It'd be nice if my overdrive kicked in 2 or 3 MPH earlier than it does, for 2nd and 2nd OD use in town. Has anyone ever successfully re-calibrated one?
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calibrating an overdrive govenor?
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Most of those governors were just a spring wrapped around some weights.
(took a few apart and cleaned them)
Then the weights slung out from centrifugal force, they contacted the sides, and completed the circuit (ground path).
Varying the spring tension, or varying the weight(s) would change the contact time.
Never heard of anyone doing that.HTIH (Hope The Info Helps)
Jeff
Get your facts first, and then you can distort them as much as you please. Mark Twain
Note: SDC# 070190 (and earlier...)
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Originally posted by DEEPNHOCK View PostMost of those governors were just a spring wrapped around some weights.
(took a few apart and cleaned them)
Then the weights slung out from centrifugal force, they contacted the sides, and completed the circuit (ground path).
Varying the spring tension, or varying the weight(s) would change the contact time.
Never heard of anyone doing that.Ron Dame
'63 Champ
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I did it to the T85's governor in the 62 GT. But its been so long, I'd need to disassemble a spare, to refresh my memory on just how. Dropping the kick in RPM is especially needed when running tall gears in the rear end. With the 62GT and 3.54 rear end, it drops into 3rd OD at less than 2000 RPM; 2nd OD around 2200 RPM, and 1st OD around 3000 RPM. I don't know why it takes more RPMs for 1st gear, but they (T-85s) always do.
It was simple enough to do, and IIRC involved a little spring. But it was guesswork, as to how much was too much. So go with very small increments. If I get time will disassemble one tomorrow to refresh memory, and will post here.
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Originally posted by DEEPNHOCK View PostMost of those governors were just a spring wrapped around some weights.
(took a few apart and cleaned them)
Then the weights slung out from centrifugal force, they contacted the sides, and completed the circuit (ground path).
Varying the spring tension, or varying the weight(s) would change the contact time.
Never heard of anyone doing that.
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Different engines and axle ratios result in different needs. Right now in a 25 MPH zone, I'd like to be in 2nd OD with the 4.27 rear, but have to blast up to 28 and then back down which can be tricky with a car ahead of you, and the 2nd/3rd shift back and forth on some of the hills (OHV 6 doen't have quite enough torque for 3rd) gets tiresome.
A Speedster has more torque and I bet a different rear ratio, so 5 MPH more could be nice.
Originally posted by SN-60 View PostThis interests Me. I'd sure like to DELAY the O/D activation in My Speedster by about 5 mph.Ron Dame
'63 Champ
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I had my service manual out this morning to look up something, and went into the transmission sction to read up on the governor.
The only thing the service manual says is not to file the contact points because they carry voltage and are made of a special corrugated material.HTIH (Hope The Info Helps)
Jeff
Get your facts first, and then you can distort them as much as you please. Mark Twain
Note: SDC# 070190 (and earlier...)
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I just opened a spare T85 governor and now recall the mod. Basically, the top is the electrical side, with a normally open switch (when stopped or at slow speeds) that looks similar to ignition points; the body is the mechanical side, which controls the switch by advance/retraction of a mechanical shaft, as the vehicle speeds up or slows down. The shaft operates per inertia, centrifugal weights, and a spring.
The factory addressed cut in/out speed by altering the speed of the mechanical side's spin, through the number of teeth on the governor, which meshed with a ring gear on the tranny shaft; this ring & pinion spins the governor faster or slower at any given vehicle speed, depending on the ratio, similar to a rear differential. Spun faster, the governor retracts the shaft quicker and the switch closes earlier; slower, it closes later.
THE MOD was to simply bend the tang of the stationary side of the switch about 1/32" toward the other side, for earlier closure. Bending it much further would affect closed tension on the switch (not good). Though the switch has a "snap" when opened & closed with human fingers, in operation, it likely moves steadily, as dictated by the advancing/retracting shaft. So the amount of bend made to the tang directly affects cut in/out speed.
For the naysayers, I am aware bending the tang affects points' alignment (minutely), and hypothetically shortens point life. I am also aware the Shop Manual says do not file the points (but have done so anyway w/o problem). All I can say is, this mod was made to this tranny so long ago I had to disassemble a spare governor to recall the details; probably at least 10 years and 100,000 miles ago; still, with no problems whatsoever.
You could accomplish the same thing by filing the tip of the mechanical shaft, but that would be a "one shot deal" and not reversible.Last edited by JoeHall; 10-20-2013, 07:52 AM.
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The switch is supposed to "snap". It has an over-center spring in it, as indeed do toggle switches. If it didn't snap, right at the cut-in speed, you'd get a chatter happening, and it wouldn't do the car any good at all. Some overdrive governors have a black plastic cap, and the over-center spring is anchored to an adjusting screw, the head of which is in a well on the outside of the cap, covered by sealant.Gord Richmond, within Weasel range of the Alberta Badlands
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Originally posted by gordr View PostThe switch is supposed to "snap". It has an over-center spring in it, as indeed do toggle switches. If it didn't snap, right at the cut-in speed, you'd get a chatter happening, and it wouldn't do the car any good at all. Some overdrive governors have a black plastic cap, and the over-center spring is anchored to an adjusting screw, the head of which is in a well on the outside of the cap, covered by sealant.
I am mostly familiar with T85 stuff, but do not recall ever seeing a T86 governor with a plastic cap & spring adjusting screw either. Are you talking about Studebaker when you say, "some overdrive governors" or about governors in general, and general theory of operation?Last edited by JoeHall; 10-20-2013, 04:27 PM.
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Last month, I worked on one in a '51 Commander, and it had the bakelite cover with an adjusting screw, which I didn't mess with because there was no need. But I did take the cover off, and ran paper through the governor points to clean them. The reason for the toggle action action is that cut-out speed has to be distinctly lower than cut-in speed. Suppose it were not; say cut-in and cut-out both occurred at 27 mph. You're driving on a road with strictly enforced 30 mph speed limit. You accelerate to 29, let your foot off the gas to engage overdrive, but the car slows down to 27 at the same time OD engages, so it immediately drops down to direct again. You'd be going back and forth between OD and direct constantly. Parts would break, and you'd be very annoyed with the car. But if it cuts in at 27, and cuts out at 15, you have no problem. You can drive in traffic in OD, and it will only cut out as you slow to stop for a light.Gord Richmond, within Weasel range of the Alberta Badlands
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Thanks Joe! That's what I was looking for!
Originally posted by JoeHall View PostI just opened a spare T85 governor and now recall the mod. Basically, the top is the electrical side, with a normally open switch (when stopped or at slow speeds) that looks similar to ignition points; the body is the mechanical side, which controls the switch by advance/retraction of a mechanical shaft, as the vehicle speeds up or slows down. The shaft operates per inertia, centrifugal weights, and a spring.
The factory addressed cut in/out speed by altering the speed of the mechanical side's spin, through the number of teeth on the governor, which meshed with a ring gear on the tranny shaft; this ring & pinion spins the governor faster or slower at any given vehicle speed, depending on the ratio, similar to a rear differential. Spun faster, the governor retracts the shaft quicker and the switch closes earlier; slower, it closes later.
THE MOD was to simply bend the tang of the stationary side of the switch about 1/32" toward the other side, for earlier closure. Bending it much further would affect closed tension on the switch (not good). Though the switch has a "snap" when opened & closed with human fingers, in operation, it likely moves steadily, as dictated by the advancing/retracting shaft. So the amount of bend made to the tang directly affects cut in/out speed.
For the naysayers, I am aware bending the tang affects points' alignment (minutely), and hypothetically shortens point life. I am also aware the Shop Manual says do not file the points (but have done so anyway w/o problem). All I can say is, this mod was made to this tranny so long ago I had to disassemble a spare governor to recall the details; probably at least 10 years and 100,000 miles ago; still, with no problems whatsoever.
[ATTACH=CONFIG]28704[/ATTACH] [ATTACH=CONFIG]28705[/ATTACH][ATTACH=CONFIG]28706[/ATTACH][ATTACH=CONFIG]28707[/ATTACH]
You could accomplish the same thing by filing the tip of the mechanical shaft, but that would be a "one shot deal" and not reversible.Ron Dame
'63 Champ
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Well...if you don't feel comfortable modifying the governor switch...you could always install a manual override/by-pass toggle switch to use when you wanted. I have had my overdrive truck for nearly forty years and never attempted to use overdrive in second gear. Instead of "overdrive"...I would consider that "secondary" drive.John Clary
Greer, SC
SDC member since 1975
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And with a manual switch, you can 'split gears' and drive it like a 6 speed!
Jeff
Originally posted by jclary View PostWell...if you don't feel comfortable modifying the governor switch...you could always install a manual override/by-pass toggle switch to use when you wanted. I have had my overdrive truck for nearly forty years and never attempted to use overdrive in second gear. Instead of "overdrive"...I would consider that "secondary" drive.HTIH (Hope The Info Helps)
Jeff
Get your facts first, and then you can distort them as much as you please. Mark Twain
Note: SDC# 070190 (and earlier...)
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