UNOBTAINIUM SUPPLIES: Rubber Bumpers for GTS side window louvers

Sometimes it's the little things that are hardest to come by. About 3 yers ago Daniel asked if I could source the little rubber bumpers for the GTS louvers. So I started looking for some in good enough condition to use as mold patterns. Of course I quickly discovered they were NLA, even using some Italian contacts & all my dealer friends.

In case you don't recall what I"m writing about , see the 2nd picture below.

Then finally early last fall Mike Tuason sent me one of his bumpers. It was almost good enough for a mold pattern, and certainly good enough that I could get dimensions off of it & machine a mold pattern. So I put the bumpers on my TODO list for my annual holidays shut down.

Then in mid October I got this eMAIL with an amazing picture from ramosel:

Of course I immediately responded taking Rick up on his offer of to let me borrow one to make a mold.

Thanks to Mike Tuason, Rick Moseley & Brian Keegan's foresight I will be announcing production has begun in a few weeks.

Meanwhile watch this thread, I'll try to entertain you with progress reports & pictures every few days.
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A few weeks later I got a small box from Rick with one of each bumper in it. I was buried with work at the time, so put them on the shelf & an entry in my TODO list.

About the middle of last month they finally made it to the top of my TODO list.
I knew that in order to make these at a reasonable cost I needed a mold that would make at least 4 & preferably 6 or 8 of these parts at a time. So I knew I was going to have to make 2 molds, one single cavity mold that I could use to make a small quantity of patterns for the second multicavity mold.

I mounted the parts half buried in clay poured the 1st half of a silicone mold that would make one each of the bumpers. When I removed the clay, I got a surprise. While the silicone had cured around the early style part, about 2mm of the silicone around the 2nd later style part was completely uncured goo. Then I remember that that particular mold silicone would not cure against a surface containing sulphur. Guess what is used to vulcanize rubber : sulphur. The silicone was NEVER going to cure around that 2nd part!

So I cut the mold in half, leaving me with 1 good mold half for making the early style bumper. I poured silicone into the area left by the clay removal & when It cured I had a single cavity mold for making the early style patterns. I've been making a part every 2-e days, so in a week or so I'll have enough early style patterns to make the early style bumper production mold.

I poured a non sulfer inhibiting silicone into the 2nd mold where the clay had been removed, keeping my fingers crossed that the part would stay in this silicone when I removed it from the partially cured mold. It worked & I just had to scrape a bunch of gooey uncured silicone off of the part & the cured silicone mold half. I was then able to pour the wnd mold half & now have a 1 cavity mold for making the new style part. So far I've made 3 new style pattern parts.

With reasonable progress I'll announce production parts for sale in a couple of weeks.

I've got a few pictures, will post them tomorrow as I left the camera somewhere I can't get at right now.

 

Here is the 1st pass mold. The left mold half had the newer bumper that inhibited the silicone from curing. The black in the right mold for the older #20106001 bumper is very thin traces of black casting compound as I'd already made a couple of parts from the mold when the picture was taken.

BTW, Just checked a couple of weeks later & that left mold half still hasn't cured. It's amazing that the tiny traces of sulfer absorbed from the bumper's surface can keep that silicone from curing! It's not usable as the uncured silicone has flowed enough so detail has been lost so I guess I'll just toss it.

The 2nd picture shows the pink & cream mold I mde from the newer # 60551400 bumper using a silicone that's inhibition resistant.

The 3rd picture shows 5 of the older style bumpers from the blue & black mold. These parts are cast in hard plastic as I will be using them to make the eight cavity production mold.

The 4th picture shows a couple of the newer 60551400 bumpers from the pink mold. Again cast in hard plastic to make it easier to form a multi-cavity production mold.

I still need to make another 6 of hard 60551400 bumpers before I can start on the production mold. Anytime I'm making a part for someone I'm mixing about 3 CCs extra & making another hard bumper. It's still slow going as it takes several hours for each pour to cure. At best I'm turning out 2/day, but there are days when I'm doing something other than casting & don't make any, so the end average is about 1/day.

Best guess is I will have the 60551400 bumper production mold finished by the end of April. I'll have to make a couple of pours before I'll know what the yield will be, how much mateirial & labor will be required, & how long it will take to trim molding flash from the parts.

Bottom line is these reproductions are going to be quite pricey compared to the NOS ones which are a bargain as far as Ferrari parts go! SWAG is there's still going to be a couple of hour's labor in each production mold pour, and the last time I bought a pint of the polyurethane rubber casting compound it was almost $100/pint. Unfortunately that would put each bumper in the $30 - $35 price range.

I'm probably not going to start on the older #20106001 bumper production mold as long as there's still NOS available. You might want to stock up on the 20106001 bumpers as you can get several of them for what my reproductions will run.
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Late last week I removed the 1st half of hte production mold for the 6551400 bumpers from the overnite pressure chamber cure. The light blue mounting clay that supported the bumpers has been mostly removed. There are still a lot of small bits of clay adhering here & there that has to be removed as well as the 'flash' from various places. Probably a good 6 hours work before I can apply rubber release & pour the 2nd half of the mold.

The 10 pattern pieces are different colors because they were made 1 at a time as I was casting othere hard parts.

I hope to finish the production mold & announce that parts are available by the end of July.
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Yesterday I unmolded the 1st batch from the production mold. It yielded 7 good parts, 1 part with a tiny bubble on the bottom, & 2 with significant bubbles.

ramosel, I MAILed you a pair along with your door handle bezels. Let me know what you think of the rubber's hardness.

70% yield tells me that I need to make another batch to get a better idea on yield before I set a price.

I'm away next week, so the next batch will be the week ending 2-SEP. At that time I'll announce the price.