MX-5 OC Forum

It looks as though the rules for Roller Brake Testing have been changed and no longer mention Limited Slip Differentials.

Compare the version of MOT testers manual saved 1st Nov 2011 with the current version on the web.

Latest victim, took the wife's in for a quote on rust correction on the rear sill, mentioned I had noticed a noise coming from what I thought was the diff.

Nice man opened the drain and went oh **** that's not good, oil was like night and there was a nice tab waiting in the hole for us when he drained the oil.

Now booked in for a replacement 2nd hand fresh import to be fitted in a few weeks when I have some cash to pay for it all.

Will call Mazda Customer Services and see what they say the process is for something like this but not holding my breath that it will yield anything. Tried to scan through all the pages here but did not see anyone say if they had any success with a Mazda claim. Mine had full main dealer servicing up until 2010 then one service with a forum recommeneded independant and last May I did the oil change myself.

Let you know what they say about this and now our holiday in October will be replaced  by a diff in the MX-5 :-(

Hi, Sorry to hear that.

If you go through this thread counting failures and also this one, http://www.mx5oc.co.uk/forum/forums/t/37470.aspx , and any others you find on the web,

I think you'll find this problem confined to Mk2.5 cars circa 2002-2004 iirc.

To me that says it was a design or manufacturing problem and certainly worth asking Mazda about.

You might have a claim if you bought it from a trader, http://www.direct.gov.uk/en/Governmentcitizensandrights/Consumerrights/Buyingacar-yourconsumerrights/DG_183047

but often these things are so much hassle that nothing comes of it.

Problem though is that if it is a design issue what do you fit as a replacement? Seems little point in paying for a new/secondhand one of similar design if that will pack up too. So again I'd ask Mazda about that and also consider a standard open diff (which may be cheaper too) rather than another one of these.

Some owners in the US have been paying the difference to get a LSD from a 2004 Mazdaspeed Miata (Bosch-Torsen) fitted, as it has the correct final drive ratio. Those diffs are virtually bullet proof.

Or you could just ignore it and carry on as normal.

I found and extracted bits from my 2003 MK2.5 Sport diff many months ago, it still works perfectly fine as an open differential though it is not very good as a limited slip differential any more. Mine has had a number of track day poundings on it since finding the broken bits with no problems. Personally, I simply cannot see a scenario where such small metal tabs lock the diff or cause loss of control, however others may feel differently.

My 2p. worth.

Martin

Hi Martin,

As the car is really the wife's cruising around toy, I think given the cost of replacement and no real guarantee that a 2nd hand one won't already be buggered I was thinking the same, change the diff oil every few thousand miles checking for more tabs and see how it goes.

Don't want her to crash if the diff did lock up but god knows how long that bit had been in there as the plug had a fair few granules on it along with this peeping out of the drain hole.

I did ask a repair place today about a rebuild and essentially it would be down to me to find out if Mazda would supply all the parts as spares then they cud do a full rebuild.

No time today to call Mazda.

Car was a private sale with full MSH, so nowhere to go on that front.

Oh well, glad my bike is as much fun and less of a money pit.

Cheers

Ian

Little update, called my local Mazda (Franchised Dealer), got the classic really sir we have never heard of such a failure in our lives ! Then we moved onto unless you have proof you have servieced the car perfectly and paid us loads of money for the privelege  then not sure what we can do, we will gladly look at your car and charge you for the privelege of us confirming you have a knackered diff.

Then suggest you call Mazda UK, who I am sure will be realy surprised at this issue.

So conclusion, sod the car off in a trade in swappage scheme for more than it is worth and take on a totally different car now, farewell and thanks for all the fish.

Was almost at the point of wasting money on the car but given it's economy, car tax and depreciation in the current market, think we can stick with the bike for super fun motoring on much less budget.

 Yes, good move vote with your feet, if you ever find you really can't live without it there are plenty around get a better model, good luck and enjoy the bike

Just had mine MOT'd again today.  Tester had no problem using Decelerometer.

Passed with flying colours.

Still no bits in diff or any dodgy noises.

Just retuned from the Cornish Spring Rally (great rally and week, thanks guys!)

Before going we had the diff oil changed again to check for more "bits", sure enough there were more present!

However, no noise or trauma during the 1000+ miles covered this week so we will just roll-on and check again in a few months.

If anyone has any info / response on this from Mazda UK then we would be most interested.

Martin &Wendy

To add another example to the list, I took my 2005 1.8 Icon to the dealer today to have a strange noise checked, and was told the diff was breaking up. I was also quoted £2k+ for a replacement, plus VAT plus fitting, but they would fit a reconditioned one for me if I could find one.

Has anyone had any joy with any help from Mazda yet? Or any success with replacement of the diff under Mazda warranty? I bought the car last year from the Mazda dealer, with their warranty, believing it would give me better peace of mind and protection than buying from "A Bloke Down the Road Ltd." It was serviced at this dealer last week at 78k miles.

Cheers,

Paul

If the diff is breaking up and you have a Mazda (Zoom Zoom?) warranty, then I wouldn't think there will be an issue with it being covered.

Can anyone who's dismantled one of these diffs tell me - does the differential core just come apart when you unbolt it from the ring gear?

It looks like it will, in the sectional drawing here: http://www.gkndriveline.com/drivelinecms/export/sites/driveline/downloads/datasheets/Super_LSD.pdf

The reason I ask is that ages ago I bought a used 3.6:1 differential which I intended to swap for my 4.1:1 diff for more relaxed motorway cruising but only recently got round to trying to fit it.  I didn't fully appreciate when I bought it that it's the notorious Tochigi Fuji Super LSD type.  You can already guess what I found when I took out the magnetic drain plug:

I took the housing off to see if the ring and pinion gears were OK - which they are - but noticed that you can just about see into the LSD through holes in the casting, and in the gaps I could see the glint of more broken tabs from the taper ring, just waiting to fall out and cause havoc.  I could reach one with tweezers but tantalisingly it just slips away:

The arrowed glint is the edge of one of those broken-off tabs.

Anyway, plan A (fit it anyway and cross fingers) is abandoned since I've seen that trapped debris hanging like the sword of damocles.
Plan B was to replace the LSD portion of the diff with either the torsen core of my current diff or the core of an open diff if I can get one cheap
But plan C is to dismantle the LSD, extract the broken bits and if the taper rings are otherwise still intact, reassemble and use it as a nearly-open diff.

(I appreciate that rebuilding a diff is more complex than a matter of reassembly, but miata.net's garage section has a description of the procedure I think even I could carry out)

Thanks in advance for any insights into the practicality of Plan C.

Yes, the differential itself is dismantelable (is it a word?) and re-buildable easily enough. It's just a matter of undoing a few counter-sunk cross head screws. Undo them evenly as the cover is under spring tension.

Just thinking aloud here, But if this is such common fault with these diffs, Surely it would be worth a large clutch manufacturer making some redesigned friction plates?

I've read about some project cars that needed one off clutch disc's making before because the owner couldn't get one off the shelf (Due to odd ball engine/gearbox combos). I'm sure it was someone like Exedy that stepped in and produced a unique disc for them of the required friction surface diameter, thickness, centre diameter and number of splines.

In my mind the friction disc's in these diffs wouldn't present a challenge to them.

Scotty B.