At what slope does a car door no longer hold itself open?
At what slope does a car door no longer hold itself open?
(OP)
my boss has asked me to find out at what driveway slope a car/truck/SUV door will close by itself onto the person getting out of the car
of course i know that this varies depending on the make and model and the condition of the mechanical components of the vehicle’s door
but i've gotta try to make my boss happy by getting him an answer for his meeting on thursday
tnx for your help!
of course i know that this varies depending on the make and model and the condition of the mechanical components of the vehicle’s door
but i've gotta try to make my boss happy by getting him an answer for his meeting on thursday
tnx for your help!





RE: At what slope does a car door no longer hold itself open?
I would start by setting up a model of the system in a spreadsheet or engineering programming language (Matlab, MatCAD, etc.). All you really need to do is construct the FBD of the system and investigate the sensitivities to each variable (hinge friction, mass, CG position, slope, etc.). Good luck.
Best regards,
Matthew Ian Loew
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: At what slope does a car door no longer hold itself open?
RE: At what slope does a car door no longer hold itself open?
2) Put everyones car in the parking lot on it one at a time, and measure the angle at which the door closes as the truck bed is tilted up. Do it a few times for each car, using all the doors.
3) Show your boss your results on thursday.
RE: At what slope does a car door no longer hold itself open?
Two extremes---my 1963 Austin Cooper---door will not stay open unless the car is 'nose down'.
Wife's 2001 Lincoln LS---door will remain open on at least a 20+ degree driveway(son in law's place) Even on that slope it requires a definate pull to get it over the detent.
Rod
RE: At what slope does a car door no longer hold itself open?
For a short term quick and dirty result, I tend to agree with Nick, only my idea was to park on a level surface and use a trolly jack and an angle finder, which is like a spirit level with a protractor built in.
More professional appearing plan would be to contact the technical service departments of all major car manufacturers and ask if they have specifications or standards for angle or closeing force, If they have one for angle, you are home and dry, however I suspect that they won't, and you will need to calculate the angle from closeing force and door geometry, provided you can collect that data, which I also doubt.
On reflection, quick and dirty looks good.
Test a lot, new and old, clean and dirty, give min, max, median and average values.
I find that when the raw data is poor, the next best course is to just give a lot of it. At least it then looks scientific.
Regards
pat
RE: At what slope does a car door no longer hold itself open?
RE: At what slope does a car door no longer hold itself open?
Rod
RE: At what slope does a car door no longer hold itself open?
I think Nick is on the right track, a sexier experiment involving a force gauge and so on, on a level road, would still fail to answer the question accurately.
Cheers
Greg Locock
RE: At what slope does a car door no longer hold itself open?
RE: At what slope does a car door no longer hold itself open?
a) Borrow you boss's car
b) Get hold of a high lift jack
c) Arm yourself with a can of WD40 - for lube experiments and, well - do I need to go on....!!
It's Thursday tomorrow - be sure to let us know the result - just I case one of my colleagues gets asked!
Regards,
Dave Marshall
RE: At what slope does a car door no longer hold itself open?
it turns out they want the information to determine whether to allow a developer to have steeper driveways that are allowed in the local ordinance
RE: At what slope does a car door no longer hold itself open?
RE: At what slope does a car door no longer hold itself open?
sorry to burst your bubbles but i won't be able to run any of your experiments on company time, but my friends and i might have some fun with them! i'll let you know the results when i get them.