107 Cruise Control - Is this right?

[rzrob]

Hello,

Since getting my '76 SL the Cruise Control never worked. My approach was to inspect and replace if necessary everything.

So besides everything else I messed with , I found that the Amplifier (this tin box under the driver's side dash) was definitely bad. I could wiggle the inner circuit board and get action. I tried solder to no avail.

It had a bunch of numbers on the outer case and among them, I noticed "2032." At the yard today I got a "2132" which looked identical, even though their was one number different. Viola, the Cruise Control works now - sort of.

If I activate at 60, and let off the gas, it pulls the car pretty hard up to 65 and then seems to let off until the speed reduces by 5 mph back to 60, then pulls again and lets off. It doesn't seem very graceful - just short of spasming . Anyone got any ideas? Is this all the better these old cars can be? I was hoping for a little more gradual and steady. Is it because of the 2132 I installed vs 2032 it originally had. I'm really mysified and wondering what to expect from a perfect Cruise Control system?

I could use some help.

RZ Rob

[airedale]

The one on my '84 is extremely smooth.

[rzrob]

Thanks Airedale. Your's ('84) is almost 10 years newer. A lot might have happened since 1976. On my 2003 the cruise control is so smooth, I find myself literally driving by it almost all the time. While basically my '76 CC is operational, it hardly seems like it's the way anyone would want.

I hope someone with an older model knows.

RZ Rob

[450sl4me]

I don't know about the part numbers, but my 1980 450sl exhibits similar characteristics. I've recently figured out that my SL is truly a warm weather car, as the cruise control has suddenly decided to work again. ALthough, it still does some sudden moves where it quits or loses speed. My experience has been that the system is not real smooth, but I may (and most likely do) have some part(s) not functioning properly.

[Strife]

I would definitely revisit the original unit's PCB. In addition to resoldering all the components (put a bit more solder on, and reflow each connection), it would be worth putting solder along the PCB traces (in the event of a hairline crack). This sounds fixable.

[airedale]

Originally Posted by airedale

The one on my '84 is extremely smooth.

It was extremely smooth until today. I was cruising at 70 today and it just lost speed. Pushing the arm up would not accelerate the car. I could fix it at a speed with the arm up but it would lose the speed steadily while staying engaged. Any ideas?

[450sl4me]

That's precisely what mine does most of the time.

[airedale]

Looks like we are both looking for the same cure because this is not normal.