Gearbox rumble

[mep12345]

Think I know what problem is, but want a second opinion, so here goes. Since the rebuild the S3 has developed a rumble/whine at the gearbox. The whine is most noticible in low gears and gets louder as revs increase. It is also present when the clutch is not depressed and the car is in neutral also increasing in volume as you rev the engine. If you are travelling in second say at 3-4000 rpm and depress the clutch the noise slowly reduces and then stops.

My thoughts are that it is the clutch release bearing, does anyone agree or disagree?

My other question is what are the risks of continuing to run with the whine and what damage will be caused if it fails catastophically? I would really like to nurse it through to next winter if poss as having checked the clutch friction material as still >50% etc during my body off I don't want to take it off the road to take out the gearbox in this weather, but plan a gearbox overhaul for next winter anyway?

Advice, thoughts appreciated?

Mark

[Barkychoc]

With your foot off the clutch the release bearing won't be turning under any real load so I'm not sure its that.
It may just be the gearbox itself is a little tired (it will be the bearings I think).
In my experience gearboxes deteriorate very slowly - so you may find that it lasts for ages if you don't do a great mileage - though it would be worth checking the gearbox oil is topped up.
I am not 100% sure but some ford gearboxes don't use the layshaft in 4th gear (is this the right name for the lower shaft in the gearbox?) so does it do it just as bad in 4th gear? I may be wrong on this with the TVR but worth a try.

Chris

[clarenceboddiger]

mep12345 said:

If you are travelling in second say at 3-4000 rpm and depress the clutch the noise slowly reduces and then stops.
Mark

If it "slowly reduces" I would suggest it must be the Thrust Bearing as all other bearing/shafts would continue to rotate at the same speed being driven by the propshaft,
The thrust bearing will slow down with the engine, that could explain the reduction

Edited by clarenceboddiger on Sunday 11th May 00:32

[pringli]

or the spigot bearing in the end of the crankshaft as that is effectively the only bearing without load when the clutch is depressed(and the car is moving). Did you change it when you had the clutch dismantled during the rebuild?

Edited by pringli on Sunday 11th May 09:59

[Barkychoc]

The thrust bearing only really has any load when you press the clutch.
I've always heard a worn thrust bearing as a squawking noise like a dry bearing - does it sounds like that or is it more of a deep rumble? (and usually happens when you press the clutch).
If there are other symptoms with a thrust bearing I've never heard them, but I am no expert.
You want to be sure what it is - there's nothing worse than taking it all to bits, replacing something then finding the problem is still there.

[pringli]

I agree with Barkychoc, thrust bearing in mine gave a dry screech and when I stripped engine and box the bearing was practically u/s. I Changed the needle roller spigot bearing as a matter of course while split. Other and worse possibility is gearbox main shaft bearing which will also be worse under load than when clutch is depressed even though still being rotated by vehicle moving. Sorry.

Edited by pringli on Sunday 11th May 11:38

[mep12345]

In fourth I can't tell if it's there (engine/exhaust noise too loud). It is definitely related to engine rev speed and not prop shaft speed. It is more of a whine that a deep rumble, but is definitely not a screech (yet?).

Stationary and in neutral it is not there when the clutch is depressed, but is there when clutch is released. As revs are increased intensity gets louder, but tone doesn't change. When rolling and coasting with the clucth depressed it is not there once engine speed has dropped to idle. If dropped into neutral and clutch released during coast it returns as per when stationary. When on overrun it is there when clutch is out and engine is driving box.

From descriptions above sounds like it could be spigot bearing. The gearbox oil is all new (drained and replaced with GL4 spec oil (as recommended on ford power forums)during winter - if anything it is slightly overfull. I conducted a gearbox inspection (through top cover) whilst the car was dismantled, but as I didn't see any signifiant wear (other than wear on synchromesh between 1st and 2nd - low rev gear changes only otherwise it crunches) I prioritised the funds to elsewhere this winter intending a full overhaul in 08/09. I only took the clutch apart far enough to check for wear on frictionplate and replaced nothing.

Thanks for help, if the above info changes any opinions then please let me know. Currently intend to monitor and see if it deteriorates

Cheers

Mark

[pringli]

If it starts to get significantly worse dont put off taking out the box, if its the spigot bearing it will cause the end of the mainshaft to deteriorate and will land you with a much bigger bill, the spigot bearing is cheap. Good luck.

[Barkychoc]

The more I think about it the more I think its the mainshaft bearings in your gearbox - this is the first shaft in the gearbox after the clutch and is engaged / disengaged in your gearbox with the clutch.

Clutch pressed - mainshaft disconnected from engine - clutch up - mainshaft connected to engine and under load.

Driving along and pressing the clutch will mean the mainshaft will still be spinning as it will be turned by th rear wheels (with it in gear), but it isn't under load so the noise will probably disappear.

Consider the 2 bearing states - under load giving it some beans means it is taking the full force of the engine torque having to propel a ton of car along, whereas when not under load the only force on the bearing is that of the shaft rotating.

When you are not moving pressing the clutch means the shaft stops turning.

Chris

[pringli]

This also applies to spigot but I would have thought mainshaft bearing would contribute the most noise especially a deep rumble. I would cut losses and
remove box now, should be easy (and cheap) to source a type9 in good condition from a scrappy if spigot is ok.

[mep12345]

Barkychoc said:

Clutch pressed - mainshaft disconnected from engine - clutch up - mainshaft connected to engine and under load.

Driving along and pressing the clutch will mean the mainshaft will still be spinning as it will be turned by th rear wheels (with it in gear), but it isn't under load so the noise will probably disappear.

Chris

Does this bit still apply when in neutral and stationary (ie I would't think the mainshaft would be spinning here)?

Noise is difficult to describe and I maybe mislead you with calling it "gearbox rumble" it is like a high(ish) pitched gearing whine rather than rumble, so maybe need to seek some advice from gearbox specialist on this one. As I said I know 1st to 2nd synchro needs doing so may have to bite the bullet.

Cheers for advice

Mark

PS have just found this thread:

foxy600 said:

Just got my S2 back from Guglielmi, my clutch (or what I thought was my clutch) went on the way back from Le Mans. After many hours getting the gearbox out they found that infact the spigot bearing had disintegrated. This is a small roller bearing that sits in-between the end of the crankshaft and the gearbox.
I had many months of crunching gears 1st, 2nd, reverse, and had started to get weird noises whining grinding, all in 1st and 2nd when accelerating
The problem was not the clutch, although I had this changed at the same time

Just a bit of advise, if you get a new clutch at some point, make sure this bearing is changed, it only costs £10:

Describes my symptoms perfectly - bugger box out time I guess and after I'd just got her back. Start this next week I suppose. This thread also seems to explain the crunching in 1st/2nd. Another picture story for the website though!!!!!!

Mark

Edited by mep12345 on Sunday 11th May 16:24

[pringli]

yep mainshaft runs (as long as clutch isnt depressed) when stationary and in neutral. The mainshaft is just an extension of the crankshaft into the gearbox with the clutch plate attached on splines. With clutch pedal up the friction plate is sandwiched between flywheel and pressure plate (cover) and drives the mainshaft, clutch depressed = pressure off, friction plate spins + mainshaft becomes idle. Just like Barky says: selecting a gear then connects mainshaft to output shaft via whichever gear you select.

Edited by pringli on Sunday 11th May 17:23

[Barkychoc]

I'd take it to a reputabe garage (Indy) before you take it out and let them have a listen - try and find an old school garage thats seen some older fords. If you can find someone in the know they will know straight away what the noise is. Well worth trying 2 or 3.
Might also be worth a post on a Capri forum - it uses the same gearbox.
TVR stuck with the older 2.8 Type N gearbox even when the engine went to 2.9
Ford switched to the MT75 gearbox in the sierra.

Ford apparently switched to the MT75 as the type N was considered a bit weak.
(I'm quoting from the Steve Heath bible here).

Well worth trying to diagnose the problem before you dive in and take it to bits.

Chris

PS If you know any HGV mechanics they are always in the know - they still fix things like gearboxes cos they are so damned expensive in HGV's, whereas most car garages nowadays just fit a new gearbox and don't repair anything.

[mep12345]

Barkychoc said:

I'd take it to a reputabe garage (Indy) before you take it out and let them have a listen - try and find an old school garage thats seen some older fords.

Intend to - I know a few in the trade down here so have asked for some recomendations. Will let you all know the outcome

Mark

[mep12345]

Well I'm and really so much so I could took the car to an Indy garage today (no chance last week) and one who knows a bit about the type 9 gearbox. He listened to the noise and said "Main shaft bearings no doubt" then went on to describe symptoms in each gear which matched identically what I was getting, and that was only with the car at idle and clutch in and then out.

So gearbox out time, start today and hopefully get it rebuit for re-fit next weekend or one after.

But the weather is good

Will post a new work page on my website to cover this one, including all the propshaft removal etc. Wish me luck

Mark

[ketvrin]

After the propshaft episode, I'm gonna let you lead and then read up your instructions on this one...

good luck indeed and I look forward to reading your notes... (I have a whine in third now - which I could not hear before because of the knackered Propshaft UJ Its not too bad so I'm hoping to keep going for the summer then investigate in the winter months...)

K

[mep12345]

Kevin,

See the other thread for spigot bearing removal - the "tool" is yours if you want it (alhough it only cost me £1.25 to make - and postage might be that much).

Went to look at gearbox under overhaul today. Shame the bearings went because the rest of the box is immaculate - the gear wheels are in new condition and even the synchros seem ok despite the high rev crunching I was getting in 1st to 2nd. However I'm sure the overhaul will improve the tightness and feel of the box; everyone else who has had it done seems to say it was money well spent.

Mark

[mep12345]

Got the box back last week but the bloody weather has stopped me getting it back in (garage too narrow so have to work on the drive). Anyway I hope the weather is better up Norf for those of you at SCH, would have liked to have made it - maybe next year!!

I want it back, I want it back - the smile is fading fast!!!!

Mark

BTW the layshaft was well and truly buggered as was one of the main bearings, also the fourth gear wheel was loose on the shaft - looked like a "cheap" overhaul had been done at sometime in the past as a coller had been shrunk onto the end of the mainshaft to make up to size following some obvous machining. All parts are new now so should be good for a few years.

Edited by mep12345 on Saturday 21st June 17:44