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#1047068 - 01/13/17 03:29 AM Are the front seat belts "inertia reel" type?  
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ChasUno Offline
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Today I took the back seat out so that I could replace a broken driver side seat belt tensioner unit (the spring loaded latch that fits at the rear of the front door pillar). That all went fine, and now the seat belt doesn't retract after the door is closed (which is the correct way it should operate).

However, even when the tensioner is engaged and stops the seat belt from retracting, the seat belt doesn't lock when you tug on it hard as an inertia seat belt should do. It just keeps on extending until it reaches maximum travel. The front passenger side is the same. Interestingly, the two retracting rear lap seat belts DO lock when tugged sharply.

Are the fronts supposed to lock when pulled sharply? And if so, why might they not be working and can they be repaired?



Last edited by ChasUno; 01/13/17 03:31 AM.

1986 Monte Carlo SS

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#1047077 - 01/13/17 03:28 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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86ttop Offline
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Yes, they should lock, I don't know about repairing them, I haven't had to do any repairs to them.


Leo Paugh
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#1047084 - 01/13/17 08:26 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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upflying Offline
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Are you doing this test with the front doors closed?


86 MCSS Notchback coupe, LS3, 4L65E, QP 9", Eaton Truetrac, 4 wheel disc, column shift, Dakota Digital, silver with maroon bench interior

#1047085 - 01/13/17 08:28 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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upflying Offline
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Are you doing this test with the front doors closed?
Are the forks from the door lever correctly engaged in the retractor?


86 MCSS Notchback coupe, LS3, 4L65E, QP 9", Eaton Truetrac, 4 wheel disc, column shift, Dakota Digital, silver with maroon bench interior

#1047100 - 01/14/17 03:34 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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ChasUno Offline
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Leo, do they lock just by giving them a sharp tug at rest, or do they require the car to be in motion? I know some types of seat belts have an internal bearing that moves under deceleration, which then locks the seat belt. No matter how sharply or quickly my belts are tugged, they don't lock.

Upflying, yes, tested with doors closed and yes, both tensioner forks engaged and operating the lever on the side of the seat belt spool. As mentioned, I replaced a broken tensioner on the drivers side, and as I had the back seats out I checked the passenger side also. I also cleaned and re-greased both tensioners while I had good access to them.

I also checked the operation of the tensioners by hand (manually moving the lever), and with them engaged I also tried tugging on the belts. Still no locking.

Can it be confirmed that an '86 MC SS should lock its front seat belts with a sharp tug at a standstill?


1986 Monte Carlo SS

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#1047102 - 01/14/17 04:03 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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mmc427ss Offline
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On drivers's door I have to open the door so the shoulder belt tensions. If I pull the belt out with the door closed it will lock in the extended position, opening the door retracks the belt against my chest. Will have to note whether the pass door behaves the same way. Never gave it much thought other than when in the staging lanes and it's time to buckle up, you need to open the door to snug the belt. Hmmm.

Just destroyed an inertia seat belt retractor from the third seat of my Astro, they are not designed to come apart. Was curious what made them tick. Under hard braking they lock holding the belt from unwinding. No lever in the jamb to release the belt, they are always "free" until locked by high negative Gs.
Bob

#1047107 - 01/14/17 06:20 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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86ttop Offline
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They should lock and on my car, if you eased the belt out because it was too tight, it would lock there and if pulled again, it would release and return to the too tight position. It has been my experience that they'll lock when the car is in a very steep downhill facing position!


Leo Paugh
It's not an attitude, it's just the way I am.
POW*MIA
You are not forgotten
If things improve with age, I must be approaching magnificent. thumbs
#1047110 - 01/14/17 01:47 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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Monte_ExpreSS Offline
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Id just like to jump in and point out that the seat belt tensioner thingy in the door jamb has nothing to do with if the belt will lock under a sudden stop or not. Their sole purpose is to stop the belt from retracting against the occupants too snuggly when the doors are closed and presumably the vehicle driving. I always found this to be a odd feature specific only to G bodies.
I can also confirm that the belt will function correctly without the tensioners installed as I deleted mine several years ago. As Bob mentioned, I became aware that as I was driving I was constantly tugging on the belt to get it to retract for a tighter fit, but it was impossible to do with the door closed. By removing the tesnioner this allowed the belt to move freely with me. It will not affect the belts ability to lock in a sudden stop as that mechanism is built into the belt retractor.
It is possible, but highly unlikely that your retractor has failed. I have found in the past it is not always possible to manually replicate the lock. The best way to test this would be a panic stop (brake hard) in a secluded area. The belt should instantly lock and stay locked until tension is released from it HTH

#1047116 - 01/14/17 03:57 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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guitars Offline
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I wonder (you say they were greased) if part of the assembly is hanging up due to grease viscosity.

#1047121 - 01/14/17 05:09 PM Re: Are the front seat belts "inertia reel" type? [Re: guitars]  
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ChasUno Offline
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Originally Posted By: guitars
I wonder (you say they were greased) if part of the assembly is hanging up due to grease viscosity.


The only parts that I re-greased were the tensioner assemblies. This is the forked arm operated by the lever on the door pillar. I didn't touch the actual seat belt spool/ retracter assembly.

Just to clarify when talking about 'locking'. My seat belts will 'lock' in position when the doors are closed, by that I mean they will not retract. If the door is open, they will, indicating that the pretensioner lever is working. If you pull on them in locked state (with doors closed), they will keep on extending. They will not lock if you pull on the sharply/ quickly, whether the doors are open or closed.

Last edited by ChasUno; 01/14/17 05:10 PM.

1986 Monte Carlo SS

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#1047128 - 01/14/17 05:51 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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Monte_ExpreSS Offline
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Originally Posted By: ChasUno

Just to clarify when talking about 'locking'. My seat belts will 'lock' in position when the doors are closed, by that I mean they will not retract. If the door is open, they will, indicating that the pretensioner lever is working. If you pull on them in locked state (with doors closed), they will keep on extending. They will not lock if you pull on the sharply/ quickly, whether the doors are open or closed.


That is the correct way they are suppose to operate

#1047138 - 01/14/17 10:44 PM Re: Are the front seat belts "inertia reel" type? [Re: Monte_ExpreSS]  
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ChasUno Offline
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Bradenton, FL
Originally Posted By: Monte_ExpreSS


That is the correct way they are suppose to operate


The front belts aren't meant to lock (stop from extending) if pulled sharply (with the doors closed)? The rear belts DO lock (won't extend further) when pulled sharply, but do if pulled gently. This is how I thought the fronts should also operate?


1986 Monte Carlo SS

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#1047149 - 01/15/17 01:14 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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maybe I misunderstood your previous post. Just to clarify, everything you said was correct up to the point where you mention about the sudden sharp pull and they dont lock.
Again, I will say it can be hard to manually replicate that function of the belts, but yes the belts in the front function the same as the rears. They will (or are supposed to) lock, whether the doors are open or closed, with a sudden jolt as they would receive in a panic stop or impact situation

Last edited by Monte_ExpreSS; 01/15/17 01:18 AM.
#1047152 - 01/15/17 03:27 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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ChasUno Offline
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Thanks for clarifying Monte_ExpreSS, I appreciate it.

Looks like both my front belts are faulty in that case frown


1986 Monte Carlo SS

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#1047799 - 02/03/17 05:30 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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tall t-top Offline
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Test them how Monte ExpreSS said. Different vehicle example but the front belts in my 91 Chevy truck will not lock by hand but if I stop hard, they lock. Had a fender bender in the rain when I slid into another car. Belt was loose while sliding (low negative G's)but when I hit (maybe 10mph) they locked. Try the hard stop test.

Last edited by tall t-top; 02/03/17 05:30 PM.

Andrew

86 MC SS t-top, 305 with port and polish, Edlebrock Performer Intake, Flowtech Afterburner headers, duals to Jeg's chambered mufflers, Jeep steering shaft, Turbo Eclipse seats (Weekend toy but a project at the moment)
91 C1500 extended cab, TBI 350, 2in suspension lift, Jeep steering shaft. (Daily driver)
2012 Mitsu Outlander Sport (wife's car)
#1047814 - 02/04/17 01:34 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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ChasUno Offline
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Thanks Andrew, I will try that once I get my Monte back on the road.


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#1048688 - 03/06/17 04:11 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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Tap the brakes while at the same time leaning forward. You will feel the front retractor lock instantly. Its almost impossible for the retractors to go bad or wear out. return spring can be tightened if it gets tired. There is a swinging pendulum in the retractors. When certain forces are encountered the pendulum will swing and the crossbar will be pushed into the teeth on the reel. The fronts are inertia type reels. Best not to grease these as the grease will hold dirt and defeat the purpose. The spring steel coil inside the plastic cap is lightly greased. Probably to help prevent rust. The door jamb actuator applies tension to the reel so it self retracts when opening the door. That prevents the strap from getting chewed by the door latch or the seat back latch.

#1048837 - 03/10/17 05:19 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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ChasUno Offline
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Bradenton, FL
Thanks for all the input everyone.

With my Monte back on the road I tried the front belts with some sharp/ sudden braking - still the same, no locking.

Luckily a member on MCSS is parting out a car with the burgundy seat belts, and he has also confirmed that the fronts do lock. I have bought that set and will get them installed into my car ASAP. Having worked in healthcare, and also having friends that work as first responders as both cops and paramedics, I've seen first hand and heard about the end results of people not wearing seat belts in traffic accidents. Seat belts really do save lives, and I will have much peace of mind knowing that those fitted to my MCSS will work when I need them.


1986 Monte Carlo SS

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#1048997 - 03/16/17 01:18 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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ChasUno Offline
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I have just received the seat belt set today that I bought off another forum member. The front reels clearly 'lock' when tugged sharply, which confirms that they are the inertia reel type and will lock under sudden movement. It also confirms that both my currently fitted front seat belts are faulty, and for safety reasons they need to be changed asap.

I have one other question regarding the seat belts. I can see that there is a "seat belt" warning light on the dashboard, and one of the front seat belt anchors has a wire coming from it (the other doesn't). Is the seat belt warning light only operated by one seat belt (the drivers)? And what should the warning do - just light up the warning light on the dashboard, or sound a buzzer as well? Mine currently doesn't light up or make any kind or visual/ audible warning!


1986 Monte Carlo SS

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#1049001 - 03/16/17 03:14 AM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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mmc427ss Offline
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Only a seatbelt switch under the driver's seat, none for the significant other. In the Convenience Center, which is inconveniently located behind the dash below speedo, is the Audio Alarm Module, along with the flashers, and something else I think. This module controls the seat belt dash light, key reminder, headlight reminder. An alarm buzzer sound when the key is inserted into the lock with the door open, alarm also if the headlights are ON with no key and door open. For the seat belts, the Seat Belt dash light will come on as soon as the key is turned to ON, but will go out after maybe 3 seconds after the engine is started. Gee I hope I got that right, something you don't think about with these cars after living with it for 25 years.

The switch under the seat is just used to ground that circuit for the module, the module controls what goes on.
Some people will remove the module, they get tired of hearing the buzzer for the key reminder, so headlight and seat belt reminder is deleted too.
If your key and headlight buzzer works check the bulb in the dash.
Bob

#1049018 - 03/16/17 08:23 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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It isn't unheard of to disable the seatbelt switch either. Lots of people just don't like the sound of the buzzer. Check to see if the wire has been cut/disconnected/abnormally grounded/etc.
Fun fact, the seatbelt buzzer on a lot of old GM stuff can be used as a handy timer to run a circuit for 3 seconds then reset. My grandpa used them for deer feeders to sling out corn for 3 seconds at a time. smile


Shawn

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It ain't much off the line, but it's nice on the highway
#1049094 - 03/20/17 05:21 PM Re: Are the front seat belts "inertia reel" type? [Re: ChasUno]  
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ChasUno Offline
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Bob, thanks for clarifying the operation of the seat belt warning switch, and also the functioning of the (in)convenience center!

My ignition key and lights on buzzer still works, so it appears that most of the system is likely in place. I will investigate as to whether the driver's seat is still connected/ still has the wiring etc. when I change out the belts. Likely the warning bulb is faulty, as were most of the bulbs when I first got the car. Have to admit that yes, the buzzer sound is somewhat annoying, though I am a stickler for having all the original equipment working as it should. Maybe after living with it for a while I'll get fed up with it and remove the entire system!

Hunter, I be that the original GM designers never envisaged their seat belt buzzers being used as deer feeders!


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