Issue with second gear slipping out...

[SteveHall64Healey]

I’m having an issue with my BJ8 going in to second gear where shifting normally (gently) into second results in grinding and slipping out of second gear. First, 3rd and 4th all work fairly smoothly.

In going from first to second, if I pull the shifter hard into second gear (pulling back very firmly as far as the selector will go), and then give immediate throttle, it will go into second and stay there with no drama.

A local Healey colleague thought that an adjustment to the 1/2 selector fork might help. I suppose this would entail moving that fork forward slightly relative to its current position.

Has anyone dealt with this problem and does this seem a plausible solution?

thanks
steve

 

[Bob_Spidell]

I just rebuilt a BJ8 gearbox and didn't see any sort of 'adjustment' for any of the shifter forks; all forks are held in position by a set pin that goes into a hole in their respective shift rod (can supply a photo later when I get to my own computer).

Sounds like what you have is a worn 2nd gear synchro. Second is typically the gear you change into and out of most often, so its synchro is usually the first to go.

Edit: Just re-read the post and realized you also have an issue with the gearbox coming out of second. I rebuilt my gearbox because it jumped out of fourth, but I think the causes may be pretty much the same: 1) end play or wear in (in this case) the layshaft and/or 2) wear in the 2nd gear cluster. It's also possible your 2nd gear selector fork is excessively worn, not allowing the hub to engage completely.

 

[SteveHall64Healey]

Hi Bob,

The issue is usually going from first to second. Unless I pull hard back on the stick and immediately hit the throttle, it will grind and likely pop out of second. If I pull hard then hit the throttle it works smoothly. Downshifting from 3rd has the same issue and the same workaround works.
steve

 

[red57]

I would check the bushing on the ball at the bottom of the shift lever - these can wear and/or disintegrate leaving you with a very sloppy shifter that doesn't move the shift fork far enough to fully engage the gear. Easy enough to check.
Dave

 

[SteveHall64Healey]

Thanks Dave. I checked the ball end and it appears to be in VG condition. Also, I replaced the plastic end cup that sits on the bottom end of the stick last winter.
steve

 

[Bob_Spidell]

Hi Bob,

The issue is usually going from first to second. Unless I pull hard back on the stick and immediately hit the throttle, it will grind and likely pop out of second. If I pull hard then hit the throttle it works smoothly. Downshifting from 3rd has the same issue and the same workaround works.
steve

Sounds like the synchro, and or second gear shift hub or gear cluster. Inside the shift hub, there are detents, balls and springs that hold the gear, if one of these got damaged somehow it could cause the problems, I suppose. Here's the gearbox from the top; note there isn't anything to adjust:

 

[Randy Forbes]

Do you want the bad news (there is no good news)?

Any way you look at it__unless you just keep living with it (which will ultimately cause more wear the longer you do)__is it's a xmsn out repair.

As Bob alludes to, the synchromesh is worn out; the brake ring is likely worn smooth on its inner conical surface__or will be__as well as having the "dog-points" worn down. The reason it pops out of gear is wear in the synchromesh hub itself (this can sometimes be corrected with__3-each__fresh springs and balls).

1st/2nd gear synchro hub being assembled; this from a side-shift, but the center-shift is identical.

This is what the inside of a synchro ring is supposed to look like (they'll either be bronze for the early cars, or steel for the later ones). Fourth gear shown, but they all look the same, just different diameters (I've taken them out completely smooth, which is what you'll see if your issue isn't corrected...).

1st gear being assembled onto the mainshaft; 2nd gear synchro ring will be sandwiched between hub assembly and 2nd gear (1st is straight-cut, 2nd is the largest helical-cut gear).

Assembled in the case, c/s trans is identical, but looking downward from top.

Shift rod inter-locking balls (prevents more than one gear being selected) and "detents" that also assist with maintaining the gear selected.

No adjustments here!

The balls and springs that maintain gear selected are the last to go in before side__or top__cover installed.

 

[SteveHall64Healey]

Thanks. I was hoping something short of removal and rebuild would carry me through to winter, when I had planned to send the unit out for rebuild. BTW, I replaced the springs and balls over the winter. This had no effect other than to make shifting from gear to gear much heavier and more difficult.

I’ve never rebuilt a gearbox - is it worth attempting? Is there a publication anywhere that covers the process?

 

[Jack T]

[QUOTE

I’ve never rebuilt a gearbox - is it worth attempting? Is there a publication anywhere that covers the process?[/QUOTE]

The workshop manual covers it.

 

[Randy Forbes]

Thanks. I was hoping something short of removal and rebuild would carry me through to winter, when I had planned to send the unit out for rebuild. BTW, I replaced the springs and balls over the winter. This had no effect other than to make shifting from gear to gear much heavier and more difficult.

I’ve never rebuilt a gearbox - is it worth attempting? Is there a publication anywhere that covers the process?

Deja vu...

Ask Bob (hint: he asked me the same question a year ago_?_and now has a rebuilt xmsn by his own hands).

The Complete Official Austin-Healey 100/6 & 3000 manual will cover all the text, and you are welcome to use the pictures in my gallery to fill in the gaps.

In a word: doable.

Disclaimer: I'm in the process of outfitting a new server, so access is/has been/might be spotty in the immediate future (and recent past) but things should go back to normal pretty soon. You can also ask me for a new link, but spcarsplus.com should at least get you to a home page; I made need to post links to the pertinent albums once the "links settle down" (being hopped from a borrowed server at the moment).

At the moment, this is the main "gearbox album" there are several albums embedded within, which will be obvious once you open it: https://spcarsplus.com/piwigo/index.php?/category/118

 

[Michael Oritt]

I have heard it said that continued driving with a hand on the gear lever can cause this condition. Is this true?

 

[Randy Forbes]

I have heard it said that continued driving with a hand on the gear lever can cause this condition. Is this true?

I don't think so, but if you look at the mechanics of it, riding with your hand on the lever will put unnecessary wear on the shift forks (the area that comes in contact with the rotating gear when sliding it in/out of the synchromesh hubs). The forks are only made of a bronze material, so they'll wear down at a much higher rate than the steel they're acting upon.

Well, I would like to post a picture to illustrate, but it seems my server's host is offline again (settling for a generic google image...).

Riding with your hand on the lever would impart wear on those machined semi-circular areas seen above (the machining on the backside will be the same). So if you have a gearbox that pops out of gear__usually on the over-run, when letting off the throttle__the natural tendency would be to hold the lever in the direction to maintain engagement, exacerbating the the condition.

 

[Bob_Spidell]

... I’ve never rebuilt a gearbox - is it worth attempting? Is there a publication anywhere that covers the process?

Yes! I was more intimidated by the OD, but it's pretty straightforward once you understand the operating principle--I changed my OD dis/engagement procedure I'd used for 30 years after the rebuild--but the gearbox was somewhat more challenging (lots of 'fiddly bits' as Edd China would say). Randy was a lot of help, especially with encouragement. Of course, study the manual, and there's some good videos here, and elsewhere on the 'net (just do a search on 'Austin-Healey gearbox rebuild):

https://healeyspecialists.com/videos/ and here: https://youtu.be/9rz6b8ZWXfc

Typically, the layshaft is worn at both ends from the side load; Denis Welch sells an 'uprated' one. I also used DW's thicker, cupped shims, which required some machining of the bellhousing and the OD adapter. Magnus mentions the importance of the shims in one of his videos, to prevent 'jumping out of gear' (usually, fourth) but didn't mention the thicker ones, but it appears from the video that the box he was working on had them.