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Cruise control with manual transmission

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nic55kel

Cruise control with manual transmission

I am in the process of changing out a C6 transmission for a 4 speed.
I know that I will have to have a clutch switch to disengage the cruise but I had a different thought on this.
Does anyone know approximately how many pulses per mile the factory cruise control operates at?
My thought was to use the engine as the signal source (tach signal) which with 3.55 gears and a 300 six would come out to about 7000 ppm. Just wondering if this would be anywhere near to or a near multiple of the factory signal.

I like the idea of the CC directly controlling engine speed and thus no chance of engine runaway with the clutch disengaged or the transmission in neutral.

Just thinking

Bob

Bob near Winnipeg

1986 F250 Lariat extended cab 300 T18 2WD
1979 Honda CX500
1992 Oldsmobile 98 touring sedan
2007 F250 6.0 4wd

kramttocs

Re: Cruise control with manual transmission

Administrator

Do you mean the engine directly controlling the speed control (as opposed to the tranny/od)?

In my digging a few months ago, 8k is what I found but that wasn't directly from any Ford doc.

Can you explain more of your plan?
Are you using a vss for the GVOD or is it manually controlled?

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

Gary Lewis

Re: Cruise control with manual transmission

Administrator

In reply to this post by nic55kel

I can't tell you how many pulses per mile the speed sensor puts out, but I can say that the target speed for the speedometer cable is 1000 RPM at 60 MPH. Hope that helps.

And please keep us apprised of your results.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

nic55kel

Re: Cruise control with manual transmission

I think 8k ppm is correct which means I can use the tach signal for the cruise control.
Yes the intent is to use the ignition system as the reference for the cruise control.
I am sure there will be a bit of waveform processing required but that should be relatively minor, the important thing is that the frequency is in the correct range.
I think it would be neat to have cruise control in all 4 gears hopefully it works out.

The GVOD will be gone along with the C6 so no concern there.

We are in the middle of a snowfall warning here with about 8" already on the ground so not much happening for the next week or so.

Bob

Bob near Winnipeg

1986 F250 Lariat extended cab 300 T18 2WD
1979 Honda CX500
1992 Oldsmobile 98 touring sedan
2007 F250 6.0 4wd

Gary Lewis

Re: Cruise control with manual transmission

Administrator

Yes, you will need to do a LOT of waveform processing. The Vehicle Speed Sensor signal is basically a square wave, but the tach signal is UGLY! Huge spikes as the magnetic field collapses in the coil, and you have to isolate that with a resistor and then process it. I'll be anxious to see how you do that.

However, I'd think about a 555 timer as it could easily provide the square wave and be triggered with the tach signal.

Gary, AKA "Gary fellow": Profile

kramttocs

Re: Cruise control with manual transmission

Administrator

So this would be more of a "set engine RPM" control that can be used as speed control

Intrigued by how you go about it also.

Scott
'Camano' 1986 F250 Supercab XLT Lariat 460/C6
'Chanute' 1980 F350 C&C 400/NP 435 - Gin Pole

But there ain't nothin' wrong with the radio

Gary Lewis

Re: Cruise control with manual transmission

Administrator

If it would help I can put a VSS on my lathe and figure out what the pulse rate per revolution is. And even take a pic of the waveform.

Gary, AKA "Gary fellow": Profile

nic55kel

Re: Cruise control with manual transmission

I am pretty sure that the vss signal will be close to a sine wave, basically it is just a little ac generator.
I would be more interested in the waveform of the tach signal.
I got this off the internet for a points and coil system which should be fairly similar:

If one just took the coil current waveform it would be easy to get that into a square wave.
Regarding frequency of the signal - it makes sense to me that the engineers designing cruise controls back in the day would have used a readily available signal as a speed reference, the obvious source being the ignition system. This tends to make me think that 8000 ppm is correct and online research confirms that.

Yes it would be using the cruise control to directly control the engine speed. I think if one tried it in say neutral the rpm would hunt badly as I am sure the units response is relatively slow and it would overshoot the corrections badly. As a vehicle speed control on a vehicle with manual transmission it should behave exactly the same as if monitoring the vss signal.

It is going to be a little while before I get to try it out but it looks promising.

Bob

Bob near Winnipeg

1986 F250 Lariat extended cab 300 T18 2WD
1979 Honda CX500
1992 Oldsmobile 98 touring sedan
2007 F250 6.0 4wd

Gary Lewis

Re: Cruise control with manual transmission

Administrator

Check out my post back on FTE which has a tach signal on my scope. Perhaps that is what you need?

As I think about it, I could put in a toggle switch in to determine whether the speed control gets a feed from the VSS or tach.

Gary, AKA "Gary fellow": Profile

nic55kel

Re: Cruise control with manual transmission

Gary thanks for that information, I see that your scope trace agrees pretty well with the waveform I had found.
I would not connect a raw tach signal to the cruise module - too much chance of the smoke escaping.
I would be interested in the wave form at the coil +ve terminal as I think it would be a much cleaner approximation of a square wave.

Now that makes me think of a really simple possible solution to getting the signal:

Even better it would be an isolated signal.
I would start with a 10t primary and 50 t secondary with maybe a small capacitor across it to bleed off any ringing and take it from there.
Just getting this on file now for when I get to play with it in summer.

Bob

Bob near Winnipeg

1986 F250 Lariat extended cab 300 T18 2WD
1979 Honda CX500
1992 Oldsmobile 98 touring sedan
2007 F250 6.0 4wd

FuzzFace2

Re: Cruise control with manual transmission

I am all for "doing your own thing" but is sounds like a lot of work to make a wheel when its already made

Dave ----

Dave G.
81 F100 flare side 300 six / AA OD / NP435 / 2.75 gear
http://cars.grantskingdom1.com/index.php/1980-Ford-F100?page=1
81 F100 style side 300 six/SROD parts truck -RIP
http://cars.grantskingdom1.com/index.php/1981-Ford-F100

nic55kel

Re: Cruise control with manual transmission

Dave I agree completely.
Problem is I don't have the manual clutch switch parts and also I read of a rather bad experience by AbandonedBronco on the Ford Truck site that occurred when his wife was driving his Bronco. He had also switched from an auto to a manual and had used the automatic cruise control set up - don't have all the details. Anyway long story short the cruise engaged or re-engaged when in neutral and buried the tachometer on his modified 300. No catastrophic failure but possibly some damage was done.

So having a little time on my hands during a snowstorm I was just considering other possible configurations that would prevent such a possibility - a rev limiter would be another idea.

Bob

Bob near Winnipeg

1986 F250 Lariat extended cab 300 T18 2WD
1979 Honda CX500
1992 Oldsmobile 98 touring sedan
2007 F250 6.0 4wd

fryntrz

Re: Cruise control with manual transmission

Did you end up doing anything for this manual trans swap and cruise?

I'm moving from a C6 to a manual and am entertaining keeping the cruise, which would need the 9F645 clutch switch and lead or NC equivalent tied in to the currently jumpered Automatic trans connector at C755.

I was curious on what started your adventure and I think I found the post (FTE cruise over rev). Without talking to him, I feel like this is a one-off and could be avoided with his dump valve adjusted appropriately - possibly an oversight when swapping to the manual pedal assembly. None-the-less, I wouldn't want to set myself up for a potential catastrophic failure on my engine with something that could be prevented, especially when I'm considering cruise delete for the restomod anyways. In my opinion, there is no threat when everything is adjusted to spec and the clutch switch is added as if it left the factory like a manual truck.

Bryan
1985 F-150 2wd frame off restomod underway, 460ci/TKO600 swapped
Instagram: @fryntrz

Gary Lewis

Re: Cruise control with manual transmission

Administrator

I know that question wasn't meant for me, but I'm running a Ford speed control unit in Big Blue and have no problems. In fact, I frequently kick it off by touching the clutch.

However one time I depressed the clutch too slowly and the engine took off. Apparently the way the clutch switch is adjusted there's a spot part way down where the clutch disengages and yet the switch hasn't tripped. It has only happened once, but I should adjust it so it won't happen again.

Gary, AKA "Gary fellow": Profile

fryntrz

Re: Cruise control with manual transmission

Thanks Gary. I think I'll start to source a clutch switch anyways just to have available.

Bryan
1985 F-150 2wd frame off restomod underway, 460ci/TKO600 swapped
Instagram: @fryntrz