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Is there an easy way to remove the first motion shaft from an OD tranny

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santarosamgb Harry .
CA, USA   USA
Besides taking the tranny apart, is there an easy way to remove and replace the first motion shaft from a MGB OD transmission. Any feedbacks are greatly appreciated.

Is it as simple as removing the front trany plate first, undoing the big nut, and carefully pulling it out from the front of the tranny?

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Rod H. Avatar
Amity, OR, USA   USA
1964 MG MGB
1968 MG MGB GT
No, sorry to say you will need to do more disassembly than that. The laygear needs to be dropped down and there will be needle bearings that likely won't all stay in place in both the lay and the interface between the input shaft and main shaft.



I can't understand why people are frightened of new ideas. I'm frightened of the old ones. John Cage

'63 MGB
'68 MGBGT
'80 VW Vanagon Kombi
'09 Mazda 3 with 5 speed manual

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santarosamgb Harry .
CA, USA   USA
Can the lay gear be dropped from the side opening of the transmission without having to take the entire transmission apart? by he way, can you disconnect the laygear without having to take the transmission apart?

I read somewhere here in this forum previously, and i remember that someone has said that he was successfully having removed the first motion shaft or input shaft by "adjusting both the lay gear and first motion shaft gear at the same time". I am not sure what he meant by"adjusting" but he did not have to drop lay gear.

Has anyone else successfully removed the first motion shaft without having to drop the lay gear?

Any feedbacks or comments are appreciated.

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geezer Avatar
geezer Silver Member charles durning
Magee, MS, USA   USA
1958 MG Magnette ZB "Chick Magnette (sold)"
1967 Morris Minor 1000 Saloon (2-door) "Marvin"
1974 MG MGB GT "Foghorn Leghorn"
Harry,

What trans OD do you have?

Sorry no on the 4 synchro trans. I don't know about the 3 synchro trans.



"Whether you think you can do something, or you think you can't, you're correct"- Henry Ford

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Harry,

You cannot remove the first motion shaft without disassembling the gearbox and removing the layshaft and dropping the laygear out of the way. The issue is that the many small teeth on the back of the first motion shaft, which are engaged by the I.D. of the 3/4 synchronizer sleeve, will interfere with the front gear on the laygear.

Some folks have reported removing the gearbox, standing it on the output flange, removing the front cover, carefully withdrawing the layshaft out the front, allowing the laygear to move out of the way, and wiggling the first motion shaft out of the gearbox main case. I would rate the likely success rate of this procedure near zero, because it would be profoundly difficult to return the laygear into line with the layshaft bores in the main case, and even more difficult to assure that the thrust washers at both ends of the laygear are properly in position so that the re-installation of the layshaft passes through both.

I encourage you, very, very strongly, to remove the gearbox from the car, remove the overdrive unit and adapter housing from the main case, remove the front cover, drop the laygear out of the way, insert a temporary thin rod to hold the laygear thrust washers close to being in position, and then withdraw the first motion shaft.

And, truthfully, you're so close to having the whole gearbox apart, that you might as well remove the third motion shaft with its gearstack, and the laygear, layshaft, and laygear bearings so you can properly inspect all the bearings and baulk rings and replace as necessary.

BTW, in MGB 3-synchro gearboxes, the bearing where the first and third motion shafts meet, as well as the two laygear bearings, are loose roller bearings, so be prepared to play 52-card pickup upon disassembly. In the 4-synchro MGB gearbox, overdrive or not, caged roller bearings are used at these locations so they won't explode upon disassembly...

Dick



In reply to # 3909041 by santarosamgb Can the lay gear be dropped from the side opening of the transmission without having to take the entire transmission apart? by he way, can you disconnect the laygear without having to take the transmission apart?

I read somewhere here in this forum previously, and i remember that someone has said that he was successfully having removed the first motion shaft or input shaft by "adjusting both the lay gear and first motion shaft gear at the same time". I am not sure what he meant by"adjusting" but he did not have to drop lay gear.

Has anyone else successfully removed the first motion shaft without having to drop the lay gear?

Any feedbacks or comments are appreciated.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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santarosamgb Harry .
CA, USA   USA
It is a late mgb od tranny

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santarosamgb Harry .
CA, USA   USA
Thanks very much for your inforamation, Dick. I m not familar with the needle bearings. Are the original needle hearings not caged? From what you are saying, i will need to buy a cage needle bearing upon assembly of the first motion shaft?

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santarosamgb Harry .
CA, USA   USA
Never mind Dick. I re read your message. Mine are caged needle bearings

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bills Avatar
bills Bill Spohn
W. Vancouver, , BC, Canada   CAN
In reply to # 3909154 by dickmoritz
BTW, in MGB 3-synchro gearboxes, the bearing where the first and third motion shafts meet, as well as the two laygear bearings, are loose roller bearings,


Except for the last ones in 1967 that used 4 caged bearings and the larger diameter shaft.



Bill Spohn www.rhodo.citymax.com/carstuff.html
Current: 1958 MGA Twincam (race car (170 bhp)),1962 MGA Deluxe Coupe (98 bhp)
1957 Jamaican MGA (200 bhp)1965 1971 Jensen Interceptor (350 bhp)
2009 Pontiac Solstice GXP Coupe (350 bhp)
2007 BMW Z4M coupe (340 bhp)
Recent: 1969 MGC roadster (175 bhp),Jensen CV8 (375 bhp),
1969 Lamborghini Islero S (350 bhp), 1988 Fiero GT turbo (300 bhp)
North Vancouver BC

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Gerald O Avatar
Gerald O Gerald O'Docharty
Wake Forest, North Carolina, USA   USA
1972 MG MGB GT
1978 MG MGB
In reply to # 3908922 by santarosamgb Besides taking the tranny apart, is there an easy way to remove and replace the first motion shaft from a MGB OD transmission. Any feedbacks are greatly appreciated.

Is it as simple as removing the front trany plate first, undoing the big nut, and carefully pulling it out from the front of the tranny?

You don't need to remove the big nut to remove the first motion shaft. It only needs to be removed if you are changing out the bearing.

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
And note that, if it is necessary to change the first motion shaft bearing, the large nut on the forward side of the first motion shaft has left hand threads...

Dick



In reply to # 3910128 by Gerald O
In reply to # 3908922 by santarosamgb Besides taking the tranny apart, is there an easy way to remove and replace the first motion shaft from a MGB OD transmission. Any feedbacks are greatly appreciated.

Is it as simple as removing the front trany plate first, undoing the big nut, and carefully pulling it out from the front of the tranny?

You don't need to remove the big nut to remove the first motion shaft. It only needs to be removed if you are changing out the bearing.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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santarosamgb Harry .
CA, USA   USA
Thank you for letting me know that... So the only thing that keeps the first motion shaft in place is the lay gear.

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
And, of course, the front gearbox cover plate and the semi-snug fit of the first motion shaft bearing in the gearbox case...

Dick

In reply to # 3910576 by santarosamgb Thank you for letting me know that... So the only thing that keeps the first motion shaft in place is the lay gear.



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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santarosamgb Harry .
CA, USA   USA
Dick, I just want to confirm that the first motion shaft is held in place only by the lay gear? I got the OD unit piece out this morning , and working on removing the shifting knuckles out before removing the adapter housing.

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dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
Once the front cover plate is off and the laygear has dropped out of the way, the first motion shaft can come out...

Dick



Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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