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DIY: Firm Up Front Suspension with Front Control Arm Urethane Mod

34K views 58 replies 14 participants last post by  RWJC 
#1 · (Edited)
For those who can't stand the looseness and jiggle of the front suspension here is how you fix it:

Step 1: buy the Urethane window glue shown in the attached photo. I got it from Autozone for a little under $30, and make sure it is not expired.

Step 2: Jack up your car and USE JACK STANDS!!! as shown in the second photo, it is the best place for the jack stands for the car and keep the stands out of your way when working.

Step 3:
Figure out which holes you want to plug per the 3rd photo and clean them out with. cotton swabs and rubbing alcohol. I also applied Vaseline to the control arm on the forward side of the bushing where I wanted to fill the gap, with the Urethane only sticking to the bushing and not the control arm.

Step 4:
Apply the Urethane, which is pretty much the messiest thing I have ever worked with, with a caulking gun. Just about nothing touches it for clean up except Acetone which just smears it around. If you get it on your hands it will be there for a week.

Step 5: Wait with the car jacked up for 12 hours if it is room temperature, or 24 hours if it is really cold.
 

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#3 · (Edited)
I didn't take the wheels off. I figured whatever the unsprung weight and remaining spring force is would be insignificant relative to the static weight. Maybe it preloads the bushings a little? I'll check the ride height tomorrow. It seemed a little high when I initially dropped the car, a nd had a bunch of stuff in the trunk.

***UPDATE*** I checked my ride height again after a few more days and without anything else in the trunk. I can notice it rides higher when scrutinizing it and measuring. The car now sits about .1" higher up front, really, almost nothing.

Which for me is actual perfect since I had a tiny bit too much rake to begin with. My CG keeps getting higher and higher but when I finally get the corksport springs on it will look like I'm running tanabes and should feel more hunkered down.
 
#8 ·
I didn't take the wheels off. I figured whatever the unsprung weight and remaining spring force is would be insignificant relative to the static weight.

***UPDATE*** I checked my ride height again after a few more days and without anything else in the trunk. I can notice it rides higher when scrutinizing it and measuring. The car now sits about .1" higher up front, really, almost nothing.

Which for me is actual perfect since I had a tiny bit too much rake to begin with. My CG keeps getting higher and higher but when I finally get the corksport springs on it will look like I'm running tanabes and should feel more hunkered down.
Common when you figure how the arm sits in the bushing with vehicle weight on it vs no weight or even opposite when vehicle is raised. This is why I insure the bushing is at center with no weight in either direction. I actually used a
jack to hold the arm "just perfect" in the center when filling.
Hence why I removed the wheel.
Either way ya do it the difference in ride height is very negligible.
 
#5 ·
So this mod is for rear and front?

Also, how does this affect the height of the car? Isn't that just doing more vibration dampening?

I really want to do this since I swear the steering is exploding every time I drive :-D

Did you get some of the wobble resolve through this mod as well

I already got rotors resurfaced .. wheel balanced .. alignment (2x) done .. etc .. this might be the solution to the annoying sounds :)
 
#9 ·
So this mod is for rear and front?

Also, how does this affect the height of the car? Isn't that just doing more vibration dampening?
Stiffening the lower control arm bushings is going to make any vibration you have worse.

It will reduce the flex of the wheel relative to the steering input, making the car feel more responsive. Its a halfway solution between OEM bushings and something even stiffer, like polyurethene bushings.
 
#7 ·
I removed the wheel for ease of access only.
Remember, ideally, you want the bushing in "neutral" position when filling! Weighted down or up is not good.
Yes, I filled all the holes.

This can be done with any bushing on the suspension or rear motor/trans mount.

On the 6 the biggest noticeable gain would be the front control arm though.
Manual trans folks would see a improvement it they filled the trans mount.

If you have "wobble or vibrations" before this mod I'm thinking you have a different issue.

I let a guy with a "3" and a "Speed3" drive my car hard around a roundabout that had a nice bump in the middle and they both did this mod afterward. Speed3 guy loved the mod!
He swore it helped in putting down power.
 
#15 ·
I got into this procedure last night and got a little carried away with trying to remove all load from the bushing. I removed the struts (which isn't necessary if you just want to use jacks) so that I could lift the arm by hand and set it on a stand. I played around with different heights and [go figure] found that the bushing looked the least bound with the arm at its normal resting angle with the car on the ground. You can see the difference in how the square-ish cavities are deformed with the hub hanging free and supported at driving height:



 
#17 ·
Yeah sorry I did a poor job of explaining the picture. Essentially, the picture on the left shows the bushing with the suspension fully extended (wheel off, car raised). You can see how the bushing is twisted a bit. The picture on the right is the bushing with the suspension leveled out to where it normally is with the car on the ground (it's happy place).


Like @davesxx01 was saying, you want to remove as much load as possible from the bushing before you fill the gaps with poly. I just wanted to share a visualization of what he was talking about.

I think @solar365 said that he filled the gaps with the suspension at full extension (left pic), which shouldn't be a problem, but would explain why his ride height increased a little. I'll be reassembling everything tonight so I can report back on the results after the weekend.
 
#18 ·
This stuff is indeed an absolute mess. Be prepared for it to get everywhere that you touch or don't touch. Good lord.

I posted my thoughts about the mod over in the results thread (spoiler: I love it).

to the urethane. It's a little more expensive than some other options, but it will cure much quicker (I waited 48 hours -- I think it was well cured within 24). Keep in mind that this stuff cures best in a warm, humid environment. I was dumping buckets of water under the car 2x a day to keep the humidity up and help it along. Yes, I overdo everything.

Here is another pic with the finished product. I actually used smoothing tools to get this finish -- that's how awful this stuff is to work with.



Good luck and let me know if you guys have any questions!
 
#20 ·
Here is another pic with the finished product. I actually used smoothing tools to get this finish -- that's how awful this stuff is to work with.


Good luck and let me know if you guys have any questions!

Hey can you help me understand how this impacts the original DIY? Are you suggesting that when the car is in the air on jackstands we should lift the front suspension up until it is at ride height, and then fill in? Or we should lift the car up and let the wheels hang down when we fill in?

Thanks!
 
#25 ·
I have a 2014 MTX and find it REALLY hard to keep the throttle constant when I'm inching along in first gear at 1000-1500 RPM in traffic. The car tends to buck slightly even when I'm trying my damnedest to keep the throttle perfectly still. I assumed it was because slight bucking when letting go of the clutch was causing the ultra sensitive pedal to cause more bucking even after the clutch was fully engaged.

Do you think this modification would reduce my issue? I think I'm going to do this mod anyways because of your glowing reviews, but thought I'd ask anyways.
 
#27 ·
I am planning to do this mod this weekend. Two questions:

1) is there any reason the car has to be lifted to do this? several posts have said it is best to put the urethane into the bushing while using a jackstand to hold it at a neutral position. so why not just apply urethane while the car is sitting on the ground/ramps?

2) do you apply the urethane to these holes on the side of the bushing toward the front of the car, the back of the car, or doesn't it matter because the holes go all the way through??


Thanks!
Daniel
 
#31 ·
I did my own version of this so it could be undone if I wanted. I bought two feet of fuel hose and crammed it into most of the little holes (quite difficult in some parts) while the car was up on ramps. I cut the hose into 1 inch pieces, lubricated the pieces with isopropanol (rubbing alcohol), then crammed them in and waited for the isopropanol to evaporate (was doing an oil change so there was ample time). I don't know if the pieces will stay in permanently, but I do like the resulting effect on handling. I might make this permanent by injecting polyurethane, IF the hose pieces actually fall out at some point.

Btw, the hose was 5$ at advance auto, so if you guys want to demo the changes in handling before actually committing to this permanent solution, try it this way. I used (I think) half inch fuel line, maybe 3/4 inch, I honestly dont remember! Whatever hose you get should be larger than the holes you are trying to fill though, and you might have to use some elbow grease to cram it in even with lubrication, if you know what I mean.
 
#34 ·
So I went ahead and did this modification WITHOUT lifting the car in the air. After doing so, I highly suggest performing this mod this way. Next time, I would stack 3 pieces of wood instead of 2 though.

My reasoning:
1) Car is at the perfect height, so you know that when it dries, ride height will not be affected
2) Car needs to dry for 12-24hrs, I can't leave my car on jackstands for that long since I live in an apartment
3) It's faster!


Be sure to use many pairs of gloves and place cardboard underneath where you are working. This stuff is sticky. 91% rubbing alcohol cleans it up well if you use a lot of it.

All in all, well worth the $30 bucks for urethane and 20 minutes of my time. Car turns in and bites like never before. Combining this mod with the new rear sway bar, and for the first time I can call the Mazda6 a decent bmw substitute.
 

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#35 ·
I still haven't got around doing this mod but I like what you did.

How much clearance did you get with the stack? I am asking because I am lowered and I need to create some clearance to get under the car.

Also did you put the stack only in the front or in the rear as well?
 
#36 ·
Thanks! I put it only under the front wheel since that is where the bushing is. My car is stock ride height and I made enough clearance to just barely pull this off and slide my shoulder and arms under. Hence my recommendation for 3 blocks instead of two.

If you are lowered, I would say you probably need 4 pieces of wood and at that point I would question the safety of it...you could go get a set of rhinoramps or similar from autozone/walmart?
 
#37 ·
Just did this over the weekend, just drove front wheels up on 2x4s, slid under there. I only filled from the back, but filled everything I could and then smoothed a thin layer across the whole bushing with my finger (like in @dp741 pictures). Took just about 10 minutes, mostly because I kept re-checking the bushings and trying to push as much stuff in there as I could, and I was done.

So happy with the way the car feels, the steering has a sense of solidity that I didn't realize how badly it needed it until now! Also doesn't feel any harsher, in fact over speed bumps I think it is more comfortable with a stable thud sensation, less giggly.
 
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#38 ·
Here's what it actually looks like, I didn't use any tools just squirted what I could to fill the gaps then squirted some on my finger and spread a layer across the whole thing (it's not super clean or precise but it's not particularly visible so why does it matter). My thinking was that I am not altering the stiffness of the actual suspension just the bushing.

Even happier with the mod after a few days. I find myself looking for excuses to throw it hard into corners!

I still plan to add strut bar, but I no longer think I need a stiffer sway bar in the front (though maybe in the back).
 

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#40 ·
Hey! Glad you like the mod. I wouldn't bother with a strut bar. Hardly noticable on most cars and the mazda6 chasis is significantly stiffer than average. Part of the design philosphy they used.

Definitely get a rear swaybar. NOT a front one. The car understeers like crazy stock. If you stiffen the front swaybar then it worsens the understeer. Best mods I have done to the car are a rear sway and this urethane mod.

I used the progress rear bar intended for mazda 3. Cheaper and I have read better made than the other options like corksport. It fit perfectly. See: http://forum.mazda6club.com/suspension-brakes/385578-progress-anti-sway-bar-new-rsb-option.html
 
#39 ·
Forgot to specify I was wearing gloves, this stuff is really annoying... if you get it on your skin or anything, it is hard to get off.
 
#41 ·
I see your point, the front feels plenty solid now so won't bother with front strut bar.
I've noticed when I throw it hard around a corner it is the backend that tends to break loose, though it straightens out fine especially with some acceleration. So I am planning on adding a rear sway bar at some point... though I will probably do Injen intake and ECU re-programming first.
 
#42 ·
Hey man, did you end up doing this and how did it help with auto-x?
 
#43 ·
Yes, I did, and it made a decent little difference, but noticed that after some time I was under the car and noticed that some of the material had come out. Though I think enough is still in there reducing the pliability of those bushings keeping it a little less wiggly in the steering.
That being said, it's not nearly as much of a difference of a strut bar.
 
#44 ·
Did you do a strut bar?
 
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