Gear selector adjustment?

[abowie]

All synchro box in a 4.2 coupe.

When selecting first gear. With clutch in, I can push the gearstick forward and seemingly PAST first gear, at which point the box grinds, just like trying to engage a gear without using the clutch.

Where do I start looking, and can I adjust this?

Clutch itself is fine and this only happens with first.

[PeterCrespin]

There is no fore/aft 'adjustment' as such but everything relevant is confined to the removable top cover, so should be fixable. Travel in the 'coronal plane' is confined by the cut-outs in the selector rods and is therefore mechanically constrained (with the strength of reverse detent being the only variable).

Travel in the 'sagittal plane' as I understand you to mean, is constrained by the selector forks being screwed to the rods and the interlock detents preventing unwanted movement in adjacent rods. The square-headed fork set screws are lock wired but this can become brittle or be forgotten, so maybe a fork is loose? Problem with that is I'd expect fore/aft slop in both directions.

I'm guessing a detent/interlock has either been damaged or broken due to a spring collapse or casing damage, or is compromised due to the ball being undersized metric instead of imperial, or some such? That might allow two gears to almost be selected at once, resulting in grinding. There are subtle differences in the width of the actual selector tab itself between models (the forged receiver into which the gear stick is mounted) and this is easily missed if mixing/matching parts. That might give you a borderline 'two-gears-at-once' issue if it was attempting to nudge two selector rods, but the interlock should prevent it and I don't see how it would cause excessive forward movement.

Time to remove the lid and inspect or swap for a known good one as a test. A worn/bent brass fork will have visible witness marks, or may be loose on the shaft. I'd re-do the o-rings while you're in there

[abowie]

Time to remove the lid and inspect or swap for a known good one as a test. A worn/bent brass fork will have visible witness marks, or may be loose on the shaft. I'd re-do the o-rings while you're in there

Weekend's task defined.

[abowie]

Update.

Test drive with the centre console off so I can see the back of the gearbox and the driveshaft. The grinding, which is just like trying to get into first in a Moss box only happens when the car is rolling; ie the output shaft is turning.

Took off the gearbox top. The external linkages look fine with no obvious play. No obvious problem inside. All bolts and lockwires in place. Everything slides ok. I've never looked at one before though so I'm no expert.

I'm wondering if it may be a problem with the first gear synchro.. I suppose it's possible the selector forks are worn but it doesn't seem that you can buy new ones..

I took lots of photos if anyone can help..

[PeterCrespin]

The only thing that made me suspect a selector issue (pretty rare) was the title of the thread and your reference to going PAST first gear and thereby provoking grinding.

For the stick travel issue you are presumably not imagining it as you have other E-types to drive. There is more than one stick length. If you have a long version it will extend the travel for all gears but feel furthest on first in a RHD car, as that is the biggest stretch.

It sounds like a dud synchro and if double-declutching cures the graunch it effectively IS a bad synchro. Close up photo may help.

[chrisfell]

Sounds like a problem I once had. At the bottom of the gear level is a rubber bush that should be in the selector rail. On mine the rubber bush had worked its way up the gear lever allowing the gear lever to slop around quite a bit. I used a large washer to keep the rubber in place.

[abowie]

The only thing that made me suspect a selector issue (pretty rare) was the title of the thread and your reference to going PAST first gear and thereby provoking grinding.

This is what happens. It goes into first fine but grinds if I push the lever forward.

What do you want photos of?

[abowie]

Sounds like a problem I once had. At the bottom of the gear level is a rubber bush that should be in the selector rail. On mine the rubber bush had worked its way up the gear lever allowing the gear lever to slop around quite a bit. I used a large washer to keep the rubber in place.

Chris are you saying that there's a rubber bush in the selector mechanism at the bottom? Mins has no bush; just a metal circle that fits within the "cup" made by the ends of the 3 gear selector rods.

[PeterCrespin]

Chris is probably talking about the bushes that locate the stick in the selector quadrant or whatever it's called. That is just a polished metal tongue/tab working in the cutaways of the three rods - no rubber involved.

If the gear engages cleanly and silently the synchro is probably fine. If it only grinds when you shove the gearstick forward beyond first, then might I suggest you stop doing it? Reminds me of a Tommy Cooper doctor joke. For all I know my car would do the same but I've never tried!

I was wondering about a good closeup photo of the first gear synchro buy if the actual gear selection is OK it's probably OK.

[abowie]

If it only grinds when you shove the gearstick forward beyond first, then might I suggest you stop doing it?

Wise words. I'd still like to know why though....

[andrewh]

Sounds to me like nothing to do with first synchro as you are already cleanly in first after which it occurs. The snarling will be the mechanism trying to engage another gear at the same time. Someone probably left a vital shim, thrust washer or spacer out . I would start by studying a schematic of the box and trying to work out what is happening that way. I think it will be a strip down though