Odd vibration

[KoppaK]

Ok, got the Minor running nicely and have noticed a strange vibration in 3rd gear, it only does it in third gear starts around 40mph and gets worse the faster you go, as soon as you dip the clutch or change up it goes, nothing at sll in 4th even at 70mph plus.All the gear changes are very good for a Minor there is some chatter on the over run but I've heard worse and no iumping out of gear at all. Anyone had this before ?

[biomed32uk]

Does it stop when you hold the gear lever ?, I asked the question here and was told to check the O ring on the base of the gear lever, mine was non existent and the vibrating noise through the lever was immense, new O ring on and all quiet.
And of course the rest of the gear lever base parts, there is a plunger in the side and a cup and spring underneath, the drawings show it, you can get all the bits as a kit.

[minor65]

70 plus At 70 mph i certainly would expect a vibration

[bmcecosse]

Nah -70 is time to consider changing into 4th with my 3.7 final drive !

[KoppaK]

Its not a vibration noise its a vibration coming through the car like a prop vibration but as soon as you change into 4th its gone. Nothing in 1st or second either however hard you push it. Spec is a Midget 1275 mated to original gearbox running to a 3.7 diff. I've resigned myself to pulling the box off at tye end of the summer and tearing it down just wondering if anyone knows what's going on in there, my gut feeling is 3rd motion shaft bearing or layshaft problem.

[bmcecosse]

Probably. The more miles it runs - the worse the damage to the gears running 'out of mesh'.

[biomed32uk]

Thats a whole different take on things then, the box has to come out whatever.

I did my box over last winter and now you mention it in third I had a horrible noise when winding the revs up that sounded like it was coming from under the seat. When investigating the box the rear extention bush where the front prop joint goes in was bady worn, with the prop rattling around. Its certainly gone now after a rebuild, but I also did the engine as well, so the whole car is running really sweetly.