Cruise control on an overdrive Healey

[Lin]

I installed a Rostra cruise control on my Big Healey in 2008 and it works quite well. However, I run a Toyota 5 speed gearbox on the Healey. Can one use cruise control with the Laycock de Normanville overdrive. Anyone here done it?

Lin

 

[vette]

Hello Lin, I have never done it, but you can configure your electrical system anyway you want it. but I believe there are a few questions about how you want it to be operateable. At first I thought it would be a good idea to make it to stay engaged only when the car is in 4th gear. That way if you come out of OD it would stay engaged. But I don't think that is a good idea. It would probably scream the rpms if it stayed engaged upon coming out of OD. So then I think it should only be allowed to stay engaged when the car is in OD. That way when you come out of OD, the cruise would drop out and you would be in normal 4th gear with no overriding system on your accelerator.
The way I think I would do that is that you can replace your dash mounted OD switch with one that looks just like it but has two separate sides, or electrical paths thru it. It would have four terminals on the back, two on top and two on the bottom. And each side is separate. It is called a Double Pole, Single Throw Toggle Switch (DPST). Each side opens and closes at the same time as the other side. Like a double knife switch you might have seen on an old clothes dryer or water heater system, but it is in the size of a toggle switch. So with that switch, one half you feed to the OD and one half would feed to the cruise control. When you flip it off, they both go off. Since both halfs of the switch are completely separate, you can run power to it from two separate sources or fuses. Or if you think the fuse and wire that is feeding the OD is strong enough to also handle the crusie control amps, you can energize this switch with the original OD power wire and then put a little jumper across the 2 top terminals. I would recommend two separate sources from 2 separate fuses. Well just thinking out loud, that's my 2 cents. Dave.
PS. I'm editing my original post here because the idea of running the cruise off the same switch as the OD is correct but not completely sorted out. If you did it the way I discribed above, the cruise control would engage anytime the OD was engaged.
But my correction would be to still wire it as above but the wire for the cruise control coming off the DPST switch would then have an engagement switch for the Cruise Control. This then would still drop out the cruise control everytime you took it out of OD.

 

[steveg]

Peter Roses has an OD BN6 with cruise control. It may be a Rostra. His email can be found in the club directories in La Canada, CA (Austin Healey Assn So Calif).

 

[Patrick67BJ8]

I installed a Rostra cruise control on my Big Healey in 2008 and it works quite well. However, I run a Toyota 5 speed gearbox on the Healey. Can one use cruise control with the Laycock de Normanville overdrive. Anyone here done it?

Lin

I saw a Healey at the 2004 Conclave that had it installed. He said he got the unit from JC Whitney. The controls for it were mounted in the ashtray.

 

[Deleted member 8987]

Whatever brand or type you use, you need it connected to the brake lamp circuit to kill it when you hit the brakes (and if the switch goes bad...you have a problem....saw it on a Mark 4 Lincoln once....not pretty).
On manual transmissions, you need a second switch on the clutch pedal (mechanical).
Otherwise, you push in the clutch, you may exceed redline before you realize the RPM's are trying to maintain MPH.