Cruise Control (80)
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Joined: Jul 2001
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From: OFallon, Illinois, USA IL
Cruise Control (80)
Bought my 80 Coup in May of this year and only have two items still in need of repair, the Cruise Control and Emergency Brake.
Does anyone know anything about Cruise? A couple of times while driving down the road, I attempted to get the cruise control to work, and it did, a few times. I had to back off very quickly as I was in traffic.
They sell a transducer through Ecklers, but I don't know if spending $100 up front without really knowing for sure what is wrong.
Any suggestions?
Kloppy80 :confused:
Does anyone know anything about Cruise? A couple of times while driving down the road, I attempted to get the cruise control to work, and it did, a few times. I had to back off very quickly as I was in traffic.
They sell a transducer through Ecklers, but I don't know if spending $100 up front without really knowing for sure what is wrong.
Any suggestions?
Kloppy80 :confused:
Melting Slicks
Joined: Oct 2000
Posts: 2,143
Likes: 195
From: Englewood FL
Re: Cruise Control (Kloppy80)
The cruise control transducers very often fail. If the speedometer
is jumping around, this maybe a sign that the transducer is failing.
To test, disconnect the lower cable at the transducer, and turn the
shaft of the transducer. If there is a fair amount of resistance, the
transducer is binding and will eventually cause the lower speedometer
cable to break and may even contribute to the drive and driven
speedometer gears in the transmission to fail.
Some additional checks:
If the transducer has power, and there are no leaks in the vacume
system, then the transducer is most likely the problem.
Rebuilt transducers are available overnight from Napa and Parts
Advance Stores for about $80. There is no need to buy them
from a corvette supplier and pay a premium.
[Modified by mark79,80, 7:32 PM 10/27/2001]
is jumping around, this maybe a sign that the transducer is failing.
To test, disconnect the lower cable at the transducer, and turn the
shaft of the transducer. If there is a fair amount of resistance, the
transducer is binding and will eventually cause the lower speedometer
cable to break and may even contribute to the drive and driven
speedometer gears in the transmission to fail.
Some additional checks:
If the transducer has power, and there are no leaks in the vacume
system, then the transducer is most likely the problem.
Rebuilt transducers are available overnight from Napa and Parts
Advance Stores for about $80. There is no need to buy them
from a corvette supplier and pay a premium.
[Modified by mark79,80, 7:32 PM 10/27/2001]
Melting Slicks
Joined: Aug 2000
Posts: 2,310
Likes: 1
Re: Cruise Control (Kloppy80)
When the cruise worked, did it work well? That is, did it maintain the set speed well?
My cruise went from holding set speed at +/- 5mph (man was that annoying, it'd slow down to 5mph below, the speed up to 5mph above, over & over & over again :crazy: ), to not working at all. I changed the transducer and it held the set speed right on the button; for about a year :mad . Now, I set the speed and it steadily creeps higher & higher until I hit the brakes (I've set it at 50mph and had it accelerate to over 70mph).
So, I'd say the transducer is a good bet. I wish I had known you could get rebuilt ones from generic auto parts stores. I spent the $100 on mine :rolleyes:
My cruise went from holding set speed at +/- 5mph (man was that annoying, it'd slow down to 5mph below, the speed up to 5mph above, over & over & over again :crazy: ), to not working at all. I changed the transducer and it held the set speed right on the button; for about a year :mad . Now, I set the speed and it steadily creeps higher & higher until I hit the brakes (I've set it at 50mph and had it accelerate to over 70mph).
So, I'd say the transducer is a good bet. I wish I had known you could get rebuilt ones from generic auto parts stores. I spent the $100 on mine :rolleyes:
Burning Brakes
Joined: Dec 2000
Posts: 1,183
Likes: 2
From: Des Moines Iowa
Re: Cruise Control (jerryp58)
Quote: ". Now, I set the speed and it steadily creeps higher & higher until I hit the brakes (I've set it at 50mph and had it accelerate to over 70mph)."
Funny thing, my '81 does the same thing after I replaced the transducer and fixed a kinked vacuum line. Only thing on my '81 is that after running about 10 miles and everything is fully warmed up, then the CC works great, just like it's supposed to without the creaping up in speed problem that it seems to have when first engagedl. I've taken the vette for long trips, and once warmed up, the CC will work hold the speed great all day long, just don't know why it wants to creap up in speed that first 10 miles or so, figured it must have something to do with vacuum increasing until engine is fully warm, or a small vacuum leak that goes away when everything under hood is up to normal operating temperature. Would appreciate other's thoughts or observations on this situation.
Funny thing, my '81 does the same thing after I replaced the transducer and fixed a kinked vacuum line. Only thing on my '81 is that after running about 10 miles and everything is fully warmed up, then the CC works great, just like it's supposed to without the creaping up in speed problem that it seems to have when first engagedl. I've taken the vette for long trips, and once warmed up, the CC will work hold the speed great all day long, just don't know why it wants to creap up in speed that first 10 miles or so, figured it must have something to do with vacuum increasing until engine is fully warm, or a small vacuum leak that goes away when everything under hood is up to normal operating temperature. Would appreciate other's thoughts or observations on this situation.
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Joined: Jul 2001
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From: OFallon, Illinois, USA IL
Re: Cruise Control (john's '81 mouse)
Thanks for all the information. From the tone of everyone who repsponded, the transducer seems to be the culprit. I'll purchase one, install it, and see what happens. Thanks
Kloppy80 :cool:
Kloppy80 :cool:
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
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Re: Cruise Control (Kloppy80)
Thanks for all the information. From the tone of everyone who repsponded, the transducer seems to be the culprit. I'll purchase one, install it, and see what happens. Thanks
Kloppy80 :cool:
Kloppy80 :cool:
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Joined: Jul 2001
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From: OFallon, Illinois, USA IL
Re: Cruise Control (BSeery)
I found a transducer at an auto parts store, new, for $61.12. I thought that was a pretty good price. I didn't realize this, but their are two different styles, two prong and three prong. The one that is on it is three prong but only two wires going into it with one prong open. That seems kind of reduntant. Any knowledge of this?
Kloppy80 :(
Kloppy80 :(
Melting Slicks
Joined: Oct 2000
Posts: 2,143
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From: Englewood FL
Re: Cruise Control (Kloppy80)
The third prong would be for the resume feature which was added
in 1981. Your 1980 would have had a two prong unit, as a resume
feature was not offered.
Before buying the rebuilt unit, spin the unit and make sure there is
not much resistance. I have seen rebuilt units that are defective.
in 1981. Your 1980 would have had a two prong unit, as a resume
feature was not offered.
Before buying the rebuilt unit, spin the unit and make sure there is
not much resistance. I have seen rebuilt units that are defective.
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From: Kristiansand
Re: Cruise Control (Kloppy80)
Quote from Jerryp58: My cruise went from holding set speed at +/- 5mph
I have the same problem and have seen numerous posts before describing it...
Many people have said that the problem went away with a new transducer.
It would be nice if someone on the forum has more details of what's involved in a transducer rebuild.
I really wonder what causes this erratic behavior.
Seems like there is far to much amplification in the control system.
My transducer looks brand new inside, I have verified that it is operating and have no vacuum leaks. My speedometer is stable.
One problem I found with mine was that the spring was slipping on the clutch. That caused large speed variations from the setpoint or no control at all. Cleaning the parts solved that problem.
As far as cruising above/below lock-in speed this is a "feature" of the design.
Can partly be compensated by adjusting the orifice position.
I have an article that explains how the CC works at my page, technical section. Also the diagram from the shop manual.
I have the same problem and have seen numerous posts before describing it...
Many people have said that the problem went away with a new transducer.
It would be nice if someone on the forum has more details of what's involved in a transducer rebuild.
I really wonder what causes this erratic behavior.
Seems like there is far to much amplification in the control system.
My transducer looks brand new inside, I have verified that it is operating and have no vacuum leaks. My speedometer is stable.
One problem I found with mine was that the spring was slipping on the clutch. That caused large speed variations from the setpoint or no control at all. Cleaning the parts solved that problem.
As far as cruising above/below lock-in speed this is a "feature" of the design.
Can partly be compensated by adjusting the orifice position.
I have an article that explains how the CC works at my page, technical section. Also the diagram from the shop manual.
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Do they make an adapter to connect the 2 cables together? (upper and lower) to avoid going under the dash and doing one longer cable?
Also to test the speedo with a drill - which way do I spin it? clockwise or counter clockwise?
Thanks
Also to test the speedo with a drill - which way do I spin it? clockwise or counter clockwise?
Thanks
Melting Slicks
Joined: Apr 2009
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From: Great Plains Iowa
Backwards or counterclockwise.
Melting Slicks
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From: Russell Ontario
St. Jude Donor '09
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From: Hermosa
I remember cars in the 70's that had CC never really held the set speed that well. Or at least it was a crap shoot compared to today's CC's.
Even the new one in my 77 varies the speed a bit unless on completely flat ground.
Also same a John's 81, it steadily creeps up in speed unless fully warmed up.
Even the new one in my 77 varies the speed a bit unless on completely flat ground.
Also same a John's 81, it steadily creeps up in speed unless fully warmed up.
