Original FAV GT-40 shift knob drawings.

Pedro

Guest
Ebonite plastic as used on bowling balls way back; I used black delrin on one I had made a few years back and it looked the part.
 

JimmyMac

Lifetime Supporter
Ebonite is still available.
It is an extruded hard rubber compound and used by pen and smoking pipe makers.
The carbon black or brown versions slowly fades with sunlight and sweat hence the original knobs have an amber yellow outer skin over time.
 

Pedro

Guest
Couple pics of the knobs I had made by a friend I am not very good at turning wood, one Delrin and one walnut. As Jimmy mentioned Ebonite is still available, we used Delrin because it turns like wood and it doesn't change with sunlight.
 

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There is a CAD model for the shift linkage on Grab Cad, under the user name Mac Mill's.
not sure how it has been developed, and if its based on original drawings.
 

Pedro

Guest
Some time ago I drew up the complete gear lever assembly from original drawings and I can share the knob cad file with anyone that wants it but I am not a cad expert so it may not be 100%; just send me a PM with your email address and I will send you a copy of the file.
Best is to use the posted drawing and have a cad expert draw it and then have a bunch CNC as a group project. my2cents
 

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I have never looked closely at the shifter of a MK II. Seems to function completely differently. The MK I is constrained coaxial about the shift rod. The MK II can’t be as that mechanism wouldn’t work if it was.

Lovely work as always Pedro.
 
Thanks Pedro, the one on the firewall would certainly need to be a spherical plain bearing to deal with the angular miss-alignment

I was trying to work out what size they are. On the MK I shift casting, after eyeballing it in for size they appear to be a high angularity metric size. Will get back to it again today, was getting late and I think I may have missed a metric conversion so will need to re do it. Think I have forgotten that the initial drawing of the shaft is in inches.
 
Drawing 5290 lists the shaft size as 0.784”, which is close enough to a 20mm ID bearing. (19.9mm) you would want some clearance here as it needs to slide backwards and forwards. The standard sized metric ones seem to allow about 24° movement over the imperial 17°, which seems to be what is required for this part as well.
 

Charlie Farley

GT40s Sponsor
Just to throw a curve ball into the mix.
Four chassis were delivered with 'ball' shaped gear knobs, straight from Slough to Dearborn.
One was used by Jack Passino as his 'personal' . That info is from the horse's mouth. So it seems
that the gear knob choices were far wider than officially documented.
 

Eddy McClements

Supporter
It's good to hear that gear knobs are installed according to owner's choice....since I am not building a replica, but a road-biased car for my own amusement I don't need to exactly replicate a particular car. In fact, as a bit of an in-joke (and a nod to the car which would replace the GT40 in the JWA team from 1970-on) I have glued some wooden offcuts together, bonded-in a metal insert and using an electric drill and a belt sander made this:-



Apologies to the purists! Reference pic below.

 

Pedro

Guest
The Porsche 917 knob definitely looks more comfortable than the one on the GT40 and I think it is better looking.
 
Thanks guys I was beginning to think I had leprosy or something. I'm slowly rounding up more drawings. I mostly have Drawing that pertain to the shifter as I was trying to make one for my left hand drive car. That project is now on hold as I went out and bought some new cables. Interesting change they made on the MKII shifter, much simpler.
 

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