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Vintage M41 Overdrive.

fige

fige

KING OF TBOT
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Joined
Dec 26, 2004
Location
Tucson, AZ
Finally dropped in the tranny...

All I needed was a driveshaft from an auto amazon... that is all, everything else was bolt on.

Now, I just installed it an hour ago... aaaand... the car didn't want to leave 3rd gear. took me two hands to wrestle it back into neutral. But 3rd shifts fine now.

The overdrive... I hooked up the selenoid to a simple switch (volvo fog switch), and I heard the selenoid pop on and off. when turning the switch on and off.

the OD worked... once. I was in 4th gear, kicked it into OD. Worked for 5seconds...then quickly started to slip. Not sure if it got kicked back into 4th gear or was still in OD. The revs simply increased. (where about 4th gear would rev at)

Then after that it wouldn't really kick into OD anymore... no rev change when pressing the switch.

So...

Is there a problem with the switch, Selenoid, or actual overdrive?

I neeeed heeeelp:-P

Is a simple switch enough... or will it burn out?
 
If it's been sitting for many years the seals inside the overdrive that seal the pistons so they push to engage may be leaking down the oil and letting the overdrive release. IPD sold a kit for that. Or passages in the overdrive may be filled with old crud. Did you clean the sump for the overdrive and change the oil before using it?

I've also had the solenoid fail in the old D type overdrive. What till you see the price for the solenoid. Then you'll know how expensive the vintage parts can be.
 
Last edited:
Redwood Chair said:
needs to be a momentary switch.
Click to expand...

Only with the overdrive that uses the relay like a 81 and newer 240. The older overdrives use a on/off type switch. That's what is in my 123GT.

One thing you do need on the J type overdrive when not using a relay is a reverse biased diode across the terminals. If it's not there the solenoid can be damaged from the backflash. I would start with checking the solenoid. You probably want to remove it to check that it moves properly. Watch for the oil coming out if you remove it. Once you know the electrical parts work properly then you can work on the mechanical parts.
 
fige said:
30w

The OD doesn't have a separate oil filler does it?
Click to expand...


Nope.

Good call on the straight 30 in the case, BTW. There has been a lot of virtual ink spilled over what to use in these boxes. I find that 30 gives you smoother shifts and doesn't lose viscosity in the summer heat.

Was this OD a known good unit when you installed it? Mine was acting like this before I replaced it with a rebuild.
 
brick-a-brac said:
Nope.

Good call on the straight 30 in the case, BTW. There has been a lot of virtual ink spilled over what to use in these boxes. I find that 30 gives you smoother shifts and doesn't lose viscosity in the summer heat.

Was this OD a known good unit when you installed it? Mine was acting like this before I replaced it with a rebuild.
Click to expand...

nope. don't know anything about the OD....

Is there a way I can maybe kick something back into place? hard clutch drops being in OD...etc?
Or maybe engaging the OD in 2nd gear?
 
Might pull the OD off the trans, and replace the o-ring on the pump. There's an aluminum collar that rides on an eccentric on the trans output shaft that moves a small piston up and down. Replace that and cross your fingers that helps the oil pressure enough to stop it from slipping.

There is a filter under the bottom plate. But it's a rather coarse screen, probably mostly there to stop it from sucking in chunks of chipped gear teeth, it's unlikely to get clogged.

Also, are you sure it has enough oil in it? When they get low, they start acting funny. Like engaging (and staying engaged) the first time you try it, and then not wanting to re-engage.
 
update!

After sitting for 4 hours, I went for a drive again. Checked the switch before i left... i heard the selenoid kicking.

Then went for a drive. It engaged, no problems (rather rough shift into OD), turned it on and off... for 5 minutes. it ALWAYS kicked in. Then the car sat a little for 10 minutes. ON the way home it worked...ONCE. it kicked in, cruised. Then i tried a second time, it started to slip... FROM THEN ON, it didn't drop in RPMS anymore when I tried to engage it.

Also, having this weird issue, when soemtimes I just CANT get into the gear I want to anymore. I tried double clutching it, force... etc. I have to shift into another gear, and then try it again.
This happened now with 2nd, 3rd and 4th gear.... but it happens at random times, and does not occur frequently.
 
drove around for an hour.

Overdrive worked everytime. I guess the seals just had to be lubed up again.

But this "won't let me into gear" thing still consists... anyone have an idea?
 
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