3 Speed Overdrive Wont engage - The 1947 - Present Chevrolet & GMC Truck Message Board Network

CATrucks · 06-11-2012, 07:21 PM

So I found me a muncie three speed overdrive, had my transmission guy rebuild it. Finally got it in the truck, hooked up the lockout cable and wired up the switch and solenoid. I did the basic wiring, not using govenor or kickdown switch. I bench tested solenoid, it works, can hear it go in and out when I flip the switch in the truck too. So I take it a test drive, push in the lockout cable so it is freewheeling, flip the switch to engage solenoid, let off gas, then gas back on, no shifting into overdrive... I checked the lever for the lockout cable and it goes all the way in each direction. Any ideas as to what the problem is?

Thanks

Joel

Gianyveedub · 06-12-2012, 10:13 PM

How long in terms of seconds did you let off the gas. I know when I first took it for a test drive, I let off the gas for only one sec and it would not engage, but when I left my foot off the gas for about 2.5 to 3 secs I could see on my tach and hear my engine pitch change to where I knew it was engaged.

CATrucks · 06-16-2012, 04:12 PM

I have let the gas off short amounts of time, and long amounts. Took it to the tranny shop so they could look at it on the rack. He was able to manually push in the pawl with a screwdriver but only whilst the clutch was also pushed in and gas off. He then tried a road test and could not notice anything. When it goes to over drive the rpm drop should be pretty noticable, right?

We are thinking maybe the solenoid does not have enough force to engage the overdrive? I know when I bench tested it, and it was popped out, I could push back the solenoid rod pretty easily, like there was a spring behind it? Is this normal? Is it possible the solenoid rod is not long enough when pushed out?

Marv D · 06-16-2012, 04:57 PM

Are you sure the solenoid isn't to shift OUT of OD?? As I remember the wiring it does not require 12v to the OD to go IN to OD, only to downshif OUT of OD.

But that's a foggy memory. But give it a try

Gianyveedub · 06-18-2012, 02:27 AM

If the O/D lever is pushed in and you let off the gas, it is not as noticeable as you would think, but if you have a tach you should be able to see it.

06-11-2012, 07:21 PM	#1
CATrucks Registered User Join Date: Apr 2011 Location: USA Posts: 14	3 Speed Overdrive Wont engage So I found me a muncie three speed overdrive, had my transmission guy rebuild it. Finally got it in the truck, hooked up the lockout cable and wired up the switch and solenoid. I did the basic wiring, not using govenor or kickdown switch. I bench tested solenoid, it works, can hear it go in and out when I flip the switch in the truck too. So I take it a test drive, push in the lockout cable so it is freewheeling, flip the switch to engage solenoid, let off gas, then gas back on, no shifting into overdrive... I checked the lever for the lockout cable and it goes all the way in each direction. Any ideas as to what the problem is? Thanks Joel

06-12-2012, 10:13 PM	#2
Gianyveedub Registered User Join Date: Mar 2011 Location: Hollister, Ca Posts: 178	Re: 3 Speed Overdrive Wont engage How long in terms of seconds did you let off the gas. I know when I first took it for a test drive, I let off the gas for only one sec and it would not engage, but when I left my foot off the gas for about 2.5 to 3 secs I could see on my tach and hear my engine pitch change to where I knew it was engaged.

06-16-2012, 04:12 PM	#3
CATrucks Registered User Join Date: Apr 2011 Location: USA Posts: 14	Re: 3 Speed Overdrive Wont engage I have let the gas off short amounts of time, and long amounts. Took it to the tranny shop so they could look at it on the rack. He was able to manually push in the pawl with a screwdriver but only whilst the clutch was also pushed in and gas off. He then tried a road test and could not notice anything. When it goes to over drive the rpm drop should be pretty noticable, right? We are thinking maybe the solenoid does not have enough force to engage the overdrive? I know when I bench tested it, and it was popped out, I could push back the solenoid rod pretty easily, like there was a spring behind it? Is this normal? Is it possible the solenoid rod is not long enough when pushed out?

06-16-2012, 04:57 PM	#4
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: 3 Speed Overdrive Wont engage Are you sure the solenoid isn't to shift OUT of OD?? As I remember the wiring it does not require 12v to the OD to go IN to OD, only to downshif OUT of OD. But that's a foggy memory. But give it a try __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

06-18-2012, 02:27 AM	#5
Gianyveedub Registered User Join Date: Mar 2011 Location: Hollister, Ca Posts: 178	Re: 3 Speed Overdrive Wont engage If the O/D lever is pushed in and you let off the gas, it is not as noticeable as you would think, but if you have a tach you should be able to see it.



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