crankshaft assembly mystery

[john.nash]

As a follow up to this:
http://forum.arielownersmcc.com/viewt ... ?f=4&t=295

FInally bought a big end from alpha.
Delivered relevant bits to local shop ( to save bothering poor old Len..)

They phoned up today to let me know that the oil way in the timing side flywheel (i.e. the hole which the oil comes out of,if you pump it through the timing side mainshaft) doesn't match with the oilway on the big end pin.

There is, of course, a keyway in the drive side flywheel and the associated key is on the crankpin. Foolproof.
When you match this up and then try to line up the oil hole, on the timing side, with the one on the big end pin ... then the flywheels are way, way out of alignment.
If you align the flywheels roughly, then the oilhole on the flywheel is fully covered over ( i.e.blocked)...

The ruined pin that came out (seized, we thought, from lack of oil as it was all gunged up inside) is exactly the same as alpha's new one and doesn't line up either ???

Flywheels both appear to have A7-856 which are VH according this:
http://www.draganfly.co.uk/data/pdf/fly ... umbers.pdf
The conrod that came out is a 500.

I don't understand ... luckily it's club night next week ...

Do we need pictures .. ?

[adrie.degraaff]

The not lining up is coused by the fact that steel flywheels have differend oil ways as cast ones.

So if you order a Red Hunter bigend, you will get a steel flywheel one.

[john.nash]

um , I am confused.

The A7-856 number seems to be used in 1954:(http://www.arielownersmcc.com/members ... HS_P10.jpg
and is cast.

In the 1956 parts:
http://www.arielownersmcc.com/members ... istP08.jpg
- VH are listed as 1051-56/1055-56, which Draganfly also list as cast.
- HS/HT are listed as 1053-56/1054.56, which draganfly list as steel

The same bigend is listed for both (1080-37 crankpin and roller bearing) and this is the part that Alpha have sent me....

[pete.collings]

I don't believe there should be any difference in oil entry holes in a VH crankpin regrardless of flywheel type, but there certainly is a difference in the alignment of oil feed holes in the timing side mainshaft between steel and cast iron flywheels, if my memory is correct the steel flywheel mainshaft has the oil feed roughtly in line with the keyway, whereas the cast mainshaft has an offset between 5 and 10 degrees fron the keyway.
Using the wrong mainshaft will have obvious consequences on the oil feed to the big end!

[john.nash]

I know about the mainshaft on the timing side.
I needed a new one but only had spares of the other two types; I had to go buy the third ....(which I needed). This one fits all later (54-58) singles.

So why doesn't the crankpin line up ...

[nevhunter]

I've only got steel, ( earlier type, pre 1954).separated at the moment. I can check anything relating to these if that helps.
You can remove the pin which aligns with the keyway in the drive side wheel, and carefully align the oil hole by eye. I put a fine line with a grinder for reference on the end of the crankpin to check and confirm alignment , during the process of tightening the nuts. After asssembly, squirt oil through the bigend to confirm it is clear. Oil should come out of the sludge trap if it is removed also, but go through the big end when it is fitted. Nev Hunter

[adrie.degraaff]

The mainshaft on the timingside is differend to, the tapered end is smaller so it cann't be mixed.

It's easy to alter your bigend, just dril a new hole for guidepin, I have done this many times.

I have steel and cast flywheels laying about but it's useles to make photo's, you just have to beleave me on my word.

[john.nash]

Ok Adrie.
I am not sure what to believe as Len Ore tells me otherwise (i.e. that they are all the same) ...


I spoke to Alpha and they only do one type of big end, the same as the 1080-37 crankpin (listed by Ariel as fitting both steel/iron). This is what I have pressed into my conrod and which does not line up.
They won't now take it back as I've "used it", but were quite helpful.

Exactly how do you drill a hole for the guidepin in the hardened crankpin ?

I have learned another valuable, and expensive, lesson

[adrie.degraaff]

I am using a 2 mm very hard drill, but the pin isn't all that hard.

I have had more than 10 steel crank Ariel's when I could only buy the "other" new old stock bigends.

With a steel crank the oil way is going stait trough the bigend, with your cast one it's along the side.

[nevhunter]

What adrie says is correct John. My belief (and practice ) is to line the hole up by eye and leave the locator pin out of the crankpin. Once it is assembled it won't move ( unless something quite horrendous happens).. AJS pins are done this way and probably many others. Nev