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MG MGB Technical - Shifting Gears, question

Although I have been working on a couple of MGB's over the past few years I have only now got one of them to driving condition. I notice on the B, my '70 Gt with OD trans, the gears are pretty tight and very close together which I expected. Only out around the block for a test drive as I shift from 3rd to 4th it is difficult going into 4th. I actually went from 3rd to 2nd unintentiionally a couple of times. Had to hold the lever to the outside (right) USA car to get it to go into 4th. Have only had it out on short runs, few minutes at a time. My question: Is there an adjustment that can be made at the shift lever? I see in the parts diagram a locating pin and a plunger on the other side of the shifter. With the car running at stand still the shifter goes thru gears smooth and easy? Hope I'm not in trouble here.
Thanks
Mike
MK Mike

We borrowed this 1970 BGT in SA in 2006, this pic was taken from it's owners other MG a TF 160. Our 67 B has the 3 synchro gearbox so I was as new to this gear shift as you are. After adjusting the seat and checking out all the controls we drove it of Johans drive and never missed a gearchange the entire trip. I found the gearbox a real pleasure to use, everything a period British sportscar should be and although I recall (please no heavying if it's the other way this was a year+ and 8000 miles away )the shift spring loaded towards 1/2 it was just about perfect to let you know where you were without needing to look down. Hope this helps I was also sent some old pics of this car undergoing a bare metal rebuild so you can get there if you persist.


Stan Best

Mike, when shifting third to forth remember to put just a small sideways pressure to the right on the shift lever and see if it shifts better. They are sprung to center between first and second when in neutral. If you are shifting rather relaxed the lever is drifting to the left when pulled out of third.
John H

When the car is running but at a stop it shifts thru all the gears as smooth as silk, when it's moving the 3rd to 4th is a bit difficult even with pressure towards the right. My wife will be the main driver and the way it is will cause problems. I will take ti out again as soon as I get some nice enough weather to install a new fuel pump. Does the spring that loads it towards 1/2 adjustible?
Mike
MK Mike

It's not adjustable, but it shouldn't cause a problem. The shifting linkage is very simple but you can't get to it with the trans in the car. The only thing you can do with it in the car is pull the shift lever and check that the plastic bushing on the lower end is in place, and if there is excessive wear in the bushings of the shaft that the lever fits into.

The shifting is accomplished thru a steel paddle that engages one of three sloted rods to move the shifter forks to change gears. There are ball detents that hold the selected fork rod in position when a gear is engaged. It is possible that one of the detents isn't working properly and the shifter fork is being moved slightly when torque is being applied to the trans which would affect the alignment of the three rods to each other. In neutral they line up so the steel paddle can move between them, if one is being pushed slightly out of the neutral position the paddle is binding when trying to shift as the alignment is off. As the gears are helical cut they do cause for and aft thrust preasures when under load, worn thrust washers in the trans or excessive clearances may be allowing them to affect the neutral alignment. When stopped with no load on the box everything lines up as it should.
John H

Mine feels about the same as you described, I have to put pressure to the right to get it into 4th(screws up anyone that tries to drive it) but it's been that way since putting back on the road in 99'. I got used to it pretty quickly, and don't notice it anymore.
Robin Meier

I've found each one of my Bs over the years has it's own unique feel - and I think much of it is due to previous owners' driving styles - which wear the "gates" (actually the selectors) in unique ways. At least one of my cars was like yours and I got in the habit of shifting 3rd-to-4th "backhanded" - that is, I turned my palm toward the knob and lever, thumb down, natural body mechanics (my own) easily kept some outward pressure on the lever and I never missed the shift. Yeah, you could have some worn selectors - easy to replace once the box is out of the car (aaarrrrrgh!), but I doubt if it's life-threatening as far as the box is concerned.

I agree with Robin - drive it some more and after awhile you won't even notice it. You can teach your wife that it is normal and minor. And for driving around town, she can use 3rd-O/D instead!

Cheers,
Allen
Allen Bachelder

My 70 GT does this in 1st & 2nd.

3rd & 4th are smooth, but 1st & 2nd are difficult.
If I start moving it down toward 2nd then move it up into 1st it's usually cooperative. Sometimes 1st is easy.

That's when the car isn't moving. If it is moving then I can shift easily into all gears up and down.
Rick Bastedo

In my old GT it was always 3rd to 2nd that got me (and everyone else). I got used to it but others would always go too far left and hit the reverse indent!

I always use my palm to change and rest it on the opposite side of the gear knob to the direction I am shifting and apply gentle pressure and it always goes in.

My 78B I am restoring now has a new spring and new nylon bush and it still feels a little loose in side to side motion when in neutral.

I have a mate who (is his car, not an MG) always traces out the shift pattern in straight lines. So a 2nd to 3rd shift for example is three distinct movements. Always makes me wince!
Simon Jansen

Mike, You mentioned that it is an overdrive trans. The lockout switch for the overdrive operates in third and fourth. It applies pressure against the 3/4 shift rail and may be forcing the selector into neutral instead of directly back into fourth. Ray
RAY

Ray and others, thanks. I will take another look at the diagrams to see the lockout sw. I also need to take a few more spins in it and see if it's something that we can get used to. Still fiddling with fuel pump problems outdoors in the cold and nasty. Will report asap.
Thanks
Mike
MK Mike

"new spring and new nylon bush and it still feels a little loose in side to side motion when in neutral"

It should move easily in neutral with no apparent resistance, but in gear with a good bush there should be no freee play at all. The first time I fitted a new bush it didn't make any difference at all, but that was because I fitted it to the socket first then tried to push the lever in, which pushed the bush out the other side. So I fitted it to the lever, and then had to chamfer the leading edge of the bush slightly before it would go in the socket.
Paul Hunt 2

UPDATE: Well I was finally able to get the fuel problems mostly sorted out. Took the car around the area a few good runs, nice and warm. Have a nice straight in my "test" area where I can get going fast enough to get into 4th. You guys were right a little side pressure to the outside and she goes right in, very nicely, don't think it's gonna be an issue. The best part thou, as I was cruising up and down mostly in 3rd gear I thought to myself well you're going to have to try it sooner or later so I switched the OD stalk to the on position and she went right in YES!!!
and manually switched it back off and right out. YES!!
I am very happy with that. Thanks to all until the next issure arises.
Mike
MK Mike

This thread was discussed between 24/01/2008 and 04/02/2008

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