Austin Healey Laycock de Normanville PDF. Instructions on fitting a J Overdrive (from Ian Roslian, NZ). Serial numbers are: 28/115873 / 007305.
MG MGB Technical - O/D - Transmission Identification and Operation This may be complicated, so please bear with me while I explain the situation. About four years ago I had the engine rebuilt in 1973 MGB. While it was apart it was suggested by the shop (an excellent shop with a great reputation) that I put in a new/rebuilt transmission with an O/D. I thought this was a great idea since the original transmission needed to be rebuilt anyway. When I got the car back, everything worked great and I had O/D in third and fourth gear. Then about two years ago something went wrong in the transmission (the cluster gears?) and the transmission had to be taken out and “rebuilt”.
When I got the car back, I only had O/D in fourth gear. Now, I travel out of the country on business for extended periods and since the car ran OK, having no O/D in third gear was never a high priority on my repair list.
I was always told it was just an adjustment and they could make it one time when my car was in the shop. Well, recently I have been having trouble with the O/D just jumping out and turning off. It was not in the switch on the steering column, but something at the transmission. Therefore, two days ago I put the car in the shop. This morning I picked it up.
They said that the switch on the O/D was not set correctly and needed a different spacer - just as I have read about in the threads on this site - and this why it was jumping in and out of position. Now the kicker - I was told today that when the engine was rebuilt and they originally installed the O/D transmission, the transmission was from a later model car which did NOT have O/D in third gear. I certainly am.
So here are my questions: 1) How do I determine by looking at it, what year car my transmission is from? 2) Did the later model MG cars with O/D, only work in fourth gear? 3) If the transmission is from a later model year, then how/why did the O/D work in third gear for over two years?
4) If this is a later model transmission and it only had O/D in fourth gear, is it possible to make it so the O/D will work in third gear too? Your thoughts? This just does not make sense to me. Thanks, Robert Robert Browning Hi Robert: If my memoery serves me correctly, the later(75- 80)MGB 4 synchro gearbox had only O/D in 4th gear. The real difference O/D functioning wise is that the 68 to 74 gearbox, which allows for O/D in 3rd and 4th gear uses a different shift tower. You can make a later O/D gearbox, with 3rd and 4th O/D by using the earlier shift tower. I have heard comment the Leyland made the change to reduce warranty repairs regarding snapped 3rd motion shafts, but I don't have any documentation regarding that subject.
Thanks: Rich Boris 67 B roadster Rich Boris Robert, I'm guessing you are seeking technical expertise to question (use against) this 'excellent shop with a great reputation.' Suggest directing your written questions to either John Twist (University Motors, MI), Chris Betson (Octarine Services, UK) or John Esposito (Quantum Mechanics, CT). Any professionally rebuilt OD transmission should function properly for years (if not decades). Sounds like they might be doing some CYA.
How much did they charge for the rebuild(s)? Just wondering if they did a clean and replace a few O-rings rebuild or a total disassembly and replace all needed parts type rebuild (e.g., who did the rebuild and what was replaced)? Steve Buchina Steve, Actually I am NOT trying or planning on doing anything against the shop. I am just curious, which I guess is even more dangerous. Tonight I drove the car for an extended period and it runs great and the fourth gear O/D shifts in and out like a smooth piece of glass.
However, I would just like to know why I had third gear O/D for two years with 'this transmission(?)' and then after the second rebuild I didn't. Also I would like to know if I can - is there a simple way someone can explain to me - to identify that this transmission really is a late model or if I am just being jerked around by the shop - which I do not think I am. As for the rebuild, it was suppose to have been a transmission that completely gone through with all new bearings, seals, etc. I do not remember the cost, but they did not charge me anything for the second rebuild or for the adjustments made this week. Thanks, Robert Robert Browning Robert, On my 69 MK11 gearbox, known to be original to the car, there are a number of ID number sets.
One of them is the casting date for the housing. Mine appears as '24 10 68'. Twentyfourth of October 1968. This is about a fortnight prior to the casting of the engine block. The casting number on mine is one of 7 number sets. Unfortunately I have not noted where this number appears on the box. On my overdrive there is the number/notation of '2806 68 D'.
This is on LHS of the overdrive case. I think this may be the casting date again. In my case these numbers are consistent with a kit having been shipped from England, assembled and sold, as is known to be the case, in October 1969. Clausager states (pp 84-85) that changes were made to gearbox and OD from the start of rubber bumper production. Gearbox casing changed to side fill (position of number sets could have changed as well) and the OD was modified and the Laycock label changed from black (as on my car) to blue. Further change was made to OD operating only on fourth for North American cars only from February 1977. It always operated on 3rd and 4th in RHD cars.
Hope this may help. Others may have the precise location of the gearbox casting number. Regards Roger Roger T Robert, Just gone back to the original notes I made when the gearbox was out of mine.
I noted that gearbox casting date as located 'flat area front of fork entry port - slave mounting area'. That means it would be readable if you had a view of the slave mounting from under the side of the car. As I mentioned above though, this may have changed on side-fill boxes. Regards Roger Roger T Roger, This is a great start - thank you. Now can anyone tell me where on the casting I find these numbers and can I see them while the transmission is in the car? Also, FYI my transmission does not have a dip stick and is a side fill (passenger side), if that tells you anything? Robert Robert Browning ive Transmissions by Tom Sotomayor February, 2003 Les Bengtson's Classic MG Pages: Articles: This article is not intended as a Steve Buchina Steve, This is fantastic and really helpful.
The following seems to fit my car from what I can see: 1974-½ through 1980 (rubber bumper) 4. Side fill plug (NO dipstick) 5. Blue label on the OD solenoid cover stamped ““22/62005”” (??) 6. 1000 TPM for OD and non-OD I am going to go check on the other items in a few minutes and I will let you know what I find. However, I would still like to get an answer about #9 - 9.
O/D operates in 4th gear only in units made from February 1977 onward So now my questions continue: Does anyone know where the casting numbers are on the side(s) of the transmission and O/D and can I see/get to them with the transmission in the car? The most confusing part of this to me and what I would most like to identify is that I drove this car with O/D in third gear for two years and then all of a sudden I am told this transmission did not have O/D in third gear. I would just like to know what year and design this transmission really is (and if this is a different transmission from the one I bought when the four years ago)? Thanks, Robert Robert Browning Help! Can of you make any sense of this? I just crawled under my car and these are the numbers I could find: The plate on the bottom of the O/D unit is the blue label and has the numbers: 22-62005 Beside that number is: 055374 On the O/D casting toward the drive shaft are the numbers: G14C3 A.D.C.1 Between the main transmission casting and the O/D units (this may be part of the O/D unit), the casting has the numbers (on the passengers side) 7283/2 LM22 The only numbers I could find on the transmission casting (again on the passenger side): 22B 590 (this could be 228 590, as it is hard to see) The next line reads 2B M2 (or 28 M2).
On the side cover of the transmission (drivers side) the casting reads: MOWOG 22B 309. Does any this make any sense? What year is my transmission & O/D? Should it have O/D in third gear?
Thanks, Robert Robert Browning One assumes that the O/D oil has been topped off. Dan Robinson Yes, the oil level is fine.
I did check it, but thanks for asking. Robert Robert Browning Robert;; This may have nothing to do with your car however this happened to me. I had a 1969 Olds Cutlass Supreme purchased new. Car was three years old and I had a leak on engine rear main seal. Took it to AAMCO for a quick fix. Picked it up next day and it did not shift the same.Checked underneath and I did not have my transmission.
It was now painted blue. Fortunately the year before I had marked all major car parts with a new electric pencil. This was not my trans. I called the local sherrif and we paid a visit to AAMCO.
There was my transmission on the shelf.Apparently this was a common thing for that shop as they were charged with fraud. I won my case against them. Could something like this have happened with your car?
Sandy Sandy Sanders Sandy - what you are saying is what I have been thinking - but I hope I am wrong. This is why I want/need someone to help me identify what year my transmission really is. I know I had third gear O/D before the second repair. Now the shop is telling me that this is a late model transmission and never had third gear O/D? How could this be?
If this is a late model transmission then I know something is fishy here!! I hope someone can help me identify the year of my transmission. Robert Robert Browning Robert, It is my understanding that whether the overdrive works in 4th gear, 3rd gear or all four gears has nothing to do with the overdrive. All MG's with OD have a lockout switch which simply stops the flow of electricity to the overdrive switch in reverse, 1st, 2nd and 3rd after 1974. Could it be that the lockout switch or the wiring to it was changed when you had the OD overhauled for the second time?
The most important thing to note is that the OD must NOT be engaged when you engage reverse gear, otherwise you will damage the clutch in the OD and have very expensive repair. On this BB at the moment is another post with a referencet to Overdrive schematics is what you want. Hope this helps, Greg Greg Taplin Greg, You are absolutely correct about never wanting to go into reverse while in O/D. From my understanding the transmission for an O/D is different then from a regular transmission. Also, there is a switch which engages from neutral to the third-fourth side of your shifter - this is what I have been told.
So again, my question has to do with the model of the transmission and what year it is and if it was designed to have third gear O/D, and I do not think this is an electrical issue Thanks, Robert Robert Browning Hello, I also posted my questions on the 'MG Experience' website and someone wrote in and said: 'Blue label transmissions only operated with O/D in fourth gear. Black label transmissions operated with third and fourth gear O/D.'
Can anyone verify this? Thanks, Robert Robert Browning No! The blue label OD units with the side fill boxes came in in 1974 and OD worked in 3rd & 4th. The restriction of OD to 4th only happened in Feb 1977. My guess is that at the last rebuild you got an exchange tranny. The OD operation is controlled by the selector arm in the top of the box - not the extension tower.
The only way to restore the OD operation in 3rd is to change the arm for an earlier one. The casting numbers won't help as the castings didn't change - what will help is that on the casting - usually on the flat part between the mounting rubbers and/or in front of the side access plate there will be a date stamp in UK format - ie 4/12/67 is the 4th December 1967 Chris at Octarine Services Chris - Thank you very much for this information.
I was also under the impression that third gear O/D was done away with in Feb 1977 and not 1974. Now let me ask, did 'all' transmissions have a date stamp?
I have just examined the entire transmission with a light and a magnifying mirror for the past hour and I cannot find a casting date stamp anywhere on my transmission. I looked everywhere everyone has said plus everywhere else I could reach and cannot find anything. The flat area between the two rubber bumpers has nothing and neither does the machined flat area in front of the side covering. So, did they all a date stamp? Robert Robert Browning All of the late gearboxes I have in stock have the date stamped on the 1.5 x 1 inch flat area between the mounting rubbers - but you won't see it easily with the box in the car as the mounting bracketery is in the way. Chris at Octarine Services Chris, If I remove the rear cross member and the the two rubber support bumpers, should I be able to see it then - with the transmission stil in th car? Thanks, Robert Robert Browning Is it possible to have a transmission with no production stamped on it?
I have looked in all the places suggested, plus everywhere else I can to with a light and magnifying mirror, but I cannot find a date stamp. Robert Robert Browning Of course it is possible that no date was stamped on the tranny you have in the car! Chris at Octarine Services Robert, it sounds like something in one of (I think) Pete Burgess's books on improving the MGB (sorry, but the book name escapes me). In that, there was some funky circuitry that effectively turned the MGB 4+OD into an easy to use 6-speed box, and the driver didn't have to worry about engaging or disengaging OD, as the 'box of tricks' did that for you. Sounds cool, but I went for a Sierra 5 Speed.
Grant:-) G Hudson North American cars from July 76 are complicated. Some had Transmission Controlled Spark Advance (to overcome problems caused by all the emissions mods) which limited vacuum advance to 4th gear only. Originally this was done by an extra micro-switch on the selector housing which operated in 2nd and 4th, which when wired in series with the OD lockout switch which still operated in 3rd and 4th, gave a 4th only output while still allowing OD to operate in 3rd and 4th.
This is the circuit that all the diagrams I have seen show. But a few months later in Feb 77 the circuit was changed so that there was only one switch, which operated in 4th gear only.
This left the function of TCSA unchanged but limited OD to 4th gear only, on all cars by this time. The reason OD was restricted to 3rd and 4th is that the OD isn't strong enough to take the torque reversals in the lower gears. This is why the V8 was restricted to 4th gear only for all but the first few examples. This makes it unwise to use OD in 1st and 2nd. To get OD in lower gears means that the lockout switch arrangements have to be changed, which depending on how you do it can leave OD available in reverse, with potentially damaging results. I have seen a circuit that claims drop OD out automatically when you change from 3rd to 4th, but that also has to have some additional mechanical work at the gearbox and isn't just electronics.
The box of tricks did it for you so you didn't need a manual OD control at all? That would seem to combine the worst aspects of an auto and a manual OD. I can never see why people go for a 5-speed and lose the option of OD 3rd, which is a very useful gear for long inclines and twisty bits, but each to their own. To go back to Roberts original question, if his gearbox was 'rebuilt', went in with OD 3rd and 4th but came out with OD in 4th only, then either the lockout switch is only just operating in 4th and not in 3rd due to adjustment issues (although wear usually causes the opposite problem); or some parts were switched with a later '4th only' gearbox, in which case the date label will tell you nothing. OTOH maybe the whole box was switched, in which case the date label (if it has one) will show a post-Feb 77 date.
Paul Hunt 2 This thread was discussed between and index This thread is from the archive. The Live is active now.
Triumph Spitfire - Laycock Overdrive I.D. I was recently given what I believe to be a D-type Laycock overdrive. It has a tail stock, plate and input shaft. My problem is that I have not been able to identify what type of vehicle it belongs to and need some help. The serial number is: SN 25/01 From previous searching, I understand the '6' in the second set of numbers may signify a 'factory rebuild'. Any help would be appreciated. Scott Morris This thread was discussed on index This thread is from the archive.
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