Gearbox/Diff/Propshaft Noise

[K10]

Fairly suddenly (over a few days), a new noise has appeared.

On engine braking, a very high pitched whining/slight grinding noise starts. I think this can be felt through the gearstick.

Noise depends on speed and only appears under engine braking. Not when freewheeling/pushing on. Doesn't change with gear used.

So far I have checked the oil level in the diff, fine.

Will check the gearbox oil level tomorrow, I'm really hoping that that's the cause, there was a weeping from the geabox tail when I had a look last weekend (so I need to replace the seal).

Is there anything else in there that could be causing this - is there a joint on the propshaft? Anyone had anything similar?

[Steve]

Backlash in the diff (does your car kinda chug back and forth a little when engine breaking?)
Change the diff oil and check for silvery bits in it...

[K10]

Yep, you're probably right, gearbox oil was up to correct level and is clean, diff oil not so clean though, not manky, but not good either.

Happier that it's the diff, not the gearbox really, probably a much easier job to switch.

I suppose now is a good time to fit a 1.8 diff, planning on a turbo down the line, so suppose it should be upgraded. Is an LSD worth it?

[Steve]

Dunno.... I've a 1.8 open diff but LSDs do look like fun (altho scary in the wet I'd imagine.. ? )

[Richie L]

Hi Guys,
I changed the diff oil recently and added forte friction lube (€14).This puts a coating on the internals allowing oil to slide more easily.It keeps the noise down too.The LSD on my mk 2.5 tightens up quickly under acceleration but if you keep the tyres in good order and dont mess in the wet you should be ok!Looks good today for a spin.Yippee

[K10]

The noise has detiorated badly, and it now seems like it's from the gearbox. I think I need to get it diagnosed (gearbox or diff) by someone in the know.

Anyone know of any gearbox specialists around Cork? I would be happy enough removing the thing, but rebuilding/replacing bearings would be beyond me.

[Steve]

When my last one (4th one) went I was convinced it was the gearbox too... lots of clanging from under the centre console..
Its usually 2nd or 3rd gear that blows if it is the gearbox but have only heard of it on 200hp+ cars..

[K10]

When my last one (4th one) went I was convinced it was the gearbox too... lots of clanging from under the centre console..

Sorry, confused now - last what? Diff?

[Steve]

yeah, actually.. 3 (1.6 diffs), now on my 4th (1.8 diff) and its been holding up v.well for 6 years-ish .

[K10]

Got a call from the GF last week, I was away, MX5 broke down in the dual carriageway, car wouldn't get any drive in any gear. Turned out the bearing in the diff deteriorated so quickly that the propshaft and diff separated.

Replaced the diff, now good as new. But what a job replacing it. Convinced it must be the hardest part of an MX5 to replace, maybe a gearbox would be harder, but not by a lot.

Really learning my way around this car now. Thanks for all the help Steve.

[Steve]

jebus! Was that the pinion bearing that came apart?
Yeah, its a fecker to get the diff off the PPF.

Where did you get the replacment? Did you go with a 1.8 diff in the end?

*edit * just saw your other post, 80e!! Bargain!

[lenny_mc]

happy days K10!

Ill be picking your brains when i start doing bits to mine!

[K10]

Yep, it seems the pinion bearing failed.

The seal failed, the diff had obviously run low on oil at some stage before I bought it though, because even when topped up, it would still whine, so when it got worse, I tried to source a replacement quick, but it failed a lot quicker than expected.

it's a 1.6 diff, in good nick too it seems. No noises, the wobble in the shaft seems to have not been bad enough to damage the gearbox anyway, so at least that won't need to be touched.

One or two small things to do, then the 5 will be the way we want it, at last.

[sidewaysreilly]

Lads and Lassies, i have done a few Corolla LSD's in the past and would be willing to take a look at a knackered one to check out parts availability locally. We have a very good Engineering supplier up here and Bearings / Seals are not a problem to find.Could be able to possibly do an exchange unit if i could work out what parts and labour costs will be.

[ger]

had a noise problem after getting the clutch done turned out to be the installation height of the gear box, check out this thread.

http://www.mx5oc.co.uk/forum/forums/t/5734.aspx

Sounded like K10's problem and i thought of the diff but sorted now.