FS:Rare 906 crankshaft

oliver07r · 05-21-2004, 12:17 PM

NOS factory 906 crankshaft 6000 Euro, 3 L RSR P/C's very good shape 2300 Euro ,ask for pics.

bmrinc · 05-21-2004, 12:30 PM

What is your asking price for the 906 crank and for the 3.0L P&C's.

KobaltBlau · 05-21-2004, 12:45 PM

looks to me like 6000 euro and 2300 euro.

hesaputz · 05-21-2004, 03:32 PM

906 crank shouldn't be any different than any 66mm 911 crank, other than maybe hand selected and checked. Anybody out there know more about this?

oliver07r · 05-24-2004, 12:37 AM

Sure it's different,i can send you pics if you want check.

ajserrano · ajserrano's Garage

Oliver, Hello!!!

This is a very interesting topic for me as well which David G and I were also discussing. Did you ever provide David G. any sample photos of the 906 crank and how it is different that a standard 66mm part? I sure love to see those photos myself if they are available.

Thanks Oliver!

Armando

http://www.pbase.com/9146gt

oliver07r · 10-26-2004, 10:37 PM

OK i send you pics!!

hesaputz · 10-27-2004, 04:04 AM

I don't know what I did with the picture I had of your crank, could you post it again? Really cool.
I have what is alleged to be a 906 crank, but it's much different than yours. I'ts very similar to a 911 crank, but has much larger oil passages, and a slightly different radius on the main and rod bearings. I thought that it might be just a modified 911 crank, but the passages look factory, not drilled, and the radius would have had to be welded up; the crank shows no signs of this. Maybe yours is a sprint crank, or from a later 907 or 910. here's a picture;

oliver07r · 10-27-2004, 11:58 AM

OK!!!

BURN-BROS · 05:31 AM

The picture Oliver07r posted looks very similar to the 2.8 RSR crank my Father has. My guess is that it is the real deal.

Edit; appears to be a factory race crank.

hesaputz · 10-27-2004, 08:33 PM

Let's ask Henry, Grady, and some of the other experts on this stuff. 906 homologation papers show pictures of the crank I have, and my friend who used to own and rebuild these motors swears it's correct. I'm very curious as to what the story is, so I'm going to consult the books and experts, get back with some answers.

bmrinc · 10-28-2004, 06:08 AM

AJ,
The picture of the crank Oliver07 registered and is shown on the red table, is a true 906 crank. It shows the lighted counterweights. They are really diffrernt and enable the engine to rev so quickly that you can feel it when drvering. I used one when I raced in IMSA 2.5L class. It helped win the Porsche Cup Championship in '74

Grady Clay · 10-28-2004, 06:55 AM

It appears Oliver’s crank is a 906/910 race crank. Most of these also had some material removed from the throws (large machining at an angle to the rod journal.)

These are cool parts. I’m assuming it is in France. If someone wants to buy it, I would have it shipped to Porsche A.G or one of the race shops for inspection, measurement and preservation coating. All Porsche crankshafts have serial numbers.

The best way to ship a crankshaft is fabricate a wooden structure that uses a set of old bearings to support the crank and it can’t move around on them.

Best,
Grady.

ajserrano · ajserrano's Garage

Now we're talking!

Can anyone shed some light on the "special rods and rod bearings" required? (availability, cost, sample photos between standard and 906 rod and rod bearing size, etc.) Thank you all for taking the time to post your photos and information!

hesaputz · 10-28-2004, 09:17 AM

That's really cool, it's similar to RSR cranks I've seen. The books I've read that mention the crank list hand selection and balancing as differing from stock; The Racing Dept. back then apparently had a radical idea of what balancing is.
Question is, what is the crank I have? Likely, it's the crank for the road/homologation 906, but I'd like to know for sure. Wonder if any 910's were made like this, for road/homologation? My friend says he tore down a 910 factory motor, and it also had this crank.

DG

126coupe · 126coupe's Garage

My 2 cents is any qualified machine shop can knife edge and lighten the counterweights like the 906 crank. I do this on my race engines, (Ollies in Santa Ana). as for the larger oil holes I have not investigated that yet

126coupe · 126coupe's Garage

Heres a photo

ErVikingo · 10-29-2004, 07:12 AM

Ollies did mine; you can see it in Wayne's book

ajserrano · ajserrano's Garage

"Grady Clay" was correct on his statement when he said, "It appears Oliver’s crank is a 906/910 race crank."

Here is the proof on "that new twist"...

http://www.pbase.com/9146gt/factory_racing_parts_906engines_910crank1

hesaputz · 06:59 PM

This has been a real interesting thread, and it's gotten me doing some research and questioning. Those who are interested should read Ludvigson's chapter on 906 development; though you won't find a definitive answer to this debate, it helps lead to a logical conclusion.

I believe that these are both 906 crankshafts; you could call one production and the other racing, or you could call one early and the other late. either way, it appears that the factory put both in 906 motors.
I have a copy of the original homologation papers for a 906 that specify and picture the stock looking crank, dated May 11, 1966. In addition, I have a very detailed 906 technical article by Ulrich Schwab from the same year, that pictures all the engine goodies for type 901/20, including the stock appearing 911 crank. I'll try to get this scanned, and post it later.
The authoratative Porsche writers (Ludvigson, Barth/Boschen, and Frere) all give detailed descriptions of the 906 engine package, and all refer to the crank as production or production selected.
Porsche wanted to contest the newly formed FIA Sports car category in 1966, and had to build 50 examples to spec in order to do so. I have to believe that the first 52 examples of the 906 produced had this stock crank, as shown in their detailed proposal to the FIA.
After the necessary 50 were produced, development and modifications began in earnest, mid 1966. This was the beginning of the Piech era, and racing development was very fast paced and intense. Ludvigson chronicles a long list of changes made to the later cars, and cars sent back to the factory for race prep or updating. The 906E, for example had about 40 developmental changes one month after the run of 50 was completed. An entirely new car (910) replaced the 906 as the factory standard bearer for 1967.
I believe that the crankshaft Oliver and Armando picture emerged from this intense development, primarily for sprint use at first. It was found to offer zippier engine response with good reliability, and it's use was continued in small bore 6 cylinders up through the 70's. I never heard of it being homologated for use by 911's in FIA events, but that doesn't mean it didn't happen. Certainly, as Tom mentioned, it was used in IMSA.

It's curious that the non-counterweighted T crankshaft was developed during this same time, and was introduced in the Fall of '66 as the European model 911T. Maybe there's a connection.

Anyway that's my story and I'm stickin' to it ( for now). The crank I have looks just like a 911 crank except for machining changes consistent with Porsche Race practice. It shows absolutely no signs of having been modified later.