airn

i think my rear might be close to being toast. how can you tell if it is in need of replacement? just want to make shure before i order stuff that cost big $$$

HeX

I can tell you one thing. **** comes out of my rear end. That's for sure. Sorry I can't help you on this one.

GoodfellaFD3S

iTrader: (213)

why do you say this? have you been drag racing and launching hard alot? also, it might be a good idea to change the diff fluid and put in some synth. I run mobil1, and it made a noticeable difference in smoothness and acceleration.

af908

what is the lifespan on an fd rear end anyways? just wondering because mine has about 157k on it...

GoodfellaFD3S

iTrader: (213)

I think it depends on how much it was abused, rather than mileage. How many launches has it endured, and how often have you changed the fluid?

Rich

airn

i havent done a huge amount of drag racing or hard lanching. it started making a noise after my first time at the drag strip. it wines when i let off the gas its only when i have let off the gas and the wine changes in pich depending on the speed of the car. its pritty loud because i have the nylon diff bushing so it sux.

GoodfellaFD3S

iTrader: (213)

What about changing the fluid?

SanJoRX7

Good lord man, what is it with you and diff fluid? This is like the 5th thread today that I've seen you mention it!

I second the diff fluid idea, but if you've changed it within about 30k miles, and you're still having crunchiness/bad noise in your diff, it might just be time.

I have about 110k on my stock diff, and while it makes some noise, I haven't noticed any major problems (of course, I don't drag at all). I figure that at about 150k, assuming that I still have the car (and I intend to), I'll consider that among my list of upgrades/replacements, unless it decides to bail on me before that.

DavidDeco

He likes the funky smell of gear oil

I have about 110k on mine and the gear oil was changed 2 times for what its worth and has redline in it now. But if it goes I guess that's a nice excuse for the kaaz, 4.3, cf shaft, ppf combo....

Silver Ninety Three

tThe stock rear is a torsen unit, so it doesn't have any clutches that can wear out. I suppose the gears themselves can wear, especially if the fluid isn't changed at the correct intervals. These units are either good or bad. When they go bad a gear breaks or strips. Then its time to replace the diff. I have an extra low milage one if you need it. The bushings ont he otherhand, wear out. I also have some extra low millage diff bushings.

flunkysama

iTrader: (4)

Change the fuild in the diff. Do it now! Check the old oil for metal particles. Use a bright light and look for shiny specks. Since the gears are steel, a magnet might come in handy. The material bearings are made of usually is not magnetic thou.

You should also measure the amount of oil that was in the diff. It should be around 1 & 1/3 quarts. (Your diff could be ruined because there isn't enough oil in it.)

Checking the fuild is trival compared to pulling the diff and taking it apart.

And while you are under there, check the CV joints for play. Generally they make clicking noises when they start to fail, but you never know.

I'm always afraid to reply to people like you because I don't know your level of technical compentence. Do you abilities end with adjusting the seat or could you rebuild an engine if you had to? Have you even looked in the service manual yet? Or are you just fishing for things you can tell your mechanic to check?

airn

i am pritty good with mechanical things. i dont have any place to work on my car. also i bearley have any tools at the house. when i really need to do anything i go work on the weekends and use the tools there. but i cant have my car there for more than a few hours so i can could never do any hard jobs.

shred

If your not much on auto mechanics, not too sure that this is a good baptism place to start, especially if you don't have the tools. Getting the axles off is a real titty-twister. Nobody that I know of has been able to get the rear diff out in less then a few hours. You probably want to take your time also to make sure that you have everything lined up right anyhow.

If it were my beast, would try changing the oil first, then see if the noise is still there. Might just be something that can be fixed with better or newer lubrication. Well, it won't fix it but it might delay the repairs for a while.

Could also just be the bearings that the rear axles ride on also (this is my best guess on what is making the noise). I haven't seen a LSD go out yet on these. From what I have picked up in a few other threads, there just isn't much to wear out, its all pretty beefy metal in there with no wear or friction (well, no wear or friction compared to other non-torsion LSD's).

airn

thanks for the info, my uncle who is a auto tech. told my it might be my input bearing. i dont think he knows anything about rx7's though. i'm not real worried about the rear that much it seems to work fine it is just noisey. i'll just let it go until i get an upgraded diff.

Hyperite

Well heck, you might as well bank on a transmission rebuild when your diff locks up. Yes somehow waiting for things to break doesn't seem like the best idea, but hey...i must not have your kind of money.