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Technical gearbox help.


sunshine

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Hello again.

 

Today I got my car down the garage to replace the clutch/flywheel and try to find the cause of the whine i've been experiancing...

 

Well i think i may have found the cause.

I noticed a large amount of play in the input shaft so i decided to remove the casing and have a look...

 

If you notice there is a large amount of lateral movement in the shaft, about 3mm. when pressed in the bearing makes no real noise, when pulled out there is a loud whine, i think this lateral movement is the cause of the noise.

 

The front casing where the bearing sits also has score marks/ pitting, further evidence of shaft movement.

 

I'm going to replace the input shaft bearing, but i belive the problem is with the ount of play in the shaft.

Can anyone here clarify if this is the cause or am i talking garbage!

Thanks

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Mine has started doing this also, I havnt had the time to have a look personally but it is a horrible noise and a little worrying. I would love to know what your solution is as I think im going to have mine apart soon to have a look

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Clutch release bearing. That's if it happens whenever you push the clutch in.

 

Need a new one... Not too expensive to buy but can cost a lot in labour to get it fitted.

 

I had the same sound/problem on mine before I changed the clutch that's how i know the sound.

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Clutch release bearing. That's if it happens whenever you push the clutch in.

 

Need a new one... Not too expensive to buy but can cost a lot in labour to get it fitted.

 

I had the same sound/problem on mine before I changed the clutch that's how i know the sound.

 

Hey mate it's the opposite, noise with pedal released.

Although the release bearing is being replaced with the clutch/flywheel/input bearing/pilot bushing anyway. If it's not cured this time next week after all this money I'm gonna rage!

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Had four gearbox related noise faults on four different 350`s in the workshop over the past 6 months ranging from 20k miles to 80k miles and all had the noise when the clutch pedal was up so suggested the gearbox input shaft bearing was tom blame, not seen the lateral play of this one but sure that is the problem in this case.

 

Jeff TT

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Yeah mate theres plenty of radial wear in the main bearing, theres around 5mm of play at the end of the shaft.

 

Currently the gearbox is off the car, going to take it apart tomorrow and have a poke around.

Waiting on Nissan to send me the replacement main shaft front bearing, pilot bushing and gaskets (stupid bank holidays).

 

By the way, is there a way to remove the transmission case without removing the rear extension? (the bit that houses reverse)

I've studied the factory service manual and it looks like the rear extension casing is bolted through the adaptor plate to transmission case, so if i'm careful theoretically i should be able to tap the transmission casing off the adaptor plate dowles without disturbing the rear extension? The reason i'm asking is because i forgot to order the rear oil seal to the prop shaft... :angry:

 

Oh, and how difficult is the main shaft bearing to put on?

I've got a hot plate to heat the bearing up and i'm gonna wrap ice around the input shaft for a few hours, will i be able to tap the bearing into place or am i gonna need a press (don't want to press it into place tbh)

 

You may have noticed by now, im a complete novice to be honest!

 

Sorry for all the questions, But there really is little information out there on these transmissions, thank god i found a factory service manual or i'd feel like Chuck Yeager :surrender:

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Think we have spoken via PM before , to change the bearing is a complete gearbox strip , your need to remove the gear cluster from the gearbox casings , large press and a puller are required to get the gearbox apart;

 

The input shaft bearing will always have play side to side as it is on located on the mainshaft only via a spigot but when it is fitted into the car the front of the shaft is supported by the spigot in the flywheel/crank thus supports the input shaft.

 

I would say if the noise is always there when the gearbox is being deiven clutch up , it will be a constant motion shaft bearings as these are driven all the time.

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Yeah we have spoken before. To be honest i've not done a gearbox before but im keen to take it apart and have a go myself hence the questions.

Im confused by what you mean by constant motion shaft?

All i was aware of was the input shaft, main shaft and counter shaft..

This is gonna be one steep learning curve by the looks of it haha

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Yeah thats what I thought you meant, thanks for clarifying.

Their roller bearings on either end of the shaft by the looks of it, shouldn't be too difficult to replace. I'll investigate further tomorrow when i take it apart.

I know what you're saying about the input shaft bearing play but my input shaft bearing is deffinatly worn, when you hold the outer race you can see play beteen the inner race/ball bearings so replacing it can't hurt. I do doubt this will cure the noise im experiancing though.

 

Luckily i found a pdf of the factory service manual with a full stripdown/rebuild of the transmission :)

 

I'll take some photos when i finally get round to getting my hands dirty ;)

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