should I or shouldn't i ?

[EDDIE SIMPSON]

hi dave,
interesting insight into the relability of the srm conversion.
looking at the failing bearing in the photo i would suspect an oil lubrication issue when the engine gets hot. i understand that the bearing relies on splash lubrication and oil there will probably linger rather than travel. therefore i think srm might have a point regarding running straight oils under the running conditions you mention in belgium . but 100,000 plus miles is a big achievement.

[DAVE BRADY]

Hi Eddie,

Just above the bearing is a drilling in the case to take more oil to the needle roller which is more than likely to exit past the ball race so oil type is probably not the problem.  I have previously mentioned that this bottom end could have done up to 130,000 miles so the 100,000 is conservative to allow for inaccuracies in the speedo.
I think that the bearing that can be fitted without major alterations is probably a tad on the small side, even smaller on A10s.  Ideally, as with Triumphs and some BSA singles a decent size ball or roller bearing, would have been better.  Having said that, the bearing has done quite well especially when considering that these small ball bearings are holding the crank hard to the timing side.  Once I split the cases I will be able to see how the needle roller part has done and it will be interesting to see how the drive side roller has fared when I get to it.

Dave.

[JulianS]

I found similar wear in the thrust bearing on my SRM'd A10.

Converted in early 1985 and bearing changed in 2007, many miles done in that period. No significant wear found in the needle roller part.

I was very pleased with how it lasted and, of course, no bush to wear and reduce oil pressure.

[DAVE BRADY]

Hi,

An update on the strip down.
I have the widely used and to some degree recommended sump plate with magnetic drain plug fitted on 3 bikes.  With this comes the convenience of a magnet to trap ferrous bits and a drain plug to make oil draining/changing easier.  There is also the gauze filter/trap for bigger bits that could block the scavenge pipe.  So a belt and braces approach is a good thing is it not?
Although this should have been one of the first things to do, I removed the sump plate today and was quite pleased but also dismayed with what I found.  It confirmed my suspicions that the big end shells are in fact past it but also highlighted that some 'improvements' can cause a bit of laziness that could have disastrous consequences.
As can be seen from the photo there is quite a bit of material sitting on the gauze and it is not ferrous as checked with a magnet.  The plus side is that none of it got through to cause a problem with scavenging.  The negative is that had I not had a functioning oil pressure light then I may have continued riding until irreparable damage was caused.   
Now to get the bottom end out and split the cases.  I am hopeful that the crank will be in tolerance so just new big end shells and bolts and nuts will be needed.

Dave.

[DAVE BRADY]

Hi,

The next instalment.
Firstly if you have a stuck bolt/stud and either can't be bothered waiting for penetrating oil to work or you simply haven't got any then try a bit of heat and a candle.  It does help as the melted wax finds its way down the stud and helps to ease any corrosion etc.
I now know for definite that I made the right decision as can be seen from the photos of the big end shells and true to form the drive side is what has suffered.  Bearing in mind the mileage that this engine has done I would say they have done very well.  You can see that rather than worn through to the backing metal the bearing surface has suffered fatigue and started to break up.  Interestingly, the crank looks fine but yet to be measured so new shells may be enough.  Despite this there was no discernible vertical movement in the con rods.  Just in time I think.
Although the drive side main bearing is fine, it will be replaced as will all the gearbox gearings - better safe today than sorry tomorrow.  Obviously the timing side combined needle roller and ball will be replaced but I discovered today that the cage for balls is in fact some type of plastic. Is this good or bad?  It has taken quite a while for the cage to wear and any microscopic bits or plastic would probably be a lot less harmful than bits of metal.  I will see what is available.
Tomorrow's job is to remove the sludge trap.  It will be interesting to what is there after all those miles but on full detergent oil and a filter.

Dave.

[DAVE BRADY]

Hi,

After a lot of effort with an impact screwdriver I got the sludge trap plug out.  The plug is obviously not reusable and the impact driver bit did not do much better.
So after trying various ways to take a photo down a hole this is the best I can do.  Very little sludge. Just some accumulated in the recess behind the plug and a coating along the inside of the tube.  It will be interesting to see how much is behind the tube.
Make your own judgement but a full detergent oil and a filter definitely keeps the engine cleaner over extended mileage.

Dave.

[DAVE BRADY]

Hi, 

I forgot to mention that the needle roller part of the timing side bearing looks perfect as does the drive side roller.

Dave.

[DAVE BRADY]

Good morning,

I have just managed to get the sludge trap tube out.  Inevitably the tube suffered terminal mutilation to get it out.
This regardless of the small amount of sludge behind it - compared to a £1 coin in the photo.
I am questioning the need for this tube when running a filter and detergent oil.  The question being that if the tube was not there would all of this sludge have been carried with the rest of it to filter to be taken out of the oil?

My next challenge is to remove the inner sleeve of the needle roller bearing from the crank.  The fit against the crank is such that even a Stanley knife blade will not go in so, any ideas on this one would be appreciated.

Dave.

[Mike Farmer]

 

Just a vague thought. Would not using the sludge trap affect the balance of the crank to any serious degree.

Mike

[DAVE BRADY]

Hi,

I suppose it will to some extent as there being no tube will make the big ends lighter but consider how the build up of sludge over time could also affect the balance.  As the crank has been balanced perhaps I should fit another tube.

Dave.

[Kevin1963]

As you are replacing bearings I would use a dremel or something similar to cut the inner race and then break it off!

Kev

[DAVE BRADY]

Hi Kev,

Yes, replacing the bearings so the Dremel idea is an option.  The bearing is very hard so will take a bit of time but that could be the only way.

Dave.

[1660bob]

if you have a welder just weld a piece of steel to the inner race and use as a slide hammer  shaft , just make sure not to weld the race to the crank !!!!

[DAVE BRADY]

Hi Bob,

I may give that a try. 

Dave.

[DAVE BRADY]

Hi,

The inner race is off.  I made couple of flats with a small cutting disc in a Dremel.   A bit if heat and few whacks on a small chisel had it moving. 
It look like I have 0.002" clearance on the big end journals so a regrind is probably required.

Dave.