Overdrive Issues (again)
 

Thought my problems were behind me.... Overdrive worked fine for a few months since my last thread. However now it works when cold, starting out from home in the morning, but after warming up - two-three miles and maybe five or six stops later it won't kick into overdrive. Even after sitting for a couple hours, it won't go into overdrive.


So, this week I:

1. Replaced the solenoid with a new unit from VanPelt.
2. Installed a brand new kick-down switch from VanPelt.
3. Traced and continuity-checked every wire.
4. Triple-checked that the wiring complied with VanPelt schematic.
5. Added a ground-strap from frame to solenoid mount bolt.

The relay was new a few years back.... and clicks as it should when testing.

I removed and cleaned the governor six months ago.... yesterday I removed and opened it. Still clean, rotates freely. I spun it up by holding the gear on the shaft end against the wire brush on my bench motor.... the weights (and center contact) suck in as they're supposed to. No way to know at what RPM.

I have tried to kick it into overdrive (by letting off the gas pedal) from 28 to over 50 mph.... but no joy. It simply will not engage overdrive after warming up.

When I got back from a test run today, I felt the solenoid.... it was too hot to hold my hand on the case. Is this normal?

Thanks for any help.

Re: Overdrive Issues (again)
 

My experience, I bought a repop solenoid and it was junk. I didn't get a summer out of it before it seized engaged. When I got home I had to get underneath and remove the solenoid just to get into reverse to get into the garage.

I found a NOS 12v Delco solenoid and it's been working great for five years now. Almost all of the R10 overdrives take the same solenoid. I never put my hand on it after driving, but I don't think it should be getting too hot to touch.

Re: Overdrive Issues (again)
 

When a relay clicks that indicates the switch is being closed but a person needs an Ohm meter on the power terminals to make sure there is continuity through that switch. I'm not saying this is your problem but illustrating that a person needs to insure complete function. The operating solenoid has two coils. One is a heavy engagement coil and the other is a holding coil. One is for quick engagement which takes a fair amount of amperage and the other kicks in at full engagement to reduce the amount of current draw. If it doesn't engage all the way then the points for the holding coil don't kick in. This is likely why it's hot. A person needs to insure full function of these items both mechanically and electrically. Make sure the electrical wiring is all in good condition and that wiring is the correct gauge.


If all the electrics are functioning properly then there may be an internal issue with the shift pawl or balk ring. There may also be problem with the shift rail or lockout mechanism blocking function due to some internal problem or an external problem with the cable pull.

Re: Overdrive Issues (again)
 

So, when your solenoid is hot the problem is it is trying but can not move the the pawl. I would start by checking my lock out cable to make sure it is working and in adjustment. One more thing ,when your solenoid gets hot it will not function. You have to let it cool . This is why I always put a under dash switch in the governor wire to stop it from trying to engage when I have it locked out.

Re: Overdrive Issues (again)
 

A dumb question have you checked the fluid level in the transmission and the overdrive housing?

Re: Overdrive Issues (again)
 

Not dumb at all. Yes, I did check fluid level. It’s good. Also had some drain out when I swapped the solenoid. It was clean, no metal.

Re: Overdrive Issues (again)
 

Pistonbroke: i’m beginning to wonder if it’s internal. I had a good mechanic rebuild the tranny and overdrive, but he had never done this type before. He used my shop manual for guidance. From day one it won’t go into reverse when overdrive is engaged. I have to go to direct drive to back up. Mystery is….. why did overdrive work fine for five years after the rebuild?

Re: Overdrive Issues (again)
 

RotorWrench, thanks for taking time to respond. I rewired the entire OD and in most cases over-sized the wire. For instance, coil to fuse on the relay is #10. The mystery to me is why does it work flawlessly for a while, then not work at all? When the engine heats up, the OD quits. I agree the solenoid shouldn't get so hot it can't be touched.... could it be that something (the pawl?) shifts as the OD unit heats up, and the solenoid plunger can't fully engage?

Re: Overdrive Issues (again)
 

If, in fact, your OD is wired like that you might want to consult a wiring diagram. The grounding points in the solenoid are passed through the kickdown switch and connected to the coil. This is a ground to momentarily kill the ignition so the OD can drop out. Power for the relay is from the battery and the voltage to activate the relay is from the ignition switch.

Re: Overdrive Issues (again)
 

Did you check the generator for charging had same problem for years it was generator not putting out e

Re: Overdrive Issues (again)
 

If it doesn't lock out in reverse then it needs to be inspected internally. The 1st/reverse lever actuates the lock out mechanism which pushes the shift/lock out rail back to lock it out. The rail protrudes into the front gear compartment so that this lever will lock the unit out any time it is shifted to reverse. I'd pull the side cover and check it. The shift rail is spring loaded so that is comes back forward just as soon as the transmission is shifted out of reverse.

The shift rail does two things in operation. It shifts the planetary sun gear in and out of planetary operation and it blocks the pawl when all the way back and locked out. When it is all the way forward, the pawl can move and the planetary is in play. When it is all the way back to the rear, the sun gear shifts into a locked position with the planet gear carrier and the shift pawl is locked in the out of OD position plus the reverse lock out switch is opened if so equipped. Only the early transmission from 1949 through early 1951 still have the lock out switch. There may be something wrong with the shift rail assembly or the spring that could be a cause of problems. The only way to check the rail completely is to remove the overdrive tail housing and look at it. The shift rail assembly has three pieces. The shift fork for the sun gear is also spring loaded and allows it to move on the rail so the rail, shift fork, and shift fork spring are what make up the assembly. The whole rail assembly also has a spring behind it to aid in application of lockout and also its return to overdrive position. It can be seen in this link P/N 56H-7680 is the rail assembly.
http://www.vanpeltsales.com/FH_web/F...-50merc-od.jpg

This is a link to the shift cover and the lock out lever 56H-7292 can be seen there.
http://www.vanpeltsales.com/FH_web/F...hiftr-hsng.jpg

Re: Overdrive Issues (again)
 

I'm using the wiring diagram from VanPelt, which matches the diagram in my 1950-'51 Shop manual. I have a #10 wire from the Ign terminal on the relay (fuse) to the bat. side of the coil. Another wire goes from the distributor side of the coil to one of the lower terminals on the kick-down switch. There is no wire directly from the battery (or starter solenoid) to the Ign terminal like on Randy Rundle's diagram. I am, however using the relay I bought from Rundle, which is just like the ones VanPelt sells.... but VanPelt says to not use that top-left terminal. Their diagram says "not used on Ford/Merc.

Re: Overdrive Issues (again)
 

I'm using a GM "one wire" alternator and a MSD distributor with a Blaster Coil. But will check anyway. Thanks

Re: Overdrive Issues (again)
 

I can't find Van Pelt's diagram on his site, but I won't argue with a factory diagram. I wouldn't run the amps of a OD solenoid through an ignition switch. Overdrives are a wonderful thing. I hope you get your problems resolved.

Re: Overdrive Issues (again)
 

Re: Overdrive Issues (again)
 

I can see where that relay wouldn't use a connection to battery.