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DT1 Seat Rebuild

There was a separate piece of foam between the bun and the pan, and it appears that the seat bun is actually molded to accept it! Adding a bit more padding under the tailbone. The Yamaha Engineers knew that Americans were used to sitting on those wide bench seats in American made cars and would like that extra padding on the tail!
Image7The upper part is not just "dented in", but actually looks like it was originally formed with a cavity for the lower piece. Any of you early bike experts ever seen anything like this?
The piece of screen on the bun was sitting on top of the hole in the pan, which I believe may be original also.
The seat pan looks really bad in the photo, but most of that is just rust scale which comes off really easy with a drill mounted wire brush. More on that in a minute.
Moving right along to the pan, I spent about 20 minutes with the drill and wire brush and cleaned it up pretty nicely.

And After:

I also removed the hinges and latch piece and cleaned them up with the wheel. All of the painted parts will get new black paint, and the rusty section will get rust treatment first. The seat hinges had one bolt that had been broken off so I drilled it out and re-threaded it.
The pan also required a small amount of hammer persuasion along the edges, but it straightened out really nice.
The most important thing is that all of the rust is surface scale - there are no thin or brittle parts. The little clips that hold the seat cover on are also all intact and in good condition! The prior cover used some pop rivets - jeez.
Image31The 5 rubber bumpers were removed and cleaned with dish soap and water, then dried, then placed in a baggie with Armor All, where they will remain until it is time for reinstallation.
That's about as far as I get tonight. I expect this whole thing will take a week or so, given my schedule and other commitments, but I will post it as I go.
For this project I used one of the custom seat buns that DEET had made up. These were all sold at the time the special order was done, but you can get a good seat bun from our friends at KDI Reproductions. I have not gotten rid of the old seat foam as it is still usable, and you never know when another project in need of a low buck restoration will follow me home!

If you don't want to spend the pittance the new foams cost, it is not impossible to make your own. That assumes you have a seat  you can use for a model.

Get yourself some closed cell foam from a kayak supply house - I got some from NRS - and one of those memory foam pillows from Harbor Freight.
Find an old electric carving knife (don't tell your spouse!) as it is the best home tool for shaping, and cut out a rough shape a bit larger than the pan. Do a bit of shaping of the bottom so it sits nicely on the pan. Then, take your new cover and make a template that looks like the seat section (just the top) and trace it on the top of the new foam you have just made. Then it becomes a bit of artwork as you sculpt the foam little by little so the cover fits nicely. Make it a bit snug.
Then - this is optional - make a layer of the closed cell foam over the top, about 1/2-1 inch thick. That will sit on top between the mini cell foam and the seat cover and make your seat feel GREAT. Think of a pair of hands cupping your nether regions!
Glue the foams together with some 3M Super 77 Multipurpose Spray Adhesive which should be available at automotive stores. Doesn't take much.
Note: you may need to shorten the first piece of foam to allow for the second one to fit, which is why you should always read ALL the instructions before you start one of my little projects.
You will also need to re-use the little rubber edging that covers the seat pan edge or it will rip the seat cover where it bends around to the bottom of the pan. You can get very thin rubber tubing or something similar to replace it if it is gone. Other folks have found aftermarket trim that does this well.
I finally got around to doing some seat pan prep, and of course, when you get started, you think to yourself - Gee - I have a couple of other seats that need to be redone too, maybe I should just tear them all apart and get the pans all ready together!.
So there you have it. Never do one seat when you can do three . . . NOT!
Image14First I went to Home Depot and got a gallon of Phosphoric Acid. Under $10 and a gallon will go a long way with using my method. Not everyone would do it this way, but I am cheap . . . Then to WalMart to get a plastic pan that was big enough to hold the largest seat pan:Image15
That was $5, and includes a lid, which is useful for keeping the cat and the 6 year old out of the solution! Seriously, if you keep any acid in the pan between jobs, make sure it is sealed. This stuff is not good for you. Or your kid. Or your Cat.
So now you put the seat pan in there and pour in some of the Acid.
Image16I didn't put in more than about 1/2 inch as I will use a shop baster (you could also use a turkey baster, just remember NOT to put it back in the kitchen when you are done) to keep dousing the seat pan. If you put in enough of the acid to cover the pan, you could completely avoid the basting.

As I said before, this pan is in amazingly good shape for a 37 year old piece of Japanese sheet metal. No holes, no cracks, and all of the little tabs to hold the cover still in place and flexible enough to re-use!

Image18After about 40 minutes, I got out the baster and recoated the pan with the acid. Each time you do this, you can see the acid is working. You can already see the acid beginning to work its magic. The rust spots are turning dark grey and black. I used the baster about every 20 minutes over the course of a couple of hours while I worked on some of the problems of the other two pans. The rust is changing even more. After letting sit in the acid for around 2 or 2.5 hours, I took it out (be careful to wear rubber gloves and you should have eye protection as this stuff stings when it gets in a cut!) and proceeded over to my hose and rinsed it off on both sides really well. End result is pretty nice.
In order to get enough in the pan to submerge it totally, I would need two gallons of the acid. Your mileage may vary. Plus, I only used about 1/4 of the solution so far to work on all three pans. Lots left for the next project. Probably be quite a bit easier, without any user intervention, if you submerge the whole part.

Image19So now we get to see the results of the process!
I let the pan dry well, then began the painting process so this stuff doesn't happen again. What is really kind of neat about the acid bath method is the surface metal is actually ready for primer at this point, as the phosphoric acid leaves behind a protective coating to inhibit further rust. I may go with a cold zinc paint since there is a fair amount of bare metal, or I will be using some of the rustoleum stuff that is also a rust inhibitor. More on that later.
With the DT1 pan about ready for paint, I turned my attention to my two other current pans, and both had a similar problem - broken off bolts for the hinges and/or latches. I thought I would add a few pictures of those so in case your pan has bad bolts, you will know what to do.





The process is really not that difficult.
First, you need to drill out the broken bolts - not a lot of pics of this step, but start with about an 1/8" bit and carefully try to drill in the very center of the broken off bolt. Makle sure you get a good center punch and then Drill all the way through. Then drill it again, slowly moving up your drill size one at a time - if you are lucky, as I was on most of them - at one point, the remaining metal of the bolt will catch on the bit, and unscrew! Cool. You can get reverse drill bits which actually work really well for this after you get the pilot drilled.
But of course, one of my bolts didn't just come out, so I ended up with a hole that was too big.
The easy way to repair this, since the seat cover is off, is to simply weld another nut on top of the existing stripped one. Don't do it like this!
Image21In this picture, I ran a bolt through the existing hole, just like when it is istalled, and put the nut I will be welding to the pan on the bolt. Seems logical, but when you weld the nut, it is very easy to get some weld overspray on the threads of the bolt, making it near impossible to unscrew the bolt from the nut!

Image23The proper way to do this is to put a nut all the way up a new bolt, then run the bolt into the existing nut BACKWARDS (the head of the bolt is on the foam side of the seat pan). If it is really loose, add a nut on the backside to hold it securely.

Then carefully take your MIG welder and add a few bits of weld to secure it on the inside of the pan. When the weld is done, the threads unscrew perfectly, as they have been completely protected! Don't ask me how I ended up knowing this little trick . . .
So we now have most all the parts and pieces.
Seat pan has been painted and prepped . . .

Note how well the new bun is molded to match the actual pan . . .

In practice, the pan fits in there like it was born in there! Amazing quality. Plus the foam has a sealed surface of some type that should make it impervious to the elements for the next lifetime or two. What is nice is the little 3/8" bit of foam rubber that extends down over the side of the pan all the way to the edge! I will still be installing the little rubber edging on the pan edge, but the length of the foam should make that somewhat vulnerable spot more wear resistant. The seat cover you may have seen before, it is from the VRM Racing on E-bay. They seem to be gone but there are several other good seat cover sources online.

Image32Before we get to final assembly, we need to assemble a few parts - the baggie containing the 5 rubber bumpers in the WD40 is located and the items pulled out, carefully dried off and laid out for assembly.
These have been soaking after cleaning since I took the seat apart a week or so ago. They don't need to be in there that long, but it doesn't hurt.
When you take them out, dry them off a bit with a paper towel to make them easier to hold onto, but don't dry the little nipple on top off completely, and they will be easier to re-install.
Image33I used a torq screw tool to install mine, but you can use most anything that is about the size of the hole in the bumper that is NOT SHARP. You want to install the bumper, not cut through it! Once you have these in place, you are ready to install the rubber edging. It is already installed in the picture.
The edging on this seat was pretty bad, so I had some rubber door edge molding made by Trimbright (part number T5502) which may not be available in your area, but it was made for the edge of your door so when you open it into a wall it protects the paint. I suspect you can find something similar at a good automotive paint supplier. It is necessary to protect the seat cover from the edge of the seat pan.
Once you have all that in place, put the foam in the cover, and the pan on the foam and you are ready to start finishing up.
Image34Start at the back, and get the Yamaha logo centered on the center of the pan, and work from there. Then get a couple of the front clips in place, and then work your way around the edge. You may find a hair dryer makes the cover stretch a bit easier on the more difficult clips. (Be careful with the clips, as they are sharp and result in a fair amount of bloodshed! :eek:) Also, be careful with the hair dryer, as this is some sort of plastic/vinyl and the heat can melt it if held too close or in one place for too long.
When you are putting the cover into the clips, sometimes you need to use a screwdriver or similar to push it into place. Try and use an old, kind of dull one, so you don't cut the cover. Also, use a screwdriver or punch to push the clips down - less blood that way. Don't ask me how I know.
Image35Here I am using the same tool as I used for installing the rubber bumpers. I am lazy and the screwdriver was out in the garage!
This picture shows a few of the clips in place, and a few to go. The last ones are actually easier than the first ones, in part because you get the hang of it as you go along. As you do this, you should periodically check the other side of the seat to make sure there are not wrinkles or other problems occurring. Take your time, as if you rush, you risk ripping the cover as a good one will be quite a tight fit!
After you finish with all the clips, go back with the screwdriver and push down on them one more time each, kind of like torquing a head. If they are in good shape, you will not have any issues, and the extra time now will save you grief later.

Image36Now we can turn it over and see the final product!



Finished at last - Now I just need the bike done to put it On! Well - after all that work, is it worth it? You decide
Go back to the top for a comparison.
I really couldn't be a lot happier with this seat. The foam is a bit stiffer than the old one I took out, but will last probably twice as long. Now I will just need to bring the rest of the bike up to this level!
I think I have spent about $130 on redoing this seat, worth it in my book.


After sitting in my office for a couple of years, the seat finally got back onto the frame of the bike it came off of. Having done the seat at that level, I felt I needed to go a bit farther on the bike restore than I had originally planned. Here is the final application:

Sun Tank DT1