Jumping out of gear downhill

Hi Guys I've just put a newly built reconditioned gearbox back into the series 3, everything was going fine on the first test drive until I go down a hill, it seems to jump out of gear, now this happens on all gears, have I done something wrong? Was thinking the main shaft castlelated nut might have come loose or not tightened properly and I'll have look at that later, but is there anything else I should look for? I really don't want to take this box back out if I can help it, I'm I being pessimistic if I think it might just need run in and it will settle down? These things in my experience just get worse, thanks all hope your all safe and well

What gear/gears are coming out?

tottot said:

What gear/gears are coming out?

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Hi tottot all of them, I say that haven't tried going down hill in 1st but definitely 2nd 3rd and 4th

Could be that selectors are not set correctly, jamesmartin will know and hopefully be along shortly.

tottot said:

Could be that selectors are not set correctly, jamesmartin will know and hopefully be along shortly.

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Thank you that has been mentioned to me that it might be the cause

hi update had a good check today and its only 2nd and 3rd gear its jumping out of and its only doing it going downhill

Cristoforo said:

hi update had a good check today and its only 2nd and 3rd gear its jumping out of and its only doing it going downhill

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did you adjust the 3rd and 2nd gear clearances and the bush

jamesmartin said:

did you adjust the 3rd and 2nd gear clearances and the bush

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Hi James thanks for your help with this, I didnt rebuild the box, the guy who did it says it might be the selectors are not set properly and if that doesn't work he will send me a new box, but I was hoping it was a easy fix so i didnt have to take it back out again, Whats your thoughts on the selector issue ? and if it is could it be done in situ and how?

Cristoforo said:

Hi James thanks for your help with this, I didnt rebuild the box, the guy who did it says it might be the selectors are not set properly and if that doesn't work he will send me a new box, but I was hoping it was a easy fix so i didnt have to take it back out again, Whats your thoughts on the selector issue ? and if it is could it be done in situ and how?

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you can adjust the selectors after removing the detent balls springs and then the top, its possible its that but my moneys on too much gear end float,

Oh dear sounds like box out job, is there a guide to how to adjust the selectors to cure this or is it trial and error? Thought I might as well try before removing the box Again

I would keep working with the guy who rebuilt it. He sounds reasonable. You don't want it to go on too long and end up becoming your problem not his.

rob1miles said:

I would keep working with the guy who rebuilt it. He sounds reasonable. You don't want it to go on too long and end up becoming your problem not his.

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yes to be honest the guys ok hes seems a genuine sort of fella and hes being fair, wants me to adjust the selectors, and if that doesn't work he will send a new box out, to be honest its the nicest changing series box ive driven if it wasn't jumping out of gear id be well chuffed with it, I just wanted to try and sort it so i dont have to take the box back out, Not really up on gear boxes so ill take the top off and see if there is anything obvious, do any of you know how much adjustment can be done on the selectors and really what adjustment can be done? cheers all

Cristoforo said:

yes to be honest the guys ok hes seems a genuine sort of fella and hes being fair, wants me to adjust the selectors, and if that doesn't work he will send a new box out, to be honest its the nicest changing series box ive driven if it wasn't jumping out of gear id be well chuffed with it, I just wanted to try and sort it so i dont have to take the box back out, Not really up on gear boxes so ill take the top off and see if there is anything obvious, do any of you know how much adjustment can be done on the selectors and really what adjustment can be done? cheers all

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yes i rebuild them, ensure you remove the 3 detent balls first

jamesmartin said:

yes i rebuild them, ensure you remove the 3 detent balls first

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i was going to do this with a small magnetic screwdriver so i have no possibility of them dropping in the box, James is there much adjustment I can do to the selectors ? I know you think thats not the problem but your advice on the selectors would be welcome

Cristoforo said:

i was going to do this with a small magnetic screwdriver so i have no possibility of them dropping in the box, James is there much adjustment I can do to the selectors ? I know you think thats not the problem but your advice on the selectors would be welcome

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not too much about 3-4 mm ,you hold selector in its neutral position slacken pinch bolt slide selector up/down its full travel then tighten the bolt when its in the middle

Thank you James I'll have a go tomorrow and let you know if it's worked or not

Cristoforo said:

Thank you James I'll have a go tomorrow and let you know if it's worked or not

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a marker pen or such helps ,push to one extreme and mark then to the other,then you can place fork in between the 2 equally,bearing in mind the cutouts in selector shafts have to align fully with detent and interlock grooves as they would when it was complete

Hi all and especially James thank you for your advice, sadly it didn't work I adjusted the selectors but it still jumping out of gear, credit where credit due though, I contacted the guy who built it and he's also been very helpful and fair and there is a new box going to be sent to me, I know its a pain when these things happen but when you get good service from the supplier it makes it a bit better thanks again all and I'll see you all when I break something else lol

I think that's the best outcome. He can sort it out in his workshop, keep his good reputation for service and you get your problem fixed.