Hot Rods Mercury Overdrive won't engage.

I have a stock, except for 12v conversion, 1950 Mercury with manual transmission w/OD. On the overdrive I replaced the relay and solenoid with 12v units along with a new OD wiring harness. I have checked all the wiring and even put a voltmeter on the relay and the relay is kicking in and out correctly at 26mph and 20 mph as the governor.tells it to. The new solenoid works when, with the key on, I ground the governor wire. With all that being said, I am confident the electrical part of the OD system is working. What inside the OD unit would make it not engage when the solenoid activates? I've not torn into one of these transmissions before so any advice would be appreciated

 

You didn't mention the lock out cable, is the cable being used and is the arm on the transmission moving with the cable.
http://www.oldwillysforum.com/forum/TechData/BWOverdriveManual.pdf

 

Got any gear oil in it ? Did it work before ?

 

The lock out cable works as it should and it is moving the rail because the rail switch is made when the cable is in and the switch is open when the cable is pulled out. I bought the car 14 years ago and it has set in my garage until this past fall when I pulled it out, put rings and bearings in it, got all the gauges working and then started looking at the OD. It wasn't wired up when I started so I put in a new relay, a new 12v solenoid, new harness and it still won't engage. It has lube in it and it shifts well and is pretty quiet.

 

Did you properly install the solenoid, getting it engaged in the pawl then turning it to lock the shaft in place?

 

So let me ask this: with the cable pulled out (OD disabled) does the transmission 'lock' i.e. no freewheeling when you let off the gas? Does it freewheel when pushed in and you let off the gas, but go back to normal when the gas is reapplied? Or do you have a 'neutral' until speed drops enough to disengage the OD?

I suspect that miker is correct, the solenoid isn't engaged with the shift pawl so it isn't shifting internally. It should also be noted there's more than one shaft length for the shift plunger, if you have a short one and need a long one it won't be engaged. If you can remove the solenoid bolts and just pull it straight out, it's not engaged. It should take a 1/2 turn to disengage the plunger. If you can't get it to engage, it's too short or the shift pawl is damaged.

If you have 'neutral' when applying gas with OD engaged, the rollers in the overrunning clutch drum are worn to below minimum size and the OD unit will have to come apart.

 

I'm sure the solenoid is engaged in the pawl correctly. I checked it a couple of times. I'll check about the freewheeling today and let you know what I find. Also the solenoid has the correct length shaft, 1 inch.
Thanks

 

I just road tested the mercury and there is no freewheeling with the OD handle in either the in or the out position.

 

I would disconnect the cable on the trans and manually lock it in and retest. If it still doesn't freewheel then it's inside.

 

^^^ Yep, what he said....

 

This is the link to the BW manual, doesn’t matter it’s on a Willy’s site. Well worth printing out and keeping handy, especially if you need to get into working on it. Mac at Van Pelt Sales probably has the best parts supply if it comes to that.

http://www.oldwillysforum.com/forum/TechData/BWOverdriveManual.pdf

 

Do you mean lock it in the overdrive position or the direct drive position?

 

You need it in the OD position, as if the cable all the way in. It should then free-wheel when you let of the throttle. That means that the transmission is driving through the overrunning clutch. OD will only kick in if you are driving through the overrunning clutch.

 

Do you have reverse in the overdrive position?

 

You never mentioned the oil,
there is a set of sun gears that must be lubed for the free wheeling to work.
it may be seized up
If you run too heavy of an oil or if the temp is way to cold it won’t free wheel

 

If everything mechanical is working correctly he should have.

 

Shift the car into gear, push the cable in, turn the driveshaft.
It should turn one way and not the other.
That will tell you the one way sprag is working.

Did you check the fluid level in the OD section, there is a separate plug from the main case on the right side of extension housing.

It sounds like you have pretty much done all the normal electrical troubleshooting and it checks ok.

Even though you said the solenoid clicks when tested in the trans, I would take the solenoid out and test it on the bench.
I had a customer last fall that did a 6 to 12V conversion last fall and had no OD.
It worked before the conversion
All the usual tests checked out normal.

What we found was the solenoid did energize on the bench, but if we put a little pressure on the shaft, it wasn't strong enough to travel the full amount.

We put the original 6V solenoid back in the trans and viola we had OD.

The 12V solenoid was not strong enough to fully engage the OD, even though it sounded like it was working normal
He got the solenoid from Mac's.

Some say you can use the 6V solenoid in 12V applications without problems. I'm not sure on that. If you still have the 6V solenoid, test it and if it works on the bench, install it on the trans, and see what happens.

If it is still not working and all electrical tests check out, then it's an internal problem

Bill

 

Thanks to all for the information. I'll address all the questions. I filled up the OD and the transmission with 80W-90 lube. I do have reverse while in the OD position, cable in. I checked and when the OD cable is pushed in all the way the lever that the cable operates is pushed against its stop on the OD case. When everyone mentions freewheeling I'm assuming that you mean when I let off on the gas pedal the engine compression doesn't provide any braking to the car.. I've energized the new solenoid, bought it on ebay, while on the bench and the rod extends forcefully. I don't know how to check if the force the solenoid exerts is enough. The old 6v solenoid is inoperable so I can't use it to test the unit. I read in my shop manual about using a tool to insert into the pawl and see if it moves freely. I think I'll make this tool out of the old 6V solenoid shaft to check the movement of the pawl. I'll try the suggestion to put it in OD with the car in gear, jack up a rear wheel and try to rotate a wheel. I'm hearing that if the sprag unit is operating I should be able to turn the driveshaft in one direction and not the other. I'll go do that now. If it doesn't turn in either direction what does that mean? And thanks again for the help. You don't have to spend your time helping me my problem and I appreciate the fact that you do.
Woody

 

I have a friend with BW o/d that wasn't working.
Seller sent video of used solenoid working using jumper cables.
Once installed solenoid didn't work.
Cleaned and sanded the mounting surfaces (grounds) and it worked fine. After cleaning, the old solenoid worked fine also.
I hope this helps

 

I just checked the sprag unit. With the transmission in gear, I jacked up the rear left wheel and tried to turn it. It would not turn in either direction.

 

The 'magic' of the OD is in the sun gear and its pinion gears and ring gear. If the sun/pinion gears can't rotate freely inside the ring gear when OD is enabled, the output will remain solidly locked at 1:1, which what it appears you have. There are multiple reasons this could happen; you'll have to tear down the OD unit on the trans to find the problem and I suspect you'll find a broken part. FWIW, I've never heard of one doing this but there's a first time for everything...

 

FWIW, in 1967 I bought a T-85 R11 with a chipped first gear. I dropped the o/d, pulled it apart, got the new gear in, cleaned it all up, and got it all back together. I was 17, and it was the first transmission I ever had apart. Worked fine. So they’re not magic or difficult. There’s a couple different tricks to getting the roller bearings in the o/d on assembly (grease or a rubber band) but there’s more experienced guys who can explain it better than me. Go for it. They’re a great combination, proven over millions of miles.

 

It sounds like you need to open up the overdrive unit, it can be a big job. You should put down your location in your profile, someone local might have a trans or a lead on another one. With the overdrive manual transmissions it's alway nice to have a spare or 2, just in case.

 

Thanks for all the help. I live in Macon Georgia. I guess my next step is to pull the tranny. I've read you can drop it out underneath or remove the tunnel cover and take it out through the passenger compartment. Which is easier?

 

Underneath.... let gravity work for you.... LOLOL

You'll have to go under to drop the driveshaft and trans mount/crossmember in any case.

 

I didn't see what body style you have. Convertible won't come out the bottom.

 

It's a four door. The cross member isn't removable without a cutting torch so maybe out the top

 

There was one question I asked but I didn't see a response to. If I put the car in first gear with the control cable pushed all the way in, with one rear wheel jacked up, I should be able to turn the wheel in one direction and not the other. If the wheel doesn't turn in either direction, which mine doesn't, does that mean the sprag unit is not functioning? I think that would mean 100% that I'll have to pull the tranny to repair.

 

I have no knowledge on working on these units. But there were a few replies that intimated (after your check) the transmission would need to come apart.