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I just had the driver's side door check strap repaired on my 993. I have attached a few photos of the broken door strap and the repair to provide some more incremental information in case anyone else is searching this topic in the future. You can see the welds on the old door strap were broken on the backside.
I had the work done at Euro Pros Collision; they did an excellent job. If you are in the MD/DC/VA area and need any bodywork done, I would highly recommend them.
Hi Porsche-Fan,
Great pictures, the internal "A" pillar parts shot really illuminates the design of the pivot mounting.
The entire problem was the design of the check strap's mid-swing detent that hammers the strap mount with an extremely high and fast transitional force when the strap passes over it. Some folks trim the tensioning blocks in the strap mechanism to alleviate this and lose some or all of the detent's function.
Replacing the strap with a new one does not resolve the force transition issue. If one looks back to the pre-1975 911 it had a great check strap mechanism that didn't have these problems. Clearly, the later 911 solution was to take manufacturing costs out of the mechanism vs the earlier design with unintended consequences.
Below is pictured the strap 911.531.037.00 used through (<or=) 1974. I wonder if the earlier one would fit later cars?
I had a discussion in 2020 with manufacturer JP Group/Dansk about this and even quantified the market and sales potential for an aftermarket redesigned part where the detent doesn't create the high transitional forces. Due to the very long model run that uses this part, it looked to be a reasonable volume/margin item to produce. At the time the product manager seemed interested,
Who knows where it went from there.
Andy
I just had the driver's side door check strap repaired on my 993. I have attached a few photos of the broken door strap and the repair to provide some more incremental information in case anyone else is searching this topic in the future. You can see the welds on the old door strap were broken on the backside.
I had the work done at Euro Pros Collision; they did an excellent job. If you are in the MD/DC/VA area and need any bodywork done, I would highly recommend them.
Very nice. They did a superb repair on my wife's A4 a few years ago.
Originally Posted by pp000830
Hi Porsche-Fan,
Great pictures, the internal "A" pillar parts shot really illuminates the design of the pivot mounting.
The entire problem was the design of the check strap's mid-swing detent that hammers the strap mount with an extremely high and fast transitional force when the strap passes over it. Some folks trim the tensioning blocks in the strap mechanism to alleviate this and lose some or all of the detent's function.
Replacing the strap with a new one does not resolve the force transition issue. If one looks back to the pre-1975 911 it had a great check strap mechanism that didn't have these problems. Clearly, the later 911 solution was to take manufacturing costs out of the mechanism vs the earlier design with unintended consequences.
Below is pictured the strap 911.531.037.00 used through (<or=) 1974. I wonder if the earlier one would fit later cars?
I had a discussion in 2021 with manufacturer JP Group/Dansk about this and even quantified the market and sales potential for an aftermarket redesigned part where the detent doesn't create the high transitional forces. Due to the very long model run that uses this part, it looked to be a reasonable volume/margin item to produce. At the time the product manager seemed interested,
Who knows where it went from there.
Andy
Intetesting. At this price, it's almost worth trying it on for size:
Interesting. At this price, it's almost worth trying it on for size:
Andreas
Hi Andreas,
Yes, at $38 it would. The present design has a raised ridge on the strap forming the indent that causes an enormous shift in force loading up and unloading as the strap passes through its center stop. This causing the force-shift that leads to play which leads to the popping sound as the parts around it begin to fail from the stress cycling. If the ridge was reversed and was an indent on the strap it might resolve the entire issue.
This could be tested with a little prototyping of a new strap profile using a bench grinder to alter the existing strap. And/or remove the pin bearing and convert it so the position is held by friction rather than force on the pin bearing that rides the strap. It could even be a perfectly flat strap that provides just a little friction over its entire length and therefore a little resistance to the door moving.
Every other car manufacturer has figured out how to make it work with a simple strap similar to the ones in our cars. In my New Beetle, the strap was very simple and not mounted in nearly as robust a way as on the 911, and it worked just fine.
Fixing it would not require reverting to the earlier expensive design just use the existing design and tweak it a little.
It amazes me with the expensive body shop repair being known that Porsche has not fixed it themselves in the 23 years it was a current production part on the 911.
Hi Andreas,
Yes, it would. The present design has a raised ridge on the strap forming the indent that causes an enormous shift in force loading up and unloading as the strap passes through its center stop. This causing the force-shift that leads to play which leads to the popping sound as the parts around it begin to fail from the stress cycling. If the ridge was reversed and was an indent on the strap it might resolve the entire issue.
This could be tested with a little prototyping of a new strap profile using a bench grinder to alter the existing strap. And/or remove the pin bearing and convert it so the position is held by friction rather than force on the pin bearing that rides the strap. It could even be a perfectly flat strap that provides just a little friction over its entire length and therefore a little resistance to the door moving.
Every other car manufacturer has figured out how to make it work with a simple strap similar to the ones in our cars. In my New Beetle, the strap was very simple and not mounted in nearly as robust a way as on the 911, and it worked just fine.
Fixing it would not require reverting to the earlier expensive design just use the existing design and tweak it a little.
It amazes me with the expensive body shop repair being known that Porsche has not fixed it themselves in the 23 years it was a current production part on the 911.
Woof!
Andy
This is timely as my driver check strap just started popping/clicking. Of course after a full respray of the car and replacing the old check straps with new ones. I might try the older versions out and see if they work/reduce the force to save the strap from major damage. I still may need to get it welded or cut out and replaced.
It could even be a perfectly flat strap that provides just a little friction over its entire length and therefore a little resistance to the door moving.
I like this idea.
When I moved to Iceland in the early '90s, it was mandatory to have additional door check straps installed if you wanted to register your car there. So I had a shop install what amounted to short lengths of seatbelt material from behind the kick panels to the doors. Super strong and ensured that the insane winds would not yank the doors off.
porsche fan my 993 has same problem did you buy a new door strap or body shop cut out the broken one and weld from the inside. I cannot find door strap on pelican site i see they list the door stop. Also would you share with us the cost i would think around $1000.00 to $1300.00. My car has 73,000 miles for those interested. Thanks George.
Definitely a body shop repair due to the design and where it generally breaks...........My 993 cab had about 58,000 miles and driver's side was repaired at a ex-Porsche body shop foreman's business in Atlanta who knew what he was doing.
It cost me around $1,000 about 5 years ago, but he guaranteed it would not break again as he reinforced the repair way beyond OEM inside the door post....so far so good.....other side is original........
Have to warn people not to swing the doors open with any real force.......
I replaced the straps on my car and the drivers side started clicking loudly about a year later. I must not have torqued the bolt up enough and I was able to stop the clicking by re-tightening the bolts.
I would like to talk to you about this repair. My email is mcgrath554@aol.com. I am looking for my body shop to do the same as what yours did, but I would like to discuss this more in depth. I am looking forward to hearing from you about this and thanks for any help.
Originally Posted by pp000830
The entire problem was the design of the check strap's mid-swing detent that hammers the strap mount with an extremely high and fast transitional force when the strap passes over it.
Would opening/closing door slowly when going over the detent position be a good thing in terms of stress on the check strap and possibly delaying this problem?
01-25-2021, 10:28 PM
993 Door Check Strap Repair
