Series III Gear box issues

[pvkd]

My 109 Series IIa has a Series III gear boax in in. Occasionally my Landie will jump out of third gear. This only happens in high range. The vehicle does have an overdrive fitted – would this make any difference? Any ideas on possible causes and remedies?

[LaneRover]

If memory serves me correct that is a sign that the 3rd gear synchro is going.

[Jim-ME]

I agree.

[Apis Mellifera]

Here's a bit of hope for you:

Mine did the same thing so I bought new detent springs. While changing them, I discovered that the 3/4 detent ball was stuck in the hole and wasn't actually contacting the shift rod. Half the hole is in the gearbox case and the other half is in the cover. This is how the hole can get out of round. I removed the ball, reinstalled the top, and then drilled out a few thousandths. Works a treat now.

[pvkd]

Because the syncro rings are new (a couple of 100 miles old) the above note sounds interesting. Can I perform this check with the gearbox in the vehicle?

[Apis Mellifera]

Yes, remove the gearbox tunnel and the detent balls/springs are easily accessible. If they don't come out with a magnet, they're too tight. On mine, the reverse ball was free before I removed the top cover to fix the 3/4 ball. After assembly, the reverse ball became tight and required repair. It's just a poor design. The 1/2 detent is how they all should have been.

The interesting thing is, I found a note to the dealer dated 10/3/73 under the driver's seat (of my '73 88). It complained about poor acceleration and jumping out of 3rd.

[Daurie]

The interesting thing is, I found a note to the dealer dated 10/3/73 under the driver's seat (of my '73 88). It complained about poor acceleration and jumping out of 3rd.

My guess is there was no fixing the first item on that list!

I will second the detent ball recommendation. After replacing the 3/4 syncro in my S3 gearbox I couldn't get the trans to shift into 1st. I instantly began sweating and cursing as I'd been dealing with the issues at hand long enough. Luckly after removing the brass "plug" on top that retains the 1/2 detent spring and ball and removing the filler cap to visually inspect as I attemped to shift it, the shifter sild easily into 1st. Strangely enough it would go into second but not first. I immideately realized the problem and had it fixed right away.

With so little milage on the syncro I would definately suspect the detent ball. While you're in there just for good measure I'd inspect the detent springs. I had a rebuilt trans give me syncro detent spring trouble and turned out the syncro springs were too long and were breaking off. I replaced them twice to have them break again within 200 miles! Did you replace the syncro with an aftermarket unit or Land Rover?

Good luck!

[pvkd]

Daurie,

I am not sure what the person I had do the work did but I would suspect there were Britpart replacements from British Pacific.

Sorry if this is a dumb question but how do I get acess to the 3/4 ball and spring once I am looking at the gearbox?

Paul

[scatterling]

the 3rd/4th ball is on the left side of the box and the reverse ball is on the right ( if you're facing the front). There is an 'L' bracket in either side of the box holding the balls and springs in place. Remove the 2 bolts that hold the bracket in place and the spring , rubber seal and ball should come out - if your ball is not hanging up it should come out with a magnet.
good luck
(Derek, sorry for hijacking your photo.)

[Daurie]

Daurie,

I am not sure what the perison I had do the work did but I would suspect there were Britpart replacements from British Pacific.
Paul

The reason I ask is because I had an aftermarket syncro assy. in my trans and after dealing with my syncro spring problem long enough I simply replaced the entire syncro with a genuine part. Upon initial inspection it was abundantly clear tht the Land Rover replacment springs were too long for the aftermarket syncro. The genuine replacment springs looked longer than the ones that came installed in the genuine syncro (go figure).

Just putting that out there..

Daurie

[pvkd]

Thanks to both of you this is very helpful. So I unscrew the brass plug (the left one looking forward as my issue is 3/4 not reverse) and I should be about to pull the ball with a magnet if not I have an issue with it getting stuck which is either a function of spring strength or case mis-match?

Paul

[Daurie]

It will not be the brass ""plug" . In your case, on the s3 gear box the 3/4 detent spring and ball are retained by an L shaped bracket on the left hand side of the selector shaft cover. As you're looking at the selector shaft cover the brass plug with the fill hole retainer is in the center and on either side of it will be the sets bolts that hold the brackets in place. of It is held in place by two short 1/4" bolts on the top side of the bracket. Careful when removing them as it has spring tension on it and once the last bolt clears it may let go resulting in flying spring and ball. It was tough for me but I managed to hold the bracket in place with one hand while I loosened the last bolt with the other. Getting it back together is a booger too and I used a small woodworking clamp to hold the retaining bracket in place while I started the bolts.

Good Luck!

[pvkd]

Daurie,

Thanks I took the tool box out to check the level of the overdrive and to see the "brass plugs" before I read your post. However I guess that the two L-shapped brackets on either side are the retainers. So I assume that looking from inside the vehicle forward the bracket on the left side is the 3/4 unit?

I am going on a club run this weekend so I will not attempt it just yet. I also noticed that the gear box oil level was a little low so I want to see it this and a 700 mile round trip changes anything first. This may be wishful thinking but we will see.

I take it from your post that the job is a little tricky. It appears that I may have access buy just removing the tool tray? It may depend upon how strong those springs are.

Thanks again,


Paul

[Daurie]

I probably wans't clear but you're correct the brass plug retains only the 1/2 shift spring. The L bracket is what you will be dealing with, the one on the left.

As far as doing the job from the tool tray access... I'm not sure.. I cant say I've really even looked at how accessable the selector cover is from that point. I would remove floor boards and the tunnel cover. It's only about a 10 minute job and you will have more working space. Not to mention you will be able to see alot more of the going on's of that area and check for problems.

Don't be intimidated by the job it's very straight forward. Just be aware of the spring behind the bracket.

Daurie

[Apis Mellifera]

Having just done this, I honestly don't think it's possible to change the springs without removing the tunnel. You definately won't be able to fix the problem if you find stuck detent balls. The springs really aren't under that much tension, but you do need to push the bracket in while tightening the bolts. That would be nearly impossible going through the seat hatch. No shortcuts here.