Hello,
I have a Moss gearbox that does not enter into first gear. The second synchro sleeve doesn’t seem to go all the way in. Here is a picture of my main shaft and syncro assembly. It appears to look differently than that of Rob Reilly’s neutral gear picture (18 May 96). Is it likely to be my first gear problem or should I be looking for something else (ball and plunger?).
Barrie
Yes, most likely it is a problem with the ball and plunger set not being in the groove in the mainshaft. Try pushing your second synchro sleeve rearwards a little bit and then see if the first gear will move.
Rob, The synchro sleeve is not seem to have moved. Here are some pictures showing how my first gear moves. Do you have any ideas on how to unstuck the sleeve (I’ve used ATF transmission fluid). This gearbox is not been used for at least 30 years.
I take it that you are selecting 1/2 gears with the top cover off,
ie it is not a problem with the 1/2 gear selector shaft.
I recall when the stop rivet is worn on the drive hub the selector
hub can move to far rearward allowing the interlock balls
/springs to pop out,so place a block of wood at the back of the box
and give the first gear a clout with a hide mallet to see if you can free it up.
If not problem ,I guess ,is interlock balls/springs plungers.
I observe that one photo shows second gear fully engaged!
It looks like the second synchro sleeve is in contact with the second gear wheel synchro.
Try a prybar to move the second synchro sleeve back about 1/8" or 3 mm. It has to be in the neutral position in order for the first gear to move back.
You are hopefully aware that first is non-synchro and that the teeth must be lined up to engage, so turn the shaft a bit as you try it.
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Rob,
Prying didn’t do anything so I checked the back side. It seems that the back syncro assembly moves correctly from neutral to second (pictures). That leaves the ball and plunger as the problem. I measured .040” between the ball and the hub while in neutral (second gear measured .010”). This was hard to measure but I think the ball and plunger were in the right place to go to first gear.
I have tried to look at the non-synchro teeth lineup but I learned that the teeth don’t seem to engage together at all. However it gets very hard to stop the two sides of the mainshaft to work together.
I’m afraid I’m going to have to open the gearbox completely unless you have any better ideas.
Barrie
It looks like your second synchro sleeve is moving too much.
This sleeve has to be in neutral position with the ball/plunger in the mainshaft groove in order for the internal tooth on first gear to pass over the ball/plunger set when it moves to the rear.
All I can think of is that your ball/plunger set is up out of the groove and preventing the first gear from moving rearwards.
If you put it in second, you should be able to rotate it and see that all seven balls are in place.
Here is one I have here, a JLE. I apologize for the rust. I found this box in a field with the top cover bolts all missing so it was full of water.
First gear.
Neutral.
Second gear. Notice the balls half visible.
Rob,
Yes, my first gear works!!! Your pictures showed me how it might be the problem. I tried moving the hub to the front a little and suddenly the syncro sleeve moved to the back. Obviously the ball and plunger had moved down, allowing the first gear to go in. Here are some pictures.
Unfortunately, when I put the selector rods back into place, first gear will not go back again. The hub wants to go all the way back before the ball and plunger moves the syncro sleeve. Do you know how the back of the hub should be? Neutral seems to be 0” back but first gear seems to require 1/8” forward.
Barrie
Well, I measured the gap in mine and it is about .036" so your 1/8" seems large, but that may be a matter of your synchro cone being more worn than mine.
But that would not explain how your ball/plunger is not staying in the groove.
It could be your rear bearing is not pulled in all the way.
This would allow the second synchro sleeve to move too far to the rear.
I wrote this in '94.
“Another discovery I made was that you have to tighten the tailshaft nut all the way, thus pulling the mainshaft bearings to their proper places in the tailcase, and then back off on the nut just a bit to relieve the preload on the bearings.”
We have to go back and ask what is the history of your box, if you know? Has it been apart?
Can you try turning your tailshaft nut? I find it easiest to do this if I put it in two gears at once, like 1st and reverse, or maybe in your case 2nd and 3rd.
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You’re right - the tailshaft should be tightened. It’s the only thing I can think of. What do you use to lock the two gears together?
Barrie
It is easiest if you can get it into 1st gear. Then also push the reverse gear lever back so reverse gear moves forward into mesh. Then it is in 1st and reverse simultaneously and they are locked.
If you can’t do that, here is the alternate method.
You can use a hammer and a flat end punch to drive the 3rd/4th synchro into either 3rd or 4th. You are overcoming spring tension so you have to hit it pretty hard to get it moving, then it is easier to continue moving it. Then drive the 1st/2nd gear forward into 2nd the same way.
Now you can put a wrench on the tailshaft nut and tighten it down. Remember to back it off maybe half a flat to a full flat afterwards. You probably will have to anyway to get the cotter pin in. Then feel it. It should turn fairly easily, not binding up.
Rob,
My first gear now works perfectly. Thank you very much. I don’t understand why I didn’t think of this first or at least after five or six times.
I used 1st gear and reverse as you suggested. At first the tailshaft nut was hard to move but after that it was easy to move about 0.09”. One flat was used to install the cotter pin and now everything looks OK. With the top cover closed, I can easily move first gear in and out (and second gear as well).
Thanks again,
Barrie
Delighted to hear it!
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While looking on the internet about Moss gearboxes I ended up here. I’m trying to rescue a nice first gear and hub from the land fill. Can anyone use it?
We would need pictures and identification numbers from the outer case to figure out what cars it is from.
Hello
I just received my XK 140 roadster 1955 with the famous original Moss gearbox…
When I put in the first gear ( not synchronised …) sometimes it goes softly without cracking and sometimes it is a nightmare … Do you have any ideas to improve this ?
Sorry for my English
Best regards
Hi Frank:
Have you tried pulling it back into second gear and then pushing it through into first?
Chris.
Hi Chris
No I did not I’ll do that this weekend and keep you tuned
Frank
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