April 4, 2010

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Oil Filter

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Triumphs of this era didn't have true oil filters.  What Triumph called filters in the sump and in the oil tank are really just coarse screens.  The only real provision for removing particulates from the oil is a centrifugal separator arrangement in the crankshaft.  Accumulated sludge could purportedly eventually reduce or even block off oil flow in the crankshaft.  Additionally, since it's the job of modern high detergent oils to keep particles in suspension, the separator may not even work as well as designed.  Because cleaning the sludge trap involves total tear-down of the engine, there seems to be some room for improvement here.  It is widely believed in Triumph circles that adding a true oil filter is one of the most beneficial modifications to these machines.

The most common approach to adding oil filtration to older Triumphs is to borrow a part from the Norton.  The Norton part uses an inexpensive spin-on automotive filter.

I bought the Norton filter mount and filter, and went looking for where I could mount it.  People have found quite a few places on their bikes to put the filters.  I wanted someplace out of sight, I wanted the filter to be mounted hanging downward for ease of cleanup, and I didn't want to modify the frame or other parts in any permanent way.  This left me with two possible places: between the rear fender and the vertical frame tube (between the oil tank and the tool carrier cover), and in front of the vertical frame tube, under the gearbox.  After doing some mockups, it appeared that the rear location just didn't have enough room, and the lower location left the filter hanging lower than I liked.  

Also, though the Norton part seems to me well made, it had a couple of things I didn't like.  It would fit my locations better if it were smaller.  Certainly the filter itself determines some of the dimensions, but even a trim of the height of the mount would help.  Secondly, if I chose the lower location for the filter, the oil tubes on the filter carrier were on the wrong side, which would require circuitous routing of the hoses.  Also, the Norton inlet and outlet are for 3/8" hose, while the Triumph uses 5/16" hoses.  A trifle, maybe, but it bothered me.

I looked around and found a lot of other automotive remote filter mounts, but none were better than the Norton.  Mostly they were bigger.

It was about this time when I started considering a shop-built oil filter mount.  I would make it as small as possible, and provide for oil lines to connect on either side.

First, I went looking for a smaller spin-on filter.  The one on the left is the one that fits the Norton mount.  It's about 3" in diameter by about 3" high.  The other two filters are a smaller series with a diamteter of about 2-5/8".  The shorter one is only about 2-1/2" high.  It is used on some small Suzuki trucks, and available as part of NAPA's high performance filter line, but I had ot order it.

I had this chunk of 3/4" aluminum, and I calculated that if I could do a mount only 3/4" thick, I'd save another 1/2" on height compared to the Norton.

A couple of days of off-and on work later, I had this.  The filters (I can use either of the smaller diameter filters) have a 3/4-16 thread, so that's what the threaded nipple is.  The nipple goes into the body, then the perforated cross-tube goes in.  The cross tube locks the nipple in so it can't come out with the filter.  The inlet and outlet galleries are drilled all the way through the body, and tapped for 1/8" pipe on both sides.  This allows feed from either side.  the unused ports will get threaded plugs.  The final assembly is about an inch shorter than the Norton assembly, and smaller in diameter.

The location in front of the rear fender still looks to be too tight, so I'm planning to use the under-gearbox location.  I like this because of ease of access.  

Here is a trial fit-up.  I worry a little about vulnerability of the filter to road debris, so I'm going to do a little more work on tucking it up further.  I might get another half an inch by bringing it in closer to the frame tube so the mount clears some features on the bottom of the gearbox.

April 24--

I got to spend a little more time on the oil filter.  I carved a chunk off one side of the filter mount to clear the gear box better.  This would let me slide the filter assembly up further.

There is now probably more than a half inch additional clearance under the filter.  The filter still hangs below the horizontal frame rails a little,  but is well above the bottom of the center stand mounting ears.  

I think I've decided to put the filter assembly here.  I'm still a little concerned about something hitting and distorting or piercing the filter, but for a strictly road bike, it seems unlikely.  I may fashion a simple deflector that clamps to the bottom frame rails.

Polished up the top of the mount for fun.  I'll probably paint it or anodize it black.  Also shortened the brass hose barb fittings to help with routing the hoses in the tight quarters.

December 3 update--Since the location under the bike will be a pretty hostile one, I decided to anodize the mount black.  That should protect it from the elements better than paint, and the color should make it less obvious.  The smallest of the filters I had was white, which would defeat the purpose of making the mount black, so I painted the filter canister black.  This bugs me a little, since I don't really want to have to paint replacement filters every time.  It also hides the part number, so I'll have to keep track of it some other way.  Maybe I can find a black version of this filter. Alternatively, the second smallest filter I found that would fit the mount is black and only about a half inch taller.

The location under the gearbox, while maybe not perfect, has a lot of advantages:   It's out of sight, it's right between the engine oil connections and the oil tank for short, direct hose routes, it's upright and and under the bike so there should be little hassle or mess in changing it.  The one drawback is it's potential vulnerability to damage.  The filter hangs
well above the center stand mounting ears, but maybe 3/4 inch below the frame rails.  Road debris is probably the biggest threat.  If it continues to bother me, I'll fashion a deflector that clamps to the frame rails.

December 22 Update:

The filter is in place and plumbed.  I had to cut off about an inch of the steel oil return line so that the 3-inch long inlet oil line could comfortably make the bend.

December 27 Update:

The tight bend on the short filter inlet line was not kinked, but I was a little worried that when it softened with hot oil, it could.  I found this spring at the local hardware store. It's a snug fit on the hose and a perfect length.  It should keep the hose round.

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