The Cal-look Lounge

Taken from the October 2001 issue of Volksworld "VOLKSTORQUE" Author Mr Seume ;)

"There is one item from those days which has had bad press in resent years (some of it from me, I have to admit) Which isn't that bad when used in the right circumstances: The Roller Bearing Cranksharft. Sadly most SPG's you see for sale today have had a hard life . There is no way at a swap to check if they have been abused - your only chance is to find one in its original packaging.

When new the roller-crank is GREAT! You don't want to use one for All out drag-racing, Unless its been index-pinned,But for Fast road use they were hard to beat. Smooth and free revving, the old roller-cranks were the mainstay of the tunning industry for many years, Heck if the roller-crank idea was good enough for Porsche's four cam Carrera,it's goodenough for me!"

And if its good enough for Porsche and Mr Seume then its good enough for me  ;) :)

Thing is, Porsche realized that the Hrith roller cranks were problematic in everyday use and discarded the use of them for plain-bearing cranks and found much much better reliability (but still fouled plugs like a mother...)

I don't know. I've never run one. I've had friends that did, some blew up some didn't. One guy, Walt had a beautiful white Ghia cabriolet, with 2110 that he "tried" drag racing at Sac one year, on street tires. Crank let go and punched a hole through bottom of case. Knocked deep sump off. On the other hand, this other guy Roger ran his (only) car very hard everywhere he went, 94 x 82 SPG, Super Flows, Engle 120. Very fast car, went low 13's on 165's full weight. Never broke that I know of.

Porsche warned roller-bearing 356 owners not to let their cars run under 2500 except for very short durations because of lubrication problems to crank. Seems like fussy, demanding requirements to me. Not sure about you, but my Bug motor spends a lot of time under 2500rpm...

At one time I had a 40hp SPG crank and was going to build a hot rod big bore 40hp with Zenith and so on. Never followed that through...

You'll never know unless you try....

P.S. Lee:

The reason Porsche used a roller crank in the 356 (pushrod) 1500's was because the only way Porsche could get that long stroke crank into the early engine cases was to do away with rod bolts and nuts, hence the one-piece rods and multi-piece Hirth cranks. After about 1957 or 58 Porsche never used roller cranks in their race motors.

food for thought

Hmmmm interesting "After about 1957 or 58 Porsche never used roller cranks"

But what about the 356/912 Super90 engine - Now that had a Roller crank and that was later than 58/59 :-\ :)

There is a big difference between a 4cam roler crank and a type 1 SPG. The porsche crank is bolted together, not pressed, and the pieces have a wedge which align the crank and prevent it from deindexing. 
(http://i242.photobucket.com/albums/ff310/vatovec/album2/DSCN5635.jpg)
(http://i242.photobucket.com/albums/ff310/vatovec/album2/DSCN5631JPG.jpg)

Hey! That's one hell of a torque wrench ;D
Lovely motor 8)

When I read the thread title, I was afraid to look – what did I say now? ;D

Thanks dude that is some VERY interesting infomation - I am planning on index pinning my SPG  :)

hey

i know what has been said about the cranks and them breaking and bending. but it must be true that it can be used fairly easily. there were so many off them used back in the day... i am certainly not an advocate for them, but i talked to lee about his crank in the summer and he is willing to put all the work into this crank to make it the best it can be.

so i think it will be as strong as most off the parts now available, only it will cost a lot more. but isn't that the same as running real 5- , 8 spokes or BRMs? there are better and lighter wheels available, but it all depends on what you want to build and 'in what spirit'?

VERY VERY well put dude  ;) :) And to be honest when you add up ALL the costs involved in a "modern" crank the roller is not that much more expensive  :-\ :)

 :-*

Interesting thread.
Years ago a buddy of mine ran an SPG 82 X 92, big valve, high compression, 48IDA motor in a '67 KG. The car saw years of street racing on radials, but never, ever on slicks.
I think the car ended up in Japan... fancy that  ;).

Just to set the record straight, 356 Super 90 & 912 were both C/W plain bearing crankshafts.

~DR.

Thanks for the input dude - see guys it can be done  ;) :) (AND IT WILL BE!)

good point eugene. The SPG cranks are a far cry from an original Hirth Porsche crank. Nice pictures. Even the plain bearing cranks for the 4 cam had a series of wedge shims to keep flywheel locked on (and these cars were never intended to be drag raced!).

Lee, the crank I mentioned coming apart in the KG cabrio, was modified to prevent twisting.

OK OK Give it up - I AM GOING TO USE AN SPG ROLLER BEARING CRANK!

please please please give a rest guys - its getting REALLY boring now  ::) ;) :)

Do it Lee!! I'm behind you!
What are you going to use for a flywheel?? A lightweight Crown aluminium flywheel would be the kittens mittens ;)

Don't worry dude it WILL be done  ;) :) Also I have been advised to use a lightened original GERMAN flywheel :-\ :)

Why is that? I've got an old AL flywheel that I plan on using on my '67... someday.
FYI, an aluminium pressure plate knocks an additional 3lbs off as well... ;)

I want to hear this motor rev!!!