The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: Colsbeeza on 01.10. 2018 08:18

Title: Pin dropped into crankcase - HELP
Post by: Colsbeeza on 01.10. 2018 08:18
Oh Dear,
Just when things were going OK - I had rings compressed with new ring compressors (photo attached), had the cylinders dropped on, and was removing the ring compressors when one of the trunnion pins fell out and into the crankcase. *problem*
What a sh--t design.!! - how could a maker not see that happening.?? I had assumed that the trunnion pin could not slide out.
It is about 1/4" diameter x 3/4" long. I cannot see it and suspect it lies beneath the flywheels somewhere.
AND I had the gasket sealer on ready.!!
I had removed the rags to make it easier - and now much harder.
As a first step I will remove the sump plate and try to wash it out or use compressed air to dislodge it.
Anybody had any luck without dismantling the engine?
Col
Title: Re: Pin dropped into crankcase - HELP
Post by: beezermacc on 01.10. 2018 08:23
removing the sump plate isn't a big job and you've got a good chance of finding it that way. Ring compressors come in various sizes and you should use a size which allows you to undo the screw enough to slip the trunnion over the clip whilst the screw is still in the trunnion, then just pull the compressor off.
Title: Re: Pin dropped into crankcase - HELP
Post by: LJ. on 01.10. 2018 08:24
Fish around with a magnetic telescopic pen. I wouldn't use an air line in there could blow anywhere and get tightly wedged in somewhere.
Title: Re: Pin dropped into crankcase - HELP
Post by: Colsbeeza on 01.10. 2018 11:31
Thanks Fellas,
Whilst you were replying, I was in the shed. I took off the sump plate and there it was. (Picture)
Yes Beezermac - It dawned on me that I could remove the ring without removing the screw- just undid enough to remove it from its clip. Live and learn eh.? Ring compressor wasn't a piece of crap afterall. *red*
I now have the cylinders and head on - finish tomorrow hopefully..
Col
Title: Re: Pin dropped into crankcase - HELP
Post by: morris on 01.10. 2018 11:39
Happened to me also. Didn’t take long to fish it out with a small flexible shaft magnet.
If you ask me which tool I use the most it’ll probably be that one  *smile*
Afterwards I closed up the eyelet that holds the trunnion to make it a push fit so it wouldn’t drop out anymore. Funny though how something has to happen before you do something about it. I remember thinking that the trunnion was rather loose and I had to watch out for it not to drop in the engine... which it did *problem*
Title: Re: Pin dropped into crankcase - HELP
Post by: RichardL on 01.10. 2018 12:04
You won't find me making such silly mistakes. *whistle* ::hh:: *smile*
Title: Re: Pin dropped into crankcase - HELP
Post by: ellis on 01.10. 2018 18:54
Famous last words RichardL.


ELLIS
Title: Re: Pin dropped into crankcase - HELP
Post by: RichardL on 01.10. 2018 19:59
All my mistakes are silly.
Title: Re: Pin dropped into crankcase - HELP
Post by: a10gf on 01.10. 2018 20:17
Did this once with a piston circlip. A small nightmare but finally recovered it. Quickly thereafter became an expert in stuffing rags etc into the crank when doing anything.
Title: Re: Pin dropped into crankcase - HELP
Post by: jachenbach on 02.10. 2018 00:00
Can't remember for sure what I dropped in my Bonneville engine years ago, but my brother and I turned the whole bike upside down and shook it until it dropped out.
Title: Re: Pin dropped into crankcase - HELP
Post by: WozzA on 02.10. 2018 02:58
I use Musky's method with the plastic drain pipe...
Title: Re: Pin dropped into crankcase - HELP
Post by: orabanda on 02.10. 2018 06:37
Did this once with a piston circlip. A small nightmare but finally recovered it. Quickly thereafter became an expert in stuffing rags etc into the crank when doing anything.

The piston clip that caused me the most grief was the one I forgot to install!

The pin acted like a slot drill, and milled a railroad track into the barrel of my friend's hotrod two stroke.

After seeing how fast I had managed to get my DT1 to go, he had asked a big favour: would I unleash my mechanical skills on his TS185?

It was the only time he asked; hasn't called in the last 45 years!

Richard

ps; NEVER made that mistake since!

Rest easy Gavin, all 4 clips WERE fitted into GF#4!

(I think?? *doubt*)


Title: Re: Pin dropped into crankcase - HELP
Post by: duTch on 02.10. 2018 08:47
 
Quote
....The piston clip that caused me the most grief was the one I forgot to install!....

 Yep was reminded of same misdemeanor today (/8" groove) while digging out my special tool...  that being a bit of tin cut to shape of the crankcase orifice, but in conjunction with other bits...;

 *Edit*  was originally intended more as something to rest the pistons on though...
Title: Re: Pin dropped into crankcase - HELP
Post by: olev on 02.10. 2018 09:42
One of the best bits of info I have got off this forum is Trevor's (BSA_54A10) method of installing rings.
Sit the barrels on the cases held up with a couple of pieces of wood, then hang a dirty great pair of stilsons on the drive shaft so the pistons are presented to the bores.
squeeze the individual rings with your fingers on each side.
The pistons magically slide up into the bore like (can't think of anything that's not rude)
you know what I mean.
I couldn't find Trev's post. He explains it much better than me.
cheers
Title: Re: Pin dropped into crankcase - HELP
Post by: BSA_54A10 on 02.10. 2018 09:58
Nothing is ever new.
It was a method I was shown by one of the old time racers.
He raced Gold Stars when they were new and on them he used some lengths of garden hose with a slot cut in them ( goldies are through bolted ).
Did not take long to modify the idea for twins.
Better still have not broken a ring in better than 20 years.
If you get a chance to look at the factory promo film you will see that the factory clamped the pistons, put the barrel on top of the clamps then wound the pistons up.
From memory he takes about 6 seconds start to finish.
It is down as a first job for the mill when we get it working.
Title: Re: Pin dropped into crankcase - HELP
Post by: orabanda on 02.10. 2018 10:42
There's a kinder way to grip the splined end of the crankshaft than using stillsons.

Rather, use an adjustable spanner (10", 12",15" whatever tickles your fancy); open the jaws until they slide across the spline. They will grip the spline well enough to rotate the crankshaft, without damage or marks.

A gold star (mark only!) to the first forum member to dash off to the man cave and try it.

Richard
Title: Re: Pin dropped into crankcase - HELP
Post by: RDfella on 02.10. 2018 18:23
Jachenbach - reminds me of the mid 60's when I was in a mates shed the night before a race. He was about to take the engine out of his single-seater to change the cam (with mushroom tappets in an ohv in-line engine, you can't get the cam out when the engine is upright or, if you did, the tappets would fall into the sump). So I suggested we turned the car upside down. Ten minutes and job done. Didn't even need to take the battery out, as it was a gel battery (rare in those days).
Title: Re: Pin dropped into crankcase - HELP
Post by: Slymo on 05.10. 2018 20:58
I made ring compressors out of packing case strap. Worked a treat. Used to working on singles and to pushing the rings in with my fingers it soon became very clear that this wasn’t an option with a twin
Title: Re: Pin dropped into crankcase - HELP
Post by: a10gf on 05.10. 2018 21:34
^^^ Nice homemade tools. ...and I like the picture's background scenery :O)
Title: Re: Pin dropped into crankcase - HELP
Post by: muskrat on 06.10. 2018 00:27
Slymo, you been using my bench while I'm not home  *????* ;)
Cheers
Title: Re: Pin dropped into crankcase - HELP
Post by: Slymo on 06.10. 2018 12:41
There is a certain disorder to my working environment it must be said. A bit ADHD as a lad I suspect would be the diagnosis.  Still qot to work with what youve got :)