i posted about the situation a few months ago.



when you would get on the throttle you would hear a fairly loud *thud beneath the bin area followed by *whirling. it was concluded that my diff was done for.



i have an s4 (clutch type). i just wanted to know exactly what went/broke. and how hard it would be to swap from the s4 TO the s5 diff.

okay, maybe not exactly what went/broke. but possibilities to cause the sounds i'm hearing

Could that not be a drive shaft problem? Or have you ruled that out somehow?

Well, how's the car running, how's the shfiting, etc? It could just be that your Diffeential mount is broken and needs to be replaced. I recommend a steel differential mount.

yeah you just need a new diff mount

most S4 diffs aren't working right after the first 50-60k miles or less anyway, not saying thats the problem, but just dropping knowledge

shifting is fine. i have my share of trans problems with the 2nd and 3rd gear sync.



i was thinking diff mounts at the time it happened. but what a few poeople replied to when i posted claimed i would be looking at the diff itself.



would bad diff mounts cause my rear to lean? clearance from fender to tire on l/r is about 3/4". on the r/r it's about 1.5"



sorry to be such a nOob. but i really haven't done anything major to this car nor have i had time to. haven't driven the car since it happened. just start it and warm it up twice a week.

Yea - it can cause your rear to lean. I had that same exact problem after my differential mount popped. I ended up doing a full on project on the car. I figured, why go through all that work of removing the differential only to replace the mount. Why not just replace the differential it self, replace the drive shaft, and tranny, and install one of these to hold the differential on tight: http://www.mazdatrix.com/getprice.as...m=28-6800-FCY1



Oh, and the Rear too: http://www.mazdatrix.com/getprice.as...m=28-890C-FB01



So you have these options:



Drive the car once in a while with a broken differential mount which thumps and whistles whne you shift.



or



Replace the diffential mount and/or replace the differential entirely.

Yeah, I'd take a look at the mount, its definately broken. Get a competition mount and install.

it doesn't thump or whine when you shift. it does that when you get on the throttle.



also, turning from a stop it does some crazy noise. that's why i thought it would be the diff. thanks for the options though sebring7. well, i already have mounts laying around. just gotta find time or a place to swap the diff. fikserx7 has an s5 diff i'm takin' off his hands.

Okay...that's information that is vital. Does the rear end make noise, or does the front end make noise? If it's the front it would be part of your steering assy.



When you are driving, and you let off the throttle and get back on suddenly, what does it do? If it bucks and makes a grinding sound its probably your mount. Mine went out not too long ago and i could actually feel the thing moving up and down. The stock nose mount came out of the car in two pieces. Go to mazdaformance.com for their mazdaspeed mount...its a better price than mazdatrix.



If the diff is making icky sounds when you're turning, though...there's a good chance it's pooched. But you may also have a bad CV joint in your axle. I'm not going to be an idiot and be all like: "Yes, that's definately what your problem is. I'm so awesome that I can read a question on the internet and know the answer for sure without even seeing the car."



Find a good transmission shop that you trust and have them look at it. It's easier than fixing a bunch of **** that might not even be broken.



Good luck.

noise = rear. when you get on the throttle i'd get a loud thump behind my seat. like it's coming from beneath the bin area. then grinds while you're on throttle.



hopefully i get some time soon to check everything out. it's freezing and so far every day off i've had it has rained. err.



thanks for the input everyone

I have same problem if i hit the brakes kind of hard and then throttle it good, i should probably check mine out too.