Replacing the CV carb sync screw+locknut with something better

[bwringer]

Yes, it would work. I just hate "hacks" like that, but I will do them when I get desperate! ;-)

I'd probably also dremel a slot in the top so I could use a screwdriver. A socket is hard to fit down there, especially on the middle one (without removing the choke bracket). And I'd use epoxy instead of solder, 'cause I'm an epoxy freak, but either would work.

*EDIT* $47.79 for 1 meter of M5x0.50P threaded rod and 50 hex nuts to match at metricspecialties.com.

The 1 meter of threaded rod and nuts is definitely workable... any leads on the springs?

Solder or brazing would be a lot more reliable than epoxy. (Hint: Jon knows a lot more than any of us about making small metal things stick together.) The solder would penetrate the threads to some degree and form a very strong bond. You could even polish them up a bit to look really nice.

 

[t3rmin]

Well I hadn't really figured on finding the springs until I had the screws with which to test for fitment...

 

[jonr]

The 1 meter of threaded rod and nuts is definitely workable... any leads on the springs?

Solder or brazing would be a lot more reliable than epoxy. (Hint: Jon knows a lot more than any of us about making small metal things stick together.) The solder would penetrate the threads to some degree and form a very strong bond. You could even polish them up a bit to look really nice.

Thanks for the kudos Brian. I'm not sure I want to polish something that I would never see though! Only Bob is that kind of purist (in a good way).

THe McMaster Carr price is $35 for the meter of threaded rod. Use the existing nut and all you have to worry about is the springs. What kind of spring rate are we talking about here? 5, 10, 15 lbs per inch? I don't know what it would take to keep a screw from backing out.

I've got a catalog with some beryllium copper springs in it and they run anywhere from $1.25 to $10.00 each. All depends on spring rate, OD and length.

J

 

[t3rmin]

THe McMaster Carr price is $35 for the meter of threaded rod. Use the existing nut and all you have to worry about is the springs. What kind of spring rate are we talking about here? 5, 10, 15 lbs per inch? I don't know what it would take to keep a screw from backing out.

Is that 0.50mm pitch threaded rod? *EDIT* N/M, I see they do have 0.50 on their website.

I'd kinda rather keep the existing nuts in case I want to go back...

 

[t3rmin]

And McMaster-Carr has M5-0.50 nuts for $13.21 for a 50 pack.

Metricspecialties.com is slightly cheaper then...

 

[t3rmin]

Got another reply from a fastener maker. $6.79 each to get them custom made. So I guess the first response was the best. I'm still evaluating the loctite by itself, though...

 

[nert]

Had a few minutes to "go back".
Anyone complete this project? another forum maybe?

 

[t3rmin]

Naw, I gave up due to custom fasteners being prohibitively expensive. Plus the blue loctite method seems to work just fine...

 

[distraction628]

Is this the type of screw you guys want to do this? This is so close to how my Concours is....Great idea guys and gals.

http://www.boltdepot.com/product.aspx?cc=25&cs=82&cm=19&cd=1366

http://www.boltdepot.com/product.aspx?cc=25&cs=82&cm=19&cd=1316

http://www.mmsacc-stainless.com/metric/html/metric_button.html

 

[t3rmin]

Is this the type of screw you guys want to do this? This is so close to how my Concours is....Great idea guys and gals.

http://www.boltdepot.com/product.aspx?cc=25&cs=82&cm=19&cd=1366

http://www.boltdepot.com/product.aspx?cc=25&cs=82&cm=19&cd=1316

http://www.mmsacc-stainless.com/metric/html/metric_button.html

Nope. It's 5MM with fine pitch 0.50mm threads. Impossible to find!

 

[Guest]

To attach a nut permanently to threaded rod, wouldn't a tack weld work well?

 

[49er]

To attach a nut permanently to threaded rod, wouldn't a tack weld work well?

Yes. You screw the nut 2/3 on and do a plug weld with Mig or Tig welds. Grind the weld flush for a nice appearnace. If you used stainless treaded rods and nuts you would get a better looking finish. A slot could then be cut into the head for those who preferred to use a screw driver for their adjustments.

 

[t3rmin]

Yes. You screw the nut 2/3 on and do a plug weld with Mig or Tig welds. Grind the weld flush for a nice appearnace. If you used stainless treaded rods and nuts you would get a better looking finish. A slot could then be cut into the head for those who preferred to use a screw driver for their adjustments.

Anyone with a welder care to whip up a bunch of these?? ;-)

Seriously, though, before you spend too much time on this, try taking the locknut off and putting a drop of blue loctite on. So far so good for me.

 

[49er]

Anyone with a welder care to whip up a bunch of these?? ;-)

Seriously, though, before you spend too much time on this, try taking the locknut off and putting a drop of blue loctite on. So far so good for me.

Yeah, loctite is easier.
I just checked the screw size on a set of 36mm Mikuni Slingshot carbs.
They are M4 x .5 x 12mm long and have a combo philips/scew drive blade head with a coil spring that is 7mm OD x 9mm L x 5mm ID. No washers required with this spring.
These springs may be suitable for the 5mm bolts? Or, for those wishing to make a project of it, you could weld in the holes on the sync tabs and drill and tap to the M4 screws. You may break a tap when re-threading though.
I have a scource for taps if anyone wishes to go this way.
I would try the blue loctite first and then use the threaded M5 rods if the loctite didn't hold.