Rattle/knocking from gearbox?

[PeteE30Tourer]

Morning all,

I noticed last week that my 325 cab was making a knocking noise from underneath, possibly from the gearbox when in neutral with the clutch up. Press the clutch down and the noise disappeared.

However, driving it yesterday, I noticed that the knocking was more persistent now no matter what I do with the clutch or gears. It's not very loud and it drives absolutely fine, but at low speeds or when standing, it's noticeable from inside the cab.

Any ideas?

[RM2186]

Sounds like the clutch thrust bearing is worn to me.

[PeteE30Tourer]

Cheers - expensive/time-consuming to replace?

[RM2186]

If it proves to be the thrust bearing, I'd leave it until you plana clutch change, that way, no extra cost

[PeteE30Tourer]

Is it ok to run like that then, or is it likely to break at some point leaving me stranded?

[RM2186]

I think the noise it will make before it busts will have scared you long beforehand.

[PeteE30Tourer]

Oh dear - things have got significantly worse. Rattle much louder and apparent whether clutch is up or down, in gear or out. Starts as soon as engine starts. Very noticeable from inside car.

Cant see it being the thrust bearing now.

Any ideas?

[e30-EVN]

Thrust bearings can get pretty loud before they go mate, maybey its getting time to fit a new clutch kit

Having said that your layshaft could be fooked, I had the same with my old box on the m50, put a new box and clutch kit on my m52 and stuck that in instead and all fine.

Does the box whine in any gear at all??

[PeteE30Tourer]

Would a thrust bearing make the same noise regardless of whether the clutch pedal was up or down?

[ed325i]

I would think its the layshaft.

Ed

[e30-EVN]

Ed, I'd be inclined to agree mate, as per the edit to my post earlier
I had the same trouble

[PeteE30Tourer]

I take this means dropping the gearbox out and stripping it down?

How many hours for a competent mechanic?

Parts cost??

Better to fit second hand gearbox?

[e30-EVN]

I would slap a new box in there mate. Would be cheaper than getting someone to strip down and rebuild your one! Tbh with you I got rid of my old m42 box and refitted a new 1 to my m52.

They can be found on here at reasonable enough price

[PeteE30Tourer]

Bit of a gamble getting second hand box - could have same problem.

Are recon gearboxes available?

[craigieeb]

http://www.chriswarburton.co.uk/parts.htm

If there's none on the website,
drop him a message

[e30-EVN]

Not if you get the box from a reliable source mate! I had a box off magpie and mine is mint

[PeteE30Tourer]

Thanks Craig - gave them a call today and they didn't have any 325 boxes in stock.

I'll head off to the "For Sale" section to see what I can find.