rustyrhinos
Well-Known Member
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- Stamford, Lincs
I know I have another thread on gearboxes, but that is bloated out to 8 pages now and will take trawling through so thought I would start a new one.
To cut a long story short, we originally took the box out because I ended up punching a hole in the box caused by clutch release bearing seizing - it was a sloppy box, jumped out of gear and all sorts so it needing sorting anyway. So got another box and set about doing a semi rebuild - so replaced anything that looked aboiously worn - we did the layshaft (series 3 later 1 piece layshaft), reverse idler and a few other service items.
After "rebuilding", box felt fine but started jumping out of 4th gear it seems to do it anywhere between 5 and 15 miles - there is no pattern to it - i.e it will do it randomly, not just on overrun, not a high speed/revs, not under load, etc. It will jump outof gear regardless of weather it is in overdrive.
Suspected it was the syncro unit and also shimmed up 3rd gear (now 0.16 which is supposed to be within toleraces). 1st/2nd selector fork was worn so did that at the same time as well as the mainshaft bush and thrust washer, 3rd gear thrust washer and shim....put box back in again, and it still jumps out of gear. Noooooo!!!! So thought perhaps was the detent springs - replaced - still jumps out of 4th gear. Nooo!!!! No strange noises, changes gear lovely, not sloppy etc just jumps out of bloodey gear! Mainshaft nut has been checked tight by the way.
So today have taken the box out again to see if I can see whats wrong, and I am really struggling. Bought and fitted gearbox pinion (pair) and replaced the primary pinion bearing and needle roller bearing, but to be honest, it had little wear or play - so I really doubt thats the problem. What i dont want to do is go to the effort of refitting (yet again) for it just to jump out of gear.
So....I guess my questions are
1)Any more suggestions to why it might be jumping out of gear still
2)The 3rd/4th Syncro clutch has a bit of play in it - about 4mm back and forth - is this normal?
3)The 3rd gear has 0.16 play - the workshop manual says tolerance is up to 0.18...so that should be OK? But would that make it jump out of 4th gear anyway?
By the way, it's a 1963 SWB Series 2a (2a/3 box)
To cut a long story short, we originally took the box out because I ended up punching a hole in the box caused by clutch release bearing seizing - it was a sloppy box, jumped out of gear and all sorts so it needing sorting anyway. So got another box and set about doing a semi rebuild - so replaced anything that looked aboiously worn - we did the layshaft (series 3 later 1 piece layshaft), reverse idler and a few other service items.
After "rebuilding", box felt fine but started jumping out of 4th gear it seems to do it anywhere between 5 and 15 miles - there is no pattern to it - i.e it will do it randomly, not just on overrun, not a high speed/revs, not under load, etc. It will jump outof gear regardless of weather it is in overdrive.
Suspected it was the syncro unit and also shimmed up 3rd gear (now 0.16 which is supposed to be within toleraces). 1st/2nd selector fork was worn so did that at the same time as well as the mainshaft bush and thrust washer, 3rd gear thrust washer and shim....put box back in again, and it still jumps out of gear. Noooooo!!!! So thought perhaps was the detent springs - replaced - still jumps out of 4th gear. Nooo!!!! No strange noises, changes gear lovely, not sloppy etc just jumps out of bloodey gear! Mainshaft nut has been checked tight by the way.
So today have taken the box out again to see if I can see whats wrong, and I am really struggling. Bought and fitted gearbox pinion (pair) and replaced the primary pinion bearing and needle roller bearing, but to be honest, it had little wear or play - so I really doubt thats the problem. What i dont want to do is go to the effort of refitting (yet again) for it just to jump out of gear.
So....I guess my questions are
1)Any more suggestions to why it might be jumping out of gear still
2)The 3rd/4th Syncro clutch has a bit of play in it - about 4mm back and forth - is this normal?
3)The 3rd gear has 0.16 play - the workshop manual says tolerance is up to 0.18...so that should be OK? But would that make it jump out of 4th gear anyway?
By the way, it's a 1963 SWB Series 2a (2a/3 box)