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Second gear disengagement

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GJM47 Gerard Monnin
La Varenne Saint-Hilaire, Paris, France   FRA
Hi everyone, my MG C GT is a 1969 left hand drive manual transmission delivered new in France and I bought it in 1974.
It always suffered from disengagement of second gear under strong deceleration.
I decided at last to take care of this unpleasantness and I am ready to remove engine and box for inspection.
Before doing this I would be intrerested to know if somebody was confronted to this issue and how it was cured.
I see on the workshop manual that the detent spring and plunger is on top of the box and I suspect the spring.
But could it comes from the anti-rattle plunger sitting on the gear lever?
Thanks in advance for your advice

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romeo69 Stephen Curtis
, Berkshire, UK   GBR
gerard its the hub that is worn ,.the indent spring that I think you refer to are the selector rods .they I have never seen worn .of check that the baulk ring is not split they get a crack in them and it opens up causing it to slipout of gear

Restoman Avatar
Restoman Platinum Member Dana R
amston, connecticut, USA   USA
Hi Gerard,
Check all that Stephen told you, and also the spigot bushing and shaft end on the rear of the first motion shaft, and the front of the
third motion shaft where they plug into each other. This area can be worn, and must be fixed, or replaced on a lot of transmissions.

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Swamperca Avatar
Swamperca Swamper CA
-, Nor Cal, USA   USA
1968 MG MGC GT "California Chrome"
1969 MG MGB GT "Rat"
1969 MG MGC GT "C-Rod"
1970 MG MGB GT "Widow"    & more
On my 69 GT it had jumped out of gear like that. Rebuilding the tranny and replacing the normal wear items seemed to take care of the problem. I never pinpointed the actual problem point but figured it could have been the synchro's which were replaced.



Sacramento Valley MG Car Club


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GJM47 Gerard Monnin
La Varenne Saint-Hilaire, Paris, France   FRA
Thanks all for your advice. Will report when the gearbox is disassembled.

Bob in Vancouver Avatar
Bob in Vancouver Bob Elwin
Vancouver BC, Canada   CAN
1968 MG MGC
1969 MG MGC GT
Gerard,
Is you trans an O/D or not? My non O/D C would attempt to jump out of 2nd gear on the overrun and I found the issue was the third motion shaft moving fore and aft depending on the power being on or off. Trying to discover why it was moving so much, I found there is a large C clip at the rear of the box which had shattered into several pieces allowing the fore and aft movement of the output shaft. This movement was reflected at the gear lever via the selector shafts. Fitting a new C clip fixed the issue - maybe something to check? Cheers, Bob.

GJM47 Gerard Monnin
La Varenne Saint-Hilaire, Paris, France   FRA
Hi Bob, thanks for the tip. My car is O/D. Will check this.
Gerard

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dickmoritz Avatar
dickmoritz Gold Member Dick Moritz
Philly 'burbs, PA, USA   USA
Before you go snatching the engine and gearbox out, be sure to remove the boot at the bottom of the gearstick and inspect the area very carefully for the possibility that carpeting, padding, or even the shift boot itself is preventing the gearstick from fully engaging second gear. You should also check the engine and gearbox mounts to see if deceleration torque is causing the drivetrain to shift rearward, pushing the gearstick out of second gear. Also check for the presence and integrity of the (usually white...) nylon bush on the small ball on the bottom of the gearstick. It is unusual for a 4-synchro MGB or MGC gearbox to pop out of gear...

Dick



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

GJM47 Gerard Monnin
La Varenne Saint-Hilaire, Paris, France   FRA
Dick, I think you got it right, because when I removed the engine/drivetrain I realized that the two gearbox mounts were broken, both rubber pads cut off. So on deceleration the transmission shaft possibly forced the whole thing to misalign.
Nothing abnormal inside the gearbox apparently after complte disassembly. The baulk rings look OK. I am hesitant to fit new baulk rings not knowing if they would be same quality as original ones.

Gerard

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