TheSamba.com :: View topic

Tue Mar 19, 2024 7:11 am

Vanapplebomb wrote: Bruce, that is only true for direct loading in tension. What you are talking about is how much force it takes to yield two different areas for a given material strength, which is a linear relationship to yield strength and cross section area. Indirectly, this can also be applied to deflection (stiffness), but it isn’t linear. So, yes, obviously hollowing out journals reduces the load that can be applied in tension and bending for a given deflection.

HOWEVER…

It’s not that simple. A crankshaft does not see a maintained static force applied in one direction. It is cyclical, and that changed EVERYTHING. Same is true for bolts. Your baseline yield or tensile strength is rendered somewhat irrelevant because the strength properties change in relation to operating conditions. Survival of the part becomes less dependent (to a degree) on force over a given cross section area (like you talk about), and more about shear stresses at the surface grain boundaries. There are a whole host of things that play into surface conditions… localized compressive forces (shot peening), part geometry, stress concentrations, etc. Remember, due to fatigue, you can fracture a part with FAR less force than the theoretical force based on the tensile strength of the material and cross section area. To some degree, you can manipulate those variables to change how strong you part is at a given number of cycles. See the picture I posted above. Cyclical loading is a whole different ball game. :wink: :wink:

:popcorn:

Tue Mar 19, 2024 8:21 am

These are the lifters I was wondering about on the last page. If anyone knows any current manufacturers, I would be interested.

Sat Mar 30, 2024 8:00 pm

Sun Mar 31, 2024 3:06 am

Is that a stock steel retainer?
Weights?

I bet it still weighs more than a Ti retainer.

Sun Mar 31, 2024 3:16 am

Bruce wrote: Is that a stock steel retainer?
Weights?

I bet it still weighs more than a Ti retainer.

Hi Bruce,

i could not find an exact weight but here is the discription from the csp page:

"These special valve spring retainers are made of Saar steel - 42CrMo4 CNC and have a strength of 900 - 1200 N/mm² with a weight saving of approx. 5 grams per piece compared to the standard Type-4 valve spring retainer. The two-stage valve spring seat allows the use of an outer Type-4 valve spring, which can be combined with an inner waterboxer valve spring if required."

https://www.csp-shop.com/en/?func=detailcall&artnr=32515a

You need to switch to the german page for the pics

Sun Mar 31, 2024 11:22 am

Neat solution for that particular problem but not the most ideal design.
I like tool steel retainers, they can be made very thin.
The retainer can be springy, it can be an extension of the spring, and springs don't need holes.

Sat Apr 27, 2024 3:14 pm

Sat Apr 27, 2024 3:30 pm

Oh for crying out loud :lol: :lol: :lol:

Mon Apr 29, 2024 11:40 am

Quite a few years ago, I walked into Dave Folts' shop, and he was carving a few ounces from the backside of a customer's ring gear, end-milling neat little pockets between the bolt holes. Needless to say, Dave appreciates the 7 POUNDS we removed from the GT version 091 TBD .. https://www.thesamba.com/vw/gallery/pix/2270675.jpg

Mon Apr 29, 2024 2:05 pm

Bruce wrote: Is that a stock steel retainer?
Weights?

I bet it still weighs more than a Ti retainer.

Stock retainers are about 17g, I trimmed some down to 14g

Mon Apr 29, 2024 2:15 pm

Trimming a stock retainer down to 14 is pretty good, actually. Took off more than I thought you could.

These are stock steel retainers for a popular V8 engine (you can probably guess which one), but nobody said you can’t use other engine parts on a VW. :wink:

Thu May 02, 2024 9:15 am

Vanapplebomb wrote: These are the lifters I was wondering about on the last page. If anyone knows any current manufacturers, I would be interested.

When Schubeck closed, a former employee picked up manufacture of the lifters (Smith Machine/SM Lifters), at least for V8 applications. Apparently, they are closed, too.

I don't believe there are any current manufacturers.

Sat Jun 01, 2024 8:40 pm

from here : https://www.thesamba.com/vw/forum/viewtopic.php?t=792537

Sat Jan 18, 2025 12:56 pm

I had a Mazzone sandrail that had drums on it like that

Sat May 17, 2025 7:17 am

Sat May 17, 2025 4:39 pm

That is completely wild! How much weight do you reckon you removed? Looks like about 30% and looks totally cool too. Like having a life size cut away learning tool.

Sat May 17, 2025 5:40 pm

Sorry, not mine, it was in the Samba photos.

Sun May 18, 2025 2:53 pm

I’m kinda opposite with crank and flywheel .
I remember when I switched to a Demello full circle crank and a nearly full weight flywheel I ended up turning faster 60 and 330 ft times which led to faster 1/4 times .
There was just more rotational mass the car would not bog and put more power going fwd , motor just maintained rpm instead of trying to recover it.
Even now I follow same program with crank and flywheel . On the street or launching at the strip just works

Wed Jun 25, 2025 8:02 pm

Thu Jun 26, 2025 4:30 am

jim martin wrote: I’m kinda opposite with crank and flywheel .
I remember when I switched to a Demello full circle crank and a nearly full weight flywheel I ended up turning faster 60 and 330 ft times which led to faster 1/4 times .
There was just more rotational mass the car would not bog and put more power going fwd , motor just maintained rpm instead of trying to recover it.
Even now I follow same program with crank and flywheel . On the street or launching at the strip just works
I suppose it may be possible to take the momentum principle to the extreme. Have a Brigs and Stratton back there winding up a huge flywheel for say 30 minutes, roll up to the starting line with it just singing and dump the clutch! Just like those little toy cars and trucks you push hard several times and lift up then drop on the floor and they scoot across the kitchen...

...or, a set of tractor wheel weights and a pneumatic bumper jack. Wind her up with your 1200cc 40 horse and dump the air when the light turns green.

I wonder if it has been tried! That would be the polar opposite of what lightening everything is supposed to do. The shorter the track the more advantage you would have.

Ok, done my morning tea, taken my meds, time to go put a set of shocks in the wife's car! :lol: