Part 2, the never-to-be-taken-apart-again VH engine

[Simon.Gardiner]

Some will say this is just general wear and tear and not a particularly Bad Thing at all, but when I re-assembled the VH bottom end with nice new (expensive and difficult to find even then!) RHP main bearings (following Bad Thing 1) I expected it to be good for many thousands of miles before it would need to come apart again.

The big-end was a new R+M that was fitted back in 1974. The bike's only done some 30,000 miles and I still think of the big-end as being the 'new' one so for it to expire unexpectedly a mere 5.500 miles further on is a Bad Thing as far as I'm concerned - especially as it's gone so far as to be breaking up and spewing bits of metal around! I know what rattling big-ends sound like in other engines and I usually reckon to catch them before they spread damage everywhere.

What came out with the sump plate

What came out with the sump oil

Discussions with people who ought to know about these things have advised that the usual life of a caged roller VH big-end is only about 40,000 miles and I think that's probably about what this one has done. The flywheels had actually put in a couple of years good use in my rigid VH in the 1970s before being 'borrowed' for the swing-arm bike in the early 1980s so the total mileage across both bikes could well be around the fatal 40k mark.

As an 'insult to injury' though, there was something else that was shocking to start with but after some thought is just another thing that needs considering. After the mysterious lubrication issues that caused the engine damage in Bad Thing 1 I fitted a filter in the return line, to make sure (after very, very thoroughly cleaning out the oil tank) that what was in the oil tank would never be the source of any further contamination. This time round I expected the oil tank to be clean, but just to be conscientious I did swill the oil tank out with petrol to get all of the old straight 50 out. What came out was pretty oily and got left in the jar. When I looked at it a day later I noticed with concern that there was quite a lot of sediment...

Sediment

Out of curiosity I checked this with a magnet, and it was all ferrous! Maybe a faulty filter installation as well? It seems not - some internetting revealed that typically cartridge filters are effective down to about 20 microns particle size (I've been using the Commando-type filter head with usual spin-on Champion filters, I asked their technical department what the spec was for the filters but they wouldn't tell me so I have to assume they're 'typical'). That's about a thou of an inch in 'old money' and that's probably enough to be a fine sludge, which is what the sediment in the jar seems to be.

Fine sludge

So - even with a modern filter in the oil return you can get fine metal particles circulating, enough to build up a metallic sludge in the oil tank and maybe fill up the sludge traps.
Time to to invest in a few magnets!

[nevhunter]

Unless you are very gentle with the revs, anything over about 30K miles is a bonus, being realistic. BSA B33's do a bit less. Your oil pump Return will have suffered also. Magnets are a good idea.. The piston will be scratched too. It's better to know early if possible. Usually metal in the oil is from the camshaft and followers with an ARIEL single. The VH is the only one with a cage. At each oil change I remove the oil tank and shake it with roofing nuts and kero in it to make sure there's no sediment remaining on the bottom. Hose out with a strong water jet and dry it with the wife's hair dryer. Nev

[Mike Nash]

Simon, how was the centrifugal Ariel Purifier plug? Looking at all that muck I'd expect it to be full. And yes, magnets, magnets and yet more magnets! Besides ferrous materials, aluminium is also attracted and captured. Ali is paramagnetic i.e. only magnetic while in a magnetic field. It's very slight but it does work, hence the debris being grey. I've had a magnet in the oil tank drain for some 50 years (and in the Morris Minor, mower, and my compressors); they've very cheap and these days very powerful. And I've added one to the engine sump plate too.

[Roger Gwynn]

Mike I never knew that about aluminium, today's lesson.

[paul.jameson]

The late Bob Brassington reckoned 15,000 to 18,000 miles on a VH type big end, but he did use high comp pistons and rode the bikes rather harder than most people ever do.

[Simon.Gardiner]

First 30k or so the bike was the 'daily driver' (both the rigid and later the swing-arm), did quite a lot of motorway work (70mph+) and for at least one year was running with an HS Mk 1 cam and one of Bob Metson's 8:1 pistons - that cracked a gudgeon pin web unfortunately, the bike quite liked it otherwise. I wouldn't claim to have given that big-end the hardest use but it hasn't been treated gently.

I wonder if Bob B. was using those uncaged Alpha bearings, I've eaten a new uncaged 350 big-end in 7k miles thrashing up and down motorways (for some reason my old 350 seemed to be quite rev-happy and I was equally happy to enjoy it.)

I've not taken the purifier plug out yet - the priority has been getting the bottom end apart. Not being intended to need any attention for a long, long time it was built with carefully-researched Loctite 6300 on the mainshafts (not as strong as 648 but better high-temp performance). I've managed to get the timing side off (without bending the main-bearing cage too much) but the drive-side assembly is a bigger problem...

SG

[paul.jameson]

I would have thought that putting it into the oven is the answer. You will need to get above the critical temperature for the loctite on the outer bearing but the inner one will come out of the crankcase easily at that so the mainshaft should just push through (he said, glad not to be the person doing this).
Then you prise the distance collar and inner bearing off the mainshaft whilst it is still hot. I would fit new main bearings. On a couple of my singles, I have had the main bearings fail, one being shortly after fitting a new big end.