Cruise Control Gears

[MikeC]

Anyone have any idea on what would cause the worm gear set in a cruise control module to grind out like this. The gears were perfect when I pulled the module apart to fix a dry joint 3 years ago.

 

[grey_hawk]

I would guess heat/lack of grease or a broken limit switch (if even fitted) Maybe the gears are made with the same shite as the odometer gears?

 

[91SS]

Are these gears in binnacle switch?

Where your dry joints in binnacle switch or elsewhere. Still haven't got around fixing mine.

With those gears thinking that if original may be made of same material as odometer gears as @grey_hawk above said. When I repaired my odometer recently myself I noticed that aftermarket two piece gears fitted in 2007 melted and picked up 1 piece supposedly made from different plastic on eBay.

Was there play on worm gear shaft?

Did you lube with silicon grease?

Or maybe simply this will become a common problem going forward.

 

[MikeC]

The gears are in the CC module. Basically the CC module has its electronics in the top half and a servomotor , gears and solenoid clutch in the bottom half.
The dry joints in the RH binnacle switch I fixed several years ago . The CC stopped working again after that and I found a dry joint where the wires from the plug connected to the circuit board- this was found by pushing the CC plug sideways and the CRS light came on again. When I pulled the top off the CC to fix the dry joint I found that the found the gears, which were perfect in April 2020 had worn to this pattern and wouldn't engage.
There was no play on the worm gear shaft 3 years ago- at that time I lubed the worm and gear with lithium grease which has now gone like soap.
All my CC bits are genuine GMH although these are getting much harder to source.
Talking to a retired auto electrician it appears that there may be some kind of torque sensor in the drive train which may have failed. I've put the bottom half of a VP CC on the VQ unit and driven 160km this morning- so far the CC is working well. But I would like to make sure the new worm gear doesn't strip its teeth as well.

 

[07GTS]

only use what grease was originally used as it can be specific to the plastic gears, wrong grease can cause friction over time as it drys out and cause them to wear out, prob need some type of silicon grease which stays good and dosnt dry out over time

 

[MikeC]

only use what grease was originally used as it can be specific to the plastic gears, wrong grease can cause friction over time as it drys out and cause them to wear out, prob need some type of silicon grease which stays good and dosnt dry out over time

The original worm gear set was unlubricated. I assume the gears are nylon few industrial plastics were more suitable for small gears 30 years ago, if so mineral oil based lubricants should be suitable- https://www.machinedesign.com/motor...cation-tips-for-plastic-gears-and-more-part-2

 

[07GTS]

yea if nothing used then keep it that way, if it lasts 30 years with nothing but 3 when lubed that's the issue, for example if u use grease on your LS timing cover crank seal u can sometimes ware a grove in the metal crank, where if u use little engine oil is fine

 

[MikeC]

yea if nothing used then keep it that way, if it lasts 30 years with nothing but 3 when lubed that's the issue, for example if u use grease on your LS timing cover crank seal u can sometimes ware a grove in the metal crank, where if u use little engine oil is fine

Yep, I'll clean the gears and try powder lube like graphite. But this could be an AC Delco design life issue, here's an Impala with the same wear pattern:

Cruise Control gears chewed!

I was having some pretty sluggish responsiveness from my cruise control, so I took the module apart and this is what I found: I'm 99% sure the worm gear on the motor's shaft isn't supposed to be "waisted" like that, and there is definitely debris from gear wear in the module's case. Damn...

www.impalassforum.com

 

[07GTS]

also check to see if the throttle is hard to pull as added pressure for the gears will cause that wear over time too, also make sure when it pulls that it won't want to go past its limit so if throttle is at 100% it should not be able to want to keep pulling as that will kill gears quick too

 

[MikeC]

I've cleaned the gear train back to bare plastic with the use of half a can of contact cleaner, the throttle is free up until the maximum CC pull position, the limit switches I'm leaving alone as they look like their electronic.
Interesting- the worm gear end is spring loaded, designed to lift if the gear wheel is jammed- however I wouldn't rely on it for any long term overloading.
I won't use any lube, as that seems to be the way they left AC Delco.