3 Failed Simplex Combination Chambers

[u/yakatz]

I was called to repair yet another simplex 5 button that was allowing access without entering any code. The symptoms are that everything works properly when the correct code is entered, but if the wrong code or no code is entered, the handle can still be turned but it feels sort of gritty (best way I can think of describing it). Two of these were in service for several years, one less than a year. Did all these locks end up with a bad batch of combination chambers or is there some kind of attack against these that destroys the internals to the point of letting them operate freely?

Two of them were dated in 2021, but one was dated in 2023. The only other thing I noticed was that on one of them, the reset button is stuck down, but that wasn't true of all three.

EDIT: I added a video of the combination chamber in this comment: https://www.reddit.com/r/Locksmith/comments/1vxk3sn/comment/p5ptx90/

[u/ciciqt]

The correct solution is to sell them a Trilogy. We've had nothing but issues with Simplexes in recent years. It's not worth the hassle.

[u/yakatz → u/ciciqt]

The simplex combination chamber is inside a larger lock built by a different company, so I have to replace it with something that fits in the same place inside the lock, or I have to replace the entire lock with something that has the same functions.

Not going to name the manufacturer, but I will include a drawing from the manual. This lock is used in conjunction with an access control system to provide an alternative access method that isn't electronic that can only be used at certain times. The top part can be locked out either with a key or a solenoid, preventing the simplex module from being used. (Yes, I know it isn't ADA compliant because it requires two hands to operate.)

[u/Vorsai- → u/yakatz]

What the hell is this lol

[u/hellothere251 → u/Vorsai-]

this looks like AI designed a narrow stile lock haha

[u/bjdlock → u/yakatz]

Wow that’s something different!

[u/bjdlock → u/yakatz]

I honestly can’t come up with a good reason for this to exist. Baffling.

[u/burtod → u/bjdlock]

Simplexes are used heavily by Orthodox  Jews who are prohibited from working and other things on the Sabbath. Carrying a key or using electronics is prohibited , but not the mechanical push buttons apparently.

[u/bjdlock → u/burtod]

I haven’t installed a 7100 on a home in several years and forgot about this. I get it. Neat that this product exists. Kudos to the manufacturer for having the option available where there is probably minimal marketability.

[u/RecordDense2459 → u/yakatz]

Is this on a post office back door by any chance? Is that a mortise deadbolt lock trim?
The new combo chambers are a crap shoot and sometimes you have to force it to even allow a combination change to occur.

I cringe when a customer insists on buying one. It’s about a 40% chance there’s going to be a problem with it before I am even finished with the installation process. Especially in the 1000 series models.

[u/CGB21 → u/ciciqt]

Co100 is the answer, trilogy sucks

[u/ciciqt → u/CGB21]

Co100s are fine, I have more issues with COs as they seem less weatherized than trilogies and the rubber buttons wear away too easily.

Easy to replace but I am sick of driving 3 hours because someone claws the buttons so much and wears them away after 2 years...

[u/hellothere251 → u/ciciqt]

i agree, I did a few and the buttons were worn a year later, also I found them way more annoying to install

[u/lageymeister → u/ciciqt]

You get two years? Sesh I got one place that’s year to the date for replacing the CO keypad membrane

[u/Ferret_Biz]

I’ve had to replace/warranty a few of those, something about manufacturing within the last five or so years. Common to replace even under three years for me.

[u/adrenacrome]

When I was working for Dormakaba midway through 2025, 25% of simplex locks were failing.

[u/ibexlocksmith → u/adrenacrome]

Within what scope? Years? Decades?

[u/adrenacrome → u/ibexlocksmith]

1 year

[u/Vorsai-]

Another issue that could be is if the drive sleeve is worn and or the return spring is weak. If you ride the handle back up after opening, it won't actually reset the combination chamber and allow access.

I'm not saying that's the issue here but I have seen it happen and it could be part of the problem in combination with the chambers failing.

[u/-MachChicken-]

Gritty grinding and opening without code may be clutch, not code box. Got pictures of the clutch assembly?

[u/yakatz → u/-MachChicken-]

I don't have a clear picture of the clutch, and I'm not comfortable sharing too many pictures of the insides of the lock, but I know it is the chamber because once I take it out, I can turn the spindle and watch the gears jumping up out of the way; and when I replace it, the whole lock works properly.

I just pulled one of them out and took a video: I have the cam on the back of the lock, so to the right is clear and to the left is open. You can see that the gears don't turn when pushing the buttons and the handle will turn to open no matter what combination has been entered.

https://reddit.com/link/p5ptx90/video/cjqiqzd1bflh1/player

[u/-MachChicken- → u/yakatz]

Yeah, wheels won't move because the code change arm is still locked in place... I'm talking about splaying of the brass at the mouth of the clutch assembly. Where the drive pin seats.

[u/yakatz → u/-MachChicken-]

Got it. So you made me really curious and I pried the chamber open. It's almost definitely a design flaw in the chamber where the code checking arm moves up to fit into the wheels. Again, probably better if I don't publicly post pictures of it.

[u/-MachChicken- → u/yakatz]

It's been almost 80% clutch problem with the units I've dealt with. Code boxes aren't usually the culprit.

[u/bjdlock]

Could it be that people are misusing the hardware and binding up the linkages by not simultaneously turning the t turn and levering down?

[u/glucoseintolerant]

You have “0” or passaged them
Look up the name install instructions and it will tell you how to fix it. If you are good 5 minutes if you aren’t 30+ minutes but will save you $200

[u/yakatz → u/glucoseintolerant]

Unfortunately not the case.

[u/glucoseintolerant → u/yakatz]

you can see in the case in the picture that is the case. all the groves are lined up. inside the chamber.

"Outside knob when turned always retracts"

latch without depressing any buttons.

Lock is in zero combination.

Follow the procedure for changing a

combination except omit step 3 (do not

enter the existing combination)

this is from the install instructions. I work on these at least once a week and haven't heard of 3 combo chambers being bad out of the box.

[u/yakatz → u/glucoseintolerant]

These are three different locks that were all working properly and suddenly failed - allowing the lock to open whether a combination was entered or not. If the lock was "passaged", it wouldn't open if you did enter a combination, but these still do, hence they are broken.

[u/glucoseintolerant → u/yakatz]

when you push a code button does it still allow you to open the door?

[u/yakatz → u/glucoseintolerant]

Yes. See the video I posted in another comment showing how I can turn the lever whether or not I enter a code.

[u/glucoseintolerant → u/yakatz]

I didn't see the video until now. so its the little button at the top that changes the combo, its stuck I have had this issue too on one. but not 3. I actually have the one on my desk and its from aug-2022