How To: Install Rear Trailing Arm Bushings Without Removing Knuckles

 

You heard that right, you can install these without the painstaking process of removing the rear knuckle (which involves unbolting just about everything in the back). This will take about 2-3hrs depending on how fast you are and how rusted your car is.

 

Tools needed:

• 1/2" breaker bar/wrench and 19mm Sockets
  
• 19mm combination wrench
  
• 14mm Socket for ABS/Handbrake holder
  
• Hammer
  
• Couple flat head screwdrivers
  
• Propane/MAP Torch
  

 

Why replace the bushing?

My OEM bushings were pretty torn and were detaching from the outer metal sleeve. Driver side one was cracked:

 

Passenger side one was detached from the sleeve, I could see it separating while just unscrewing the retaining bolt.

 

This guide will have pictures from both sides, so if it looks like the wrong side of the arm, that's why.

 

Removal Steps

Raise one of the rear sides and remove the wheel, the bushing can be seen on the far left under the car.

 

Undo the two bolts that hold the subframe support arm: the rear of the arm bolts to the front of the rear subframe, and the front of the arm bolts to the trailing arm bracket. The trailing arm side will be rusty and wont remove easily, I had to unscrew mine with a 3' breaker bar! After subframe support arm is out of the way, unscrew the handbrake bracket and ABS sensor bracket, move these out of the way.

 

If you've never removed the trailing arm bolt, it's gonna be STUCK. I didn't want to heat it because that might burn the ABS sensor wire, so instead I used PB Blaster and used my foot to break it loose. The outside facing bolt doesn't have enough room for even my low clearance craftsman socket, so 19mm combination wrench is a must, but it will fall off often. Also, you really want the trailing arm bracket be in place when breaking this guy loose, so don't touch those until you get the bushing bolt loosened.

 

I was real hopeful that I wouldn't have to loosen the rear trailing arm bracket from the body, but the bushing bolt was way too long and would hit the body before it came out. Thus the bracket had to be loosened.

 

Now the trailing arm bushing wont hang low enough give you access to burn it out or hammer it out. I found that if I jack up by rear of the knuckle, right at the toe arm, it will angle the front of the trailing arm to be below the body giving you plenty of room to work.

 

Now it's time to heat the bushing, you mainly want to heat and loosen the glue on the outside rim of the bushing, where it attaches to the metal sleeve. Be careful not to burn the handbrake and ABS wire!

 

I then took a big screw driver and was able to remove the bushing really easily, seriously one of the easiest removals I've done.

 

On my left side the sleeve was so rusted, couple taps with a hammer and screw driver got it out.

 

On the right side the sleeve was less compromised so it required a little more elbow grease to punch it out, once again a flat head and a hammer is your friend.

 

After the bushing's metal sleeve is out I cleaned up the knuckle's hole with a file and spray painted it. After this we can now install the new bushings.

 

 

Installation Steps

 

I personally went with Whiteline W63398 bushings, there are a few other options on the market though.

 

Installing these bushings is really easy since you install one half at a time. For Whiteline W63398, thinner bushing faces the outside and thicker one faces the inside of the car.

 

Since these are poly bushings, I torqued them to the rear arm bracket right of way. FSM Torque: 111ft-lbs

 

Afterwards the bracket needs to be rebolted to the body, this one is trickier to align. I used the jack under the shock mount and pulled the jack towards the front of the car, which helped me align the bolt holes. These need to be torqued to 92ft-lbs.

 

Afterwards reinstall the handbrake & ABS holders and finally bolt on the subframe support arm. The support arm torque for the trailing arm bracket is 92ft-lbs, while the torque to the subframe is 129ft-lbs.

 

Here is the bushing in place and everything torqued.

 

Update: After 200 miles, it does look like the bushing walked out a little:

Edited December 10, 2018 by covertrussian

Thanks for posting this. Mine are looking pretty sad lol.

 

j.

so sorry if this is a stupid question to the suspension gurus, but why don't you have to have the weight of the vehicle on the trailing arm bushing when you torque it like you do wirh other bushings?

so sorry if this is a stupid question to the suspension gurus, but why don't you have to have the weight of the vehicle on the trailing arm bushing when you torque it like you do wirh other bushings?

 

No problem, that's how we all learn

 

If it's a rubber bushing that has a chemically bounded (glued) center crush tube (aka all OEM or OEM like bushings) it MUST be tightened with full weight. It's with any Poly bushings that rule doesn't apply to, since the center crush tube is free spinning.

 

More detailed explanation:

Rubber bushings with chemically bonded crush tubes are designed to rotate a little bit, in each direction, to account for the wheel & suspension going up or down. When you torque the rubber bushing outside of it's designed range then lower the car back down, it will cause the bushing to over rotate and rip it. It also binds a lot more reducing effectiveness of the suspension, but ripping is the biggest issue.

 

Poly bushings always have the center crush tube free spin, meaning you can have the car in the air (suspension at full droop) and when you lower it they will just rotate freely to their happy spot. Basically Poly bushings work like ball bearing without the all metal harshness, which is why they are so much superior to rubber, but at cost of increasing NVH (noise vibration harshness) over oem soft rubber.

What's the nut part number for the rear trailing arm bracket? Is it possible to get a hackzall in the area to cut the bolt out?

You should be able to find the part number on Subaru parts page, I reused mine so didn't have to buy new ones. As for getting a hackzall in there, I wouldn't too much other stuff to damage. I would remove the bracket and use an angle grinder to cut the head off the nut instead.

Already checked all I can find is the bolt the subaru parts list at opposed forces does not show a part number for the nut but it lists it on the page I don't know what's up with that.

 

 

If this stops the rear end swaying I want to do it.

Already checked all I can find is the bolt the subaru parts list at opposed forces does not show a part number for the nut but it lists it on the page I don't know what's up with that.

 

 

If this stops the rear end swaying I want to do it.

 

I don't use Opposed Forces for this reason. Found it on heubergersubaruparts.com in less then one minute:

20550AA010

I don't use Opposed Forces for this reason. Found it on heubergersubaruparts.com in less then one minute:

 

20550AA010

 

 

 

Thanks that crap had me pissed off when I ordered lots of parts during my rebuild.

Question since this is said to stop the side to side motion I really haven't looked but on the end of the trailing arm is it fixed in place and this bushing is the only area that allows side movement?

 

 

I was just wondering if some other bushing comes into play? What about those camber bushings? I'm hoping when I do this and get my car aligned I wont have any more issues with heavy tire wear like hardly 20k on a set of tire wear.

Hard to say, depends on the tire wear. Could be a lot of things at play that cause uneven tire wear including bad shocks. What kind of tire wear are you seeing?

Hard to say, depends on the tire wear. Could be a lot of things at play that cause uneven tire wear including bad shocks. What kind of tire wear are you seeing?

the KYB G2's only have maybe 30K by now..

 

 

Between all the side to side motion my rears are bald but my fronts have like 40% left.. I know going over some manhole covers I could hear my tire chirp when going straight so I'm not sure if it's a toe + camber issue..

 

 

I will get a picture of the tire pretty much how it was when I got the car for the first time extreme inner wear and some otter wear.

the KYB G2's only have maybe 30K by now..

 

But your running those KYB's with lowering springs, which means they went shot as soon as you lowered the car from the jack stands .

 

Between all the side to side motion my rears are bald but my fronts have like 40% left.. I know going over some manhole covers I could hear my tire chirp when going straight so I'm not sure if it's a toe + camber issue..

 

 

I will get a picture of the tire pretty much how it was when I got the car for the first time extreme inner wear and some otter wear.

 

So inner strip of the tire is bald? That's Toe + Camber. Rear's are supposed to have toe in for straight line stability (about 1/8"). Stock camber is about -0.5*. Since you are lowered, your static camber would increase, but who knows by how much. Do you have an alignment printout?

 

Bad bushings cause the tire to bounce or loose camber in a turn, which leads to cupping or feathering, or outside tire baldness (due to camberloss). Though it's possible that your toe link's bushings are shot causing your toe to move around a lot and causing odd wear too.

To get back on topic a little I took a picture of the drivers side rear

Oh man your's is toast too, the rubber has separated from the metal sleeve! Get those replaced asap .

Went ahead and replied in your build thread .

Hey I just saw this I saw their is a bit of a gap where the toe adjustment is I wonder if I could use my saw and cut it off between the rear crossmember and the lateral link? That way I won’t have to go crazy trying to cut the head off.

thanks for the write up, great pictures and info, just completed this yesterday on my new to me car. Just fyi i used an air hammer to pop the old bushings out, took about 2 minutes per side.

thanks for the write up, great pictures and info, just completed this yesterday on my new to me car. Just fyi i used an air hammer to pop the old bushings out, took about 2 minutes per side.

 

Good idea, now I rarely ever use an air hammer, mind explaining where you usually hit with it?

Good idea, now I rarely ever use an air hammer, mind explaining where you usually hit with it?

I used a straight blade, but really you can use any pointed blade. and i just hit it a few times on the back (inside) to break the rust loose, then just hit the outside in like 3 or 4 places around the outter ring and it popped right out (towards the middle of the car). you just want to be careful to just hit the metal ring the bushing is in and not ding up the knuckle too bad. I have some air tools i used to clean up the small marks i made with a grinder. still way easier than burning and hammering by hand. cheers

Just to start off a big thank you for this thread CovertRussian!

 

Both my bushings were coming apart. I noticed some odd tire wear and picked up a "new" rear pair to match the fronts (actually the same brand and wear as the fronts) going through your process was great, probably the saving grace was the jacking point you noted at the rear of the knuckle to drop the front of the trailing arm down. It made it easily workable. As sandro said above me here, air hammer, those bushings and sleeves were out in seconds even with 313,000 kms on them.

I used the whiteline bushings and yes those babies push right in by hand and feel great.

Probably one of my favorite upgrades for the car so far.

As always Great Walk-through Write-up - thank you.

 

Will get this PDF'd as well.

 

 

And moved 1-2-3-4's suspension discussions posts to his build thread.

Time to tackle this today... wish me luck it’s freezing I think I have all what I need

Question why do I need to remove both subframes bolts from the support arm? Can’t I just remove one and swing the trailing arm down?

 

Looks like it would clear?

Cleared just got the drivers side off thanks to the cordless tools not that much sweat but good greef the worn parts flex like crazy