Misc: Everything Else Series 'D' Speedo Drive Threads Stripped

[Gary Gittleson]

The threads on the drive output where the cable connects are stripped. It's a new cable. Any ideas for holding the cable in place short of replacing the drive housing? I assume the housing is made of what we in the USA call "pot metal"; zinc alloy in other words. There are still other words for this stuff. The bike is a D Rapide.

 

[Magnetoman]

short of replacing the drive housing

With the above as a constraint, and with no warranty on the following advice, the threads on mine are ½" × 26 tpi. Ignoring the trifling detail of the thread form (although they do appear to be triangular, not rounded), I would be tempted to tap a piece of teflon with my ½×26 CEI tap, smear a fairly slow-setting metal-filled epoxy over the remnant threads (after thoroughly cleaning them), and threading the teflon nut onto the piece. After waiting long enough for the epoxy to hold its shape, but not fully set (as can be judged by the excess epoxy you mixed), I'd remove the teflon nut and wait for the epoxy to fully set.

There are enough threads on the piece, and the cable doesn't have to be much more than finger tight to do its job, that I wouldn't have any worry that the epoxy would easily hold.

 

[Gary Gittleson]

I guess we have sort of the same idea. I'm thinking of using Permatex (loctite?) form-a-thread, using the nut from an old cable as a mold for the threads. I'm going to try that and post the results. I agree that strength is not a big concern here.

Gary

 

[Gary Gittleson]

Well, I just looked at some reviews of this stuff. The results seem to be very mixed, from great to "do no buy this stuff".

I had also thought of just using teflon tape, since there's a bit of thread left. Again, it just needs to be tight enough so as not to vibrate off.

 

[Russell Kemp]

I had also thought of just using teflon tape, since there's a bit of thread left. Again, it just needs to be tight enough so as not to vibrate off.

I used this fix on my Shadow and it worked for years.

 

[robin]

The thread size is 12mm X 1.

 

[Robert Watson]

Not according the E M G Stevens in know they beast 1/2 - 26 bsc

 

[Magnetoman]

½" × 26 tpi.

12mm X 1.

In the interests of keeping the peace, I propose a compromise. I'll accept your pitch of 1 mm…

… if you accept my diameter of ½"

Seriously. Upon more careful measurement, the 1 mm pitch gauge fits the threads perfectly, while 26 tpi only fits pretty good. However, the measured diameter of 0.49605" (12.60 mm) is simply too large for it to be 12 mm, but it's perfect for ½" since the OD of bolt threads are always slightly smaller than their nominal dimension. The next photograph shows this for an actual 10 mm bolt.

Not according the E M G Stevens in know they beast 1/2 - 26 bsc

It just goes to show, you can't believe everything you read. Trust, but verify.

 

[Gary Gittleson]

I had a couple of other thoughts. The nut on the cable isn't long enough to catch all the threads. Thus, there are some good threads farther down on the housing. I could probably cut a bit of the bad threaded portion off, allowing the nut to reach the good threads. I would probably have to also cut the flat spade connector back an equal amount. I haven't had time to check this out but will let you know what I find. In the meantime, I'm going to try teflon tape over the threads to see if that gives it enough bite to stay in place.

There's one more point I should mention. Since this is an open D and I have the TT/JE steering head mod, the routing of the cable is "special". I have been using the "standard" cable length called for, but that forced the cable into a rearward curve which rubbed on the back of the lower link. It might have caused some pulling on the cable at certain positions of the fork. I now have a new cable, 1" shorter which brings it in to the front of the spring box. I realize that I need to check things with a jack under the engine so the fork is at full extension. I'll be checking all these things in the next day or so and report the results.

 

[Robert Watson]

Having been prompted by Mr Magnetoman and being able to pop out the KTB size so readily as I was just tackling this exact problem, I went out to the shop, where first I had to discuss with Mr Covid the suitability of my functionality for engaging in this process, As I am getting an upper hand on him and his army of terrorists, I decided I was good to go.

I recently acquired a job lot of perhaps a dozen of these style of gearboxes. All in various states or (dis)repair. One lovely brand new brass tach drive with original protectors on the thread, all the way down to a very sad speedo drive with signs of very significant abuse. The first one I tackled was a nice looking one but with the hub drive shaft pretty much worn the housing oval shaped, remarkably the rest of it including the gears appeared to be in good nick. I took it all apart and mounted the housing in the lathe and bored out the housing until it was a clean bore, quite significant I might add, Made a sleeve in 7075 T6 to fit the housing and bored it for the gear shaft at 5/16. Pressed it in with a light press fit and some red loctite, finish reamed the hole and all is well again. That wasn't so hard.

the next one I picked was just as Gary was seeking advice on my next problem, hence already having the thread size ensconced in the covid fog.

As MM questions everything, as one should I went out there today and collected up 1/2 dozen of these housings. Now None of my 3 or 4 thread gauges have a 26 tpi gauge, so I went up a step and got out my 1/2-26 BSC tap (one need this of course if one messes with Brampton forks, also in 7/16, and of course LH and RH threads, but I digress). I tried the tap on all the housings, and thinking I must be missing something I also got out my 12 X 1 metric tap. Nope not missing anything, they do fit much better in the 26 tpi than the 1mm pitch. Now I wont go into thread forms---------.


I also raided my rather large box of used and abused cables and pulled out three of the female connectors. After cleaning them I ran a 1/2 - 26 bottoming tap and found that no material, apart from a little bit of greasy dirt was removed from the fitting itself.

So I set about turning the threads off the housing to about .415 dia, Next, back the the 7075 T6 and made a sleeve threaded 1/2 -26 OD and drilled 13/32. A few minutes of "dusting" the bore to a size for size fit, some more red loctite and it all went together. once setup for it, it's easy peasy.


My conclusion is that although doing all this is a bit fiddly, I won't drive down the road dreading impending speedo cable doom.

Have at it