Set-screw size?

[Air-Cooled]

One of my Aprilia turn signals is missing a set-screw.  I tried to match the thread size at Ace Hardware as well as the area's largest fastener supply company -- Copperstate.  Neither could match it.  Does anyone know the thread size of these?  Copperstate said it was a 10-32 and indeed, I was able to screw and existing Aprilia screw into their 10-32 test socket, but the actual 10-32's are too wide fit in the signal. 

[Matt Story]

I don't share your bike.  I think there is almost a 0% chance that a European company would use an Imperial thread size (#10-32) on any product from the last 30 years.  An M5 is very close in diameter to a 10-32, but the thread pitch is different.

There is always a chance it has been stripped, worn or re-tapped

Best regards

[Air-Cooled]

I agree that the 10-32 being is an unlikely thread on a European bike, but the guy at Copperstate said that electrical items, even European, often use 8-32, so he thought it might work.  The M5 did not fit the Aprilia (I tried that one too).  The threads are not stripped because I swapped in a set-screw from one of the other turn signals and it fit fine.  I can't get a 10-32 or an M5 to even start threading in, that's why I thought I'd pose it to the group.  I'd hate to have to buy a used Aprilia turn signal just to get the set-screw, but it is looking like that may be what will happen.

[FarmallA]

Could you just run a 10-32 tap into it and use a 10-32 setscrew?   Do it on both turn signals so the bike still goes in a straight line.

Edit:  Or a M5 tap if you have that setscrew and want to keep it metric.  Still have to do both turn signals or you're going to screw up the steering.

FarmallA
Steve

[ridingron]

Did you take the screw with you to the store? Find a nut that fits the screw properly.

Is there an Aprilia dealer near? Any motor cycle or auto dealership can probably tell you what size it is and probably sell you a screw.

I would look a little harder before re-threading the holes to an Imperial/SAE size.       

[Air-Cooled]

Yes, I took it to the store.  It fit well only into the 10-32 test socket they had, perhaps the slightest bit loose. It would not fit into. an M5 socket. I'm not gonna drill and tap it, just trying to find out what size the thing is if anyone knows.  If no one knows and three hardware stores can't help, I'll just buy a used Aprilia turn signal and use the screw.

[nc43bsa]

Did you try an M4.5 setscrew?

[Air-Cooled]

I didn't even know they made an M4.5.  I'll look --- did not find one on the internet.

[nc43bsa]

Yeah, I've run into some weird ones in the past, like M1.1. 

M4.5 is the largest of the "in-between" metric sizes that I've dealt with.

[Air-Cooled]

I found one source for M4.5 set screws -- in England. My guess is the Aprilia used M4.5.  M4 is too small, M5 is too large.  Time to find a used turn signal and grab the screw.  Oh and Locktite as well!

[Matt Story]

The M4.5 crossed my mind, but I dismissed it.

For reference, those diameters are very close:

4.5mm = 0.177"
#10(3/16) = 0.1875"
5mm = 0.197"

[nc43bsa]

In the past, I've used a cut-off M4.5 cap screw and cut a screwdriver slot in the cut end.

[Stretch]

In the past, I've used a cut-off M4.5 cap screw and cut a screwdriver slot in the cut end.

The backyard machinist's solution!     

I'm always doing stuff like that.....

                                    -Stretch

[Frenchfrog]

Europe is not as metric as one would assume : all the European specification plumbing threads are metric adaptations of Imperial measurements for starters .Pipe bores are metric though and go up in steps of 2mm whereas when the British went metric they took the nearest metric size meaning that the two types of pipe have to have special adapters to join.The two types of fittings are however completely interchangeable so I would not be surprised if that is the same for electrical fittings too.

[Moparnut72]

Back in 1971 I put a full Avon fairing on my R75/5. It took me a whole day because the forks had to come off as well as the exhaust system. Turn signals, headlight as well as other stuff had to be relocated. But one of the reasons that it took so long was that the fasteners that came with it was a mixture of SAE, metric and Whitworth. It was worth it in the long run, very calm behind it and the rain didn't get in.
kk

[Air-Cooled]

I guess we'll never know for sure about the thread size on Aprilia set screws, but I have a used signal coming to me in the mail.  Purple Loctite will be applied to all four screws.

[Kev m]

I mean, we CAN know. All it should take is a proper thread gauge. No?

[Air-Cooled]

Unfortunately, I used thread gauges at three different stores.  The only one that would accept it was a 10-32, but 10-32 screws will not fit into the turn signal.  That is the reason I posted the question here.  I hoped someone might have had to replace one and would know. 

[ridingron]

What model are the turn signals from?

There has to be a parts fiche on the net some where that will give the information.

[Air-Cooled]

There has to be a parts fiche on the net some where that will give the information.

Been there, done that.  The set screw is not identified, no surprise there.

[Antietam Classic Cycle]

Original Lucas signals had stems that were threaded 7/16-14.

I have an Aprilia signal somewhere around here, will have dig it out and measure the set screw.

They were used on some 850-Ts as far as I know. 

[Air-Cooled]

Original Lucas signals had stems that were threaded 7/16-14.

I have an Aprilia signal somewhere around here, will have dig it out and measure the set screw.

They were used on some 850-Ts as far as I know.

Aprilias were also used on V7 Sports sold in Italy.  The one in their museum has them.  When I bought my V7 Sport many years ago, it came with no turn signals.  Lucas signals were standard on US V7 Sports.  I needed to add turn signals, so I figured why not go with the Aprilias?  They are made of metal, unlike the plastic Lucas ones. But I'd be very interested to know what your Aprilia signal takes for a set screw.  Thx!

[Kev m]

Unfortunately, I used thread gauges at three different stores.  The only one that would accept it was a 10-32, but 10-32 screws will not fit into the turn signal.  That is the reason I posted the question here.  I hoped someone might have had to replace one and would know.

That just means they didn't have the thread size in the gauge.

[Air-Cooled]

That just means they didn't have the thread size in the gauge.

Uh, yeah.

[Mike Tashjian]

So why not just tap the hole to a size that you can easily get or already have?   Personally I like the socket head set screws in stainless for this application.