or TBD does not require LSD flanges. You can use the stock open differential flanges with our units.

Kind Regards,

Matt Monson
Guard Transmission LLC
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Hey Ron,

I completely agree with your view of staying with the 914 bits as long as possible. Since you are still running the 901 box, huge axles would just asure the trans as the weak link in the power train!

That said, I believe the 901 will survive with careful shifting: After all, there are a BUNCH of 901's bolted up to V8s with torque matching your 911 engine.

As far as messing with a 915 trans, I don't know, as all I've heard is that they aren't any stronger than the 901...What do you hear? Since I'm running a built 383 Chevy, I HAD to run a 930. I would LOVE to have a G-50, even though the back end of the trans would end up right about where the rear bumper sits.

Good luck on the Great Flange Search!

Terry

It seems ultimately a wash in strength overall, but the 915 R&P is certainly better, even in the 7:31 version simply because it's bigger... more meat, and first gear isn't cantilevered so you can explode from a start with more confidence. Especially the AX crowd. I also think a late side-cover is required in any case magnesium or not.

And I don't have a problem with the mag-case 915 differential housing since it's bearing race bosses are steel like in our 914 transaxles.

So, if the material cost of replacing more 914 boxes over time is the same as higher cost 915 boxes but fewer overhauls, I'd choose the latter to avoid down-time if the gear ratios are to my liking. My ultimate take is this. If I didn't have a few at the house I wouldn't do it.

But since I do, The 915 build/install will be a really fun project so why not? But I won't use 108 CV's until my torque/hp demands it. And you're right.

Smooth shifting saves these boxes... both of them. To the G-50. Yummy

That's a really nice machine and I love the thought of a six-speed short bell housing G-50. But like the 108's the darned thing is so heavy I'd have to run a lot more torque/horsepower to justify the hit to the power-to-weight ratio.