Hello everyone,

took my rx-8 in to the dealer today to check out and fix some grinding and violent vibrating that was occuring in 1st and Reverse when accelerating. I assumed it was a problem with the brakes, since i would often smell the burning brakes smell after a particularly harsh grind/vibration. When i took the service guy for a short spin to demonstrate, he said it felt like the rear brakes were catching or rubbing when they shouldnt be...great, i was right.

well, i got a call a few hours later and the guy says he was wrong. turns out either the previous owner or CarMax replaced the rear-slip differential fluid with the wrong fluid, or put in some sort of additive that is now, over time, causing the problem. so they've done their best to completely drain out the fluid, and replaced it with 'good stuff.' i'm going back over tomorrow to take it for a spin to make sure the problem is gone first of all.

truth is, my knowledge of cars is limited, so its hard for me to sift through bullshit from guys who's job it is to sound like they know what theyre talking about. The reason I'm skeptical is because the guy says that it is near impossible to completely drain this fluid, so problems may come back...sounds like BS to me. Any help would be appreciated before i go in and pay for a service that may have NOT been the solution to my problem.

 

if the wrong fluid was used and caused harsh rubbing/damage to the dif then it prbably needs replaced. putiing in the right fluid could just mask the problem awhile

 

so at this point, if the wrong fluid was used, and the differential is screwed, is there any way it is still covered under warranty?

this dealership has provided ALL service thus far under my ownership.

 

i think i'm going to throw up

 

who put the wrong fluid in? thats who should pay if that is the cause

 

someone before i got the car apparently...CarMax? the guy said on the phone that the tech noticed yellow paint around the fluid uuuh entry hole(?) which generally means it was taken to jiffy lube etc and that is a way for them to "check off" fluids they are changing etc.

interestingly though, i had my car in for the 30k checkup a few months ago, so i asked the guy why they hadnt noticed when they were doing their inspection, and i guess they merely top off all the fluids. seems kinda lame. i also mentioned that the problems started not long after having it in for the checkup. he said that often an inappropriate fluid will take time to cause noticeable trouble.

 

what kind of an ******* would use the wrong fluid in the first place. arg im furious right now.

 

Jiffylube would. There are so many lawsuits out against JL that its a wonder they still stay in business. Its because they have an army of lawyers, pay their techs minimum (or close) wage, and offer the fastest cheapest service on the market. Moral of the story- I wouldn't take any vehicle I own from a lawnmower to a $50k car within 100 feet of those places.

I know this doesn't help you now, but if it was JL that F'ed up the differential, you are in for a long hard fight to get them to pay for it.

 

first of all, who whould change the fluid in the diff before it was scheduled???? that is at 30 k...

if someone just topped it of that is unlikely the problem...

beers

 

heh. My transmission/diff were swapped with RL at about 5,000 miles. At 30,000 they were swapped again with RP. So you must be talking about people like me...

 

mazda just replacing it with the right fluid seems weird. the correct fluid will not fix the problem that is present cuz its just a liquid. maybe they're trying to get around from actually replacing the complete diff. plus who knows who put the wrong fluid in, if that is even the case to begin with. i'd investigate this a little more bro.

{post edit bro, i was just talking to my mechanic and he said you'll need a new diff cuz the weight was probably wrong from the old diff fluid}

 

but you did it yourself and put in the right fluids.... i change my stuff to rp at 30k miles....

this is a different story..

beers

 

i sure did, with full on RL stuff too. Prevent more gear wear such

 

Ok now I'm not a mechanic but **** I know a decent amount of the basic's (Thank you Speed Channel and several mechanic friends). Now a Diff is what.. a huge set of gears right?... now if your hearing rubbing and grinding.. and a guy says "oh we will just replace the fluid and it will be fine" erm.. yeah major no-go. If they are grinding it means they are being worn out. I say read through your warrenty see if it covers the diff and talk to a service rep and just have the sucker replaced. Make up some b.s. story about how you drive handicap children and mental challenged kids sometimes in the car and you'd hate to have to explain to the parents how your rearend blew up because Mazda wouldnt replace a diff. If all else bring a mechanic friend and between the both of you raise holy high hell, doing that shyt is always fun.

Overall I say the guy is hoping the problem will partial go away till "after" the warrenty expires and hence they make a huge buck off of you.

 

Yup. I smell a lawsuite

 

yikes. at present i dont feel i have the time or money for this.
im already expecting that Mazda hasnt REALLY helped the situation at all. my question is (and i'll read up): can my warranty still cover a differential if the damage was not caused by normal wear, but by some fool's mistake/carelessness in the past?

i find it hard to believe that Mazda will be of any further assistance without charging me up the poo-poo.

 

The Torsen differential should last quite a while unless wrong fluids are used in the first place

 

Actually, they pay really quickly. I took my car in for an oil change there (back in 1990 - a 1988 Honda Accord) and the morons had used an AIR WRENCH on the oil drain plug to install it, and of course twisted it into the oil pan and stripped the threads. The car started to drip oil a few days later. I took it to the dealer and they said that is was leaking from the oil drain plug and that I should immediately return to JL with the car. They also wrote me an estimate for the repair (which required dropping the engine/transaxle/front subframe from the car, uninstalling the engine, and replacing the oil pan. About $1320.00.

I went back to the JL store, they went under the car, I went with them, they saw the leak, the guy noted that the plug was freely rotating in the hole with light wrench pressure, and the manager met me and wrote me a check for $1320.00.

I went back to my dealer, and they fixed it that day.

The trick is coming to them with a proven/written up problem from the dealership, and a receipt for the service that was done. If you don't have a receipt for their service, you're cooked.

 

If a "brake" smell is one of the clues, I doubt the differential is involved. My guess is that you have a clutch problem. Get a second opinion.

1.3L

 

I don't have a receipt, i dont even know where the deed was done.

i think my plan now is to pick up my car, see how it feels now, and then take it to a different dealership ^^^for a second opinion.

 

[QUOTE=Clavius]Ok now I'm not a mechanic but **** I know a decent amount of the basic's (Thank you Speed Channel and several mechanic friends). Now a Diff is what.. a huge set of gears right?... now if your hearing rubbing and grinding.. and a guy says "oh we will just replace the fluid and it will be fine" erm.. yeah major no-go. If they are grinding it means they are being worn out. QUOTE]

there's more to wear out than just gears. There are bushings and bearings that are a lot more likely to wear out than the actual gears. The wrong API rated fluid can eat up the bushings.

 

anyone have any idea how much it would cost to replace and install a differential?

the guy never said it would be fine now that the fluid has been replaced. he pretty much said, its much better, but you might expect problems in the future. i'm going to be talking to CarMax. Their supposed 160-point inspection was a failure since they didnt check the diff fluid, or put in the wrong type. Even if the previous owner screwed this up, it seems CarMax ought to have noticed the problem when they checked out the car, since they pride themselves on being so meticulous.

 

yea, but nobody in the world will check what type of diff fluid you have installed in the car. I doubt they thought anyone would replace it with the wrong stuff to begin with

 

even if you dont care im contnuing my story:

just picked up my car. it feels grrreeeeeat!...for now.
the guys at the dealership have been very easy to deal with, even saying that further work should be covered under warranty should i begin to have more problems. whether or not they solved anything is still to be discovered, but at the very least they were extremely pleasant and accomodating.

so i'm pleased my grinding is gone. still very nervous at the thought that my differential is screwed now or soon, but happy for the time being. thanks for your suggestions etc. and sorry to clog the forum with my bull$h1t

 

Cptn Mercury>Glad it's working better...

One test to tell if a Torsen (i.e. torque-sensing via helical gears) differential is working is to take off in first or reverse while turning sharply. This places the greatest torque load on the helical gears. You don't have to take off hard, and in fact, perhaps a normal roll-off would be best. My guess is the vibration you were feeling (backing out of a parking space while turning, right?) was coming from the faces of the helical gears as they had to slip past one another in order to allow the inside and outside rear wheels to turn at different speeds. When they won't slip, they'll stutter, which would probably feel quite violent. As for the smell, perhaps the diff lock up was dragging a tire on the pavement? Even I doubt that though so I'm puzzled. Maybe the incorrect fluid in the diff was just "burnt up"? It would have a very distinctive "stinky sock" sort of oily smell... no better way to describe it than that.

Torsens are very robust. I'd worry more about the pinion bearing and the side carrier bearings.