rx7ofmine

Has anyone replaced their differential bushings yet?? If so, how did you remove the diff mount? Did you have to drop the differential completely? I want to get them done on my car, but it did not look like a trivial task at all, help!!!

Alpine

same question here...

Bacon

iTrader: (12)

from jimlab

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.

The shop manual is next to useless for this, which is odd.

rx7ofmine

Thanks.

Wade

iTrader: (1)

Don't forget to remove the PPF and support the transmission with the spare tire jack or something. I removed the exhaust too, it just seemed like it was really in the way. Be sure to locktite everything when you put it back, I had PPF bolts go loose on me last year. Might want to overtorque those, I used a 2.5 foot cheater.

The shop had a really hard time pressing the old bushings out and the new ones in. I think they said it took 15,000 PSI to remove the stock ones, but less to put the new ones in.

Wade

TailHappy

I'm going to be changing the diff mounts soon. If you're going to be spending the time to get in there, should the PPF be switched out for a stronger aftermarket piece? What about the diff mounts...stock sufficient for normal amounts of power or should they be upgraded?

Thanks for the tutorial!!!

Trexthe3rd

O.K. I am doing the work for rx7ofmine, and after closer inspection, here is a few more questions.
1. What is PPF? is that the same as the drive axle?
2. the front of the diff housing is bolted to the center frame and does not look like it will move at all. How is the diff going to drop just by removing the 2 cross bolt from the diff mount??
3. Even if the diff drops, there is only about 3/4" clearance untill the drive axle comes to rest and that does not provide enough clearance to get to the 4 bolts on top of the diff mount (not unless there is a wrench with one wicked curve in it).

Thanks for all the help

Wade

iTrader: (1)

I have only had the UnObtainium Diff bushings in for about a month or two and it has been snowing most of that time, so I haven't been able to know yet how much I really like them. I can hear gear whine, that is cool, but the car is definitely louder at WOT. Also, I now hear lots of clunks from slop in the driveline at low RPMs on and off throttle. Don't know how bothersome this will be yet. As far as the ride quality, well it does seem to tighten things up a bit, but I'm not sure these are a great mod. I think all the other rear Unobtainium bushings will be more useful and probably won't transmit as much noise into the car. Anyway I'm trying to eliminate wheelhop and the rear unobtainium bushings are my last effort before I give up.

The PPF is the big metal torque arm that connects the diff and tranny, probably what you are talking about in #2.

#3, yeah you need to remove the driveshaft. I removed it from the Diff and hung it on the e-brake cable so I didn't have to worry about oil leaving the tranny. After doing this you can rotate the diff downward quite a bit. Getting to the bolts on top isn't easy but it can be done.

If you are installing the Unobtainium bushings then measure the center pins, there are TWO that are slightly longer (like 0.02", hard to detect with the eye) that are meant for the trailing arms.

Hope this helps,
Wade

KZ1

This was teh worst job I ever did. What a PITA to remove the two bolt sthe mount the bracket to diff. holly ****, I woudl never do it again in a million years. Whatever you do, put in stock mounts as well. They are fine. I put in unobotanium and could tell the differnce in stifness except now my car shakes and vibrates with the gears. And if you think you have slack in drivetrain, it is probably not the diff mounts. trust me, you will regret taking this prtoject on. I can see how it woudl be easy if you had a lift, on my back it was horrible. It was just getting at the bolts with enough leverage that took me 4 hours to get off 2 bolts.

cheers

TailHappy

Thanks for the tip! I've gotten lazy and tend to pay a trusted mechanic to do my work that's under the car. I usually run out of creative profanity before I even get myself wedged under there (which is about when I realize I can't reach the tool I needed)! I'm a little sad to hear that the mounts won't take up my slack. What other common things should I check that cause the problem? Differential, u-joints, PPF....

Thanks and hope I'm not asking dumb questions. Just got the car and have been scrambling to learn all about it!

superior_force

back from the dead.....this is a good thread

I was about ready to dive into it (installing Jim's diff bushings) until I read this....anyone else have experience, good/bad? thanks!

note: I also talked to a guy on the phone who said the vibration/noise was so obnoxious he took Jim's bushings back out and replaced them with new stockers

what are some of the other sources of driveline slop, besides the trailing arm bushings?

superior_force

btw, on a related note, does anyone know what became of "rx7ofmine"? she was quite hot

superior_force

anyone? anyone?

Bueller?

Scrub

iTrader: (25)

I'm in the process of installing a new differential (cusco) and some new bushings as well. The job really wasn't that tough. I don't know why you think those bolts are so tough to get to. I didn't really have a tough time getting to them....just hook two 17mm open head wrenches together to get enough leverage

superior_force

are you replacing the bushings with stock or nylon?

jimlab

I only know of one person who claimed he did that, and the guy was such an *** that I sent him his money back just so I wouldn't have to listen to him any longer.

I've ridden in four different cars with the differential bushings and driven two of them, and never noticed obnoxious noise or vibration. I suspect that if that was the case, there were a lot more problems with the rear suspension (probably related to high mileage) and possibly the drivetrain that the bushings just made glaringly obvious. For example, if you have worn U-joints, the bushings aren't going to remove that slop from the drivetrain, nor will they mask the noise.

jimlab

Yes, she was, but no posts since 9/03. She probably got tired of being harassed

This will have to do...

superior_force

thanks Jim, much appreciated Atlanta has some fine ladies

7racer

Jim,

your instructions for the install of the bushings are EXCELLENT. Thanks for the addendum with the torque specs...mad the install of the zerks alot easier.

As far as noises, my issue came from my coilovers...there are NO noises from the bushings even before greasing the pins and install of the zerks. *I also have the diff bushing installed.