peterjjoc Posted November 11, 2009 Share Posted November 11, 2009 HI, The gearstick in my 1979 Series III wont move, i think the only gear i have is third. The clutch seems fine as i can drive in third, but just cannot select any other gears, if i clutch it comes out of gear. I have removed the top of the gearbox, and all looks fine. Unfortunatelty i dropped a little roller into the top while trying to remove them, I am draining the oil and hopefully the litte roller will come out with the oil. Would it be the syncro springs, if so is this towards the engine or toward the back of the gearbox, should i be able to see them through the top to the gearbox. How can i rotate the gears in the gearbox to see if there is anything like a broken syncro spring. Any ideas would be gratefully accepted. Quote Link to comment Share on other sites More sharing options...
rtbarton Posted November 11, 2009 Share Posted November 11, 2009 The top off and the detent rollers and balls out of the way can you move the selector rods? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted November 11, 2009 Share Posted November 11, 2009 If I remember right, there's a roller under the brass cap on the top of the gearbox cover, then 4 spring loaded ball bearings (2 either side). Drop the oil and hopefully any bits will come out. A flat piece of sprung steel is from the synchro hub, and there are 3 altogether. The hub usually still works ok if only one spring is bust, but symptoms of a failed hub is usually it jumps out of gear on a neutral throttle/going downhill. I think a worn or broken synchro mesh would just chuck it out of gear/noisy engagement. I would guess at selector mechanism, rather than something internal. Check the pinch bolts for the selector forks are nice and tight and that the forks aren't broken. You can remove the forks without dismantling the gearbox, but there's a trick to it. Les. Quote Link to comment Share on other sites More sharing options...
peterjjoc Posted November 11, 2009 Author Share Posted November 11, 2009 With the top off i can move the reverse and 1st and second rods ok, the third rod will only move a small amount. Everthing inside looks fine and the oil level was ok. Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted November 11, 2009 Share Posted November 11, 2009 Its probably down to a displaced syncro spring in the 3rd/top syncro Quote Link to comment Share on other sites More sharing options...
Snagger Posted November 11, 2009 Share Posted November 11, 2009 Its probably down to a displaced syncro spring in the 3rd/top syncro That sounds very likely - a broken or jammed synchro hub leaf spring could freeze the hub in an engaged position. Quote Link to comment Share on other sites More sharing options...
Johnyninetynine Posted May 30, 2022 Share Posted May 30, 2022 Did you resolve the issue with the gearbox stuck in third? The same issue has just happened to my series 3. Stuck in third gear , the clutch still works and the overdrive still engages using the clutch. The gear stick is locked in position. I have taken the overdrive off and checked the main shaft nut is tight. But can’t see any thing obvious yet. Started to take the floor up to get to the selectors. Quote Link to comment Share on other sites More sharing options...
Cornish Rattler Posted May 30, 2022 Share Posted May 30, 2022 It could also be the flap thingy for selecting reverse that the bottom of the lever moves to engage reverse, had this trying to fit a slickshift as the instructions didn't say it had to be removed 😡 Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 31, 2022 Share Posted May 31, 2022 6 hours ago, Cornish Rattler said: It could also be the flap thingy for selecting reverse that the bottom of the lever moves to engage reverse, had this trying to fit a slickshift as the instructions didn't say it had to be removed 😡 That tends to fall flat across the 3rd/4th selector and prevent the lever from entering that gate, limiting you to forward gears but not restricting them if the springs on the flap fail. Quote Link to comment Share on other sites More sharing options...
Johnyninetynine Posted May 31, 2022 Share Posted May 31, 2022 Thanks both, the gear stick is completely stuck in third and can’t move. The spring on the reverse flap is still intact and in place. I have managed to get all the floor up now and the selector rods are all locked solid. Today I will have the top off the selectors. The main shaft is locked in gear but when the clutch is depressed the main shaft can be turned. Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 31, 2022 Share Posted May 31, 2022 Almost certainly broken leaf springs in the synchro hub, then. Quote Link to comment Share on other sites More sharing options...
Johnyninetynine Posted May 31, 2022 Share Posted May 31, 2022 So I have opened it all up following a bit of a YouTube search and have the selectors out. Pressing down on the clutch with one hand I can rotate the main drive shaft until I can see the leaf spring which is unfortunately in place and appears undamaged. Quote Link to comment Share on other sites More sharing options...
steve b Posted May 31, 2022 Share Posted May 31, 2022 There is more than one I think three from memory , should be one between each rod. Steve Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 1, 2022 Share Posted June 1, 2022 Correct, three springs. They sometimes shatter in a way that they can look intact by are wedged between the moving parts of the synchro hub. Drain the oil through a sieve and see if you get any shards of dark grey metal. But even if it’s clean, my money is still on those springs, and the box has to come out and be stripped down to fix it. Quote Link to comment Share on other sites More sharing options...
Johnyninetynine Posted June 1, 2022 Share Posted June 1, 2022 Thanks Snagger/Steve b, I will be in there this afternoon to have a better look, I found a YouTube video on replacing the springs although the guy doing it had some “modified” tools, looks like it can be done without taking the gearbox apart. Will let you know how I get on. One I know. Ordered the springs any way as they are on pennies. Quote Link to comment Share on other sites More sharing options...
steve b Posted June 1, 2022 Share Posted June 1, 2022 Yes , no need for a full strip down . once TB guide is off and layshaft bolt removed the front will come off then the cage is right there an with the selector fork already out it just comes out . Did you order a new needle roller cage for the mainshaft to input shaft ? Another thing to note is the reverse detent ball spring is much stiffer than the forward gear detent springs . Steve Quote Link to comment Share on other sites More sharing options...
Johnyninetynine Posted June 1, 2022 Share Posted June 1, 2022 Had a proper look at it and yes 2 flat springs have been eaten by the gearbox the third one was jammed forward locking it in gear. Just sit and wait for the bits. Thanks for the guidance guys. 1 Quote Link to comment Share on other sites More sharing options...
Snagger Posted June 2, 2022 Share Posted June 2, 2022 Many of us have had the same thing. I tried to replace the springs in situ, but ended up removing the transmission. It doesn’t require a full gear box rebuild, but the bell housing has to be separated from the gear box case to get the synchro unit out for repair. It is worth replacing these springs any time the gearbox is opened as they do this fairly reliably with age. If you do remove the gearbox, it may be worth checking your clutch and spigot bush while it’s all open. Quote Link to comment Share on other sites More sharing options...
Johnyninetynine Posted July 10, 2022 Share Posted July 10, 2022 (edited) Managed to replace the springs in situ. Would not have been able to do it without the 11” pliers set. Synchro now working. I drained the oil out of the gear box as I dropped the springs a couple of time whilst trying to fit them. Now putting it all back together I found that I can’t remove the filler plug on the side of the gearbox. Lots of effort and I eventually got it off. Decided to replace the mid and rear section of the exhaust whilst I had the seat box out and that of course was not straight forward. However it is all back together now and I have had a short drive to see if it works. So far so good. Edited July 10, 2022 by Johnyninetynine To correct my spelling. 1 Quote Link to comment Share on other sites More sharing options...
Arjan Posted July 10, 2022 Share Posted July 10, 2022 Good ! Alwiays nice to read a positive result ! Quote Link to comment Share on other sites More sharing options...
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