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Discussion Starter #1
The **** door check straps on the Duetto just could not be made right, and after reading many, many posts of frustration on the matter I decided to do whatever it took to find a solution. There are (as many of you may know to your cost), two kinds of aftermarket check straps available from our friendly Alfa spares venders; both of which are pretty much junk.
1) The most commonly supplied one is an overly heavy section, shiny black and rock hard plastic part which will destroy the door roller catch assembly and which also de-laminates from it's steel inner core very easily. This part does however, have a very strong, spring steel core.
2) The other kind have the correct shape sectional thickness, but are molded using low grade rubber which is not only too soft, but degrades in the elements very quickly. This type also has an additional problem in that the steel core within it is not spring steel, but (easily bent) mild steel and they have a tendancy to bend under use!
So , what to do? Take #2 and create molds from it. Buy #1, tear out the inner spring steel core (easily done due to the terrible molding). Degrease, prime with bond promoter and then insert spring steel core from #1 into mold taken from #2 and pour part with UV resistant, marine grade polyurethane (colored black). This grade of material is used for the molded pivot rod at the base of windsurfer masts.
I am going to surface grind the poured side on these parts and deflash this weekend. These should virtually last forever and give the doors the correct opening feel and hold.
This was a pretty major project for what many probably think a relatively unimportant part of the car, but for me it became a quest to solve the problem of totally unacceptable aftermarket parts, and a poor spec. part from the factory in the first place.
I am delighted with the way the parts turned out and look forward to fitting them to the car. Unfortunately, these were a serious PITA to make and it is not economically viable to make more of them to sell.
 

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Thanks for sharing your findings. Please show some photos when they are finished and installed.

Marc
 

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Great looking work.

My 69 spider has no door straps. WHile this same problem lead to small dents in the fenders from my doors opening too wide on occasion in my '76 spider, in my '69 the door opening appears to be limited at the door jamb by the hinge arm hitting the inner edge of the jamb. The door can't open far enough to do any damage and I am thankful for that. Is this the usual finding with the S1 alfa's, or has someone buffered the opening in the jamb to solve this little curse?

Rumi
 

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How much did this cost you to make? What are the molding materials and where do you get them?

Thanks
 

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Discussion Starter #5
I had to buy new sets of the thick, hard plastic door straps for their metal cores as well as a set of the correct profile (but bendable) straps to take molds from. Making molds for the type of urethane used was not cheap, as they needed to be raised to high temperature in order to suit the type of material I wanted to use for molding (a grade of high temp and slow cure PU).
The urethane used is not a home project type material, as it needs high temperature accurate machine processing. I am fortunate that my business has relations with a high tech PU plant, and they are able to mold things occasionally for reciprocal favors from us, but these parts were particularly tricky and time wasting for them.
I have ground down the molded side and de-flashed the parts now, and will fit them when the new wind wing rubber finally arrives from Italy. While at the same time working in the doors, I plan to change out the reproduction window winder mechanisms for NOS ones that were recently found.
 

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I had a similar problem when I was doing my Duetto.
Solved it by replacing one of the two rollers with a smaller diameter one.
Works perfect!
 

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You may have a future with NASA !!
 
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