Hi Everyone

I have a '67 1800s and I'm having problems with the O/D unit. It's not holding pressure so there's likely some internal o-rings that're not holding. There's oil leaking out the end of the O/D solenoid where the wire connects so that tells me the O-rings on the solenoid rod need to be replaced. This may also be why the O/D occasionaly tries to engage by itself even though it's turned off.

My car has an older style Laycock "D" type O/D unit and I had hoped that I could pull the solenoid and change the o-rings, etc. without having to take the whole tranny out but it appears that's not true and I'll have to take the whole darn tranny out just to service the stupid solenoid. What a drag. :(

Of course, it's quite possible that the problem with the O/D has to do with more than just the solenoid o-rings and if that's the case, getting parts for that old unit will be difficult and expensive.

If I have to go to all the trouble and expense of taking out the whole tranny then I have some other options to consider. I happen to have a used M41 which was taken out of a 70 or 71E sitting in my garage. I'm not real sure how good it is but I think it's ok. It has the later style "J" type O/D on it. I'm told those were a bit stronger than the "D" type Laycocks. The solenoid just screws on that one so it'd be easier to service than mine (mine bolts on) .

Option 1 may be to keep on using my current transmission but swap the overdrives. Does anyone know if it's possible to swap a J type Laycock for a D type ? I have a feeling there may be some incompatibility with the oil pumps so this may not even be an option for me.

Option 2 would be to swap the entire transmission. As far as I can see there are at least two technical issues involved with doing that. One is that my car has a hydraulic clutch and my spare tranny is set up for a cable clutch. I assume then I'd just have to bolt the bell-housing from my car onto this other transmission and I'd be good to go. Am I Right ?

The other issue is the shifter. My '67 has a different remote and the short little gearshift lever and this other tranny has the longer gearshift lever. The reverse light switches are in different locations too but I don't know if that's much of an issue. I'd prefer to keep my original shifter. My assumption is that I could just swap the remotes from one tranny to the other but that's just a guess. Does anybody know if it can actually be done ?

Are there any other issues in swapping an older style M41 w/ D type O/D for a newer style M41 with a J type O/D ?

Thanks in advance,

Roj

Before you start working on the overdrive I suggest that you read a manual and find out how the thing works.

The solenoid doesn't have any rings on a D type, it just pulls a plunger.

First check is to make sure one of the circuits hasn't gone on the solenoid. You take the rubber boot of the end and re solder the connections on the windings. The whole solenoid comes off with 2 screws.

Make sure the adjustment on the solenoid is correct, you check with the plate on the side removed, activate the solenoid, check the hole in the brass arm lines up with the hole on the alu casing.

Check the gearbox has enough oil.

You can up the oil pressure a bit by shimming the relief valve.

You can't fit a J type overdrive onto a D type mainshaft, the splines are different on the planetary gear.

Bell housings can be swapped any incarnation of M40/M41 will fit onto any age of M40/41 bell housing irrespective of whether it came off a 120, 140 or 1800.

The gearbox tops similarly also swap.

However you're likely to have 2 different boutput flanges and those don't swapm between M40, M41 Dtype, M41 J type.

Regards


Pete

You can not attach a j type overdrive to a d type tranny, the output shaft is smaller on the d type. This is the shafr that mates gearbox to overdrive unit.
--
Lee Boerner, Lots of old Volvos, Little hair.

My car has an older style Laycock "D" type O/D unit and I had hoped that I could pull the solenoid and change the o-rings, etc. without having to take the whole tranny out but it appears that's not true and I'll have to take the whole darn tranny out just to service the stupid solenoid.

You can get the solenoid out by removing the vertical plate that's just forward of it. There's an adjustment in there that comes loose (J-types have no adjustment). However, there is nothing hydraulic about the solenoid or what's behind the plate, so I don't think you'll solve your problem that way.

Option 1 may be to keep on using my current transmission but swap the overdrives. Does anyone know if it's possible to swap a J type Laycock for a D type ? I have a feeling there may be some incompatibility with the oil pumps so this may not even be an option for me.

I would advise against this...

Option 2 would be to swap the entire transmission. As far as I can see there are at least two technical issues involved with doing that. One is that my car has a hydraulic clutch and my spare tranny is set up for a cable clutch. I assume then I'd just have to bolt the bell-housing from my car onto this other transmission and I'd be good to go. Am I Right ?

Correct. Leave your current bellhousing in the car, and just bolt the "new" tranny to it.

The other issue is the shifter. My '67 has a different remote and the short little gearshift lever and this other tranny has the longer gearshift lever. The reverse light switches are in different locations too but I don't know if that's much of an issue. I'd prefer to keep my original shifter. My assumption is that I could just swap the remotes from one tranny to the other but that's just a guess. Does anybody know if it can actually be done ?

Your remote cover will bolt right on the newer tranny. However, the newer tranny will not operate the reverse light switch on your old cover. See if the newer tranny has a terminal for a single wire in the oval can at the upper rear of the gearbox. If so, that's the reverse light switch. It takes some minor rewiring of the car to make it work -- we can follow up on that later.

Are there any other issues in swapping an older style M41 w/ D type O/D for a newer style M41 with a J type O/D ?

The J-type provides slightly less rpm reduction in OD -- you'll be turning a little bit higher revs on the highway with the OD engaged. I don't see this as a problem, but you should know that.

My car has an older style Laycock "D" type O/D unit and I had hoped that I could pull the solenoid and change the o-rings, etc. without having to take the whole tranny out but it appears that's not true and I'll have to take the whole darn tranny out just to service the stupid solenoid.

You can get the solenoid out by removing the vertical plate that's just forward of it. There's an adjustment in there that comes loose (J-types have no adjustment). However, there is nothing hydraulic about the solenoid or what's behind the plate, so I don't think you'll solve your problem that way.

Which plate is that ? The one on the passenger side just forward of the solenoid ? How will that help me take the solenoid out ? The solenoid has a flange on it with mounting bolts above and below it. I can get at the lower one but I can't get at the upper one. It's too close to the solenoid to use a socket on it and there's no room to get at it with a wrench.

Are you saying I can get at the o-rings on the solenoid rod by taking that side panel off ?

Option 1 may be to keep on using my current transmission but swap the overdrives. Does anyone know if it's possible to swap a J type Laycock for a D type ? I have a feeling there may be some incompatibility with the oil pumps so this may not even be an option for me.

I would advise against this...

Option 2 would be to swap the entire transmission. As far as I can see there are at least two technical issues involved with doing that. One is that my car has a hydraulic clutch and my spare tranny is set up for a cable clutch. I assume then I'd just have to bolt the bell-housing from my car onto this other transmission and I'd be good to go. Am I Right ?

Correct. Leave your current bellhousing in the car, and just bolt the "new" tranny to it.

Ok. So do you mean I can just disconnect the tranny at the bellhousing and just leave the bellhousing in place ?

The other issue is the shifter. My '67 has a different remote and the short little gearshift lever and this other tranny has the longer gearshift lever. The reverse light switches are in different locations too but I don't know if that's much of an issue. I'd prefer to keep my original shifter. My assumption is that I could just swap the remotes from one tranny to the other but that's just a guess. Does anybody know if it can actually be done ?

Your remote cover will bolt right on the newer tranny. However, the newer tranny will not operate the reverse light switch on your old cover. See if the newer tranny has a terminal for a single wire in the oval can at the upper rear of the gearbox. If so, that's the reverse light switch. It takes some minor rewiring of the car to make it work -- we can follow up on that later.

The newer tranny has the reverse light switch at the rear of the gearbox instead of on top like it is on my car.

Do I need to get a new gasket for the remote when I change it over ?

Are there any other issues in swapping an older style M41 w/ D type O/D for a newer style M41 with a J type O/D ?

The J-type provides slightly less rpm reduction in OD -- you'll be turning a little bit higher revs on the highway with the OD engaged. I don't see this as a problem, but you should know that.

That's ok. It's a small price to pay for having an O/D unit that's much easier to get parts for and that can easily be replaced by one out of a junkyard. I think the O/D units in the 240s are Js too aren't they ?

I don't have a tranny that's convenient to look at right now, so I don't know what to tell you about accessing the upper bolt for the solenoid. However, I'm also not aware of there being any O-rings in a D-type solenoid -- there's no oil in contact with it, other than what might seep in there. That's why I say I don't think replacing it will cure your problem. If you take the plate on the right side off, you'll see what I mean -- and it would have to come off anyway to remove the solenoid.

The tranny would need to come loose from the bellhousing before it will come out in any case. At least, I can't find enough room to take it out with the bellhousing attached in an 1800S. An invaluable tool is a 3/8" hex socket (often sold as a brake caliper socket). Use two 12" extensions with this to reach the upper bolts that hold the tranny to the belhousing.

The reverse light switch on the remote cover switches 12V to the lights. The newer tranny won't have the cam that actuates that switch. Instead, the terminal on the oval can becomes grounded in reverse. That means you have to add a relay to handle the 12V switching, and actuate the relay by applying the ground from the can.

Yes, you need a new cork gasket for the cover swap.

Boy, it sure is a good thing I read the Brickboard today because this is the day I was going to swap ODs on my M41, from D to J. Y'all just saved me a heck of a bunch of work. I'm a bit confused though. I have two M41s, one with D and one with J OD. Both have the same old cover with remote shifter (1800) and the two switches, one for backups and one for 4th gear OD engagement. One wire goes to the solenoid but I know the solenoids are different from D to J. J has two wires but I'm pretty sure one is ground. I have always r & r'd gearboxes in the 1800 leaving the bell housing on the block. Yes, it's a bit tricky getting to the top gearbox mount bolts but it's not impossible. What I guess I'm looking at is a simple gearbox/OD swap with no wiring issues. Everyone agree or not??? Just one more thought, could a guy change the output shafts from the J box to the D box and make the J OD fit?
--
Roy Olson

If both have the same reverse light switch, you won't have any wiring issues. One terminal on the J solenoid jumpers directly to ground, correct.

I don't think anything much swaps between J- and D-type ODs -- I may be wrong. It's pretty easy for a driveline shop to modify the front drive shaft to fit whatever flange you have.