Mitsubishi 3000GT & Dodge Stealth Forum banner

Solid Differential Bushings: Installation/Tips/Review

8K views 7 replies 6 participants last post by  AlmosN8kd 
#1 ·
This past Sunday, I had solid rear differential bushings installed on my 97 VR4. Originall purchased from:
http://www.3si.org/forum/f4/new-product-solid-rear-diff-bushings-583337/





This is my review:


The process is fairly simple given that you have the correct tools (jack/stands, 2x 17mm wrenches, 17mm socket) and if the car behaves nicely. Overall process should take no more than 2 hours MAX.
The only special tool needed is a press to remove the old metal/rubber bushings. This is a must have unless you want to spend 7-8 hours (like I did) removing those old bushings.

1. We began by dropping the entire stock exhaust from the cat and back (IIRC, using a 12mm socket?). This took only 5 minutes and is a lot easier than it sounds. If you’ve never touched your car before, I suggest using liquid wrench to help with removing those frozen bolts.

2. After the exhaust was removed, we decided to take the easy route by doing one bracket at a time (there are 3 brackets holding up the rear diff). I’ve rear of people removing the CV boots from the diff, etc, but that isn’t necessary.

We started by using a jack to support the rear diff (just in case) as we removed the rear U-shaped bracket using 17mm wrenches/sockets. There is a bolt on each bushing and three more bolts on the back of the differential. Some liquid wrench and muscle goes a long way to break those bolts loose. This bracket came off fairly easily.

3. Once the rear U-bracket is off the differential, it’s just a matter of removing those stock bushings (there’s 2 bushings on this bracket). It’s highly recommended taking it to a professional shop with a press to get the metal/rubber bushings out.
I did not have a shop opened nearby to help with the process so a makeshift method in removing those bushings was improvised. I WOULD NOT ADVISE DOING THIS. EVER! GET IT PRESSED OUT!

4. Once the stock bushings were out, the solid differential bushings were installed onto the bracket with a rubber mallet. With a few strokes, the bushing slid in nicely. Snug and tight. Viola, Done! Reinstall the U-bracket by reverse the process of removing. Don’t forget to tighten everything down!

------

Part 2: Removing/Installing the last two brackets.

The last two brackets are flat (there’s a driver’s side and a passenger’s side) and each has their own bushing. There is 1 bolt on the bushing, and three more bolts holding the bracket to the differential. Removing these brackets are tricky because the bolt that slides into the bushing can only be removed by first unbolting the last piece of the driveshaft that’s connected to the rear differential. There’s no other way.

5. You will have to remove the 4 bolts (14mm/12mm wrench) that link the driveshaft to the rear differential. There is not a lot of space around this area for tool clearances. My driveshaft had about 6mm of play so I was able to rotate and position those 14mm nuts for access. If your driveshaft was perfect, there should be no play. So I’d suggest first marker-marking your driveshaft to the diff for reference then remove the first two bolts you can access, move the car a few feet to rotate the driveshaft until you can access and remove the last two bolts. Remember to support the rear diff just in case while you remove those brackets.

6. Once that driveshaft is out of the way, the bolt holding those brackets can now be pulled out, old bushings pressed out, install new solid bushings and reverse installing.

7. These brackets look similar but there’s only one way they will fit back onto the car. You can’t get confused by them, so don’t worry. Make sure the bolt that slides into the bushing is installed the same way as it was removed (both bolts points away from each other) otherwise the driveshaft will hit it as it turns. Very bad. Make sure the nut is on the outside, touching the bracket. Do the same for the other bracket.

8. Bolt up the driveshaft the same way it was removed. Tighten down everything.

9. Finally, reinstall that exhaust you dropped in the beginning. Check everything and finalize.
10. Go for a drive and have fun!


------

Wrap-up/Conclusion/Thoughts

I sought to remove the funky clunk noise from my VR4 long ago. Every time I step on the throttle, let it off, or shift gears, I had a THUNK. It definitely came from the rear of my car. My carrier bearings were definitely shot and so I started with replacing them along with a PST 2-pc hybrid driveshaft. Sadly, clunk was still there. I then went with replacing all my motor mounts with seattle’s Poly motor mounts. Car immediately felt tighter, but again, clunk remained present. I’ve already replaced my clutch and my output shaft was perfectly fine when observed. I did some research and read that some members have replaced their rear differential bushings with solid bushings. So I purchased these from Pampena and just recently had them installed.

I can confidently say 90% of the clunk is IMMEDIAETLY GONE. I can definitely feel power being transferred to the wheels the moment I hit the throttle. Until now, I previously didn’t know what “slop” felt like. I definitely had slop in my drive train with those stock rubber bushings- despite them looking completely fine in every way. Overall, everything feels tighter and solid (no pun intended) with these bushings. However, because I am able to rotate my driveshaft a small amount while parked, I’m sure I have a tiny amount of differential backlash. I read that this is a rather complicated process to fix, and in my case the benefits of fixing it is miniscule, thus I will not go that route. Overall, I am incredibly satisfied with the improvements of these solid differential bushings. The difference is amazing and, in my case, almost night and day. Driving my car feels more enjoyable. I’d highly recommend them looking at it from the point of cost/benefits and ease of installation.

Pros:
- Stock exhaust sounds a bit louder
- My shifts feel smoother
- Clunk is almost completely gone.

Cons:
- From 40-45MPH, I have a teeny, tiny whirl noise from the rear differential, but that’s only because I was listening for it. Hardly noticeable, if at all. A member described an annoying whine noise with a 2-pc driveshaft- I don’t appear to have it. Your experience may differ?

** Accompanying pictures will be attached later. Though not many taken at all **
 
See less See more
2
#2 ·
Very nice write-up. It sounds like you found similar results to mine. Now that I have the solid diff and solid subframe bushings, there is definitely more noise which I'm now wanting to get rid of. Dynamat is my friend, and I'm probably also going to go for something different from my big honkin' Cherry Bomb for a muffler to quiet down the exhaust a bit. Other part is I'm getting older and so loud isn't as much fun as it used to be.

One thing I'd add from when I did them - you don't need to press out the old bushings. I got mine out with a sawzall in a couple minutes for each bushing. I'm not sure what method you used that took so long, but it was quick and easy for me.
 
#3 ·
.So nice of you to ask. I'll explain.
Although my car only has 66k miles, those stock rubber/metal bushings were frozen on there.
First, we used a clamp with an impact gun to press out the center rubber piece hoping it'll slide the metal off as well. No luck. That rubber is incredibly strong and barely wanted to come out, but it eventually did. Just the rubber. The metal ring was still on. A hammer didn't help either.
We then decide to use an impact hammer to shock-out the metal ring. That barely helped.
Then we used a sawZALL, to create a weak spot on the metal and used the impact hammer to peel off the edges of the metal away from the bracket.
Its was an incredibly long process and the metal was very stubborn.
A sawZALL can only help cut out the center rubber, but the metal ring is another thing to tackle, which a press would best be utilized for removal.
 
#4 ·
Mine will be going in very soon. Nice write up!! I bought mine pre pressed.
 
#5 ·
That's why I made my own poly bushings for my car. My friend had solid ones in his dsm and I didn't care for the added noise. It sounds like the vr4s are not as loud though, because his dsm made me think something was about to break. I bet having the stock subframe bushings helps quiet the noise.

As for removing the stock ones, do it like you do the motor mounts. Drill big holes around the center metal sleeve then knock that out. Then take a sawzaw and cut the inner metal ring in half. Then you can hammer a screwdriver behind the ring, pry it inward and it will fall right out.
 
#6 ·
I found using the sawzall in two places on the outer metal ring of the old bushings worked great. Did it for the diff and the subframe bushings. A single cut will usually not weaken it enough to get out easily. Sometimes I've needed three cuts.

The VR4s don't have the same noise factor as the DSMs. Mine is never loud enough to make it sound like it's exploding, but it is absolutely louder now, hence my desire to try to reduce the noise via more Dynamat. I did one layer, but want more, and I didn't get all the areas covered I'd like to. I've found the VR4 is never a very quiet car, so it needs the help anyway.
 
#7 · (Edited)
I found the hardest part of this job was getting the new bushings in. I beat the crap out of them so hard that I had to drill the hole to get a bolt through. So, after I did the ubracket, i waited to do the others until another weekend. This time, I put the solid bushings in the freezer before hand. That helped quite a bit. For the last bracket, I heated up the hole. Coupled with the freezer bushing, and that sucker dropped in easily. I didn't press mine out either, just used a hacksaw. Made two cuts and hammered an old flat head screwdriver in there to which bent the old bushing out. Also, a 32mm autocraft deep socket is the perfect size to hammer out the bushing.
 
#8 ·
Freezing the bushing for about 20-30mins and leaving the brackets out in the sun for about the same time will allow them to drop right in without any trouble.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top