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General => Douglas Motorcycles - General Discussion => Topic started by: PaulW on 10 May 2019 at 18:36

Title: Headstock Bearings for S6/T6?
Post by: PaulW on 10 May 2019 at 18:36
My recently acquired T6 has headstock bearings that are very "notchy" and steering feels awful and dangerous.

Having dismantled the headstock, I see they are taper rollers with an OD of 54mm and an ID of 27mm; (width about 16mm);  they also have some very heavy grooves in the shells which are the cause of the terrible steering.

According to my bearing catalogues, this seems to be a non-standard size, so what have other owners done?  Is it a case of sleeving / grinding a standard taper roller bearing, and if so, which one?  Or has the club had any made?

While I'm posting, my parts list seems to be missing the first few pages, so I'm having problems working out what "A", "B" and "C" means in the column just before the price column.

Thanks for any help.

Title: Re: Headstock Bearings for S6/T6?
Post by: Doug on 11 May 2019 at 03:18
The A, B, C, ... refers to the interchangeability table; see here:

(https://www.douglasmotorcycles.net/aa-files/images/doug/2019/s6-interchangeability.jpg)

When I faced a similar head stock bearing problem with my F28 (600EW), I was able to use a pair of slimmer taper roller bearings. To make up the difference, adapters were turned on the lathe. I think I only needed an adapter for the outer race diameter and height. I did a similar thing for my Birmingham Scott that had indented races. But there I was changing from loose ball to a taper roller bearing. The size was more of a challenge but I was able to use special taper roller bearings made to convert older BMW twins. Even so, adapters needed to be made, which were made to look like the old ball races and disguise the modification.

-Doug
Title: Re: Headstock Bearings for S6/T6?
Post by: eddie on 11 May 2019 at 07:28
Paul,
         Have a look at 'Simply Bearings' website - they list a taper roller bearing that is 50.29 O.D. x 26.99 I.D. x 14.73 high - that should fit the S6 with just a stepped sleeve to make the O.D. and height correct.

  Regards,
                Eddie.
Title: Re: Headstock Bearings for S6/T6?
Post by: PaulW on 11 May 2019 at 07:50
Thanks Doug for that chart...I assume that is at the front of the parts book....I'm wondering what else I'm missing  :frown:

Thanks Eddie, I'd found that one on the BearingBoys site and will probably use that.  I found an old article in the New Conrod where someone had used angular ball bearings but as the nearest ID is 25mm, they had to turn down the sleeve that the bearing fits to.  Your taper roller with an ID of 26.99 (1 1/16") is spot on, so I'll go with that.

While we're talking bearings, as I was missing one of the races for the clutch bearing, I converted it to a sintered bronze thrust bearing and gave the bike a ride yesterday.  Although it works, the "drag" of the large surface area of the bearing gives rise to a rather weird feeling; it feels like a brake is being applied and the quicker you release the clutch, the better.  I'm still finding the optimum adjustment for it (on the cable adjuster) but I'd like to get back to a roller/ball bearing if possible.  Going to take a closer look at some of these needle roller thrust bearings and see if I can make one fit...

...now off to garage to make a tool to remove these headstock outer races.
Title: Re: Headstock Bearings for S6/T6?
Post by: eddie on 11 May 2019 at 08:54
Paul,
         If the outer tracks are worn to the point of not being reusable, a method I have found that is very effective for their removal is to lay a short run of arc weld on the inside - as the weld cools, the track contracts enough to slacken it and get it moving.

Regards,
              Eddie.
Title: Re: Headstock Bearings for S6/T6?
Post by: PaulW on 11 May 2019 at 12:27
I'm pleased to report that my headstock bearing removal tool worked rather well.  Not my design, but I did make it  :wink:

Piece of hard steel; small diameter to clear the outer shell, while the large diameter is thin enough to fit under outer shell but not too wide to foul the headstock sides:

(http://electric-watches.co.uk/photos/wp-content/uploads/2019/05/Douglas-T6-Headstock-Bearing-Removal-20190511-1.jpg)

Slice it into 6 pizza segments and then insert four of them.  Using the same drill that you used to drill the initial hole (1/2" in my case), centre and straighten the four pieces and hold it together with a jubilee clip.  If you've got the sizes just right, you might have to tap the drill into place and then use the jubilee clip to straighten the pizza segments.  It should be rock solid before the next step. 

(http://electric-watches.co.uk/photos/wp-content/uploads/2019/05/Douglas-T6-Headstock-Bearing-Removal-20190511-2.jpg)

From below, tap it out.  Mine came out quite easily; top and bottom.

(http://electric-watches.co.uk/photos/wp-content/uploads/2019/05/Douglas-T6-Headstock-Bearing-Removal-20190511-4.jpg)

(http://electric-watches.co.uk/photos/wp-content/uploads/2019/05/Douglas-T6-Headstock-Bearing-Removal-20190511-3.jpg)
Title: Re: Headstock Bearings for S6/T6?
Post by: Bert on 12 May 2019 at 03:51
Paul, if you use the search function “T6 steering head bearings” you will see my solution and measurements. It works well.
Title: Re: Headstock Bearings for S6/T6?
Post by: Bert on 12 May 2019 at 03:51
Paul, if you use the search function “T6 steering head bearings” you will see my solution and measurements. It works well.
Title: Re: Headstock Bearings for S6/T6?
Post by: PaulW on 12 May 2019 at 09:35
Paul, if you use the search function “T6 steering head bearings” you will see my solution and measurements. It works well.
Thanks Bert, I've already ordered some bearings but having read your article....I've ordered the same as you!  :)