Cruise actuator and amp...???

[vwbuge]

Where are they?????

[The Warden]

The amplifier is under the dash, at least on a 123. I think the 126 is in the same spot, but I'm not 100% sure. You'll want to remove the lower panel (by the brake and throttle pedals) to access it. At least on my car, it's a silver box just ot the left of the steering column.

The actuator's on the engine, and is just behind the power steering pump and the vacuum pump. If you look at the throttle linkage, the forwardmost part of the linkage is attached to the actuator.

Hope that helps some...good luck!

[whunter]

Cruise Control Amplifier.
http://catalog.eautopartscatalog.com/mercedesshop/part.jsp?partner=mercedesshop&year=1985&make=MB&model=300-SD-002&category=P&showChildren=false

[whunter]

Cruise Control Actuator.
http://catalog.eautopartscatalog.com/mercedesshop/part.jsp?partner=mercedesshop&year=1985&make=MB&model=300-SD-002&category=P&showChildren=false

[300SDog]

Great pics!!!

But god almighty, that amplifier busts the wallet at $460 and the actuator is another $230...... It looks like junk to me, one of several bogus MB accessory component systems that oughta be hurled into the woods or thrown into the nearest lake.

Yet there are USA built modern aftermarket CC units that will probably outperform and outlast the original at fraction the cost: http://www.jcwhitney.com/webapp/wcs/stores/servlet/ProductDisplay?productId=6774&catalogId=10101&langId=-1&storeId=10101

For alot of their stuff, its like MB uses crackpot demon engineers they keep chained to basement walls designing climate controls and cruise controls using wacky electronics and weird servo systems.

Oh well, what can you say against the finest handling and longest lasting, most soulful automobile that has ever been built??

[81Wagon]

Having just disassembled and cleaned/lubed my actuator yesterday, I don't think I would say there is anything wacky about it; seems like a fairly simple, straightforward device. On that note, $230 for it is crazy -- a few plastic gears, one diode, a small electric motor, an electromagnet, and a few other odds and ends must cost a total of 10 bucks to produce.

The cruise amp on the other hand... Well, I know very little about electronics so I can't comment on the engineering, but they sure seem to f*** up a lot! I bet it would be possible to use some modern electronics to design a better, more reliable CC amp to take the place of the stock one; for 500 bucks a pop I'm surprised some enterprising electronics student hasn't taken a crack at it yet...

[wolf_walker]

Two issues with the cruise amp. Solder joints that get flakey over time. I dont' know what in hell those guys used for solder back then, but it was not overly good. Often you can just wet each pin and let the solder re-flow and it will be fine again. This applies to almost any part of the car that is soldered. Not gauranteed, but it seems to work often.

Second, there driving a DC motor off transistors. This is a Bad Idea. When the amp draw goes up on that motor, say if your throttle is sticky and takes more force to move it, you can easily burn that amp, happens a lot. I've toyed with the idea of setting up a relay kinda arrangment that would remove the load from the amp, but I have to find myself a truly *right* amp to play with first. And I'm not about to spend that kinda money on one, even though a rebuilt one for my w123 is a bit cheaper.

As an upside, often salvage yard actuator's are often pretty good, as the cruise did not work for very long!

Most motors on an MB, the monovalve, the aux coolant pump, and anything else I'm forgeting, should really be on relays to take the load off the device they are controled by in my humble opinion.

I'd like to try an aftermarket cruise as well, there not hard to splice into the stock control stalk. Might be a better solution in the long run. I've used a ton from JC Whitney on my VW's..

[81Wagon]

How do the aftermarket ones work? Where's the actuator go? Do they work as well as the stock CC? (uh, assuming a stock CC that works properly! ;-)

[wolf_walker]

I have no idea how well a stock CC works to be honest, I'd imagine it works pretty well though.

Depending on the brand, type, most aftermarket models that I've used have some sort of vacuum powered actutator you rig a mount for underhood, a control box(amp) and a control stalk.
I always used the input lead for two magnets and a pickup attached to the driveshaft. You calibrate them, and your set. Not a whole lot of grief to install one, but not an oil change either.

Some work better than others, I can't place a finger on which ones have worked better honestly, but most of them seem OK.
PO of my 300D tried one once, this is how I know you can use the stock stalk for control, and it couldnt hold speed. I think it was a combo of a crap load of vacuum leaks and un-lubed controls, but have had no chance to try it again.