TailHappy

Sorry, this sort of belongs in the rear end noise thread but was afraid it wouldn't be noticed there and I need to know something before this weekend!

Anyway, I need to know the best way of replacing the differential mounts. The shop manual seems to show having to take the drive shaft and axles off plus tons of other stuff (and then recommends realignment of the wheels). Is it possible to swap them out without disassembling everything?

Also, I need to change the fuel filter. Will that be easier to do while in there with the mounts?

Thanks a billion to anyone with some helpful advice!

Bacon

iTrader: (12)

as per jimlab's instructions when i asked him how to get to diff mount
"The diff mount is no problem. Just unbolt the 10mm bolts holding on the two rear belly pans. Then unbolt the braces on either side, which are 12mm I believe. This will give you all the access room you'll need (and are going to get) to the diff mount. Unbolt your exhaust from your midpipe or main cat, no need to remove it unless you're just really gung-ho.

Support the differential and remove the two cross bolts holding the mount to the subframe. They're 14mm, I believe. Let the differential down slowly and it will rest on its axles on the rubber pads on the rear subframe. No real need to support it at this point, since it can't go anywhere, but keep a jack under it if it makes you feel better.

Your last step is to remove the 4 17mm nuts on top of the differential carrier which hold the mount bracket to the top. They're on there GOOD, so you'll need to be creative about getting leverage on them. They are also loc-tited in place to make things even more fun. An impact air wrench would be perfect, obviously (the ratchet style, not an impact gun) but you can get them off with your average 17mm open end/box end wrench and a pry bar with some creativity.

As usual, support the car adequately and wear eye protection while you're under the car.

Replacement is the opposite of removal. The OEM bushings can be pressed out easily with a large socket and a hydraulic press if you're doing it yourself, and the new ones go in slick as snot."--jimlab

Lost Time

Thanks Bacon. I have to replace my diff mounts too and have been looking for the info.

slipperyslater1

yeah, thanks from me too, bacon bits. Any idea who sells them for a good price?

TailHappy

Thanks a BILLION Bacon!!! I was starting to get intimidated about the whole project but it doesn't sound too bad, now.

Slippery, I did some research on mounts before I bought mine, and I found several people that were unhappy with the jimlab and unobtanium (any urethane) bushings. They are strong, but they apparently transmit a lot more gear noise into the car. I think the quality and strength of both were good, it was just the noise that people didn't like. I ended up going with Mazda Comp's competition mounts since they are supposed to be something like 40% stronger, but they're still rubber and aren't supposed to have any downsides over stock. And you I don't think you have to worry about pressing anything out. They're supposed to be plenty strong for any normal levels of power.

DomFD3S

Bacon bits? Is that your pet name for him or are you trying to create one for him?

Rotary93

Len,

How is the BaconSports vented hood coming out?

Bacon

iTrader: (12)

well the almnuim side pieces should be in early next week..then i just goit to line up a tig welder and the first vent will be done shhhhhh dont want everone knowin abt it just yet


man ive heard a million varations on bacon--its my last name so u cna only imagin growing up with it

bacon bits..bacos..bacon double cheese burger...bacon and eggz..u name it
its all good

Lost Time

Cool. Now we have someone else to play the "five degrees of seperation" game with.

Hey Bacon, did you actually put your bushings in? Was it as easy as Jim said, or does it require a certain degree of mechanical savy? And did you just use a floor jack to support the diff?

Bacon

iTrader: (12)

well i havent done the diff ones yet...im planning on puting in a kazz sometime b4 car goes back on the road so ill kill 2 birds with one stone... but from under the car yea it looks as easy as jim says it is...the only hard part i see is removing the 4 nuts that hold it to the diff, but if you can squeeez a air rachet in ther it should be cake

slipperyslater1

nah, not really a pet name. Its just he always has helpful bits, and it just seemed to fit. Anyway, thanks for the info. I'm sure its going to come in handy. Got the lift, tools, etc. Now I just have to find the time , plus order a few mounts, i guess. First things first though. I'm off to Asheville tomorrow for new ECU and Pettit intake. Thanks again.

MOSTIN

How do you know the diff mounts needs to be change?

TailHappy

Woo hoo, I did it! I initally wasn't totally sure I could pull this one off....

It took me the whole weekend, but I managed to get the differential mounts, fuel filter, and high flow cat installed. The differential mounts are definitely do-able, but like someone said, it takes creativity......so for those novices like me, here's exactly what I did....

I first got the back of the car up on jackstands. If you don't have a creeper, go buy one before you start!!! I wouldn't have had the patience to do this if my back or neck had started hurting, and I was constantly sliding around to either see or to get a tool. Then remove the two nuts that are on the bolts that go through the diff mounts. They're on there tight, but have fun 'cuz it's gonna get worse. Jack up the differential and pull the bolts out. Then slowly lower the diff and it will come to rest on the axles. Fortunately Mazda put rubber bumpers for your axles to sit on, so this shouldn't hurt them. Now for the fun. I don't have any air tools, so they probably would have made this a much simpler job, but there's not much space to work up there so I dunno. You now need to remove the four bolts on the top of the differential. These things are on there tight!!!! If you're laying under the car with your feet straight out the back, the top left one is the easiest to get to. I put a shorty wrench on it, and then used a crowbar pulling against the axle on your left to finally break it loose. Next I put a deep socket and an extension on the end of the wrench I was just using (to make its handle longer), and took the right two nuts off using the exact same crowbar pivot location (the wrench went across the differential). Unfortunately, the fuel filter is in the way of the last nut (bottom left). So I used a regular wrench positioned across the diff and crowbarred it from the right side.

Once all the nuts are out, you have to figure out some way to wiggle the entire bar out from in there. I ended up having to take off the plastic canister, which is held on with two bolts (have no idea what the thing is, but it looks like something for emissions). Ultimately you can get the bar to slide all the way to the left into the area between the wishbones, rotate it down and slide it out.

That was about 3 hours worth of work for me. The next couple hours were spent trying to find someone to press the old mounts out and the new ones in. Note that they aren't symmetrical...one side is marked "top." I also changed the fuel filter at this point since you now have a tad more room to work with.

Just reverse the process to get everything back together. I was pleasantly surprised that the bolts weren't hard to get back in the mounts. To get the holes aligned, I had to use a crowbar to push the diff away from the crossmember, and then I was able to push them in with my hand. After changing motor mounts on another car one time, I was afraid getting the holes aligned would take hours. I may have just gotten lucky on this one.

I'm not sure of the final results since I haven't slammed any gears yet. I had to use some JB Weld to hold one of the mounts in place so I want to let that dry as much as possible. The guy that pressed them out used a socket that was slightly too large, so the new mount was loose in the bracket on one side. I don't think this should matter since it really doesn't have anywhere to go, but I want to let the JB Weld set anyway. However, just driving around everything feels a lot tighter. I think it may have solved the sledgehammer 2nd gear shifts, and it definitely took out a lot of the on/off throttle transition slack. One of the old mounts was completely torn and fluid was running out of it, but the other didn't look too bad. The new Mazda Comp mounts are solid rubber and are supposed to be stronger, so hopefully this won't have to be done again. Plus there's no additional noise such as like gear whine, either.

While I was in there, I also noticed my PPF has about a 6" crack in it (real 6", not a guy 6"), and is only about a quarter inch from making it to the other side (thus being broken in half). Guess that'll be my next project.....

Thanks again Bacon for the jimlab instructions!

TailHappy

MOSTIN, my symptoms were...
1) Excessive driveline slack during off-on or on-off throttle transitions
2) A horrible clunk when shifting to 2nd gear quickly near redline. As others have said, it sounded like someone hitting the back of the car with a sledgehammer.
3) When taking slow 90-degree turns on the gas near the traction limit (~20mph, like turning right at a light) I would get something that felt similar to wheel hop and the shifter would shake back and forth.

Hope this helps

rotary-tt

TailHappy, this sounds like my symptoms although I've not experiened #3(I'll need to try this). I'm anxious to see if this solves the sledgehammer 2nd gear shifts. How much driveline play did this get rid of? Is there any way to get a visual on the bad mounts if you don't see any fluid? Are the mounts mushy from the fluid loss or they torn? Can you see any of this from under the car without taking it all apart?

TailHappy

Weelllll, it's sort of difficult to describe how much play it got rid of. I had very excessive play and now it feels normal again. From being off throttle, if you didn't ease into the gas extremely easily, the car would bounce forward and back at least twice. Basically there was just so much slop that I thought the rear end gears were worn out. It was extremely annoying and felt bad enough that I knew something needed replacing. That's about the best I can describe it.

One of the mounts was very visiblly torn. Unfortunately I think it had to be out of the car to see it. From memory it seems like the place where it bolts to the body is solid so you wouldn't be able to see it without taking it all apart.

JAMMNN

Do you have a link or part #`s for this? any pics would be cool!

TailHappy

Sorry, no pics. Still don't have a digital cam yet...

No part number either. Just give Mazda Comp a call. They know their stuff. You can get their number off the web page (but the part isn't listed on it)....
www.mazdamotorports.com
Just ask for the heavy duty differential mounts.

TailHappy

I've lived with the new mounts for a couple more days and just wanted to add some more observations. Unfortunately, it doesn't look like this has removed all my driveline slack. I haven't had the sledgehammer sound anymore, but I'm suspicious it's just because I learned to drive the car in such a way as to prevent it.

On the positive side, it has significantly reduced the turning wheel hop I mentioned, and it absorbes the shock from the slack in the drivetrain a lot better now and just generally feels tighter. I think I may also be getting a little more gear noise, but it's hard to say and it's not loud enough to be annoying.

JAMMNN

I wonder if the engine brace mod would help with driveline slack?

rotary-tt

The slack may be in the rear. I am finding that I can rotate a tire(without the other side moving) an inch or 2 before the driveshaft engages.

TailHappy

Yup, I'm thinking it's either the rear end or maybe the u-joints. I can turn my wheels like that too. The car's been driven hard all it's life, so it's probably finally starting to show. So how 'bout that Kaaz?

Steve Jarvis

I hope you are at least going to have the crack in the PPF welded up until you can replave it.

Later, Steve

TailHappy

Plan on doing it sometime this month, so I didn't plan on doing any welding. A little late to ask, but what are the ramifications of a totally cracked PPF? Just a bigger clunk or does it decommission the car? Fortunately it survived MADS!

TailHappy

Just wanted to post a follow up to this thread. I finally got around to replacing the PPF and was horrified at what I found. There was a major crack all the way through at the hole near the rear end. However, what I didn't realize until I got it off was that there was also a crack at the top bolts at the rear end that only lacked about an inch from causing the top mounts from totally breaking off. Then there was ANOTHER crack on the bottom halfway down the PPF. Pretty well destroyed!

The new PPF was like night and day. The sledgehammer shifting is absolutely totally gone now. Definitely the culprit. In addition, I get a lot less wheel hop, the car's not fishtailing as readily as it was, and when it does it's much more exact-feeling and controllable. It used to just wallow around but now you can feel more of a subtle snap as it gets back in line. And the drivetrain has MUCH less slack in it, making shifts feel more like I actually have a clue what I'm doing. The differential mounts helped, but it was really the PPF that was causing all my woes all along. Check it out if you have the symptoms! Just $289 from Mazda Comp and worth every penny!!!