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MG MGA - Rostra 250-1316 Cruise Control?

At the risk of fanning flames on the "It's not original" wars I'm planning to add a cruise control to my roadster for the trip to Reno. The Audiovox unit appears to be no longer available. But, it does appear that the Rostra 250-1316 unit is. I have found some info in the Archives. Anyone currently using one of these? Any tips/advise on the installation? What is actually needed? I'm seeing that just the cruise control is not all. Apparently you need a drive shaft magnet, control switch, some type of "Actuator". Any help would be appreciated.
Thanks,
Gerry
G T Foster

I have cruise control on my modern car but I have no experience with one on a MGA.
But based on my system you will need at least an operating switch, a VSS (vehicle speed signal) and switches on the brake and clutch pedals.
The VSS will require a magnet and signal pick up for the drive shaft.
My car uses the brake light switch to also turn off the cruise control.
You will also have to fit a clutch switch otherwise the engine RPM will go out of control when you depress the clutch pedal and the car slows down.

Mick
M F Anderson

Check Barney Gaylords site. He has pictures of my installation in the front fender well under power brake booster. I am sure he has informaton on cruise control. I ran a steel line against the firewall to a bulk head fitting into the fender well. This is for the vaccum that will be needed. I drilled the end of the manifold to fit the connection to to get vacuum. If at a later date I want to get rid of it, all I have to do is put in a new "freeze" plug. Unless someone is looking real sharp it is not notice-able. I ran my connections to the right side of the gas rod control under the dash. Oh I forgot, my unit is the Auddiovox
JEFF BECKER

Barney's page is at:

http://www.mgaguru.com/mgtech/electric/et209.htm

He describes both the type that operates off a signal from the ignition coil and the type that measures the rotational speed of the drive shaft.
The first method is keeping the car at a constant RPM and the other is keeping to a constant road speed.
I guess these two methods give the same result.
Using the clutch disables the system and you reset it in the gear you are using.

Mick
M F Anderson

If you use automatic transmission with slippage in the torque converter, then speed measurement at the propshaft is important. For a manual gearbox, the ignition points work fine for the speed reference, and no magnets required on the propshaft. Connect two wires to the original brake switch to kill it when you touch the brake pedal.

Optionally you can add a clutch switch as well, but it may not be needed. The c/c units I was using in the late 80's and early 90's had an engine speed limiter. If engine speed increased or decreased 20% the unit would disengage. So if you depressed the clutch when c/c was working (going up hill, down hill, or on the level), the resulting change of engine speed would disengage the c/c without need for a clutch switch.

For vacuum servo c/c units, when used with a small displacement engine you may need to ad a vacuum reservoir. Going up a steep hill may result in full throttle operation which may drop manifold vacuum below the level needed to operate the vacuum servo. Even with a vacuum reservoir, continuing up a log hill for a few minutes may deplete the reserve vacuum and disable the servo. I had a factory vacuum c/c on a Pontiac in the 80's. When driving in mountains above 600o feet altitude there was not enough atmospheric air pressure to operate the servo.

The newer all electric c/c does not use manifold vacuum, but has an electric servo motor. This avoids all of the problems with low vacuum. If I ever get another c/c for my MG it will be the non-vacuum electric type. The Rostra 250-1316 is electric servo type. You can download a copy of the installation manual (1.2-MB PSF file) here:
http://www.thecruisecontrolstore.com/1223inst.pdf
Barney Gaylord

Thanks for the input guys.
GTF
G T Foster

GT,
I put one of the electronic cruise controls from the cruisecontrolstore.com on my TD about 2 years ago and it works great plus the tech people were great the few times I needed them. Didn't have to cut or drill anywhere. I had to make a small clip to attach the servo cable to the throttle. If you go to there web site don't let the instructions intimidate you? Lots of wires you don't use.

Ed
ECS Stanfield

Gerry, there is an article on the fitting of the Audiovox CCS -100 system to an MGB in the latest (March 2011) MGCC Safety Fast magazine.Good luck - Cam
Cam Cunningham

This thread was discussed between 26/02/2011 and 06/03/2011

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