Big Blue's Transformation

[Gary Lewis]

Ok guys, I've just gotten back from a test run with the red, white, and blue jets. Here are my notes:

• Red/.125: Initially I thought it was better than the .105 but after some more testing I don't think so. Has too much off/on/off.

• White/.154": Constantly twitching. On/off/on/off. On one slight downhill I watched it go from 10" of vacuum to 20" to 10" to 20" to 10" and it just kept doing that until the grade changed. Very unacceptable.

• Blue:.189": Not much difference than the white. Apparently by .154" there's really no restriction so the .189" didn't make any difference.

So I think I accidentally found the sweet spot at .105". But that's still not as smooth as I want, so I've gotten the green light to order the one-piece 1986 and later speedometer cable and a pigtail for the VSS. I'll make up a cable that will plug into the VSS on one end and the connector where the current speed control sender is connected below the master cylinder on the other. It'll be a plug and play arrangement.

Ok, the MPC says that an '86 4WD takes E6TZ 9A820-C, which is 92" long. Went on Amazon and found this ATP Y-869 Speedometer Cable which it says is for an '86 4WD for $10.65 and it'll be here Wednesday. Oh yes, it is 92" long and shows to have the right ends.

Then I found that the pigtail, BND PT331, is available at the Owasso Advance Auto Parts and since we are going tomorrow I've ordered it up and will pick it up then.

I sure hope that smooths things out as I'm running out of things to "fix".

[85lebaront2]

Ok guys, I've just gotten back from a test run with the red, white, and blue jets. Here are my notes:

• Red/.125: Initially I thought it was better than the .105 but after some more testing I don't think so. Has too much off/on/off.

• White/.154": Constantly twitching. On/off/on/off. On one slight downhill I watched it go from 10" of vacuum to 20" to 10" to 20" to 10" and it just kept doing that until the grade changed. Very unacceptable.

• Blue:.189": Not much difference than the white. Apparently by .154" there's really no restriction so the .189" didn't make any difference.

So I think I accidentally found the sweet spot at .105". But that's still not as smooth as I want, so I've gotten the green light to order the one-piece 1986 and later speedometer cable and a pigtail for the VSS. I'll make up a cable that will plug into the VSS on one end and the connector where the current speed control sender is connected below the master cylinder on the other. It'll be a plug and play arrangement.

I'm going throw a monkey wrench into your theory mr. engineer. Vacuum, somewhere you mentioned the vacuum drop-off during cruise acceleration. 20 inches down to 10 inches. At 10 inches the cruise servo has only 1/2 the power it has at 20 inches, since the valve(s) are modulating and the speed is dropping off more than it expects, the "brain" is going to open the vacuum side further, truck builds some speed, cruise starts letting off the throttle, vacuum jumps up and cruise servo surges open more.

For the purpose of testing, add a vacuum reserve tank (like older power brake systems used) with a check valve between the source and the tank. See if this smooths things out. I never had the issue with Darth, but when he had the vacuum cruise control he also had the C6 which due to the converter slippage would mask small changes. I don't recall having a problem with the E4OD, but I changed to the electronic one not long after that and sent the 1990 servo to Matt for his 1986 F150.

[salans7]

Ok, the MPC says that an '86 4WD takes E6TZ 9A820-C, which is 92" long. Went on Amazon and found this ATP Y-869 Speedometer Cable which it says is for an '86 4WD for $10.65 and it'll be here Wednesday. Oh yes, it is 92" long and shows to have the right ends.

Then I found that the pigtail, BND PT331, is available at the Owasso Advance Auto Parts and since we are going tomorrow I've ordered it up and will pick it up then.

I sure hope that smooths things out as I'm running out of things to "fix".

A new speedo cable is only $10? I kept the one from the F250HD and was worrying about how to fix the broken plastic retainer at the speedo end. Guess I'll be picking up a new one as well, after you give us the microanalysis on it.

[Gary Lewis]

I'm going throw a monkey wrench into your theory mr. engineer. Vacuum, somewhere you mentioned the vacuum drop-off during cruise acceleration. 20 inches down to 10 inches. At 10 inches the cruise servo has only 1/2 the power it has at 20 inches, since the valve(s) are modulating and the speed is dropping off more than it expects, the "brain" is going to open the vacuum side further, truck builds some speed, cruise starts letting off the throttle, vacuum jumps up and cruise servo surges open more.

For the purpose of testing, add a vacuum reserve tank (like older power brake systems used) with a check valve between the source and the tank. See if this smooths things out. I never had the issue with Darth, but when he had the vacuum cruise control he also had the C6 which due to the converter slippage would mask small changes. I don't recall having a problem with the E4OD, but I changed to the electronic one not long after that and sent the 1990 servo to Matt for his 1986 F150.

Shaun - I was surprised with the $18 price when I followed Cory's link, but when I checked with Amazon and it was $10 I was shocked. And quickly pushed the ORDER button.

Bill - I understand completely what you are saying. But, I don't think it works quite that way as there is already a reservoir in the system. Having said that, the FSM does say that the diesel-engined trucks do have an extra reservoir:

Vacuum Reservoir Assembly (6.9L Diesel Engine)

The vacuum reservoir assembly is provided to supply vacuum to the servo during peak demand. The reservoir is located on the right hand apron on Econoline (Fig. 15) and on the left hand apron near the servo on F-Series, Fig. 18. A check valve is integrated with the reservoir to prevent reverse vacuum flow. There are two 5/16 inch diameter vacuum ports on the reservoir. The "VAC" port is connected by a 5/16 inch I.D. vacuum hose to the vacuum source distribution port. The other port is connected by an identical vacuum hose to the speed control servo vacuum source port adjacent to the 6-way electrical connector.

So, I'm willing to try adding a reservoir to see what happens. However, I don't know that I have one with ports that size, and certainly don't think I have a check valve that size. On the other hand, if I'm metering everything through a .105" orifice, why would I need .313"? Given that, I'm thinking I'll add a reservoir with the check valve used on the HVAC system and see what happens.

Thoughts?

[Rembrant]

Ok, the MPC says that an '86 4WD takes E6TZ 9A820-C, which is 92" long. Went on Amazon and found this ATP Y-869 Speedometer Cable which it says is for an '86 4WD for $10.65 and it'll be here Wednesday. Oh yes, it is 92" long and shows to have the right ends.

Then I found that the pigtail, BND PT331, is available at the Owasso Advance Auto Parts and since we are going tomorrow I've ordered it up and will pick it up then.

I sure hope that smooths things out as I'm running out of things to "fix".

Gary,

While you're in the middle of all this, maybe you can answer/confirm something for me. My truck as you know was originally a 3 on the tree manual, which I swapped out for a 1991 M5OD-R2 5spd. I was very lucky as the trucks original speedo cable reached the hole in the new 5spd, so I simply plugged it in and it worked just fine. (I was even luckier in the fact that the speedo drive gear in the 5spd was for a 3.08 rear diff, which I already had, so my speedo stayed correct).

So, the driven gear in my truck, which is the original 1984, will it swap over to the trans mounted VSS? Or, will I have to buy a new/different driven gear that fits the VSS?

 

[Gary Lewis]

Gary,

While you're in the middle of all this, maybe you can answer/confirm something for me. My truck as you know was originally a 3 on the tree manual, which I swapped out for a 1991 M5OD-R2 5spd. I was very lucky as the trucks original speedo cable reached the hole in the new 5spd, so I simply plugged it in and it worked just fine. (I was even luckier in the fact that the speedo drive gear in the 5spd was for a 3.08 rear diff, which I already had, so my speedo stayed correct).

So, the driven gear in my truck, which is the original 1984, will it swap over to the trans mounted VSS? Or, will I have to buy a new/different driven gear that fits the VSS?

Cory - I'm very confident that the driven gear will swap over. I say that because the charts on the Driven Gear Part #'s tab on the page at Documentation/Drive Line/Speedometer Gears, Cables, & Sensors don't say boo about "year". And yet the part numbers on the Speed Control Sensors tab do show that 1980 - 85 used the sensor in the cable under the master cylinder, and 1986 and onward use the one that mounts in the transmission or transfer case.

However, I've not done it. But I'll try it in the morning and let you know. I have a driven gear that came off the end of a speedo cable and I have the transmission/t-case style VSS, so I'll see if it goes on. Sure looks like it will though as that clip is the same as on the end of the cable.

[Gary Lewis]

Gary,

While you're in the middle of all this, maybe you can answer/confirm something for me. My truck as you know was originally a 3 on the tree manual, which I swapped out for a 1991 M5OD-R2 5spd. I was very lucky as the trucks original speedo cable reached the hole in the new 5spd, so I simply plugged it in and it worked just fine. (I was even luckier in the fact that the speedo drive gear in the 5spd was for a 3.08 rear diff, which I already had, so my speedo stayed correct).

So, the driven gear in my truck, which is the original 1984, will it swap over to the trans mounted VSS? Or, will I have to buy a new/different driven gear that fits the VSS?

Cory - Can your question wait until Thursday for a definitive answer? I can't find my spare driven gear to put on the tranny/t-case mounted VSS. But if my new speedo cable comes in tomorrow I hope to install it Thursday, and in the midst of that I'll be installing that VSS and moving the driven gear over. OK?

As for Bill's idea on the vacuum, I have the reservoir shown below. The reservoir measures 4 1/4 x 7", which is apparently a #3 cylinder and should have 83 cubic inches of volume. Turns out it has a check valve in it, so I've installed it in the feed to the servo such that the check valve is on the inlet side of the reservoir and it'll hold engine vacuum.

The inlet and outlet ID's are .115" so they shouldn't be a problem since I'm running the .105" jet between the vacuum valves and the servo itself. But I didn't want to cut my vacuum hose for a temporary test, so there's a bit more hose than needed, which may dampen things as well.

Anyway, it is installed and we'll take the truck on our errand to Owasso this afternoon and I'll report back. But I may need to take a cruise out by the lake as that's where I've been testing, and since the land to the east toward Owasso is flat it won't be a fair test.

[Rembrant]

Cory - Can your question wait until Thursday for a definitive answer?

Gary, my question can wait months...lol. I was just curious as I'm collecting parts to install an aftermarket cruise kit later on.

 

[Gary Lewis]

Cory - Can your question wait until Thursday for a definitive answer?

Gary, my question can wait months...lol. I was just curious as I'm collecting parts to install an aftermarket cruise kit later on.

Ok, Cory, I'll plan to answer the question on Thursday.

 

No for my report on the test run with the vacuum reservoir.

 

Janey thinks it is better, but if so we are talking incrementally better and I'm looking for dramatic changes. The video below was shot on essentially level ground with the first 15 seconds on speed control. But at 16 seconds I kicked it off and held the speed manually. Notice how the vacuum stabilizes. That's what I want.

 

After the new speedo cable and transfer case-mounted VSS go on I'll test again, but if that doesn't give dramatic results, which I seriously doubt, then I'm done playing with this!

 

Bill - You say the electronic speed control will fit right where the vacuum one is. But how much hysteresis does it have? I do not want something that tries to keep the speed exactly on the set point.

 

In fact, I'm going to watch my first football game of the year, the Cheez It Bowl, and search for Arduino sketches that will do what I'm looking for. I want to be able to tune it with my phone via bluetooth. (No, I'm not going to build it right now, but it'll be on the drawing board for later, before our trip this summer and after the other things get done to the truck that are needed/wanted for the trip.)

 

[Jstitts]

Ok, Cory, I'll plan to answer the question on Thursday.

 

No for my report on the test run with the vacuum reservoir.

 

Janey thinks it is better, but if so we are talking incrementally better and I'm looking for dramatic changes. The video below was shot on essentially level ground with the first 15 seconds on speed control. But at 16 seconds I kicked it off and held the speed manually. Notice how the vacuum stabilizes. That's what I want.

 

After the new speedo cable and transfer case-mounted VSS go on I'll test again, but if that doesn't give dramatic results, which I seriously doubt, then I'm done playing with this!

 

Bill - You say the electronic speed control will fit right where the vacuum one is. But how much hysteresis does it have? I do not want something that tries to keep the speed exactly on the set point.

 

In fact, I'm going to watch my first football game of the year, the Cheez It Bowl, and search for Arduino sketches that will do what I'm looking for. I want to be able to tune it with my phone via bluetooth. (No, I'm not going to build it right now, but it'll be on the drawing board for later, before our trip this summer and after the other things get done to the truck that are needed/wanted for the trip.)

 

It's good to see some things haven't changed over the years! Waiting for your Raspberry PI 4 - vacuum control module integration...