T Air Cleaner Felt Replacement

In this article, we'll cover the re-assembly of a T Air Cleaner, using a new filter "sock" from Zarwerks. But before we get to the pics and details, we'll answer the question that puzzles most people about these (expensive!) air filters: How the hell do you get them apart???


Taking it apart

Well the reason that I don't have any pictures of the "taking apart" stages is that it takes two hands to do it! The "endcaps" of the filter, as you can probably tell looking at it, are pressed over the ends with a slightly rolled edge to keep it on. To start, assess the looseness of the end caps by firmly grabbing each end of the filter and twisting the endcaps. If they are loose, the will spin on the end of the housing. If they are right, rusted, or heavily painted over, they won't.

I have removed a precious few with no tools at all, but more or less "manhandling them". These would be the ones with "loose", turn able ends. By gripping the housing firmly and squeezing it a bit just under the cap, you can sometimes "walk" the cap off. Once you get a bit of the lip over the end of the can, you can walk the rest around. You can carefully insert a thin screwdriver to help the cap off, but be careful not to deform the metal. Success with this method alone is rare, they usually need the one of following techniques.

Prying the lip up gently will help release the grip of the endcap on the housing, but great care is required to keep from deforming the metal. Yes it can be bend back usually, but on a particularly nice specimen, it is worth the effort to go very slowly. I have made a tool for this purpose, a picture of it is below. It allows me to gently grab the lip of the end cap and bend it out just a bit, working my way around a bit at a time. The objective is not to pry the lip all the way out 90 degrees from the endplane of the can, but just to release it a bit so I can "walk" the endcap off with the "manhandle" technique described above.

When this doesn't work, or even if it does loose the cap a bit, I often have to lay the filter flat on a folded towel or rag, and lay a flatlblade screwdriver along the side of the housing and and tap at the lip in a few places to nudge it off the end of the housing. You do not want a "sharp" screw driver for this, use and old one, and square blunt the end of it a bit on your bench grinder so it has a flat end about 1/32" thick.

No matter how careful you are, these techniques will bend and mar the metal at least a tiny bit. The presumption is that you are restoring and repainting this filter as you go. If you are not, be prepared to live with a few "tooling marks" worst case....


Restoring and Repainting the Metal Parts

I highly recommend stripping all of the metal parts addressing any dents or damage issues, and repainting the inside surfaces of the parts prior to reassembly. Also paint a thin coating of paint on the outside ends, where the endcap lips will cover (the last 3/16" or so). If not, rust can form on these unpainted surfaces. Blasting with an extra fine aluminum oxide followed by a glass bead will leave a real nice surface and will not damage the embossed lettering.

Once it is reassembled, the outside can be repainted. Use the technique in the pics below to tape off the inlet holes. A large wooden dowel or pipe inserted into the carb opening will allow you access to all surfaces without any masking, and will give you a "handle" to hold the piece while shooting it.

For paint, it is best to use whatever paint is used on your engine tin for consistency. I am a big fan of Eastwood's "Chassis Black" semi gloss epoxy enamel. It covers very well, comes in quarts or spray cans and it quite durable. I personally do not like ceramic coatings on the filters as, because of their thickness and "flow" they tend to soften the crispness of the embossed lettering, making it look a bit "melted".



After the procedure shown below, reassembly is as simple as putting the endcaps back on. If you created crimp marks on the lips by bending and prying, address those now using a narrow pair of pliers. You should be able to "walk" the caps back on the same way you got them off. You can gently tap the lips back down flush against the housing, but do not use a sharp, flat tool for this, as it will eave marks. A soft tool, plastic or wooden works better and tends to leave no marks. Picky? Get a few wooden paint stirrers and gently shape the ends with a slight concave curve that matches the curve of the housing. Lay the housing on a clean towel and gently tap all the way around. Patience is key.

One detail that is not addressed in the picture series below is that of the "split rivet" that is used to secure the bottlecap to the endcap on the inlet end. In sime cases, an original rivet can be re-used. But most of the time, it is too waekend or broken to be used again. Split rivets are available from hardware suppliers, but most all we have found that have the right shank size and depth, have heads that are way too big and don't look right on the endcap.

Our best results have been to create out own using a nail with about a 3/32" shank. The nail is first cut off to the proper length, then placed upside down in a drill press and turned at a low speed. A file can be used to then shape the head to that of the original rivet. It is a pretty narrow "button" head. Once that is done, a Dremel tool and a "409" disc can be used to carefull slit the end and make a suitable rivet.

A long steel rod with a wedge shapped end can be used via the "holding tool" shown to split the rivet ends once installed, followed by a blunt end rod to flatten it inside the bottle cap.


Installing a New Filter "Sock"

In the series of pics below, 2 sets of pictures are used. In the first set, the filter parts are freshly blasted and unpainted. It is possible to restore a filter this way, and paint it afterward, but it is not the best way. It leaves the inside of the housing, and over time, depending on the environment, it will rust. The advantage of doing it this way, is that you do not have to press fit the ends on freshly painted parts.

You may click on any pic below for a full sized image in another browser window.

Good luck!!

Here is the tool mentioned above. It is basically a flush cut "nibbler" type wire cutter, with one edge flattened with a grinding disc. This edge is used above the lip of the lid, while the sharp edge is used to gently pry up the lip a bit.

We'll start with these parts:

            • The filter housing
            • The two end caps
            • The "bottle cap"
            • The large and small steel rings

The first step is a simple one. Pick up your new filter sock, and drop the smaller steel ring into it.

Now insert the sock, open/wide end first, into the end of the housing with the round flange and holes. The ring will stay down in the small end of the sick.

Flip the housing over and pull the wide end of the sock out of the end of the housing and roll the edge of the sock over the lip of the housing much like you do with a plastic trash bag in a trash can.

The ring is still down in the small part of the sock (it is too big to fit through the flange opening actually, it has to stay there......)

Now slip the large, flat steel ring inside the open end of the housing as shown in the pic. It is a tight fit, and it is best to keep the ring perfectly round, and not kink or crimp the ring and then try to round it out once inside. That will often weaken the ring.

Tap lightly all around it with a small hammer. There should only be about 1/2" (13mm) of felt sock rolled over outside the housing.

The ring should seat evenly just below the top edge of the housing. Inspect the outside of the housing to see the recess rolled into the housing if needed.

Now flip the housing over and the smaller end should be hanging out, with the smaller steel ring inside.

Pull the small end of the sock out and taught.

As you pull the small end up, work the steel ring inside down against the flange.

Make sure the felt is reasonably tight and even when looking in from the other end. If it is bunched up on one side, remove the large steel band, adjust the large end of it where it rolls over the housing edge, and re-insert the band.

Once the large end of the felt is stretched tight and smooth, push the small end of the sock down through the ring toward the other end of the housing.

Once the small end is pushed all the way to the other end, drop the "bottlecap", dished side up, into the sock.

Use a dowel or screwdriver to push it all the way to the bottom.

Here is a tool I made to help with the reassembly of the air cleaner. The challenge is being able to hold the "bottlecap" down at the bottom of the small end of the filter and keep it tight while you tap the rivet in place. Read on...

Here we jump to some pics of a cleaner being assembled after paint to see the use of this tool. The steel tube goes down into the filter sock and its end rests against the bottle cap. The bolt heads, with the oblong, offset heads are slipped into holes on opposite sides of the circular flange and the bolts tightened. This presses the bottle cap down toward the far end, tightening the filter sock.

"Orthoscopically" you now have a clear shot at the far end of the filter.

You can see the filter sock is stretched tight (a slightly different version of the tool was used here, but it is the same idea).

On the flange end, the function of the small steel ring is evident. It is normal for it to be tilted slightly as seen in this picture. This is because the stitched seam along one side does not stretch as much as the remainder of the sock. The ring is larger than the hole in the flange and it cannot slip through no matter how much it is tilted.

If you are happy with the "stretch" of the felt overall, trim off the excess on the big end. If the sock is not stretched tight or has folds or creases, you may need to pry out the steel band again and reset it. If the tool you use cannot push the small end of the sock all the way to the end of the housing, you may need to remove the steel band and reset the sock, allowing more felt inside the housing.

A nice tight felt with no sags or creases is nice, but keep in mind that even if it not perfect, it will still function a and the felt is pretty hard to see once the filter is assembled.

Making a hole in the sock end for the rivet will make installing the rivet easier. One way to do this is to heat up a nail with a torch and burn a hole through the felt over the hole in the bottle cap. This makes a clean, ragged free hole.

As stated above, assembling the filter before painting is not the best way, but if you happen to have to do it, you can tape up the holes on the cap end from underneath....

....and work the cap on the end as described above. Once the paint has dried, you can push the tape back into the filter and fish the pieces out with tweezers or needlenose pliers.

Here is a picture of the finished job, after painting.


JH 4.4.08