Timing side screws

Started by Phil C, 15 Nov, 2020, 11:54

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Bess

#15
21 Dec, 2020, 22:48
Hi Phil,
           Phillips screws originated in the US, I guess BSA pandering to that market used that standard fixing. Bizarrely they were designed to enable more torque to be applied which may have contributed to threads being stripped.

Best wishes...

leon bee

#16
21 Dec, 2020, 23:28
I'm starting to wonder why Pozidrive isn't being mentioned here at all. Is that something that came along later then the early 60s? Most of my English bikes are late 60s BSAs. I like the original look, so all of my case screws are posidrive. Usually when I drag a bike home all the case screwheads have been hogged out by Phillips drivers over all the years. When they're all out I get new PD screws and with the PD# driver they work great, the tip never slips.

I looked at the Draganfly site, didn't see the word Phillips. Here in the states we have british fasters.com. I never see the word Phillips there either, only posidriv. So for 20 years I've thought all the britbike phillips looking screws were PD......beginning with the change from slotted screws. I'll stay tuned, I like to know this stuff.

Bess

#17
22 Dec, 2020, 08:14
Hi Leon bee,
                  Sorry you are correct they are Pozi drive screws.

In my circle of friends in the UK, Phillips seems to be readily used as a generic term for cross head screws.

Best wishes...

leon bee

#18
22 Dec, 2020, 08:58
Esoterica for sure. I have a bucket just like that!

Phil C

#19
22 Dec, 2020, 10:07
Quote from: Bess on 22 Dec, 2020, 08:14
Hi Leon bee,
                  Sorry you are correct they are Pozi drive screws.

In my circle of friends in the UK, Phillips seems to be readily used as a generic term for cross head screws.

Best wishes...

So Bess, are you saying the screws would have been Pozidrive back in 1965? If so, I'm surprised, I thought they arrived later.  Phil

DAVE BRADY

#20
22 Dec, 2020, 10:35
Hi,

I think the extra 4 lines on the screw in Bess's bucket indicate 'Pozidrive'.  I do not think that Philips have these.  The Pozidrive probably came about because the Philips had a tendency to slip.  I have a selection of crosshead screwdrivers and sometimes finding a good fit is not easy especially if screws have been replaced over the years.  It seems even more complicated today as there are several formats for crosshead screws and none fit another well enough to use.  The more non-original the screw the less likely it is to be Philips or Pozidrive.   

Dave.

Phil C

#21
22 Dec, 2020, 10:49
But to return to my original question, what would the original screws have been on my 1965 bike's timing side outer casing?  Phil

DAVE BRADY

#22
22 Dec, 2020, 11:10
Hi,

Maybe not definitive but I would say Philips rather than Pozidrive.  Philips came out about 1936 but have conical flanks that can cause an 'ejection force' when being used to do things up tightly.  So OK for outer covers.  Pozidrive came out in 1963 and have a parallel flank so putting all the effort in to the rotation of the screw as there is no 'ejection force'. 
However, it is quite feasible that with the availability of the superior Pozidrive head from 1963 that this was specified for uses where a tighter screw was needed such as inner and outer covers that bear a load.
Is there a toolkit page in the B40 workshop manual that give the type of screwdriver included?

Dave.

MGI

#24
23 Dec, 2020, 09:30
I think that many stainless screws appear to favour Philips, which have a much smaller cross point whereas most wood screws and engineering applications appear to have Pozi drive which, as previously noted, can handle higher torque applications. All the fittings on lock mechanisms with UPVC doors seem to be Philips. (useless info I appreciate) I find that a Philips head that is tight, especially if there is any corrosion, are extremely difficult to release without damaging the head!

Rog1

#25
23 Dec, 2020, 13:43
I don't use screwdrivers with Phillips tips any more; I use JIS (Japanese Industry Standard) tipped screwdrivers instead. They are designed not to cam out, unlike the Phillips ones, and can be used with success on both JIS and Phillips screws. But you can't use a Phillips driver on a JIS screw without damaging it; the source of all those tales of Japanese case screws being made of cheese.

I use the Vessel brand. They are fairly widely available and are of good quality. If you buy some, one peculiarity is that compared to Phillips screwdrivers, you'll seem to be using too big a size on any given screw. It doesn't matter. I've used them to undo JIS screws that were quite well mangled from being got at with a Phillips previously, and when a Phillips will no longer grip it.

Joeblogs

#26
23 Dec, 2020, 16:45
The outer timing cover screws (and the 5 on the inner timing case) plus all the clutch cover screw threads are all 1/4" (UNC) unified national course.

As above, I have fitted socket head Alan screw as I find them a breeze to screw/unscrew, you just have to take care not to over tighten them as screwing into the soft aluminium case the threads can be easily striped with the extra leverage.

You can still buy the original fitment Pozidrive cheese head screws from Draganfly in the UK (Drag an Fly) if you want to keep the bike original.

https://www.draganfly.co.uk/index.php/bsa/bsa/b50/category/431-kickstart


Phil C

#27
23 Dec, 2020, 17:29
I suppose one down side to using Allen screws is that you would have to cut them down to the various lengths, given that you're unlikely to find a supplier happy to provide one of this length, one of that, etc.  (I think I'm right in saying the outer casing screws are of various lengths?) Not that shortening them is a huge task, but if doing in a vice you'd ideally want a couple of nuts to hold the screws, and you'd want to be sure the end of the thread where you sawed it was nice and clean, ie no burrs etc, before fitting, in order not to damage the aluminium female. So for example you might want to run a die nut down it (but might not have one, of course.) So it is a little bit of a faff, but I guess you could say "so what, it's all part of the fun." By the way, I notice in this hobby how often it would be useful to have a little centre lathe.  Phil

Bess

#28
23 Dec, 2020, 17:46 Last Edit: 23 Dec, 2020, 17:57 by Bess
Hi,
    For a 1965 B40, worth looking here for clarification, seems a high probability they are CEI Pozi drive.

https://www.draganfly.co.uk/bsa/bsa/b40/category/1187-1187-

https://www.bsaunitsingles.com/item.wws?cpubcode=BSA&sku=76-0546

Best wishes..

Bess

#29
23 Dec, 2020, 19:14
Hi Phil,
           Yep, nice to have a centre lathe.

However a bench grinder or a power file is a great assist to dress and put a small chamfer on the cut end.

Best wishes...
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