Just tonight my car started popping out of first gear. I've never had this happen before.

It shifts into first fine (3 syncro, remote shift) and starts out fine, but as the rpms and speed increase, you can see the shifter start to move back. When I let off the gas before it pops out, the shifter will move forward again, but as I accelerate again, will creep back and pop out. At about 3000 rpm it pops out. I can hold the shifter forward in first and it runs normally all the way up to 4500rpm (or wherever I decide it's time to shift into 2nd gear). All of the other gears stay put; it's only doing this in first.

I'm not sure if this is most likely linkage, a bad motor mount or something internal to the transmission. I'm hoping one of the first two.

I checked the upper engine steady and bushings are fine/ no cracks at firewall mount. Engine mounts look good visually, but I'm going to take a closer look from under the car in the morning. I couldn't make the motor rock around by hand. It's solid as usual.

Any ideas or suggestions?

Thanks,

Craig

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With a 3 synchro box (NOT 4 synchro) there are a few things that can cause this-
1. too much endfloat in the laygear/cluster gear.
2. worn teeth on the cluster or the 1st gear outer ring.
3. badly worn layshaft (1st gear end).

These items are all related, and have to do with the 1st gear being a sliding sleeve. Unlike 1st gear on a 4 synchro which is in constant mesh.

Anything like the 3 items above which generate end thrust between the 1st gear and cluster gear teeth can slide the gear out of mesh.
Look carefully for wear of the teeth on both the 1st gear and the cluster gear.
The only real cure is parts replacement.

(Of course, a badly worn 1-2 shift fork or detent spring can cause jumping out of gear too).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Thanks Kev,

I'll save this information for when I tear it down this winter (which it's looking like that's the way I'm headed). I'm only half way through the driving season here, so is there any harm to other tranny components in just holding the stick in 1st so it doesn't pop out to get me through the next 2000 - 3000 miles?

Are all of these components still available?

Hopefully I find a missing motor mount bolt or something (fingers crossed).

Craig

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Continuing to drive it whilst holding it in gear will wear the selctor fork more, that`s all,,, easy fixed when stripped down & most likely that it`s worn quite a bit already anyways

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Craig, the 22G1100 Mk1S laygear is still listed at MiniMania. US$179.95
Also used in Spridgets so I bet it's available.

1st gear outer ring 22G1119 is listed there too. US$129.95.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Glad parts can still be had.

Is it worth it (or even possible) to turn it into a 4 synchro box while I'm at it? Anything else to check or replace as a matter of good practice when it's opened up? I'm thinking oil pump at the least - tho I'm still getting 25psi when hot.

This is all new territory for me!

Thanks for the info.

Craig

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No the 4 synchro is a different casting. You would need another complete box.
Look for 22G1128 cast on the front.

Actually, the gear ratios in the Mk1 S are the best. Pity 1st gear gets worn with age.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.