BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Phil C on 26 Jan, 2021, 14:48

Title: Primary chaincase Allen bolts - tightness
Post by: Phil C on 26 Jan, 2021, 14:48
I've learnt from this forum that the bolts which secure the timing side outer cover should not be tightened very hard atall. I wonder: does the same apply to the primary chaincase allen bolts? (There is a gasket on the pc side, but not on the timing side, if that is atall significant.) The reason I ask is that when I first removed my pc the bolts were very tight, and so I've done them up tightly, in order to avoid leaks. Maybe that's wrong? Maybe it's risky damaging the female thread (which would be a bit of a disaster)?       Phil
Title: Re: Primary chaincase Allen bolts - tightness
Post by: A10 JWO on 26 Jan, 2021, 14:59
The problem with Allen bolts is that everyone does them up too tight because they can. Thats why they were screws, that's all they need; a hand and screw driver. This is another reason that the threads get worn out in the cases. Does this make sense. ???
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 26 Jan, 2021, 15:03
Quote from: A10 JWO on 26 Jan, 2021, 14:59
The problem with Allen bolts is that everyone does them up too tight because they can. Thats why they were screws, that's all they need; a hand and screw driver. This is another reason that the threads get worn out in the cases. Does this make sense. ???
Okay, thanks, in future I'll be gentle with them.   Phil
Title: Re: Primary chaincase Allen bolts - tightness
Post by: AdrianS on 26 Jan, 2021, 15:06
I think it easier to get a uniform tightness with an Allen key. Screw heads were often chewed up because the wrong sized screwdriver was used. We have all come across heads that are that chewed up it is difficult to get any purchase on them and also vastly over tightened.
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Bess on 26 Jan, 2021, 15:42
Hi,
    If you're worried about overtightening it maybe worth investing in an Allen screwdriver:

https://www.ebay.co.uk/itm/Bondhus-Hex-Screwdriver-Allen-Balldriver-Ballend-Imperial-Key-Lifetime-Warranty/251516663415?hash=item3a8f8fb677:g:aqcAAOxyBotTXRML

Best wishes...
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Rog1 on 27 Jan, 2021, 11:25
With Allen headed case screws, I do them up first using the short end for leverage, but not very tight. Because I find that when using the short end for leverage it's difficult to be consistent, to finish I reverse the key and use the long end for leverage to finally tighten each screw. But importantly, I do apply anywhere near full force. This has worked for me for years.
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 27 Jan, 2021, 11:37
Thanks Rog1, I think that's probably what I'll do, as it's cheaper than buying a set of screwdrivers (but thanks anyway Bess.) What I hope won't happen is that I tighten gently and it leaks, so I tweak it a bit more and it still leaks a bit, so...you can see where that could end up. I guess it's a matter of ensuring good surfaces and even tightening. I think maybe in the past I've been too reluctant to use much jointing compound, maybe I should use a bit more.  Phil
Title: Re: Primary chaincase Allen bolts - tightness
Post by: PeteRae on 27 Jan, 2021, 11:54
Phil,
when you are tightening them up, do it in a sequence like a cylinder head. Bit like opposites on a clock face....plus the one in the middle. If you've still got a leak have a go at smoothing off the casing faces by rubbing them on a piece of flat glass/mirror with some grinding paste. Tightening bolts/screws over the years can deform the alloy a bit.
Pete
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 27 Jan, 2021, 11:58
Thanks
Title: Re: Primary chaincase Allen bolts - tightness
Post by: PeteRae on 27 Jan, 2021, 17:50
If the picture has uploaded....this is why you need to check the bolt length and clean out the holes...
Pete
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Rog1 on 29 Jan, 2021, 14:49
Quote from: PeteRae on 27 Jan, 2021, 17:50
If the picture has uploaded....this is why you need to check the bolt length and clean out the holes...
Pete

A drill bit fed in by hand (I only heard about this method recently) can remove a surprising amount of old gasket sealant etc from screw holes.

If a previous owner has been levering at the cases or been clumsy, that can cause raised sections on the gasket faces; something to watch out for. Careful use of a fine file can remove those bumps.
Title: Re: Primary chaincase Allen bolts - tightness
Post by: DAVE BRADY on 29 Jan, 2021, 15:17
Hi,

A light touch with a drill bit quite bit larger than the hole will also remove any bulging and tidy up the hole.  To get the threads really clean gently run a tap down to the bottom of the hole.  You may find another bit of depth so a slightly longer screw can be used which can come in handy if the shallower threads are bit worn.

Dave.
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 31 Jan, 2021, 16:22
Hello everyone,
I see that Rupert Ratio (vol.1, p.250) gives a torque setting for timing and primary cover screws of 3.5 - 4.5 ft/lbs. I'm not sure if this is for all models and years but it looks like it to me.
I don't know much about torque settings but I'm guessing that's a very gentle tightening indeed. For example, as a comparison, carb flange nuts he gives as 10ft/lbs.
So I think I'll be taking my primary chaincase off and when I put it back on it will be more delicately.
I've just ordered a torque wrench but it doesn't go that low. So I'll just tighten gently, turning the short end of the Allen key. In any case how would you fit a torque wrench to an Allen screw?
Phil
Title: Re: Primary chaincase Allen bolts - tightness
Post by: AdrianS on 31 Jan, 2021, 16:58
Quote from: Phil C on 31 Jan, 2021, 16:22
Hello everyone,
I see that Rupert Ratio (vol.1, p.250) gives a torque setting for timing and primary cover screws of 3.5 - 4.5 ft/lbs. I'm not sure if this is for all models and years but it looks like it to me.
I don't know much about torque settings but I'm guessing that's a very gentle tightening indeed. For example, as a comparison, carb flange nuts he gives as 10ft/lbs.
So I think I'll be taking my primary chaincase off and when I put it back on it will be more delicately.
I've just ordered a torque wrench but it doesn't go that low. So I'll just tighten gently, turning the short end of the Allen key. In any case how would you fit a torque wrench to an Allen screw?
Phil

You buy a set of Allen sockets.
For the timing side cover, just nip them up first , then go around again and tighten a tad more and that should be fine. Evenness is more important and also the length of thread that is engaged. The more thread, the bigger the safety margin before stripping.
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Bess on 31 Jan, 2021, 19:39
Hi Phil,
           A torque screwdriver would be the best option:

https://www.machinemart.co.uk/p/wera-7445esd-torque-screwdriver-2-5-11-5lbfin/

Best wishes...
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 31 Jan, 2021, 19:44
Hello Bess, Thanks for this. Natty bit of kit. Shame about the price tag.  Phil
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 21 Mar, 2021, 11:05
We've discussed that when tightening the Allen bolts on the outer timing cover, and on the primary chaincase cover, we should only tighten them gently. Fair enough, but I guess when I do that I'll be wondering if they're going to come loose. Should loctite be used?   Phil
Title: Re: Primary chaincase Allen bolts - tightness
Post by: JulianS on 21 Mar, 2021, 11:15
They need to be tightened sufficiently to prevent them slackening off. A matter of judgement.

You may find a thicker gasket settles after some miles and needs the screws tightening slightly to compensate.
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Phil C on 21 Mar, 2021, 11:37
Loctite or not?
Title: Re: Primary chaincase Allen bolts - tightness
Post by: Pete A10 on 21 Mar, 2021, 19:44
No loctite
Just tighten them up until they feel solid