Problem with oil filter housing mating surface on lower case

[markb]

Many of you have probably seen this on my restoration thread but if not, here’s a photo of my problem.  There is pitting on the mating surface on the lower case where the oil filter housing contacts which could potentially cause oil leaks.


There have been many suggestions on how to repair this including various metal fillers, welding and machining or just machining the surface to cleanup.  All seem to have advantages and disadvantages.

I initially talked to the guys in my machine shop but they were reluctant to tackle machining it probably because of the risk of ruining a valuable piece.  After talking again with one of them he thinks we can do it.  So I think I’m down to two choices.  Either build up the area with weld and machine it to match the present surface or machine off the entire surface until the pitting is gone.  It appears that it might take up to .030” (0.75mm) to clean up.  With the second option, one question is whether or not to also take the same amount off the center hub.  So, any thoughts?

Sorry if I’m beating this one to death but posting here is kind of a double-edge sword.  You can get plenty of excellent feedback but if I screw it up the whole world will know so I want to make sure I have the best fix possible.  Thanks for all your help.
Mark

[cb7504]

Mark:
       My opinion is to machine the surface down to surface desired. Once this is achieved do an in place fit check with the oil filter housing and (NEW) sealing O ring.  I use regular white writing chalk on the mating surface of the O ring to be matched to the case this will leave a chalk ring on the case letting you know if the surfaces are seated. Try to keep oil filter housing from spinning as spinning my give a false reading on your mating surfaces. Consider trying several attempts or until you get the desired results you want.
      As for the threaded center case oil filter bolt hole you should not have to do any thing to this area. Marty K.

[hondasan]

Couldn't resist more "bog" for the benefit of those of you who say no to it. See attached pictures of the inside of E338 crankcase (you may need to double click to enlarge it). This bike was very low miles, and had never been apart prior to me restoring it a couple of years back.
THIS WAS A FACTORY REPAIR carried out before the bike left the factory. Apparently not uncommen as Honda struggled to get enough good sandcast crankcases to meet demand. I can only assume the casting was defective in the region of this oil feed gallery to the gearbox bearing, as there appears to be a metal tube inserted and sealed with an epoxy compound (bog!). There are two other minor areas of the same elsewhere too. 40 years on that factory repair was absolutely sound. Not preferred, but good enough for Honda (must work!).

Good luck with the repair, which ever way you go - Chris

[Steve Swan]

Thanks Chris, for the fine post and picture.  The "bog" looks similar to JB weld !  I am certain there were other two part epoxys available to the Japanese before JB weld went on the market in 1968.

Simply goes to prove the machines were designed and manufactured by humans (in a factory.)  Not to mention us restorers who have the luxury of what Honda did not.  Which, was to look at and discuss from our private workshops every possible aspect and nuance we find as well as what we think may have been the reason for these nuances and what we feel is the best repair 42 years later.  

Our work does not roll off a high paced, closely managed assembly line.  The defect and the repair in E338 cases were very probably taken into consideration by more than one man in the factory.  The foreman who ordered the repair was not a stooge with a goo gun.  Nor, did the man on the assembly line squirt some epoxy on the defect and tell no one !   I am sure the foreman and others, inspected the defect, discussed the possibility and type of repair to be made, inspected the repair during and after it was being made in a location apart from the assembly line.  After inspection of the repair by someone who signed off on the repair, the case went back to the area where men built these cases into engines.

Honda knew they could make effective certain repairs on castings that were not perfect or they would not have made the repair.  In all liklihood, Honda also probably knew in advance these large aluminum cases being produced by the sandcasting process would very probably not all be without defects.  Because Honda knew they could make these effective repairs, it saved them time, man power, materials and  money.  These repairs were just as effective and more cost effective than the repair option(s) we have the luxury of time and no expense barred to discuss and make.

The area of consideration on E100 is not subjected to mechanical movement.  Some of us have seen sucessful JB Weld repairs on broken cases in the countershaft area.  I'm not suggesting JB Weld is a good repair medium or procedure for that type of issue, what i am saying these epoxys have their place and they work very well in certain applications.

[markb]

Chris,
Yes, interesting observation.  I had noticed what looked like liquid metal repairs on my early diecast and my newer sandcast.  The early diecast had to have been a factory repair because I was the first to take apart that engine.  Don't know on the sandcast engine.  Here's two spots on that engine, E5491.




And, most interesting, there are three spots on the lower case of E100 with it too, two near the same area.


Almost looks like it's plugging a hole here.


Another spot by the neutral switch.

[markb]

Sorry for hijiacking my own thread here, but as I was looking at the above pictures I noticed something odd.  Here's a closeup of one of the shots from E5491. 


Here's a shot of the same area of E100.  Notice the hole?


Here's a shot from the opposite side.  You can see the hole goes all the way through and through a larger hole perpendicular to it.  I'm feeling really stupid here, what is this hole for?  Either hole for that matter?  And why isn't there a hole in E5491?