gearbox/clutch rattle

[PhilXXJ]

ive noticed a rumble /rattle with the clutch out in neutral . it disappears at about 1200 rpm or dipping clutch so im thinking maybe spigot bearing worn away .. or worse? I put a new one on when I fitted the box about 35k ago.

[CovKid]

Could be - or release bearing more likely.

[Aidan]

which engine ? which box ? what clutch set up ?

AAZs in t3s do this a lot, so do some TDi's especially if using the 215mm clutch or a hybrid clutch set up

[PhilXXJ]

its an AAZ engine, Aidan with the 1.6D clutch and 5 speed box from a 1.6TD ( 094? ) if its the release bearing, wouldn't it more likely happen with clutch pressed?

[Aidan]

snot the release bearing, it's either the centre plate of the clutch or the 1st reverse synchroniser oscillating back and fro between the gears and going clack clack clack (the two gears are spinning in opposite directions so the synchroniser touches one is spun one way, bounces against the other gear and it's spin is reversed
if you look at the centre plate of the TDi clutch it's quite a bit different springwise, but like I say even some TDi with TDi flywheel and clutch do it, spring breakage is fairly common
the 215mm clutch isn'r really upto the torque of the AAZ long term, it was marginal with the 1.6TD but depending on how much JX is in the AAZ installation it could also be a slight misfire on the engine (diesel misfires are virtually impossible to detect and fix) causing a pulse on the drive so on, off, on, off, again causing the gears to pulse

If you've got 30k miles out of the clutch then it's probably due for replacement, it's the same clutch as used in the 1.6 NA diesel where they do 60k miles but with a lot less power and torque and driven softer generally

[PhilXXJ]

thanks for the info., will be putting a new clutch in soon so will eliminate that possibility, could be the synchroniser thing.. the clack clack is more of a 'dull' clackity clack. If it is this will it cause major damage if left? The AAZ is all AAZ as it was a 1.6n/a previously apart from a jx airbox I put behind the light cluster. I guess the misfire is also possible as it sounds more prominent when the engine is cold and disappears when revved to above 1200rpm.

[Aidan]

try and isolate where the noise is coming from, front of box is 1st reverse synchro, bellhousing it is clutch; but it's really hard I find to zero in on noises on a diesel though as even with a stethoscope or screwdriver to ear most of what you can hear is the pump on the engine which is really noisy and that noise is pulsed through the engine and driveline

also take a look at the engine and gearbox mounts to see how much it vibes that pump pulse can sometimes be evident at the mounting points, check bolts are all still tight

if it's the synchrohub then they can sometimes fail, they are riveted construction three legs hold the sandwich together and the slider is banging against the legs to make the clacking noise, but usually they fail when something else goes breasticles up like 1st gear needle bearing collapse which is due to wear in pinion bearing allowing the shaft to move under laod and compromise the space that 1st gear is in.

Oil change will give you an idea of overall wear in the box since last one