should I or shouldn't i ?

[ferretjuggler]

Personally, I wouldn't bother regrinding a crank with just 0.002" wear on the journals, only just over the wear limit.
I'd purchase another crank that was more badly worn and have that reground instead, the finished result should be just as good, and you'd still have the slightly worn crank as a spare.
Of course this could be a recipe for disaster if you buy a worn crank that is stress fatigued, or cracked by someone butchering the sludge trap plug, you have to exercise some common sense and caution.

[DAVE BRADY]

Hi,

I know it is just out of tolerance but I need to use this crank as it has had the end feed conversion and has been balanced.  To get another crank done would just add to the cost.  If it been right on the wear limit I would have gone just for new good quality shells and new big end bolts and nuts. 
I am unlikely to do another 100,000 miles on it but when the time comes I want to pass on a good engine.

Dave.

[ferretjuggler]

Yes you're right, I wasn't aware of the end feed or balence job.
And of course you know the history of your crank for the last 100,000 miles or so.
A worn crank from an autojumble could have suffered massive abuse in a previous life

[DAVE BRADY]

Hi,

I should be getting my crank back this week so work can commence. I opted for Cotterel Engineering in then end and it was interesting to chat to the youngish chap and see some Sunbeam S8 bits in for some work.  I have everything else plus some new sprockets, PRV and oil light switch.  It is surprising how small a box is needed to send over nearly £600 worth of bits.

Dave.

[DAVE BRADY]

Hi,

A minor issue I have to overcome is that one of the small ends is a bit worn.  New bush you may say but on these late rods there isn't a bush.  The gudgeon pin goes directly in to the small end.  I have a spare rod that is not worn but it is quite a bit heavier than the one from the engine.  In order to use it I would have to get the total weight the same as well as ensure that the small end weight and big end weight are the same as on the original rod.  Within a gram is probably OK to ensure that the balance of the crank is maintained. 
Rather than do this I bought some small end bushes as the rods can be opened up to take them.  I considered farming it out but that would mean finding a good engineer and then waiting for the work to be done and it would incur a cost.  Instead I have ordered two adjustable reamers for less than the probable cost of the work. It will be a two stage job with the smaller reamer taking out the bulk of material and the other one finishing the job leaving a good fit for the bush in a warmed up small end.  Although I have fixed reamer of the right size, I could use one of the new ones to do the final ream for the gudgeon pin.    I will also have two reamers for the future jobs.

Dave.

[DAVE BRADY]

Hi,

A more accurate tot up takes the figure to nearer £700 and it does not look like a lot.  Just the bottom end!

Dave.

[chaz]

Dave
I know your pain, The Triumph was running when I decided to decoke it, top off, barrels off, cases out, stripped, ended up powder coating the frame etc as well.  £2500 later and that didnt include my time!!

[DAVE BRADY]

Hi,

Crank collected today so just waiting on a reamer and it can all kick off.

Dave.

[Mike Farmer]

 

As I said a while back. The final cost always involves the "while I'm at it I'll just do this-----and maybe that" its only a few my squids.

Mike

[DAVE BRADY]

Hi,

The reamers eventually arrived and I plucked up the courage to get the job done.  Adjustable reamers have a limited range so two were needed to open up the small end and a final one to finish off the bush once pressed in.
Wanting to keep everything square I put the reamer in the chuck of my pillar drill and with the con rod on the bed everything looked square.  The idea was to disconnect the drive belt and turn the chuck by hand and slowly feed the reamer through the small end, gradually opening it out from 19mm to 21mm and then from 21mm to just under the OD of the bush to give an push fit with the rod heated.
These are relatively cheap hand reamers and look OK but once in the chuck it was evident that whilst the reamer part fine the rest was not that straight resulting in a bit of eccentricity.  B...er, I thought, but an idea soon formulated.  Using the chuck in the pillar drill was not an option.
These adjustable reamers were to open up the small end to take the bush and I already had a reamer of the correct size to ream the bush out for the gudgeon pin.   With lot of slow and careful work I got the small end opened up enough for the bush and and it looked nice and square.   
With a nice warm rod I pressed in the bush using a vice and it lookled perfect.  Once the oil hole was drilled I now had to finish it off to take the pin.  I was not too fussed about the oil hole lining up with the 'scroll' in the bush as no other small end bush I have fitted has had one.
This was the part that had to be spot on so I fastened a good rod to the one to be reamed.  The reamer would go through this first and it would ensure that the reamer was straight as it took out the last bit of the bush to get the correct size.
With the bush reamed out the gudgeon pin slides nicely through both small ends with the rods held together.
So job done but with hind sight I think that it would have been worth taking it somewhere to get done as it took quite lot of time.

[DAVE BRADY]

Hi,

A bit more progress but not without a bit of fiddling about.
As the crank had been balanced with a sludge trap tube fitted I thought it best to replace the one I had to butcher to get out.  So line it up with the hole through the flywheel and tap it in to place.  It took a bit of tapping somehow in the process it had turned slightly so now the fly wheel bolt would not goo in fully as it was fouling the tube.  B....r! 
An easy solution would be to open up the hole a bit.  File it or drill it perhaps but what about the bits of metal from filing or drilling?  How would I know if I had got them all out?
So the answer was to remove it and re-clean the internals of the crank. 
Would this mean destruction and the need for another new one?  Despite seasonal brain fog I managed to recall something about tapping a thread and using a bolt like a puller.   So a 3/8 BSW tap was press ganged into cutting a thread.  It was a snug fit and took a bit effort to start the thread cutting process.
After few turns I though it was slipping and not actually cutting a thread at all but it had bitten in to the tube and with the turn in force the tube had started to rotate.  The hole in the fly wheel now lined up easily so job done.  Not quite as there still be some metallic bits in the crank so the tube was pulled quite easily and the crank cleaned out again.  Tube refitted, plug inserted with some thread lock so now for rode to be fitted.

Making sure they went back the same way as they had been fitted.  Plenty of clean oil applied to the journals and a smear of oil was applied to the big end bolts but not the threads.  This ensured that the bolts pulled the cap to the rods without any resistance whilst the dry threads ensured the correct torque was applied.
With the cam and breather bits carefully put in place and the drive side case sitting securely on the B&D workmate the next job is to put the crank in the case and then fit the timing side. 

Isn't it a sod of a job to tighten up the gearbox sprocket nut when it is all assembled so why not do it before assembling the cases.  Straight forward - it should be.
More about that next time.

Dave.

[DAVE BRADY]

Hi,

It is far easier to get a spanner on the sprocket nut with the cases still split but how do you hold the sprocket.
After a bit head scratching I cut about 18" off an old chain and put it around the sprocket and clamped the two tails together with mole grips.  With suitable piece of steel through the chain I was able to hold the sprocket still whilst pulling on the spanner.  As in effect I had two levers to use against each other I was able to get it really tight.
I think I would say tighter than trying to use a box spanner over the main shaft whist attempting to keep the rear wheel locked with the brake.

With some oil smeared on the bearings I put the crank into the cases and just nipped up a few bolts to check the rotation.  Nice and smooth so the next job will be a thin smear of Hylomar on the joint, some oil on the cam bushes and together thewy will go.

Dave.

[DAVE BRADY]

Hi,

I bolted the cases together today but just as an extra check on the new hand reamed small end bush I carefully put the reamer through both small ends ensuring that the parallel part was through both small ends and rotated the rods around the crank. Everything was nice and smooth. 
Next job is to touch up the frame and then put the cases in the frame.  This is lightest the engine will ever be  and it is quite easy to built everything on to cases rather than try and lift the whole engine.
Luckily I have a bike lift so it is a simple (now there's tempting fate) matter of picking up the bottom end, turning through 180º and putting it in the frame.  I will get my wife to help so that if it goes wrong I can blame her.

Dave.

[EDDIE SIMPSON]

hi dave,
i m surprised you dont build up the engine on the bench and block up the engine on the ground  then lay the rolling chassis over. once you have the front and bottom bolts in  you can lift the whole lot onto the sidestand. with the top end rebuild method i m always banging my head on the handlebars.

[DAVE BRADY]

Hi Eddie,

I have seen this method described before but not tried it.  I don't really have room to do this and apart from the handle bars occasionally getting in the way it easier when tightening things up as the engine is stable in the frame.  Also, the complete engine is a heavy lump to pick up off the bench and then put it down on the floor.  Being tall, I have a higher than usual bench to avoid stooping and the height difference between the bench and the frame on the lift is minimal so I am not actually lifting or lowering the engine that much.

Dave.