DIY poly rear LCA bushings

[Preloader]

The stock rear LCA bushing has a vertical axis and has a little too much give IMO for those of us that want tighter suspension and better steering response.

Upon theenico's suggestion and helpful advice, I decided to fill my bushings with a two part urethane mix, and can say that it makes a pleasantly noticeable difference in suspension stiffness and steering response.

I ordered the 80A mix from McMaster Carr, it was like $35:
McMaster-Carr
p/n 8644K11

Removing the LCA is a cinch with the right tools.
15mm socket and wrench
18mm socket with 6" extension
13/16" socket (or metric equivalent (21 I think))

Jack the car up, and support it at the frame, and remove the wheels. Then remove the ball joint bolt with the 15mm socket and wrench.

Remove the front bushing bolt, 18mm with an extension. You can reach it from the front through a tunnel in the subframe.

Lastly remove the rear bushing bolt, 13/16" socket. And the arm comes right out.

Here's the voids you want to fill.

The instructions say the urethane mixing portions are critical, so I just poured the whole activator bottle into the can and stirred. I ended up with waaaaay to much, but whatever, I wanted to be sure the mix was right.

First I filled the void on the underside of the bushings, and let it set up for about an hour. You can cover the other side with duct tape to prevent it from leaking out the other side.

Once it got set pretty well, I flipped it over and filled the topside. Final result looked like this.

I then let it set for about five hours, and it got nice and stiff. I recommend letting it cure overnight before re installation.

Put everything back in reverse order, and enjoy.

The labor takes about 1-2 hours, but the curing is what makes the job a lengthy one. The results are immediately felt. You will feel more feedback from the road and much quicker initial response from the steering.

Not bad for less than $40.

 

[theenico]

Nice write up sir.

 

[JohnT]

I'm curious to see if the poly stays bonded to the rubber over the long term, I did this to a motor mount before and had pretty good results initially, but then it came apart after a while.

It seems like every car is using some form of lollipop bushing and they really allow too much movement. I'd prefer a higher durometer rubber unit, but thats unlikely to happen. Urethane is not ideal, although there are solid units with contoured pivot centers, but I'm not sure how well they do long term either. A rubber encapsulated spherical bearing would be ideal, but I have to imagine it would be $4-500 as a product.

Luckily control arms are only $34 from GMpartsdirect....cheap enough for experimentation

Here's a link to a similar process: Energy Suspension - Motor Mount Inserts Information

 

[sx sonic]

Exciting.

Good write up!

 

[Preloader]

Fortunately, if they don't hold up in the long term, at worst, I'll just end up back at the stock performance level. No real harm done. And hopefully by then, a better alternative will be available. But until then, at least I know as of now, I've got the best option going.

 

[Fry]

Great writeup! I saw the other thread on this and was wondering how long until a DIY would come around.

I have a question. I'm trying to wrap my head around how this is helping reduce the give on the LCA. Really, I'm trying to wrap my head around a lot of things.

I guess what gets me is that I don't understand how the part gives and how your urethane mix stiffened it. So my current thought is that the urethane goes in the voids to stiffen the connection between the rubber and the metal? Am I on target with this?

Thanks for the help.

 

[JohnT]

Great writeup! I saw the other thread on this and was wondering how long until a DIY would come around.

I have a question. I'm trying to wrap my head around how this is helping reduce the give on the LCA. Really, I'm trying to wrap my head around a lot of things.

I guess what gets me is that I don't understand how the part gives and how your urethane mix stiffened it. So my current thought is that the urethane goes in the voids to stiffen the connection between the rubber and the metal? Am I on target with this?

Thanks for the help.

The rear front-arm bushing acts as both a cushion and a pivot point for normal suspension compression. The movement of the bushing reduces NVH and makes things feel smoother over rough roads...unfortunately this cushion also results in significant movement from the forces applied during either acceleration or braking. The change in control arm position results in unwanted dynamic toe changes leading to poor performance in acceleration and braking. If you ever watch an OEM sonic or really any FWD car launch you can easily see the movement of the wheel in the wheel well.

Another thing to worry about is the clocking position of the bushing. I have purchased new OEM parts where the pivot center of the installed bushing is not correct in relation to the pivot center of the arm...this will lead to worse performance and wonky handling. If installed correctly the solid portion of the bushing should be in-line with the pivot of the arm on the front bushing as a fore-aft force is applied to the hub. This will lead to less fore-aft movement while still allowing the arm to rotate for suspension compression.

Here is a (boring) video I took of a similar bushing in action on an IS300. This was of a replacement bushing that was advertised as stiffer, but in reality was much softer than even OEM. IS300 Hardrace #2 bushing uncut - YouTube

Makes you laugh when people try to align OE cars to .1 degree when you realize how much slop is in there

 

[Preloader]

+1

Even the slightest bit of movement of the LCA from its initial position, translates to BIG movement in the alignment geometry.

I remember when I got 4 new tires on my beater car. I asked the shop to do the alignment, and the guy said my ball joints were so worn that he couldn't do an accurate alignment because within a block of driving, it would be way off again.

I believe the slop in the LCA bushing played a huge role in the wheel hop I was getting. That was my original motivation for this project. And now that I've done my best to tighten them up, I feel much more comfortable about getting a proper alignment done.

 

[Fry]

JohnT: Thank you for the reply; that helps a ton. I appreciate your thorough explanation, the picture, as well as the video you showed. Though simple, the video shows parts in motion, which helps me quite a bit.

Thanks again Preloader for the DIY writeup and follow ups. I feel much more informed about my car.

opcorn:

 

[Eric Smit]

and to think I was about to text you and ask for a brief write up.

 

[$ub$onic]

Thanks preloader and John

 

[cndctrdj]

How do they feel

 

[Preloader]

and to think I was about to text you and ask for a brief write up.

I was gonna text you this morning and tell you that you MUST do this mod. I took some turns aggressively on my way to work. The car feels like its on rails. Very similar to the feeling you get from upgrading swaybars and end links.

 

[Preloader]

Who's gonna be next to do this?

I wanna hear some feedback about it, besides my own experience.

 

[sx sonic]

Who's gonna be next to do this?

I wanna hear some feedback about it, besides my own experience.

I would. Except layed off again. That and finding the stuff, not online. This sounds like my kinda mod...

Pre did you tighten up the LCA's while the control arm was loaded, such as on a drive on lift?

 

[Preloader]

Nah.... Totally forgot, but with the vertical axis style I don't think it's as critical. I'm not worried.

Good catch though. That is definitely standard practice.

 

[sx sonic]

Nah.... Totally forgot, but with the vertical axis style I don't think it's as critical. I'm not worried.

Good catch though. That is definitely standard practice.

You just cleared my memory lol. I recall doing certain bimmer bushings on the alignment rack, for a logical reason.... Couldn't remember reason lol.

Way too many concussions and too many beers have left me with the opposite of "instant recall memory". I have "it's there, jog my memory and give me a day" memory.

But yeah I don't seeing it making a difference with these bushings for the reason you stated. The bushing does not change its clocking relative to the "housing?" Under compression or rebound, as in it will experience whether torqued with or without a load.. The style I was thinking of would always be under load if torqued with the wheels off the ground.

 

[Preloader]

Need more convincing? Here's a video of the response.

Also I took some right turns without slowing down at about 25mph. It hardly rolled at all. My knuckles are still numb. I'll try to get some better video soon.

 

[Preloader]

Here's a hard turn video. Pardon the rattling from the headrest poles.

Notice how flat the car stays.

 

[Eric Smit]

gotta do it tonight.