Gear adjustment screws - What screwdriver?

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Spinners
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Gear adjustment screws - What screwdriver?

Postby Spinners » 18 Jul 2017, 7:35pm

What is the exact type of screwdriver required for adjusting Shimano front and rear mechs?

Like most households, we have a good selection of cross head screwdrivers but I can't seem to find one that's a perfect 'Goldilocks' fit :lol:
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reohn2
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Re: Gear adjustment screws - What screwdriver?

Postby reohn2 » 18 Jul 2017, 7:43pm

It's a size 2 Phillips or a size1 Pozidrive
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Samuel D
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Re: Gear adjustment screws - What screwdriver?

Postby Samuel D » 18 Jul 2017, 7:51pm

I think it’s technically a JIS #2, and I furthermore think the whole JIS screwdriver sizing system is basically obsolete, with screwdrivers unavailable. However, the torque needed for derailleur limit screws is so low that almost anything works okay in practice.

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Spinners
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Re: Gear adjustment screws - What screwdriver?

Postby Spinners » 18 Jul 2017, 7:59pm

Ah, the less than intuitive Shimano website shows the stroke adjustment screws as being M4 x 13.
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Brucey
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Re: Gear adjustment screws - What screwdriver?

Postby Brucey » 18 Jul 2017, 8:04pm

The screws are slotted for crosspoint or flat blade tools; if the screws turn easily, more or less anything will do the job. But otherwise it is a (Japanese spec) #2 phillips, or a 5.5 x 1.1mm flat blade. Other flavours of phillips or supadrive or pozi are not quite right and will risk wrecking a tight screw.

5.0mm x 1.0 is a common size and will work OK (better than phillips usually) but if you meet a tight screw you really need the 1.1mm width blade for a tight fit.

Apologies if this is obvious but the screws are easier to turn when the mech isn't bearing against the stop screw. It is also a very good idea to clean the dirt out of the screw heads before trying to turn them.

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Spinners
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Re: Gear adjustment screws - What screwdriver?

Postby Spinners » 18 Jul 2017, 8:10pm

Thanks for that. Time to invest I think.
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keyboardmonkey
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Re: Gear adjustment screws - What screwdriver?

Postby keyboardmonkey » 18 Jul 2017, 8:20pm

As SamuelD writes, such Japanese Industrial Standards are reported as no longer being 'standard', but my relatively modern 9sp M772 and 10spd 6700 rear derailleurs have the tell tale single dimple on the head of each limit screw. More on this, which I have to confess is fairly recent news to me, too...

http://www.bikeradar.com/gear/article/t ... ove-45914/

Samuel D wrote:I think it’s technically a JIS #2, and I furthermore think the whole JIS screwdriver sizing system is basically obsolete, with screwdrivers unavailable.


There are a few independent retailers in the UK who sell them, mainly for motor bike fans, but Amazon.co.uk will sell you them, too. Search for 'Vessel screwdriver', especially if you've rounded off a limit screw or don't want to. Not cheap, though.

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Re: Gear adjustment screws - What screwdriver?

Postby profpointy » 18 Jul 2017, 8:24pm

as said upthread the head is a bongo fitting and also,on my experience the screws are made of some metallic looking cheese. I replaced all mine with stainless steel cap screws (ie allen key heads) and they now don't rust and are a doddle to adjust. Can't remember if they were m3 or m4 (metric) but a standard thread at any rate. Years ago I bought a £30 box of assorted A2 grade stainless cap screws and it is so handy always having the right size for almost anh job

landsurfer
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Re: Gear adjustment screws - What screwdriver?

Postby landsurfer » 18 Jul 2017, 8:25pm

Seriously .... what screwdriver ? ..... your doomed ...... :)
I will fear no evil .....The shadow is mine .. And so is the valley.

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Spinners
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Re: Gear adjustment screws - What screwdriver?

Postby Spinners » 18 Jul 2017, 8:44pm

landsurfer wrote:Seriously .... what screwdriver ? ..... your doomed ...... :)


Not really. I've fettled my own bikes for 26 years now but I changed my chainset last night and when adjusting the front mech I realised that what I was using wasn't quite an exact fit.

Thanks again to those who have made a positive contribution and not a derogatory one albeit with a smiley face.
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gregoryoftours
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Re: Gear adjustment screws - What screwdriver?

Postby gregoryoftours » 18 Jul 2017, 8:54pm

profpointy wrote:as said upthread the head is a bongo fitting and also,on my experience the screws are made of some metallic looking cheese. I replaced all mine with stainless steel cap screws (ie allen key heads) and they now don't rust and are a doddle to adjust. Can't remember if they were m3 or m4 (metric) but a standard thread at any rate. Years ago I bought a £30 box of assorted A2 grade stainless cap screws and it is so handy always having the right size for almost anh job

Good call, those screws are a bloody bad idea, in the places where they're most likely to seize up too, especially the balancing screws on old dp road calipers. Sram have the right idea and use cap screws nowadays, as do some shimano.

landsurfer
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Re: Gear adjustment screws - What screwdriver?

Postby landsurfer » 18 Jul 2017, 9:08pm

Spinners wrote:
landsurfer wrote:Seriously .... what screwdriver ? ..... your doomed ...... :)


Not really. I've fettled my own bikes for 26 years now but I changed my chainset last night and when adjusting the front mech I realised that what I was using wasn't quite an exact fit.

Thanks again to those who have made a positive contribution and not a derogatory one albeit with a smiley face.


After 40 years as an engineer i can tell the difference between real need and OCD behaviour ...
It's a screw ... Turn it ......
Exact fit cross point, kitchen knife, what does it matter as long as it works !!!!!!! :evil:

"Oh no ... my LEJOG is over ... I haven't got the right screwdriver to adjust the derailleur " ....

Perspective .....
ETP
I will fear no evil .....The shadow is mine .. And so is the valley.

The Road Goes On Forever

profpointy
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Re: Gear adjustment screws - What screwdriver?

Postby profpointy » 18 Jul 2017, 9:28pm

now that's just crazy talk; call yourself an engineer. It would, and has,really bugged me using the wrong tool on a fastener.

Remember the 3 rules of engineeering:

1 use the right tool for the job
2 the right tool for any job is a hammer
3 any tool can be used as a hammer

gregoryoftours
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Re: Gear adjustment screws - What screwdriver?

Postby gregoryoftours » 18 Jul 2017, 9:35pm

Before you invest in a jis screwdriver you could try an old philips no2 with the point ground down a bit. I don't think it's ocd to want a screwdriver that fits those screws well, they can be quite seized up, and as has been said often seem to be made of cheese. Often a flat blade will work better than a philips but I find it quite hard to keep it aligned correctly if I'm adjusting whilst sighting down the back of the mech to see what effect the adjustment is having. In my ooinion cap head screws are way more suitable for that application, as has been said by others in this thread.

keyboardmonkey
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Re: Gear adjustment screws - What screwdriver?

Postby keyboardmonkey » 18 Jul 2017, 10:21pm

gregoryoftours wrote:Before you invest in a jis screwdriver you could try an old philips no2 with the point ground down a bit...


Yes, I saw a bloke on YouTube suggesting that workaround, but...

landsurfer wrote:
After 40 years as an engineer i can tell the difference between real need and OCD behaviour ...
It's a screw ... Turn it ......
Exact fit cross point, kitchen knife, what does it matter as long as it works !!!!!!! :evil:



... is a fair point. I once dismantled the carburettor on my MkI Escort using just my finger nails, but I have to get the JIS screwdriver set because they match the colour of my favourite tool box.