SPIN ON OIL FILTER UPGRADE

   There has been considerable controversy as to the viability of converting the earlier MT-10 centrifuge oil filter to the newer MT-11 spin on oil filter.  When I first learned of the availability of this upgrade kit, I was told that it was a simple bolt on conversion.  The kit was to come with a new crankshaft, timing gear cover, oil filters, and all the necessary parts to make the conversion.  It sounded pretty straight forward and though a bit pricy I went ahead and ordered the complete upgrade.

   When it arrived the first thing I noticed was that the crankshaft journals were badly pitted.  After a cursory inspection I tried to fit my connecting rod big ends onto the crankshaft.  I realized that this was going to be a much bigger job than anticipated.  The first thing I had to do was to have the crankshaft journals turned down to eliminate the excessive pitting.  My supplier tried to assure me that this was a new crankshaft and that the pitting was minimal and normal and would do no harm.  I did not believe him for one minute and when he refused to even consider allowing me to send it back to him for inspection and possible replacement I knew that from this point on I was on my own with this project and I let common sense take a front seat to thriftiness.  

   I got the crankshaft back and they had to turn down the journals so far that the rod big ends no longer could be fitted.  They then had to spray weld the journals to build them back up, and turn them back to stock tolerances.  The rod big ends then had to be refitted with a new set of bearings, and then balanced.  Finally I was ready to begin the upgrade conversion.

   Everything seemed to be pretty straight forward and I had no problem getting the new crankshaft installed using new American manufactured bearings.  (The stock bearings and seals are not known for their quality)  I got everything bolted up and put the timing gears onto their shafts when I noticed a new problem.  The primary drive gear floated on the crank axle even after the gear had been fully tightened down, and the nut bottomed out.  There was somewhere in the vicinity of ¼” of play in the assembly.  There had been no such floating when this gear had been installed on the original crankshaft.  The gear walks enough that it can disengage from the other timing gears allowing them to possibly go out of alignment.  We checked the bearing to ensure that it was properly seated and was not the cause of the discrepancy.

    Furthermore I noticed that the woodruff key which was on the old gear to keep it aligned with the oiling hole on the journal under this gear, now hangs out a considerable distance.  This did not look like an acceptable arrangement, so I consulted with members of a couple of the forums.  It seemed that a few others had attempted to make this conversion with disastrous results.  The crankshaft was walking out from centrifugal force, causing the bearing to become dislodged with horrifying results.  There were instances of not only crankcase damage but even cylinders becoming destroyed by the crankshaft floating forward and the connecting rods hitting the crankcase and cylinder bases doing catastrophic and irreparable damage. I was repeatedly told that this conversion was not feasible or even possible.

   Not being one to spend this much hard earned cash only to be stopped dead in my tracks, I enlisted the aide of my friend Sam at Regional Cycle in Niagara Falls.  He had never worked on a Dnepr (or a Ural or BMW for that matter) but he, having been the one to notice the problem in the first place, rose to the challenge and began to devise a plan to make this upgrade work.

   I spent the afternoon shopping for some steel and drill bits for the lathe. First I measured the distance from the bearings on the crankshaft to the end of the shaft. Then I measured the thickness of the gear/collar, and did the math. Then I found some material that was almost the same OD as the OD of the inner bearing race, and the OD of the collar on the back side of the gear. The ID of this stock is close to the OD of the shaft so I just need to enlarge the hole a little, as opposed to buying a larger piece of solid stock and having to machine the OD, and drill a huge hole to match the OD of the shaft. (Less time on the lathe) There will be a couple of mm difference between the OD of the spacer and the OD of the gear collar, but I don't believe that it will matter. I also bought another piece of material with the same OD but with a much smaller ID. I just need to drill the ID a few mm to fit as a washer on the nut that holds the gear in place. I may not need to do this but bought the material as a backup just in case the nut still fails to bottom out once I get the spacer in place behind the gear and have the three gears all properly aligned. Better to have the materials and not need them. 

   This is the collar that we made to put behind the timing gear to space it out. Its .365" thick with an ID of 1.335", and an OD of 1.75". The step collar on the gear is actually 1.835", but the stock was so close and we felt it was better to have it a few thou smaller so as to ride on the bearing inner race and not take a chance on it interfering with the bearings.

   With the collar in place the timing and cam gears lined up pretty darn close. Could've made another one about another thou and a half thicker but this isn’t a 200 mph Harley. Here is how they ended up aligning.

   Next we went to work on building a washer to allow the nut to bottom out. First we ground the woodruff key (1/2 moon) almost in half to get it to not hang out of the gear. Sam, the real mechanic in this project, decided to put a little top hat step in the washer to ensure an even tighter fit. The ID was 13/16", while the OD was 1.75" the same as the collar.  The washer is .140mm thick. At the step it was increased to .204mm, and the step we used was .30mm wide. The ID was .790.

   Lest I forget, the washer does fit snug to the flat spot on the nut, I just took the picture this way so as to show it in proportion to the nut. Here is the whole thing finally assembled and snugged up. We made the tolerances really tight as we had no way of knowing just how much play there was going to be once the front housing and oil filter are fitted up.

   Next I went on to install the timing gear cover and ignition. 

   The final thing to complete the upgrade was to relocate the oil pressure sending unit.  I simply removed the original unit from the crankcase and inserted a brass plug into the hole, then relocated the original sending unit into the hole on the rear of the spin on oil filter housing, and hooked the wire to the oil pressure light in my dashboard to the unit. 

   One final note:  When we put the sidecar back on the front attachment did not clear the spin on oil filter, and I had to take a small hammer and put a small dent into the filter.  The biggest problem that I have encountered so far is that when I need to change the filter element, I have to disconnect the front bar to the sidecar to get the filter wrench onto the element.

   As of this writing I have managed to log on 1,500 Km’s with this system in place and to date have had no problems with the upgrade as described above.  I have had the engine apart for other repairs and while it was apart did take the time to check the bearing and other components for signs of wear and misalignment and to date have found nothing amiss. 

   If you should decide to undertake this upgrade, DO NOT take my measurements as gospel, but simply as a starting point as each and every model seems to vary from the factory.