Rear Diff Mount: Round 2
 

I had an issue with a loud thud in the back of my car and realized it was the rear diff mount...i got a mazda factory replacement and had it installed....my cars been having some problems with hot start and what not so since ive had the mount put in it has had AT MOST 30-40 miles put on it...and while i had it running the otherday i had the thud come up again... im positive its the mount and at this point im possitive the people who put it on fucked it up somehow becuase mounts dont go bad after 40 miles...what im wondering is if anyone here knows a way to make the mount more...for lack of a better word..effecient....or a place to buy a better one...or tips on (if its not broken...again) putting it on better.

you can order energy suspention polyurethane bushings for it they are are a very nice upgrade

Take a look under the car and make sure it's not installed backwards. Though that won't have an effect except on hard launches/clutch kicks and stuff.

ON my old diff cover the original mounts looked like they were in backwards, but I said to myself "Mazda did it, must be right." Put my new competition mounts in, and a week later they both slid out as I went to launch. Put them in the opposite way and haven't had a problem since.

Remember on a hard launch the diff assembly is gonna wanna go up in the front, and down in the rear. The mounts have a lip on them, install that lip closest toward the pavement.

ill look into the polyurthane bushings..thanks for the tip

and if you or anyone had a diagram of the backwards/upside down that would really help, i just think its crazy that someone could put a mount on so wrong or bad that, less than 50 miles later its broken or comming un-done....plus i havnt done anything even close to a hard launch

and what would you suggest works best for working on the underside of the car...obviously a lift would be easiest...but what do you do if you dont have a lift readily available

Well... I wound up putting the mount in backwards, read above. The way mazda originally had it, the lip of the mount was above the diff cover, closer to the body of the car. When installed that way, a week later the diff was bouncing off the street cause it dropped out of the mounts, which were still held to the studs from the chassis.

Imagine an Abe Lincoln style hat. The way it should be worn, is the way they go in.

it sounds like someting else may be wrong with the diff or suspention...get your self a good floor jack and some tall jack stands and raise the rear and the front that should give u plenty of room to work ...ive swaped like 6 compleate rears myself without a lift its not to bad it just takes a bit longer....

spot skater - any pictures of what you mean by chance, i get what you say but im having trouble immagining it on a car....not the abe lincoln hat..i get that haha.

13bturbofc - what else could be going wrong, i dont have reason to believe that anything else was wrong but then again ive only looked at the mount.

I actually just had the same problem happen with my 7! Heard thudding so I just threw on some solid tranny mounts *thought it was the tranny mount*

Still thudding, damnit! Now I have to install these diff mounts. Anyone know what a good price in Texas for a shop to install diff mounts is?This is work I won't do myself cause I don't have a lift and a lift helps when farkin with the diff mounts!

Summit Racing has a Energy Suspension Hyperflex Bushing Kit...comes with

Front Control Arm Bushings
Rear Control Arm Bushings
Front Sway Bar Bushings
Rear Sway Bar Bushings
Ball Joint Dust Boots
Tie Rod End Dust Boots

for $97.39

would that help/be a good deal?

i mean if something was not put back together right i would think that that could be causing all your problems....are you wearing tires really bad or anything?

http://www.mmr-direct.com/catalog1/RX7FC/index.htm Heard some good things about their rear diff mounts.

when you say something not being put back together right are you saying when the place put my new mount on? and as far as the tires go, if you are in fact talking about when they put my mount on....like i said...ive barely driven the car...i cant tell wether or not the tires are wearing bad or not yet.

well thanks to the help of spot skater i realized that mazda didnt send me a rear differential mount....they sent me a front differential mount...so now im facing one of two options 1) i have a new front differential mount on the front of my car 2) i have a new front differential mount on the rear of my car.

OK hold on....the rear diff mount is on the front of the rear diff. WTF is up with a front diff mount. 7's dont have a front diff? I had the same problem, turned out my subframe was broke. Go to the mazdatrix website it has a pic of all the mounts. The diff has 2, one on the front, and the top bushing type.

:wallbash: :wallbash:

Dude, you're driving a effing RWD car. There's only one differential, yo.

There are three mounts for it though. Two in the rear, and one in the front. Hence there are rear diff mounts, and a front diff mount.

Correct but the top rear mounts come as a set, so your really only buying 2 separate part #'s. :icon_tup:

Okay, to clear some of this up... usually it is the FRONT diff mount that goes bad, and causes the "thud" under accel/decel... The rears are pretty much just solid rubber, which can be replaced, but usually is not the main problem. You can get the delrin replacements for the rears(2) which will tighten things up a bit... but the front diff mount, you will have to source from mazda(or anyone who supplies mazda parts) ie: Mazdatrix. They also have a Mazda Comp front diff mount, with more solid rubber and no counterweight...

I have welded/boxed in my front diff mount, and am running AWR Aluminum rear diff mounts... its not for those who want a "quiet" ride... but it works for me...

ALSO: Check to make sure that on the front diff mount, that there is a piece of metal that is on the bolts that go into the diff housing through the front diff mount. It goes between the two diff mount bolts, and keeps them in place on the mount. If that is missing, those two bolts don't stand a chance in keeping your diff in place.

Sounds like a fix to the broken subframe issues, got a link to the work maybe?

Here's a couple shots of my setup:

Placing the REAR Alum diff mounts...

http://www.ziptied.com/Coppermine/al...DAVESFC021.jpg

Subfram setup... pre boxed in front diff mount(the front diff mount is the rubber piece closest to my feet in the pic...

http://www.ziptied.com/Coppermine/al...DAVESFC023.jpg

NICE, where you get the adjustible stablizer links?! AWESOME!!!

Alright, clear some things up...mazda sent me this (see picture) labeled as a Rear DIfferential Mount... so i took it to shop and told them to replace the one on the car, with the one mazda has sent me.

As i said before, what i dont get though was that obviously they had to put it somewhere, becuase for a while i didnt have the thud, but its comming back so im at a loss for what exactly happened/is happening here.

and as far as the subframe, how would i check.

the two bolts that stick off the diff mount go into a L shaped bracket that is welded to the subframe. This bracket can break the welds, or more common, is the metal between the holes breaks out of the bracket. To check jack up the car and see if you can grab the front of the diff and move it up and down. If it moves either the mount of the bracket is broke.

do you mean the mount OR the bracket is broken?

ALSO: Check to make sure that on the front diff mount, that there is a piece of metal that is on the bolts that go into the diff housing through the front diff mount. It goes between the two diff mount bolts, and keeps them in place on the mount. If that is missing, those two bolts don't stand a chance in keeping your diff in place.[/QUOTE]
I agree with this statement.. i bet they forgot to put that clip in and you must be sure that clip is there or you will have big problems!!!

Im not 100% certain...but i do not remember a piece of metal that was on or even around the bolts....so that could be my problem...where could i get just the clip...or even a semi-detailed picture of one.