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MG MGF Technical - Gearbox Noise

I have a rattle from the gearbox when in neutral.
As soon as I put my foot on the clutch it goes away.

Is this the thrust bearing and is it anything to worry about or just general wear?
DB Ferris

DB Ferris,

yes, it certainly sounds like the thrust bearing.
In time the grease in them dries up and the internal bearings become worn, loose and noisy.

In Neutral there is no pressure at all on the bearing but when you press the clutch the release forks press the bearing case ontot the fingers of the clutch.

The only way I know to fix is to replace it. When at that stage then also check the clutch/flywheel if they are OK.

You plan to DIY?

Cheers,
Branko.
Branko

No way!

This is the first mid engine car I have owned, so I think I'll leave it to the professionals.

There is an independent garage near me that has been servicing MGs since the mid 70's

They also do MGFs and TFs. They have a good reputation
So I think I’ll give them ago.

Funny though, this morning it's so quiet you can hardly hear it! I was tanking it about yesterday with the roof down. I wonder if engine temperature plays a part?


Thanks

Dave
DB Ferris

Dave,

Here is what I did to change my clutch.

http://www.mgfcar.de/gearbox/clutch_replacement_MGF.htm
(Will be adding some pics soon.)

Cheers,
Branko.
Branko

Thanks Branko!

What's the time over there, must be late!
DB Ferris

Dave,

now it about 9PM so there it must be 10am?


Just settling down to a nice cuppa.
Branko

Don't rush to replace anything. Here is a "cut and paste" of a post from another forum about this issue:

The PG1 gearbox has a very good reputation and usually doesn't give any problems. The noise you describe is however sometimes an issue (I have it on my TF 160) but the knowledge and understanding about it seem rather limited among MG technicians (at least those I've come across...).

The information below was given by Nick Adams, Chief Engineer at Lotus, on the sorely missed "Lotuslife" bulletin board. It explains it all in a very clear way:

"It's not unknown for the first motion shaft bearing to give trouble on the K series box, but the trouble usually goes no further than a little noise. What happens is the bearing develops a little play and chatters when the box is in neutral and under no load. Dipping the clutch allows the shaft to turn slower or stop and the rattle goes away. When the shaft is transmitting torque (ie you are driving) the side loads generated by the gears take up the tiny amount of side play and the bearing runs happily. Therefore the problem rarely gets any worse. It's not worth fixing the noise unless it really wories you, it's a common feature of just about all gearboxes with an unsupported 1st motion shaft and will not affect the gearbox function or reliability at all. My advice would be to leave it alone, but it's your call...

(...)

The first motion shaft is the input shaft that transmits the power from the engine into the gearbox. The shaft runs on a bearing fitted into the back of the engine crankshaft and a second bearing in the gearbox itself. These bearings are designed to be able to cope with a small degree of misalignment which is inevitable when the engine and gearbox casings are machined seperately as they will be in a mass producion situation. If the misalignment is smaller than average the bearings can generate a little noise as the shaft turns without transmitting power (ie: in neutral). As soon as any load is applied the shaft loads the bearings and the noise disappears. Don't worry about it, it simply shows you have a good engine to gearbox matching!! "

I hope this reassures you (and saves you a lot of money... ;-) )

Per
Per

Cheers Per.
I was on tender hooks there for awhile.

I still own a Mini Cooper(Rover) and that has a "lay"
bearing in the gearbox which makes a similar sound
and also goes away when the clutch is engaged.

In that case I left it alone thinking it wouldn't get any worse. How wrong I was, about a month later the bearing dropped smashing the gearbox and engine!!!

I had a whopping repair bill for £1500 :o(

So thanks for the report :o)

Branko:

Shouldn’t that have been a cold beer? :o)
DB Ferris

DB...

I had this on my old Rover 216 Coupe... and they (non-dealer) stripped down the gearbox and rebuilt it after fixing the problem... cost me £850 so yeah, if you do get it done, it ain't cheap :-(

Chris.
Chris Tromans

Hi Dave,

Noticed the noise you describe on a Trophy 160 I had from new, around the 10k mark. Suspected clutch release bearing as you do, but asked the dealer and got the 'they all do that, sir' response. Another 30k miles of generally hard driving and the noise was no worse, and still no other symptoms. As Per has suggested, you're likely to spend a lot of money curing something that really wasn't a problem.

HTH

Mike
Mike Hankin

well that's it then. leave well alone!
Thanks for the info guys, now all we need is to get
rid of this shi@#y weather and get the roof down!!

Dave
DB Ferris

Dave,

yes it normally it is, What was I thinking!
Now where is that Guinness.?



Cheers,
Branko.
Branko

Hi all,

just want to add that it might be a good idea to check the oil level. It is rather common that the gearbox is underfilled from new and there is also a slight weepage in time. We had a check on a few cars here in Sweden and all had level below recomended. After topping up box is much smother and quieter.
PS. You are talking about motion shaft noise,eh?
Ever driven or been into a Porsche 944 ?? Here we are REALLY talking about noise! Even as brand new this noise was not regarded as warranty work,more as a "feature" ;O) / Carl.
Carl

Thanks all for useful info.

I've often seen this oil level problem discussed and on my recently acquired 2002 TF the gearbox is definitely noisier (in every gear) than my previous 2001 VVC. Was obvious within the first few miles. This may be due to better soundproofing in the TF although I doubt there would have been many changes.

I'll ask the dealer to check the level. Unless this is something I can do myself (do you need to raise the car on a lift?)..

Thanks, Anthony
Anthony Braham

No need to use a car lift.
But you will need to raise the rear of the car using your jack and safety stands.

Here is a link that says it all.
http://www.mgfcar.de/gearbox/refill.html

also check out the recent previous post "how to change gearbox oil"

HTH

Branko.
Branko

This thread was discussed between 03/04/2005 and 09/04/2005

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