Side Window Latch Repair | FerrariChat

Side Window Latch Repair

Discussion in '206/246' started by fhenley, Jan 21, 2023.

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  1. fhenley

    fhenley Karting
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    Sep 5, 2022
    57
    Saratoga California
    Full Name:
    Francois Henley
    The passenger side window latch fell off on my 1972 Dino 246GT. It is a glass to metal bond that has been known to fail over time in these cars. This occurred about a week after I acquired the car a few months ago. I tried to reglue the latch but it failed again, primarily since it seemed too tight when I attempted to close it.

    I have also seen the last two Dinos on BaT having the same issue. Without building a higher gap for the latch, the latch will either not close or the latch will fail again.

    A more permanent, simple, and inexpensive fix is described here. It uses a spacing disc to increase the latch gap and thus allow the latch to close with little force.

    I used washers to select the gap increase and settled on a disc of 12 gauge (7/64”) thickness. I bought ¾” diameter 12-gauge aluminum discs from Bopper Metal:

    https://boppermetalsupply.com/products/aluminum-discs-heavy-gauge

    A bag of 10 discs cost $4.50 + tax & shipping. At ¾”, the disc is slightly larger in diameter than the latch surface diameter. I used fine sandpaper to roughen & prepare the disc and latch surfaces. The glass was also cleaned, and any old epoxy residue was removed.

    I used JB Weld #50112 clear epoxy. I first bonded the disc to the latch surface, then bonded the latch & disc assembly to the car using a C-clamp. Pictures show the aluminum discs, C-clamp, and the final latch in open and closed position. With the additional thickness, the closed position is snug only. I do not think it will ever fail again due to the low forces on the glass-metal bond.
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  2. mccand

    mccand Karting
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    Mar 17, 2020
    118
    San Jose
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    Greg McCandless
    Nice!
     
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  3. pshoejberg

    pshoejberg Formula 3
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    Dec 22, 2007
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    Peter H
    Nice repair. Sorry to let you know that it will only hold for a limited time (At least if you have any tension on it at all). I’ve tried the same over a period of several years using all sizes of stand-offs and all thinkable types of glue and even roughened the glass. I use my car a lot and use the window opening as fresh air supply / aircon. I finally gave up on the design and have just changed the glass and locks in both sides to glass with drilled holes from Dino parts. It took me about 2 hours per side and I can now look forward to a driving season without having to catch the lock when it jumps off with the most unfortunate timing. I’ve saved the old glass for when the car goes into a museum. The glass was changed without dismantling the doors or glass frame.

    Best, Peter
     
  4. Edward 96GTS

    Edward 96GTS F1 World Champ
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    Nov 1, 2003
    10,858
    never latch it. and dont open the window far enough so when glue fails it does fall outside the car.
     
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  5. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    4,164
    Norfolk - UK
    Full Name:
    Tony
    Nice repair but imho you have over thought the problem. My solution was to reduce the thickness of the striker plate so it just touches when closed. Then I never open it and has stayed like that for 15 years!
    Best
    Tony
     
  6. npwmd2

    npwmd2 Formula Junior

    Mar 31, 2015
    253
    Hudson Valley
    Full Name:
    Neal
    All Dino owners have probably experienced this issue. Anytime there are so many solutions to a problem, more than likely none of them are any good. When there is no good solution to a problem; change the problem. Take the latches put them in the glovebox and forget them. Open, close the window without effort or worry as you may, the rubber will keep the window closed. Be Happy, No Worry!!
     
  7. itsat34

    itsat34 Rookie

    Nov 26, 2020
    26
    England
    Full Name:
    martin jones
    Mine will be used for many road miles and parked up and used on the Hillclimbs so I need a robust and secure solution.
    Ive gone for the Superformance drilled windows and bolt through catches. That should fix it!
     
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  8. UroTrash

    UroTrash Four Time F1 World Champ
    Consultant Owner

    Jan 20, 2004
    40,215
    Purgatory
    Full Name:
    Clifford Gunboat
    ^^This.

    Don’t touch it.

    Count your blessings.
     
  9. fhenley

    fhenley Karting
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    Sep 5, 2022
    57
    Saratoga California
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    Francois Henley
    #9 fhenley, Jan 22, 2023
    Last edited: Jan 22, 2023
    Thanks for all the comments! I think this shows it’s so common every owner had to contend with it.

    I am not ready to replace the window for a through hole solution or just not mount and leave them in the glove compartment. Maybe I haven’t learned the hard way yet, but as an engineer with some knowledge of fracture mechanics it seems doubtful to me that a good epoxy cannot hold with minimal K1 stress intensity factor well below the epoxy’s failure point.

    Tony, I considered your solution of increasing gap by lowering the striker thickness but I didn’t want to modify the latch in any way. Inserting a plate seemed the most inconspicuous change without interchanging or modifying parts. Your result of not having issues for 15 years proves this can work. Bravo!

    Peter, I’ll take the Pepsi challenge on this one. I’ll be honest about this and post a reply if it fails.
     
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  10. docf

    docf Formula 3

    Sep 14, 2008
    1,405
    Florida
    Full Name:
    Gary
    I owned a 246GT from 73 to 80 something. This latch problem was a never ending problem. I currently have a 15 458 & a problem arose with the interior rear view mirror repeatedly falling off, reglued the happen again a few month's later. The repair's were done at the Dealership. Then I found out the Widow glass repair shops had a different variety of glue , much stronger, still working for some time. The 458 inside mirror set up is quite heavy. Maybe ck it out. I do miss my Dino.
     
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  11. fhenley

    fhenley Karting
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    Sep 5, 2022
    57
    Saratoga California
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    Francois Henley
    #11 fhenley, Jan 22, 2023
    Last edited: Jan 22, 2023
    The issue of the type of glue to use is not simple. When told you need much stronger glue, what does that mean exactly? If by that you mean hardness, this may actually work against you. Glues between dissimilar materials must accommodate differential thermal expansion coefficients. If the glue is too hard, it is too brittle and won’t handle the substantial in-plane shear (K2) that can arise when the car window cycle in temperature. This can be quite substantial in summer heat. They will work loose and separate.

    Most general purpose epoxies need to have some compliance (limited ability to deform when stressed). The JBWeld #50112 is made for bonding various materials including glass and metals. I don’t have its exact material characteristics but I concluded it has the necessary compliance required to handle thermally generated shear from thermal coefficient mismatches.

    I wonder if the failed repairs had to do with this issue. It can also be from insufficient surface preparation and cleaning. Time will tell but when selecting a glue for this application, but beware to just go for the hardest, « strongest » glue.
     
  12. TonyL

    TonyL F1 Rookie

    Sep 27, 2007
    4,164
    Norfolk - UK
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    Tony
    Very true, if you acheive the desired "strong" bond this can cause high stress point on the glass (when closed) and there is the risk the quarter panel will shatter...........ask me how i know!

    Best

    Tony
     
  13. fhenley

    fhenley Karting
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    Sep 5, 2022
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    Saratoga California
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    Francois Henley
    #13 fhenley, Jan 22, 2023
    Last edited: Jan 22, 2023
    Yes, thermally induced stresses and separating forces with leverage (such as what is present at the edge of a torqued disc) are some of the easiest ways to generate very high stress concentration. I saw that my window was spalled, meaning that a thin surface layer of glass was actually removed. That’s close to breaking and the only reason it didn’t was due to tempered glass which has a compressive surface layer to bend the fracture plane back towards the surface. This works but only to an extent. A big enough spall or rock and the fracture will go through the glass thickness.

    I take it that in your case the stresses were too much and the fracture went all the way through the glass. This could happen if the glue is too stiff/hard.
     
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  14. Edward 96GTS

    Edward 96GTS F1 World Champ
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    Nov 1, 2003
    10,858
    let me try to explain this scientifically the best i can……….dont touch the latch, dont latch the latch!
    poor design.
     
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  15. TTR

    TTR F1 Veteran
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    Mar 29, 2007
    5,764
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    Timo
    Common issue with Daytonas too.
    A manufacturing defect that can be fixed to allow full, intended use (closing and opening) of vent windows, but …
     
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  16. swift53

    swift53 F1 Veteran
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    Nov 17, 2007
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    Alberto
    3M produces an adhesive, with a watery catalyzer with brush, number escapes me at the moment, but I
    used it very successfully on all sorts of USA trucks.
    I will try to post it later. Will eventually try it on Dino.

    Regards, Alberto
     
  17. TTR

    TTR F1 Veteran
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    Timo
    Edit:
     
  18. Rifledriver

    Rifledriver Three Time F1 World Champ

    Apr 29, 2004
    36,781
    Cowboy Capitol of the World
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    Brian Crall
    There is a commercially available glue in the glass industry. It is not an over the counter product that will hold the latch to the glass. Because of a very common fit issue they can still come off but it takes some of the glass with it.

    I advise the never use it method. Been successfully used since Daytonas were in production.
     
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  19. docf

    docf Formula 3

    Sep 14, 2008
    1,405
    Florida
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    Gary
    I personally didn't search for a new glue type. I simply questioned the Dealership problematic approach to fixing what I thought should be a reasonable approach for a rearview mirror problem on my new at the time 15 458 having fallen off repeatedly after being repeated repaired. That entailed the Dealership consulting with what I would say was another approach by someone who is more attuned to glass problems/mirror attachments( different glue) in that they serviced many varieties of autos that have mirrors attached to windshields. The result which took place was No more mirror problems.

    To my knowledge way back when the 246 wing latch problem was universal in all Dino's per club events etc. esp if one attempted to utilize said window. ( Dino's air conditioners were terrible). Most including myself solution was to not use the window, then when the latch fell off one would find it on floor. When wing vent windows were fairly easily available many used the drill approach ( wing/latch).
     
  20. Mark Shannon

    Mark Shannon Formula 3
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    Dec 28, 2003
    1,231
    Surrey, UK
  21. DWR46

    DWR46 Formula 3
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    Jun 19, 2012
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    Mark: What is your source for those?
     
  22. Mark Shannon

    Mark Shannon Formula 3
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    Dec 28, 2003
    1,231
    Surrey, UK
    Hello Dyke

    I have never found a supplier of anything like this available for sale.

    I have seen various versions of this solution, none identical. So have assumed they are individually made.

    My car is in my friendly metal shop right now having a bare metal and I have discussed having something made. I only have one of my original catches, so will drill and tap two new repros and screw them to specially made brackets. Might have something a bit more stylish whilst keeping strength. Need to look at the gapping carefully, due to living in UK, and being quite happy to drive the car in our rain.

    Mark
     
  23. Mark Shannon

    Mark Shannon Formula 3
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    Dec 28, 2003
    1,231
    Surrey, UK
    p.s. this method avoids changing the glass for the Maranello Classic Parts drilled glass option, developed, I think, sometime in the 80’s, and can cover up areas where the surface of the glass has been damaged by strong glue pulling off the surface of the glass, like mine.

    Mark
     
  24. malcolmb

    malcolmb Formula 3
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    Apr 17, 2002
    1,205
    San diego
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    Malcolm Barksdale
    DWR46: Dyke- I have these u-shaped mounts for my Daytona. Mine were fitted by Gary B many years ago and have not failed of course. I assume he made them.
    Malcolm
     
  25. garybobileff

    garybobileff Formula 3
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    Feb 5, 2004
    1,175
    San Diego CA
    Full Name:
    Gary
    We still make them all the time for 246 and Daytona's
    Gary Bobileff
     
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