78 B no OD / Laycock LH T OD

Hey guys, looking for a definitive answer and I`m just too lazy / tired to search through all the previous threads where this question has probably been asked and answered a hundred times, SOOoooooo

I`m reconditioning a 78 B w/o OD and I`ve been given (yes given!) a transmission with an OD tagged (green) Laycock LH T . The unit out of mine has a dipstick and the OD unit does not. The main shaft on mine is about an inch and a quarter proud of the bell housing, while the main shaft on the OD unit is about flush with the edge of the bell housing. What is the best/ easiest way to adapt the OD unit to my 78 ? Would the OD unit itself swithch to my tranny? Would the older tranny AND od unit readily install into the newer car?

Thanks for any and all replies.

If the trans in your '78 has a dipstick, it's not original to the car. Late Bs fill through a plug on the right side of the trans case (whether or not they have OD) - earlier cars used the dipstick.

Ok, this is not too surprising, as it appears some major work has been done to the motor. Can you give me any further input as to the OD install?

Thanks Joe

With a mainshaft that's a different length and disameter, I've got to ask, is it an MGB transmission? Got pictures?

I agree with Derek. Have you compared the bolt pattern between the two gearboxes? MGB LH overdrives have either blue or black label, don't know what cars used a green label OD. Laycock overdrives have been used on many British cars, Volvo and some American cars (AMC Gremlin For example).

Clifton

I am also wondering if the engine/gearbox combo in your car is from a much older vehicle - do you know if you had synchromesh on 1st gear? Do you know the engine number?

I'm certainly not a transmission specialist but it seems obvious that a shorter input shaft will not work. Have you measured the bell housing (i.e. maybe your bell housing is shorter than the OD unit)? Do the bolt holes for mounting line up? are the splines the same? For the 2nd question - can the OD unit be placed on your old one? I'll leave that for the more informed gurus.
Can you further identify the OD trans. for application. As mentioned, I dont think the # has any MG application.
Rob

Good evening gentlemen, I`m sure you`ve been anxiously awaiting my post. - I`ve been sweating it out at work , and monitoring your posts from time to time, wondering how I could be so stupid not to examine a few of the basics you have all mentioned, - very good points I might add ( thank you ! ) also wondering why I would assume ( yeah I know what that does) it was a "B" transmission because it was in a pile of stuff given to me along with a 68 "project" ( Hey , - thats what we do down here- screw e-bay! ) BUT! ....... it is in fact a "B" transmission w O/D -- the cases are the same, the shaft diameter etc. however, someone in their infinite wisdom cut the shaft on the OD unit.- looking at it closely, it is clear that that is what has been done. The end of the shaft has even been "relieved "or beveled . The 68 may have been used for racing, - would that make sense? - (the splines are in tact etc.) SOOOoooooo Now , what is the easiest way to access this OD unit? Does everyone agree the transmission with the dipstick is the older unit? Is the OD readily adaptable to another gearcase? - Or shoud I adapt a new shaft to the one it`s in?

Once again thanks for your input. - I`d send my pics, but my kids not home to show me how !
Clint

Clint,
The changeover to OD would take quite a bit of work. If the input shaft's beyond use on the OD it "might" be possible to use the input shaft from your non-OD in the new unit but you'd be going deep into the tranny.

I'm with the other's on the green label, never seen that. You might contact the folks at Quantum, tell them what you've got and see what info they have.

Thanks clay, - what you say makes perfect sense. Pardon my ignorance, but who is Quantum?- I haven`t had the opportunity to play with one of these things for about 30 years. I must admit , I`m spending way too much time with my new toy. Unfortunately, in South Florida I don`t think I have too many comrades, - especially herein the Keys.

Where do you weigh in on the comment that the unit with the dipstick is the older of the two? It seems to me that the dipstick would be an improvemnt and would be on the newer models, -- Yeah?

I`m a ways off on needing the tranny info , just trying to do some research now. Trying to decide how brave I need to be to dig into it myself. - Once again in South Florida, I haven`t located a shop thats into cars that don`t speak Spanish yet.

Clint

Any ideas as to why that shaft would have been cut?- Looking at it now, it`s clear that that is what has been done. Other than that and the dipstick, the gearcases are pretty much identical.

Clint

33037 Wrote:

Thanks for your response Naomi, - sounds like logic need not apply here. Must admit, I`m somewhat disappointed ( sp?) that someone hasn`t come up with an explanation as to why the shaft on the unit with OD would have been cut other than sheer stupidity ! - My thinking at this point is I may as well dig into it and see what makes it tick, as it is no good to me the way it sits . Worst -case scenario is I`ll get an education out of it , as it was given to me . Any ideas?

Naomi Wrote:

The cut shaft makes no sense at all - probably somebody having trouble installing the engine (it can be a PITA if the clutch isn't lined up properly) and took the easy, and stupid, way out. DO NOT install it like that - sooner or later it will cause BIG problems.

The good news is that the input shaft from your non-O/D gearbox should fit. You will have to dismantle both boxes, but it really isn't too hard to do. It is also a good excuse to put new O-Rings and gaskets into the O/D and generally clean everything up.

You can find instructions on how to do the job HERE

Good luck!

Thanks Eric,
Perhaps this weekend I`ll open up the unit with the cut shaft and begin to familiriarize myself with it to see what I`m up against.- I`ve got a bunch of other things going on but that one is on the horizon ! I really want an OD in this thing because here in the keys there is a lot of straight road driving . - What can you tell me of this talk I hear of "black" or "blue" label overdrives. The tag on the one I have appears green but could easily be a faded blue. What are the difference`s?
Thanks again, Clint

The main difference between the "Black" and "Blue" label O/D units is the the O/D housing. The castings are slightly different and the newer one (blue?) has a different thrust bearing that is prone to failure. However, it can be replaced, even upgraded to the older "pressed in" version.

Other than that - they are thee same. Operation and all the basic parts, are identical.

http://www.quantumechanics.com/

Call up John Esposito and tell him what you have but in the meantime post pictures if you can.

Thanks Carl, Here's a few pictures of what I'm up against. The two units side by side, one on right, non OD out of the 78, - gearcase has dipstick. O D unit from both sides, and finally a close-up of the work of a true genius, the cut shaft.
What do you think? What would be the easiest way to make this work? - would the OD readily adapt to the non OD gearcase? I'm obviously concerned about using the unit with the OD because god only knows what went on when the shaft was cut.

Here are two other pictures.
- Clint

Clint - you really have two options:

One: It IS possible to fit the O/D unit to the old gearbox. However, in order to do that you need the output shaft from the O/D gearbox which you then install in the non O/D box. It isn't a terribly difficult job - but it isn't easy either.

Two: You can take the input shaft out of the non O/D box and install it into the O/D box! Again, this is not really hard to do - but it is slightly easier than changing the output shaft!

Don't worry about the dipstick issue - it is only a variation in the casting and the newer gearboxes didn't have a dipstick - they have a fill/level plug on the side of the casing. There are as many opinions about which is easier/best as there are MG owners!

Hey Eric, - Thanks once again for responding to my post .
Looking at the schematic in Moss, the input shaft exchange does look like a relatively easy adventure. However, - understand my apprehension at using the unit that someone decided to alter this shaft on. (still haven`t heard a rational explanation !)- I guess what I find when I open each case up will determine which route I decide to take. - I`m determined to at least take a peak inside both of these gearcases this weekend. - When you speak of the "output shaft" are you refering to what that schematic calls the "main shaft"? - That shaft is the major difference I see between the OD and non OD schematic, - yeah?
Clint

Looking at the pics on the OD unit, do not be mislead by angle and Lighting, the " dimple" on the end of the shaft is not there and there is only an inch (approx) to the splines as opposed to a full two Iches on the non - OD unit !

Clint

That is correct - Moss call it the "main" shaft, the workshop manual (Bentley) calls it the "third motion" shaft, and Eric calls it the "output" shaft! Yes, it is the only major difference between an O/D and a non O/D gearbox (there is a bearing difference too).

If your non-O/D box is working well, you can actually transfer all the "wear" items (mostly some bearings, and the synchros) to the O/D box along with the input shaft - but B gearboxes are pretty bullet-proof. I would guess that a good visual inspection (follow the Octarine instructions), will be enough to convince you what is good, and what needs replacing.

If you take your time, working on a gearbox is actually not that hard!

Wjat was to outcome of this thread?