New Cruise Transducer Disk Gap when new?

J

JHeslinga

Member
Feb 9, 2011
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Does anyone know what the new gap is between the Magnet Disk (Drive disk) and the Speed Disk (Vacuum Control) is on a Brand new (or specifications)
Cruise Control Transducer? I have at least a dozen transducers and they are all so worn that the disks are crashing. I am currently repairing one
and need to machine the pin and bushing to create the appropriate gap.
Any service manual Ive seen states that the Transducer needs replacing if it does not work properly. (OK BUT!!) I've looked in a lot of other places
and have not been able to find this specification. (nor its discussion for that matter) I'm (educated)guessing that about .038" is about what it
should be. Any help on this would be appreciated. The following Photos may help identify what I need.

Thanks a million. John Heslinga

This is the Magnet Disk. (driven by the speedometer cable coming from the transmission.)
http://www.gmcmhphotos.com/photos/discussion-photos/p63320-cruise-control-transducer-magnet-disk.html

This is the Speed Disk that has a rotational force applied to it by the rotating magnet. Note that I have a feeler gauge indicating that I need this
gap measurement.

http://www.gmcmhphotos.com/photos/discussion-photos/p63321-cruise-control-transducer-speed-disk.html

This is the assembly of magnet disk and speed disk. In this case the two disks have no gap. I need to know what the specified gap should be for
these two disks.

http://www.gmcmhphotos.com/photos/discussion-photos/p63322-cruise-control-transducer-magnet-and-speed-disk-combination.html
--
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
 
> Does anyone know what the new gap is between the Magnet Disk (Drive disk) and the Speed Disk (Vacuum Control) is on a Brand new (or
> specifications) Cruise Control Transducer? I have at least a dozen transducers and they are all so worn that the disks are crashing. I am
> currently repairing one and need to machine the pin and bushing to create the appropriate gap.
> Any service manual Ive seen states that the Transducer needs replacing if it does not work properly. (OK BUT!!) I've looked in a lot of other
> places and have not been able to find this specification. (nor its discussion for that matter) I'm (educated)guessing that about .038" is about what
> it should be. Any help on this would be appreciated. The following Photos may help identify what I need.
>
> Thanks a million. John Heslinga
>
> This is the Magnet Disk. (driven by the speedometer cable coming from the transmission.)
> http://www.gmcmhphotos.com/photos/discussion-photos/p63320-cruise-control-transducer-magnet-disk.html
>
>
> This is the Speed Disk that has a rotational force applied to it by the rotating magnet. Note that I have a feeler gauge indicating that I need
> this gap measurement.
>
> http://www.gmcmhphotos.com/photos/discussion-photos/p63321-cruise-control-transducer-speed-disk.html
>
>
> This is the assembly of magnet disk and speed disk. In this case the two disks have no gap. I need to know what the specified gap should be
> for these two disks.
>
> http://www.gmcmhphotos.com/photos/discussion-photos/p63322-cruise-control-transducer-magnet-and-speed-disk-combination.html

John, I've had success just pushing the shaft thru the disk a little more to gain clearance. Used a vise and socket, not very scientific but it did
work. Just made it so the disks clear and don't rub. Running a transducer revived in that manner now.
--
Wally Anderson
Omaha NE
75 Glenbrook
Megasquirt III injection
Bob Stone hydroBOOOOST
Manny reaction arm system
Branscombe Kelsey Hayes park brake
http://wallyandsue.blogspot.com/
 
John,

I don't know what it should be -- haven't fooled with an OEM CC for the 10
years or so since I went to the 90's Electromotor II -- but IIRC, Bill
Bramlett always set it with a business card as his gauge. That's probably
less than your 0.038".

Ken H.

> Does anyone know what the new gap is between the Magnet Disk (Drive disk)
> and the Speed Disk (Vacuum Control) is on a Brand new (or specifications)
> ​
> Cruise Control Transducer?

​...​

​...
I'm (educated)guessing that about .038" is about what it

>
>
 
AN IBM 5081 80 column card was .007". We use to set the throat of the machines feeding them at .009" so 2 cards could not go through at the same
time.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
One of our silent partners says:

"A random check of about a dozen different business cards averages to about
.012” (.009 to .013”) in thickness."

Ken H.

> Does anyone know what the new gap is between the Magnet Disk (Drive disk)
> and the Speed Disk (Vacuum Control) is on a Brand new (or specifications)
> ​ ​
> Cruise Control Transducer?
> ​...
>
 
Thanks to everyone (including the wonderful private messages I received) for the Input on this problem. When I could not find the new gap
information I disassembled a Speedometer Head to measure the gap between the magnet and the speed disks on it. As seen in this photo, I found the
gap to be 0.032 inches.

http://www.gmcmhphotos.com/photos/discussion-photos/p63331-speedometer-head-magnet-gap.html

I wanted to know what the factory measurement was so I could establish the amount of wear that had occured in order to get to failure. (How much
actually wore off the end of the shaft or into the thrust bushing.)

I deduced that the gap in the transducer would be similar and that is where the 0.035 measurement came from. After getting the input from you, (
approx 0.012 inches) I was surprised at the the difference. Maybe I should not have been surprised, because my experience in Briggs and Stratton
Ignition and magneto Repair, we gapped the flywheel to coil gap of about 0.012 to 0.015 inches. (a thick Card stock used for parts identification and
labeling)

Because I had a few transducers to play with, I tried both gaps for the repair. It turned out that both transducers performed the same, and each one
seemed to be a successful repair. (I was pleased)

Given that both transducers operated well, it would seem that Without the actual Factory prescribed measurement, The range seems to be acceptable.
However: In future repairs I think I will use a gap that is in the smaller end of the range. Even if the the wear lifetime to failure is shorter.

Thanks too, to Wally for the advice of pressing the speed disk back on the shaft. That worked like a charm!!

Regards to All !!!
--
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
 
I looked at those pictures and the design of that unit and think about where we have come over the years.

I started with IBM in the 1960s repairing computer equipment. Most things at the time were electro-mechanical with 90 to 95% of the service calls
being mechanical wear and mechanical failures. Over the years we designed out most of the mechanical components items and replaced them with
electronic ones. The failure rate went way way down and today the repair guy is an electronic parts swapper. There are very few around as they are
no longer needed.

That is a true 1960's design you are looking it, but it works.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
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