1.6 Miata Diff reliability

[tnord]

us in SM have all kinds of problems breaking diffs, with failures including bearings, ring gear bolts backing out (the most common), cooked fluid, and broken teeth on the ring/pinion gear.

we have not been able to track down a cause for our failures, and it seems to be completely random which ones fail, but i haven't really heard much about ITA miata diff's giving it up. do you guys break too and we just don't hear about it, or are you not having any problems?

if you're not having any problems i'm curious as to what you're doing differently than us. we use the mazdacomp unit in the factory casing with no modification, new bearings, new axle seals, and plenty of loctite in the ring gear bolt holes.

[zracre]

The 1.6 diff is a fragile piece. If it is not set up right there are many things that can go wrong with it. I have found that the biggest culprit is extreme abuse...not matching revs on downshifts seems to do them in. I know many seasoned fast drivers that have not had failures with silly amounts of mileage on them. If one gets rebuilt it is real important that all the clearances are set carefully, bolts torqued carefully and rechecked. If a bearing starts to fail in them they will grenade as well. It is important that the vent is operable and not munged up, the exhaust is not leaning on it, the diff mounts are good to avoid extreme shock on it, wheel to wheel impacts avoided etc...I'm on borrowed time with the one in my SM now so well see how long before i need to man up and spend the green on it. Good luck!

[tnord]

i agree that those can be factors to the failure, but for every 2 seasoned fast drivers you can show me who hasn't had a diff problem, i can probably show you one that has. and we've had diff failures from people who are "reputable," it's just that nobody wants to publicly name these outfits.

if it's a problem even the ITA people are having then that'll help rule out some things i think. if they aren't having the problem, i'd like to learn what they're doing and share with everyone.

[joeg]

I'd hazard a guess on it being a lubrication issue (if it is a problem).

This has probably been talked to death on specmiata.com

[tnord]

it has, and i think it's very difficult to get a straight answer there. too many people with too many ties to major shops who always claim "it's a setup issue." then we'll send our stuff to the same place, and low and behold, the thing blows after 30minutes. and even over there it's very devided on who thinks it's a setup issue, who thinks it's driver related, and who thinks it's just a weak part, with representation for each skill level in each camp.

[Andy Bettencourt]

The SMAC has asked for member comment on this issue. Currently, while the failures seem to be increasing, they also seem to be localized and can not be pinned down to any one problem. And while they are 'increasing', the statistical number isn't significan't enough to warrent a change given the variety of information on the subject.

Most failures seem to occur when stock bearings are left in on new builds. Some drivers have 3 years on the diff with no problems and some have 2 weekends and then failure. Weird.

AB

[tnord]

andy you got my take on this a while ago, how much response did you get from the input request?

i have a new theory on why these are failing, but i wanted more input first.

can you share the info you have on this localization trend? i'm guessing it's centered around us. if you don't think the figures are significant enough to warrant a change, i'll give you a dollar statistic on what we spent on blown diffs last year in this division only that might change your mind.

[Andy Bettencourt]

andy you got my take on this a while ago, how much response did you get from the input request?

i have a new theory on why these are failing, but i wanted more input first.

can you share the info you have on this localization trend? i'm guessing it's centered around us. if you don't think the figures are significant enough to warrant a change, i'll give you a dollar statistic on what we spent on blown diffs last year in this division only that might change your mind.

[/b]

I don't know them off hand (I don't know where you are either) but this is the current thought process with the committee. Send in your info, the more the better.

AB

[JIgou]

tnord, check your hotmail account.

Andy, look for a message from me in the next few days.

Jarrod

[tnord]

thanks Mr. 59.

andy-

are standardized yet well constructed letters worth their weight in donkey doo, or do they actually hold water.

i would guess they hold water judging from the Toyo....i mean Spec Tire outcome.

[Andy Bettencourt]

thanks Mr. 59.

andy-

are standardized yet well constructed letters worth their weight in donkey doo, or do they actually hold water.

i would guess they hold water judging from the Toyo....i mean Spec Tire outcome.
[/b]

Every letter counts for something but if we get 10 letters that have the same text and just a different name on the bottom, I tend not to dig that. It is important to *me* that people put their own thoughts down. When people are forced to write things down, they are forced to think about what they are writing. You should SEE some of the things we get.

A standardized format is fine, but let it be your own thoughts with your own experience, not a 'petition'.

AB

[tnord]

sooo...........


any IT miata diff failures out there?

[Gregg]

You might want to talk to Brett at RP Performance. I'm pretty sure he lost his diff in his 1.6 ITA car at our second race of the year at VIR last year.