Blooming gearbox

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ben waine

Active Member
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588
I've got a 1984 series 3 diesel, the gearbox has a few issues, rattling overdrive handle (sorted that with a large socket) but when everything is warm, (say 10mile drive) if I'm in neutral and the clutch pedal is up, there's a rattling noise, any ideas what it is? From what I've researched it's the mainshaft nut that's loose???? Also when in 3rd or 4th, if I'm going along let off the throttle then back on the gear stick 'snicks'. Any help appreciated, yes I am a novice, please be gentle
 
snicks ?whats that ,loose m/s nut would cause a few issues 1 been jumping out of 1st /2nd gears, is it noisy in any gear ,difficult to engage 3rd 4th
 
No real difficulty engaging any gears, it doesn't jump out of gear, when I say snick the the gear stick moves, say I'm in 4th, let off power then back on, the gear stick moves backwards and makes a click when It's moved, but while crusing it's fine.
I've not noticed any particularly noisy gear.
Thanks ben
 
The rattling in neutral will be the clutch release bearing and it may grumble when pedal is down,not much to do as it;s a box out job.but may last a long time like that. Check the mainshaft nut by removal of over drive and at same time see if the slop in the linkage can be sorted.
 
check your gearbox and engine mountings if they are split gearbox can move on mount and gearlever is held in gaiter so will move in relation to moving gearbox.
Applying power will make gearbox lift even if mountings good but not as much.
 
Ill look into the mounts, (as taking the box out and doing anything meaningful is prob out of my skill set, also It's my only transport so can't just take it off the road for a week or 2), do I just check the mounts visually? And if the rubber is splitting it's fooked? Also can they be changed without engine removal?,
Thanks ben
 
Could movement be caused by broken 3/4 syncro springs? And is it worth dropping the oil to see if anything unwelcome is present?
 
I've done an oil change (engine, main box, transfer and OD) there were some dust sized metallic pieces, but nothing like a chuck, (Didnt seem anything worth worrying about) and is there any way to check the synchro springs without taking the box out ( I can't see a way)
 
ben waine said:
No real difficulty engaging any gears, it doesn't jump out of gear, when I say snick the the gear stick moves, say I'm in 4th, let off power then back on, the gear stick moves backwards and makes a click when It's moved, but while crusing it's fine.
I've not noticed any particularly noisy gear.
Thanks ben
Click to expand...

if its a d suffix thats normal as like later boxes dog teeth were shaped so that load pulled selector hub and gear in to greater mesh ,but it can be a sign of mainshaft moving as gear teeth are helical and so shaft has a force along it one way under load and the other on overrun with everything as it should be you dont notice this but you would if there was movement in shaft
 
You can do the mounts with everything in place, just make sure handbrake is disconnected and jack up the back of the box to change. Dont lift it too far. Worth changing as they are cheap
 
the rattle you hear when in neutral with your foot off the clutch pedal and ticking over "could" be the shudder springs in your clutch friction plate

over time they can become slightly compressed and loose which creates a rattle on tickover, it's not necessarily something to panic over but damned irritating

i've even "broken" shudder springs in two 9.5" borg and beck clutch plates in my Series, really annoying when one spring broke into four pieces and then hopped out into the clutch pressure plate and created a "dragging clutch" when i attempted to release it

i've not seen a S3 clutch release bearing yet that rattled, so far they either "appear" to work pretty quietly or wear/dry out/sieze up (mostly dry and sieze) at which point they then spin on the carrier and melt it, the first giveaway is the bite point gets closer to the floor until eventually the pedal goes solid as the slave cylinder runs out of travel

gearbox noises are generally whines that get louder as the wear gets greater, the gearstick movement when "on and off" the throttle has potentially been explained as the "shape of the teeth" i think i'd probably go along with that but i don't possess a later box to compare
 
Thanks for all the replies chaps, I think I'm going to look into the gearbox and engine mounts, and not worry about the rest ( as from what I understand, it probs won't blow up soon and also have minimal funds!) so thanks again:)
 
I'd look at the mainshaft nut as well. It won't cost anything and , from what I understood from mr.martin's post, is a strong candidate for allowing the movement.
 
Ok I will do, is there any way of viewing it without taking the overdrive off? I.e that inspection plate on top of the box? At this stage I'm not bothered about tightening it, to to look and feel how loose it is.
Thanks ben
 
No you wont see it with over drive still fitted. If you look on my rebuild thread theres a few pics of it and of fitting the tab washer if it'd help
 
Thanks chaps, am i safe to lift the engine with a bottle jack and a thick bit of wood on the bottom of the sump, or am i likely to damage the sump?
 
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