'917' Gearknob

[chris_seven]

Does anyone know the diameter of the '917' wooden Gearknob?

They look like 50mm but this seems to be on the big side.

Tahnks

[Mycar]

Afternoon Chris, hope you are well. Tr Motorsports has them at 48mm...

917 Style

Although Jamies' were 43mm

DDK - Die Deutschen Klassiker • View topic - 917-style Shift Knobs

Here's one in situ if that helps,



And there's a guy in Denmark making them, perhaps he can help.

DDK - Die Deutschen Klassiker • View topic - Balsa wood or similar gearknob

Regards, Mike.

[chris_seven]

Mike,

Thank you, as with all these old parts there is a huge debate about original spec.

I thought 50mm was a bit too big.

[MrBonus]

Nice! I'm ordering one now.

[Noah930]

Check with Slodave. He's been working on making replicas.

[MrBonus]

I have no experience or affiliation with this company but I did find this:

http://classicowheels.com/shiftknobs.htm

[wachuko]

Oh man... I want one... for that future long hood project... might as well start buying and saving the parts.

[Joost73]

I have got one from Marek Lappok from Denmark, really look cool and size is 4,3- 4,4 cm in dia meter.

You can PM him here on Pelican.

[HawgRyder]

Were the originals not made of Balsa wood?...to save weight?
Don't believe they would stand up to every day driving.
Bob

[Mycar]

...Let alone the ravages of the race track.

I agree, it's unlikely the gear knob was an exercise in trimming weight and I doubt a flimsy balsa knob would stand up the number of gear changes made in 24 hours at Le Mans.

Far more likely, the originals were a mahogany/ash laminate, used to reduce heat transfer from what would become a very warm gear lever.

Regards, Mike.

[MichiganMike]

My cheap version made from these: Four 2" Solid Unfinished Wooden Balls for Crafting Wood Turnings Shapes | eBay

You can get 1.75" which would be closer to the 43 mm but I got the 2" which is the 50 mm and feels great!

[slodave]

Originally Posted by HawgRyder

Were the originals not made of Balsa wood?...to save weight?
Don't believe they would stand up to every day driving.
Bob

They were not. The mystic is that the wood knobs were for weight reduction. In fact, the wood was for insulation. The 908 and 917 trannys were rough. Plenty of heat was transferred to the shift linkage.

In my research, I have found that the shift knobs were not uniform. They were turned from various thickness of wood. I believe the wood was layered in a way that resembled plywood.

The wood used was most likely beech. Beech/balsa... Both start with a "B", balsa happens to be light and probably helps add to the mystery.

[chris_seven]

I am fairly sure that they were 'yellow' Birch with the grain crossed in the laminations to stop it splitting.

I think this is one fitted to a 917.



This one is 48mm dia.

[slodave]

Birch alone, as you and others have described, would not create the patterns in your pic. But I'm 99% certain it would have been beech, not birch.

This is as close as I have come (one on the right), and this only mimics one knob. They are not the same.

48mm

[slodave]

BTW, I don't believe the knobs were made from one type of wood. I tried laminating blocks of the same wood (birch), perpendicular to each other. I could not get the same results as the few pix that the Internet turns up.

[VFR750]

The harder grades (higher density) balsa look like the grain structure in this picture.

it would be interesting if someone tried that grade for the knob. Certainly a good choice for model airplane gliders where it will drag on the ground during landings.

Can someone ask Norbert Singer? He probably knows!

I am fairly sure that they were 'yellow' Birch with the grain crossed in the laminations to stop it splitting.



I think this is one fitted to a 917.







This one is 48mm dia.

[leichtbauer]

Original 917 shiftknoobs are balsa! The diameter of the hand-size are adjusted and are between 40 and 50 mm. The weight of a 44mm button is 18g. The reproduction is not easy.
My buttons are made ​​of balsa.

[RWebb]

some wt. comparisons of shift knobs I use:

Momo Race Air Leather 8-hole shift knob 0.31 lb.
8 Ball shift knob 0.41 lb.
Wood 917 repro shift knob w/collar 0.04 lb.

[tazzieman]

Originally Posted by RWebb

some wt. comparisons of shift knobs I use:

Momo Race Air Leather 8-hole shift knob 0.31 lb.
8 Ball shift knob 0.41 lb.
Wood 917 repro shift knob w/collar 0.04 lb.

Incomplete research , without some 0-60 times!

[m110]

Heat transfer in old cars was certainly an issue, especially for longer races (GP races were # hr + back in the day). I heard Han J Stuck mention that for the Auto Union Type A-C that the drivers got heat blisters on their gas pedal feet and wore heavy gloves due to how hot they got.