Car door lock motor - Page 1
Forum section: electronics / repair

author: mad-elec
author_rank: Newbie
timestamp: December 21, 2023, 08:22:11 am
content: Hi all, I come from a mechanic background and usually fix most things myself but need a bit of guidance on this, it's outside my area of expertise.I have this door lock from a car that was making a grinding noise when you lock and unlock the door. Now, I could go and buy a new one but that wouldn't be any fun would it? And I don't see the point in buying a new one if it could be easily fixed.After taking the mechanism apart, all of the associated plastic gearing inside is fine, there are no ground down teeth or broken bits so I'm certain the grinding noise is coming solely from the electronic motor.Now, it looks to me like a very simple motor that you might find in a toy car or something like that, so I'm hoping is it possible to just buy these kinds of motors? And if so, beside ensuring the outer case is the same size and the cog is the same, is there anything I should be looking for? Or are these types of motors pretty simple and any will pretty much do?And also, I haven't taken it apart to have a look but is it possible to actually fix the internals and if it is possible, is it even worth doing or would it be easier just to get a new motor (if that is an option)?I'm not sure if these things have certain speeds or torque ratings or anything like that but hoping they are just simple motors, does anyone have any idea what I could do? Appreciate the help.

author: fzabkar
author_rank: Super Contributor
timestamp: December 21, 2023, 08:36:57 am
content: https://www.aliexpress.com/item/1005005892775991.html

author: mad-elec
author_rank: Newbie
timestamp: December 21, 2023, 08:45:26 am
content: Wow, had no idea they were a standard type of thing, thanks for that!

author: mad-elec
author_rank: Newbie
timestamp: December 21, 2023, 10:12:42 am
content: FYI I ordered that exact motor at the link you provided. The measurements were exactly the same as I needed, so I assume you didn't have a lucky guess, is it a standard type of motor used in a lot of cars?

author: fzabkar
author_rank: Super Contributor
timestamp: December 21, 2023, 06:46:46 pm
content: It appears to be a common motor. Only the gear or pulley varies.Typical faults are worn brushes and/or carbon dust between the commutator segments.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2023, 07:27:15 pm
content: The only thing that stands out to me is that the shaft extension and gear are on the brush end of the motor, that's rather unusual. The brush end bearing doesn't normally see any radial load. I can't remember off-hand whether this bush is smaller than the one at the normal load end. Any wear on that bearing will have a much greater effect on the commutator to brush alignment though.

author: pienari
author_rank: Regular Contributor
timestamp: December 21, 2023, 07:38:18 pm
content: I know, long time ago i dissambled Toyota Corollas door locking mecanism.Motor was dead so i took it a part.In side the motor there was some kinda resistor and i just bridged it.Motor start to work but much higher rpm.It served few years without problems.

author: mad-elec
author_rank: Newbie
timestamp: December 21, 2023, 09:17:50 pm
content: Yeah I noticed as well that most had the extension protruding from the other end. I think I could probably have used a motor with the extension from the other end, all other measurements being equal, as long as the wiring blades could still be inserted.I also considered taking it apart and cleaning the internals up etc. but it looks like they really aren't made to be taken apart, at least easily.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2023, 10:51:14 pm
content: I guess the good thing is that the brushes will stay with the commutator, unlike the normal type where the armature stays in and it's almost impossible to get them back onto it without damaging them.

author: mad-elec
author_rank: Newbie
timestamp: December 21, 2023, 11:36:54 pm
content: Even though I've bought a new one, I'm a curious guy so thought I'd open up the old one and see if any damage was obvious.Looking at it with my inexperienced eyes, I can't see anything obviously damaged or worn. By looking at my photo, is there any clues as to what would cause that grinding type noise when actuated?

author: amyk
author_rank: Super Contributor
timestamp: December 22, 2023, 12:54:57 am
content: It could be the bearings. The brushes look OK and there's still lots of material remaining. You can try to reassemble and apply a few volts to ee if it runs smoothly.

author: Haenk
author_rank: Super Contributor
timestamp: December 22, 2023, 10:04:29 am
content: Quote from: mad-elec on December 21, 2023, 11:36:54 pmDoes not look too bad.However the greasing on the mechanism itself might have vanished or hardened. Try to clean and put a good grease (I mostly use Lithium based grease on these things, but other stuff will work as well. No oil though...)The motor bearing might be worn, this is not visible and unfortunately this type of bearing will not last forever. The axle might move around too freely, as a test you could drop a bit of grease in there, but that is only a very short term fix (if it works).Replacing the motor is the way to go.

author: Gyro
author_rank: Super Contributor
timestamp: December 22, 2023, 01:09:46 pm
content: Yes, it could be down to bearing play, you ought to be able to check for out-of-round and loose shaft fit. As for the explanation for the grinding, it looks as if the armature pole pieces may have been rubbing against the magnets, hard to say from the photo, but the surfaces look uneven - see what residue is stuck to the magnets. This would also be down to slack bearings.

author: pienari
author_rank: Regular Contributor
timestamp: December 22, 2023, 11:39:26 pm
content: If you measure that black disc left side to to brushes it is the reason why motor is not running.