10AEturboII

I had the dreaded clunk in my drivetrain, so I installed the MMR rear diff bushings and welded my broken front mount the other day. However I still have a "clunk" back there somewhere. The driveline noise has increased Alot, I can here a severe whining as well. Possibly the driveshaft??? I forgot to mark the driveshaft when I took it off. My main concern is the clunk that is still there.

My question is: How much did you tighten the mounting caps on the rear of the diff? I used an air gun, and tightened quite a bit.

According to the MMR site: "When installing rear differential mount caps tighten them until the metal part of the caps touches the new differential mounts"

so I gather that means that the " rubber castle looking part" of the cap should be completely compressed. Which I believe mine isn't.

Hopefully somebody that has installed these can shed some light on this.

10AEturboII

Anybody with any thoughts?

nexpo8

well i dunno about all that whining noise you said but i think that clunk that you hear is the front diff mount. i had that same problem also.

10AEturboII

Yes I realize that, in the original post it states that I welded the broken one. That clunk is now fixed. I think the "new clunk" is coming from the new rear diff mounts. Maybe it is just loose enough to create the clunk and perhaps throwing the angle of the driveshaft off just enough to cause the whinning noise. I can't see it because I hit them pretty hard with the air gun, I dunno??????? I guess I will go at them again and see what happens.

initial D is REAL!

Does the MMR mount come with a metal sleeve for the diff bushing?

Ill hopefully have some pics for you to see tonight, I just finished mines, I just need to press my metal sleeve in.

10AEturboII

No they didn't, and I didn't put the factory ones in. To be honest I didn't think they had to. There is no mention of re-using them in the instructions on their site. I am going to send them off an email and find out for sure.

initial D is REAL!

You dont need them, but its nice. If they didnt, I would go to the hardware store and buy a big washer and drill out the center.


I am saying this because the way the stock one was made. It's that washer with rubber on it. Your basically bending it as your torque it down, its not even sitting on anything. Your jsut jamming the rubber towards the alluminum frame of it.

I made mine like stock, I made a metal sleeve and it sticks out enough so the the bolt bottoms out, and the rubber is slightly pushing the alluminum frame of the diff mount


I have seen a few pictures of their mounts, and I was wondering about this issue you are asking about.

10AEturboII

That rubber castle looking thing is squished pretty bad on mine. I couldn't get it any tighter. I wonder if I should just remove that rubber piece all together?

initial D is REAL!

You might be able to find a really big washer, but the oem one is pretty thick honestly. Your going to want something just as strong or stronger.

If there isnt enough threading for the nut to torque down, use some washers to space it out

Im sticking with my oem one because mine is fine

Nitrometano

I have MMR bushings too and mines are exactly tightened like that. Check for driveshafts u-joints play and cv joint play. Maybe your clunk is in another part of the car and not on the diff bushings.

10AEturboII

That could very welll be the case I guess. Were the rubber castle things still visible after everything was tightened up? On mine I can still see about a 1/4 of inch or so of them.

initial D is REAL!

GUY's, that 1/4 gap is not good!!!!!!!!!!!!!!!!!!!!!!!! Is this nut supposed to be some special locking nut that never comes out!!??????????

10AEturboII

Yeah that exactly what I was thinking. But how is this close to a 1/2 rubber washer supposed to compressed down to nothing. Its not like it can just disappear, or am I missing something here.

There is not really a "gap" there so to speak. I can see about a 1/4 of an inch of rubber between the mounting cap and the bottom of the rear diff mount. Should I remove that rubber pc all together or perhaps try to tighen it up so more?

btw, thanks for your continued help....

Nitrometano

Do you install the bushings properly? With the bushing seat upwards?

Try to jack up the diff until he rise anymore. Then tighten the nuts. Remember that the diff weight a lot and can damage the studs and nuts threads.

Boost or Bust

iTrader: (1)

I think the best way to find out for sure is to jack the car in the air with jack stands and look to undeneath the car while it is running. There could be many reasons why you rear end is clunking and making a whining noise.

10AEturboII

Yes, Installed them from the top and hammered them down, with the seat of the mount on top of the diff.


Yeah I think you're right. That will be my next step.

farberio

iTrader: (7)

I had a whirring noise that I attributed to diff noise, I don't know whether or not it was a bad diff (thats what I thought) or extra noise due to the bushings.

I don't remember how tight my castle was, and its off the car again so I can't go look. If I remember we started to crush the bushing and then backed off....but it was awhile ago and my friend was wrenching while I was tending to putting the transmission back in.

Boost or Bust

iTrader: (1)

I agree usually a whining noise points to the diff. It could be that your diff has high miles, low fluid or even that the gear oil has lost it's viscosity. I would suggest check the fluid or even use a additive like lucas.

farberio

iTrader: (7)

Yeah, it also points to the diff as the trans bearing was TOAST when I got the car...It probably led a pretty abused life. Oh well thats what RX7s are for.

The diff is already out as I am going to a turbo driveline so I didn't worry about it. I did tell the new diff owner to change the fluid so we will see then.

10AEturboII

My whining noise started after I changed the mounts last week though. So i highly doubt that it just happened to go bad. I will change the fluid though for ***** and giggles.

10AEturboII

I also received an email back from MMR today and they said....

"The castle looking part should be compressed tightly against the bottom of the differential and the center of the cap should touch the differential mount. There shouldn't be any air gap between the washer that goes on the bottom of the bushing and the bushing itself. The steel sleeves from the old mount are not reused"

initial D is REAL!

If you wanted your metal sleeve in there, you would also need to drill out the delrin to fit the metal sleeve. I got my pics. At first I made my sleeve a tad too long, maybe 1/8 or so. I didnt measure, which ended up being my mistake.

even with the amount I have sticking out, its too short still. I will probably end up using some washers to fill in the gap a little bit.


photo bucket is giving me ahard to time to dl the other photos

initial D is REAL!

here is another pic. There is still a gap in between. I might just add some washers. Machining those metal sleeves is hell on the drill and it takes a decent amount of time

RETed

Aren't those things hard *** plastic?
If so, of course you're going to get more drivetrain noise.
This is the reason why Mazda designed the OEM parts to isolate noise.
Now you're throwing that design away - live with it.

Does the clunk only happens on one side or when unloading one of the rear corners?
Might be that you didn't tighten the big *** nut in the front corner(s) enough when you put back the subframe.
It's a typical mistake most people do.
If everything else is tight, you don't want to hear the last option - broken bracket on the front diff mount.


-Ted

10AEturboII

No question at all about the added drivetrain noise, I fully expected it to be there, I am not concerned about that. It's the clunk that I have to fix.

I will double check all of the bolts on the subframe and the diff.

As I said in my first post, the front diff mount was welded at the same time. There is no way that is broken.

thank you everyone for the input so far.