Fork thread specification for top nut R60/6

I spent the weekend changing the front fork springs. I am using progressive springs replacement. I did the left side and it went fairly well. I then did the right and ran into a problem tightening the top nut. It stopped about 4mm from being flush to the plate. This left the legs uneven buy the same amount. I tried loosening the nut several time but no go. It goes in but takes effort. The left side goes in easily by comparison. I then took the left side apart and ran the RIGHT side nut into the LEFT fork. It WENT IN SMOOTH AND EASY . So some how I messed up the threads in the RIGHT fork. I need to buy a tap or at least a thread chaser. Does anyone know the specification? Any one else mess up like I did. any advice appreciated.


WHEN i POSTED THIS LAST , i GOT LFT AND RT MIXED UP IN MY DESCRIPTION. i HAVE CORRECTED IT ABOVE. iT IS THE RT FORK TUBE TOP THREADS THAT ARE MESSED UP.

Easy enough to measure the diameter of the cap threads; a ruler should work for something that big although vernier calipers are better. Then you can get a thread pitch measuring tool or an app for your phone. 'Wonderbolt' seems like it would work.

ccolwell said:

Easy enough to measure the diameter of the cap threads; a ruler should work for something that big although vernier calipers are better. Then you can get a thread pitch measuring tool or an app for your phone. 'Wonderbolt' seems like it would work.

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Thanks. I took a look. Measuring it its 30mm dia with a 2mm thread pitch. According to the on line charts, that requires a 28mmX2 tap. Checking on line that's about a $40 tool. Better than a new tube. I will check with a few friends first to see if that might have one. Thanks.

Where's your top washer? I just checked, and on an R90/6 I have here in the shop,the top nut bottoms out early without the top washer.

You do need that washer

It looks like its been missed in the picture and its about 4mm thick.

69zeff65 said:

It looks like its been missed in the picture and its about 4mm thick.

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It appears it never had one and this is the first time I have taken it apart since I bought it. The other side has no washer either but I will order a set for sure.

Correction to the tap it needs to be an M28X1.5. I got a proper feeler gauge to measure. Thanks for the washer info!

I think you just need the washer or the bracket that supports the fairing/instrument/whatever. They are about 2.5mm thick and take up that gap. The top plate is about 4.5mm thick and you can see the gap is far smaller than that.

Not sure at all why you'd want a 28mm tap for a 30mm thread, but I don't think you need a tap at all. That thread is recessed and you aren't going to get a tap into the bottom of it without taking out a lot of metal.

As for why it works OK on the other side, it could be that one tube was replaced and the new one has a bit more thread there, who knows. What I do know is that I have three /6 models in the shop right now, all of them have either the bracket or the washer up there, and the one that is apart won't go together the way you show and there's nothing wrong with it; it just needs the washer.

AntonLargiader said:

I think you just need the washer or the bracket that supports the fairing/instrument/whatever. They are about 2.5mm thick and take up that gap. The top plate is about 4.5mm thick and you can see the gap is far smaller than that.

Not sure at all why you'd want a 28mm tap for a 30mm thread, but I don't think you need a tap at all. That thread is recessed and you aren't going to get a tap into the bottom of it without taking out a lot of metal.

As for why it works OK on the other side, it could be that one tube was replaced and the new one has a bit more thread there, who knows. What I do know is that I have three /6 models in the shop right now, all of them have either the bracket or the washer up there, and the one that is apart won't go together the way you show and there's nothing wrong with it; it just needs the washer.

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Thank you for the info on the washer. As to the tap, that is they way they are spec'ed on all the tap sites I have researched. I guess it has to do with thread depth and blank hole size needed for tapping. The 28mm refers to the valley of the thread , the peak is at 30mm.

Thanks again for the info.

wasserwolf said:

Thank you for the info on the washer. As to the tap, that is they way they are spec'ed on all the tap sites I have researched. I guess it has to do with thread depth and blank hole size needed for tapping. The 28mm refers to the valley of the thread , the peak is at 30mm.

Thanks again for the info.

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30mm at peak of the male threads or valley of the female threads?

PGlaves said:

30mm at peak of the male threads or valley of the female threads?

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30mm at the peak of the male thread.