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Adding OEM cruise control?

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panthercity
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Adding OEM cruise control?

Post by panthercity » Fri Oct 12, 2018 10:01 pm

Hi, I have a '85 635CSi Euro with a manual transmission that did not come with cruise control from the factory. Does anyone have a link to a write up or thread showing how to do it..gotchas etc. ?

I don't have any of the the parts yet.
'85 635CSi Euro
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Pod
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Re: Adding OEM cruise control?

Post by Pod » Sat Oct 13, 2018 7:49 am

Thinking about it, I don’t recall ever having a manual car with CC - I wonder if you really need it anyway?

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Brucey
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Re: Adding OEM cruise control?

Post by Brucey » Sat Oct 13, 2018 9:53 am

Pod wrote:
Sat Oct 13, 2018 7:49 am
Thinking about it, I don’t recall ever having a manual car with CC - I wonder if you really need it anyway?
I have had several; if you do a lot of motorway work it makes a lot of difference. In particular you

a) don't have to worry about speeding (provided you set it at a sensible speed) and
b) you can have a proper wriggle every few minutes (a very good idea from a circulation POV) without alarming passengers/ other road users.

I have all the bits to retrofit a system; however sloth means that it is yet to be installed. I will do a write-up when I do it, but at the rate I'm going someone else will beat me to it for sure.

FWIW the control stalk needs to be the correct type to match the control unit and the actuator. There are basically two different types fitted to BMWs of this vintage; one has more wires between the stalk and the ECU. Thus there are (at least) two different types of stalk for E24. It is a good idea to use an OEM stalk if you want an OEM look. It is possible to cut the steering column shroud to fit the cruise stalk, but this will obviously leave a hole if you ever delete it.

If taking a control unit from another BMW of that vintage, you need to match it to the correct stalk. Because the wire colours in OEM ECUs vary to match the car, you may need to look at multiple wiring diagrams to figure out which wire connects to which. It is a lot simpler if you get an E24 ECU that matches your car for age; the wire colours will match the E24 wiring schematics. [I have a cruise unit that comes out of a later E30 and the wires are all different colours....]

Again in the engine bay the neatest installation uses the OEM actuator which sits on a special bracket below the PAS reservoir.

M30 engines already have a cable mounting on the throttle linkage for the cruise control. S38/M88 engine models don't always have anything to connect to. Note that when the cruise control is working, the throttle cable usually slides through its mounting at the throttle linkage. This imposes different loads on it than normal, so any deficiency in the cable/mounting condition is liable to result in trouble.

Obviously if you want to fit a later cruise unit to a pre 5/82 car then there is no readily accessible pulse vs speed signal, without which the cruise won't work. Something to do this job will have to be added to the car.

hth

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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panthercity
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Re: Adding OEM cruise control?

Post by panthercity » Sat Oct 13, 2018 2:12 pm

Hi Brucey,

My longest highway trip has been 8 hrs each way and most of the millage I put on her is from 3~4 hr drives on the highway. I think cruise control is a nice to have for my situation. It reduces driving fatigue a bit and can result in increased mpg/range.

On a recent trip to Carlsbad New Mexico my son was driving and was pulled over for speeding. Thankfully, the young Texas highway patrolman was more interested in checking out the car than in giving a ticket :) Cruise control may have prevented that incident.

Thanks for the detailed information on the system.

Regards,
Tony
'85 635CSi Euro
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sansouci
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Re: Adding OEM cruise control?

Post by sansouci » Sat Oct 13, 2018 3:12 pm

It is interesting how "cruise control" has evolved with integration of crash avoidance, lane departure, platooning and GPS. Adding primitive CC seems like a lot of work. I would imaging that CC would become a smart phone app. I've worked with a company that did event recording for trucks to capture driver behavior (drinking, phone chatting) as well as speed and accidents via accelerometers and front/rear video. Initially there was a big upfront installation of hardware and software. But we determined that many of these functions would be replaced by smart phone apps. Nevertheless, you have big players (Bosch, Siemens, etc) integrating some of this in newer trucks with dedicated and proprietary hard/software.
Since I don't have a new 7-series or S-class Benz, I haven't experienced the newest technology. Anyone want to chime in?
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

Drew
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Re: Adding OEM cruise control?

Post by Drew » Sun Oct 14, 2018 9:23 am

This is going back a long while, but I did this mod to a manual pre 5/82 car. Not trivial, but the difficulty, as Bruce notes, is to generate a speed signal for the cruise Brain to work with. A later car doesn't have this issue as the speed sender in the diff generates the square wave the brain needs
If you do a search on the site, about 10 years back....
I used the actuator, brain and loom from a M30 engined E32. So the actuator's Bowden cable fits the M30 throttle, no issues there. I fab'd a bracket to support the actuator in the engine bay and connected the loom to the brain, which I tucked behind the dash. I sourced a control stalk for an E24 and pushed out the cut-out from the steering column shroud. The control stalk took a bit of wiring up IIRC, and I think I needed a relay which altered how the stalk connected to the brain when cruise was engaged.
Then I put a tell-tale in the lights cluster
You need to connect up a wire to the brake pedal switch so it disconnects the cruise. For a manual you should also ensure cruise disconnects when you press the clutch pedal, I never did this last bit, I just remembered only to engage cruise when in 5th
I still have the wiring diagram I drew, pm me your email if you want it

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