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MG MGA - Cruise Control Knowledge/Opinions
|Several old posts/threads...what's happening NOW for cruise control for my A?|
|Cruise control can be a generic device. The most common units use vacuum to pull the throttle cable, and take signal input from the ignition coil distributor side terminal. For automatic transmission without lock up torque converter, the speed signal should come from the propshaft. Any cruise control should have a shut-off signal from a brake switch. Some also have a shut-off signal from a clutch switch, but not all. Some without a clutch switch may shut-off if engine speed changes by +/- 20% (or something like that). That is, depress clutch causing engine speed up, and it shuts off the cruise control.|
The most common problem with a small engine is loss of vacuum under heavy load conditions, high throttle setting, such as pulling up a steep hill in top gear. The specified fix for that is to install a vacuum reservoir about the size of a baseball with a vacuum input check valve. This will store and provide vacuum to the cruise control for a short time, while running up a short hill. It will likely fail on vacuum when running up a hill for more than a minute at a time. Many vacuum powered units will also fail completely at high altitude (6000 feet limit) when atmospheric pressure is insufficient to operate the vacuum diaphragm.
Some newer designs use an electric actuator, no vacuum involved, and these should be more reliable, especially with a small engine. I do not have any particular model to recommend.
I did have a vacuum cruise control unit in my MGA between 1989 and 1997. It was replaced three times for various failures (failed electronic control, failed plastic parts. I could never keep it working for much more than a few thousand miles at a time. In 1998, after running most of the Alaska trip with no cruise control, I finally decided it was time to throw in the towel and pitched the thing in the dust bin. If I ever had a notion to try it again, I'm sure I would try one of the electric actuator units.
|Best place to purchase???|
|I think you can get them at the same place that has MGA air conditioning units and air bags. Ha!|
|As an alternative you might consider an Alfa Romeo style Hand Throttle. My Dad had a 1972 Alfa GTV with one that you could use as a simple Cruise control, you pulled it out and it was stiff enough to hold the throttles open. Obviously it won't maintain speed on inclines or slow you down on declines but it will save your leg from cramping.|
|Hay Joe - Going to put one of those on Jackie's TD also;-) Cheers - Dave|
|As said, cruise control can be generic, as long as you don't order one for a specific model car. JC Whitney may have them.|
|Joe, I have an Audivox unit on my MGB, works great. I purchased it about 2 years ago on Amazon for about a $100.|
I've been running an Audiovox (was ~$75 at common parts stores, eg Checkers)with a reservoir ($10 JC Whitney) continuosly since the Grapevive GT (when was that?) with very little problems. I have the CC module under the passenger-side dash with only a twin throttle cable showing to let you know there's a CC installed. The reservoir is up in the extreme corner, left of the voltage regulator (as you're looking at it). Mounted the control on a cantilever bracket that folds out of site under dash after engaging. Don't go across country w/o one if you're long-legged. Tyler
|I also ran the Audiovox and it is an easy install. I put my unit into the right fender well and hid it. The throttle cable is hooked to the gas throttle bar on the passenger side of the car. Since I had vacuum in the front fender when I ran my brake booster, that is when I put in the cruise control.|
This thread was discussed between 05/11/2010 and 08/11/2010
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