Stearing head bearings

[saluki42]

Hi just starting to look at the refurbishment of my 1934 Model Z frame and have immediately come up with a question hopefully somebody can help with. The lower bearing is a taper rolling bearing fitting into a full size bearing housing. The top bearing is a mystery, the bearing housing has an internal diameter of 1.717" (1 23/32") but a depth of only 0.152" (5/23") I have attached some pictures of the this though I apologies if they are a bit out of focus.
My question to you all is does anybody have any information on this upper bearing.

Regards
Chris







[link images. 20Nov21 -Doug, Admin]

[eddie]

Chris,
           From the mid twenties till the T35, Douglas used a deep track thrust bearing on the top of the steering head (not all models). That bearing consisted of 2 identical halves (part number 2016) and loose 3/16" balls. Unfortunately that is an imperial size bearing that is no longer generally available - the O.D. you quoted (1.717") is actually 1 21/32", so it matches. Whilst bearing stockists no longer keep them, you may be able to get them from LDMCC Spares - at one time, they were getting them remade for the T35.

   Regards,
                 Eddie.

[saluki42]

Thanks Eddie I'll certainly be giving them a go and fingers crossed thats the next big hurdle overcome.

Chris

[eddie]

Chris,
          As I said earlier, the T35 had the thrust bearing in the top of the steering head - later Mks had a cup and cone bearing (in 2 versions). Now, the cup had the same O.D. as the 2016 bearing but the cone was threaded internally 1" x 20 tpi - if your fork stem has the same thread, you may be able to use a complete Mk top bearing. The 2 versions only differed in that the later one had a spigot (and an enlarged hole in the fork bridge plate) so that the bridge plate did not bear directly on the threads of the fork stem.

  Regards,
                Eddie.