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Discussion Starter · #1 · (Edited)
Installing the Mugen Sport Suspension

This is a fairly complete DYI for the Mugen Sports Suspension, with some additional explanation and measurements for those who may not be familiar with it.

Description and data:

The Mugen Sport Suspension for the Acura RSX Type-S (really the Japanese Integra Type-R) consists of complete front and rear replacement struts (springs, matched shocks absorbers and strut assembly). The only other hardware supplied are two cotter pins for the tie-rods and six 14mm flange nuts for the front towers. Installation instructions are in Japanese. Illustrations are straight out of the Acura RSX shop manual. The Mugen SS provides a 35mm (1.4 inch) drop. Spring rates, according to the website I bought them from, are 279 lbs/inch front and 458 lbs/inch rear compared to 207 and 413 for the stock springs. Unlike a coilover, the Mugen SS is not adjustable.

It's been posted that the Mugen SS weighs more than the stock suspension. I weighed all parts with the following result:

Mugen: front 23.7 pounds each, rear 10.4 pounds each. Total 68.2 pounds
Stock: front 22.5 pounds each, rear 11.5 pounds each. Total 68.0 pounds

I ordered mine online from King Motorsport (www.kingmotorsport.com) in Wisconsin. Price was US$1,000 plus US$70 shipping. Delivery was very prompt. The boxes are marked "Sports Sub Kit Showa, Mugen, made in Japan" and are sealed with Mugen tape.

Tools needed are:



- Socket wrench with extensions
- 10, 12, 14, 17, 19, 21, and 22mm nuts
- needle nose pliers
- Torque wrench
- gear puller or similar tool for tie-rod separation (Kragen, US$ 10)
- 14mm wrench, preferably with ratchet
- RSX tire wrench
- jack stands, jack

Without any prior suspension work experience, it took me and a friend about 4-1/2 hours to remove the stock struts and install the Mugen sports suspension. The work can be done by one person, but I strongly recommend having a helper.

Rear strut removal and installation:

Summary: To replace the rear struts you need to jack up the car, remove the wheel, remove a trim piece in the trunk to remove two 14mm nuts that hold the strut, remove the bolt from the bottom of the damper, and install the new strut.

1) Open the hatch, move the seatbacks down, use a screw driver to gently remove two plastic clips (where the red arrows point) that hold a trim piece in place, and bend back the trim piece to get access to the two 14mm flange nuts on top of the strut. Loosen the front nut with a 14mm wrench or nut a bit. Use a 14mm ratched wrench to get to the rear nut and loosen it a bit. Sharp metal there! Be careful not to cut yourself (I did). The rear nut is a pain to get to, but it can be done.



2) Jack up the rear of the car. It's best to have two jacks for this as you'll need the second one to compress the struts. Also, use a jack stand for safety. Remove the wheel.

3) Remove the flange bolt from the bottom of the damper. The bolt may not come out easily. You may have to use the jack to compress the shock or use a screwdriver to get the shock into the right position.

4) Have helper remove the two 14mm flange nuts in the trunk, and the strut will come right out.

5) When installing the Mugen struts, make sure the white dot on top of the Mugen faces towards the center of the car. Inserting the strut is no problem (have the helper put the two nuts on in the trunk, but don't tighten them yet), but getting the holes aligned to insert the flange bolt is a pain (see below). You may have to use the jack again to move compress the shock and align the holes.



6) Tighten and torque the flange bolt at the bottom and the two flange nuts in the trunk. It's next to impossible to properly torque the nut behind the strut in the trunk, so do your best with a 14mm ratchet wrench.

7) Gently put the trunk liner back in place and tie it down with the two plastic fasteners. All done with the rear. For us it was the more difficult part of the job.

Observation when comparing the Mugen and stock rear struts: The Mugen springs have eight revolutions instead of seven. Stock springs seem a consistent 12mm from top to bottom whereas Mugen springs are about 11mm at the top and reduce to about 7mm at the bottom.



Front strut removal and installation:

Summary: To replace the front strut assembly you need to jack up the car, remove the wheel, pop open the tie-rod end ball joint, remove bolts that hold brake line and wheel sensors to the stock strut, remove two bolt from the damper, remove three 14mm flange nuts that secure the top of the damper in the engine compartment, gently remove the stock strut, and then install the new strut.

1) After jacking up the front and removing the wheel, you need to pop open the tie-rod ball joint. That is the most delicate operation of the entire installation. The ball joint has a rubber boot which means you can't use a standard tie-rod fork or you'll damage the rubber boot. Honda's manual suggests a special tool that I was unable to find. Instead, I used a gear puller (see middle picture below). Here's how: Remove the cotter pin and loosen the nut from the bottom of the tie-rod. Unscrew it beyond the end of the bolt. Put the gear puller in place. I used a flat piece of metal between the point of the gear puller and the nut. Align it and use a wrench to pull. If all goes well, the tie-rod joint pops loose (shown in third picture below).



2) Remove the wheel sensor (10mm nut) and brake line harness (12mm nut).



3) Remove the two bolts that hold the strut in place. The nut is 22mm, the bolt side 19mm. They look intimidating but fortunately the RSX tire wrench fits and they easily open.



4) Have assistant remove the three 14mm flange nuts from the top of the damper in the engine compartment. Make sure you hold the strut so that it does not drop and damage the drive shaft rubber boot or rip the brake line. Remove the strut assembly.



5) Gently insert the Mugen strut, making sure you don't rip the rubber boot of the drive shaft and that the brake line and wheel sensor cable are in the proper place. Have partner put nuts on top of the damper in the engine compartment.

6) Insert the two large bolts, put the nuts on them, Attach the break line (12mm nut) and wheel sensor (10mm nut).

7) Seat the tie-rod and put the nut back on. Strangely, while it took a lot of force to pop it open, it goes right back in and the nut goes on easily. Don't forget to re-install the cotter pin.

8) Tighten and torque everything. The two big bolts took more torque than my torque wrench could do (101 and 116 lbf-ft). All done.

Observation when comparing the Mugen front strut assembly to the stocks: Mugens have a nice telescope rubber boot whereas stock has a basic cover. Mugen springs do four turns while stocks only have three.



Before and after closeups (here you can clearly see the 1.4 inch drop):



Took the car for a ride after the install. Everything worked fine, no rattles or noises. Car feels tighter and more controlled but the ride is no less comfortable than with the stocks. Composure in fast turns is vastly improved. Before, the car required constant steering corrections in fast turns. That is completely gone.

I took the car in for an alignment check the morning after the install. Amazingly, camber, cster and toe were all within the Acura specification range. The car would not have needed an alignment at all after the Mugen SS install (needless to say, do one anyway!).
 
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Awesome thread man! Great job on the install. Great pictures! Great instructions. If you could maybe make the comparison pic of the before and after drop a little bit bigger. Awesome job!
-Jalal
 

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Excellent guide, I was considering getting the Mugen as well, although I'm really foggy on a lot of suspension stuff. At least the longer I wait the more money I'll have...
A couple more car shots would be nice, and I can't wait to hear your comparison.
 

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Excellent Guide. I had King's install mine at their shop. You are going to love the ride. Get their bars too. Have fun, I sure know I did until I parked it for winter in November. Can't wait for spring!
 

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Discussion Starter · #7 · (Edited)
Well, took the car with the Mugen SS on the road this morning. First impressions: the ride is almost like stock, but firmer and more controlled, sort of like I remember from my M3. Huge difference in fast cornering. On a tight highway onramp where the car constantly needed correcting at high speed it now feels like on rails. I always missed the old Honda wishbone suspension which felt so solid and unflappable in tight curves, and with the Mugen SS it feels like having one again. I really love that part of the Mugens.

Stopped by Big O to check the alignment. Amazingly, camber, caster and toe were all within spec range. No alignment necessary at all. So anyone installing the Mugen SS doesn't have to worry about needing camber adjusters and such.

As for the drop, it is definitely 1.4 inches. It can plainly be seen and for me it's just right. I feel my car now has the suspension it should have come with. While the struts and strut assemblies look very much like the stock parts, the springs and dampers are very different and from what I can tell Mugen did a bang-up job in optimizing everything for the RSX.

Below a pic of the car with the Mugen SS installed and a before and after.

 

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Maybe the Mugen steering arms are located at a different angel than stock, as viewed from the top (radial location)? After I installed mine, my front wheels were extremely toed-out.
 

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So you have had the Tien SS, JIC and Mugen on your car? Care to give us a comparison on them? Which one you think is worth the money and best performnce/comfort?
 

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As far as Tein SS vs Mugen...

I switched to the Mugens because I'm not autocrossing much these days and I don't really reed the adjustable shocks anymore. That said, I basically just set the Teins to full stiff in back, and half stiff in front and left them there. That was the only place where they really handled well, and changing them much just screwed up the handling. The Teins also were kind of noisy, which I was sick of.

So far, the Mugens don't really seem to be that much softer than the Teins, even though the springs rates, especially in front, are less. The Mugens do not have the impact harshness of the Teins on sharp bumps, though. Handling with the Mugens seems to be as good as the Teins. The Mugens do give you more front body roll than the Teins, but I feel like they also give the front wheels better traction.

The only real downside to the Mugens (vs. Tein) is the lack of front camber plates, but eventually, I may try and see if the Hotchkiss camber plates work with the Mugens. Since they were designed for the stock suspension, I assume they would fit because the Mugens look physically the same as stock. The hotchkiss plates are pretty expensive, though, around $400, I think.
 

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jeffbatt said:
As far as Tein SS vs Mugen...

I switched to the Mugens because I'm not autocrossing much these days and I don't really reed the adjustable shocks anymore. That said, I basically just set the Teins to full stiff in back, and half stiff in front and left them there. That was the only place where they really handled well, and changing them much just screwed up the handling. The Teins also were kind of noisy, which I was sick of.

So far, the Mugens don't really seem to be that much softer than the Teins, even though the springs rates, especially in front, are less. The Mugens do not have the impact harshness of the Teins on sharp bumps, though. Handling with the Mugens seems to be as good as the Teins. The Mugens do give you more front body roll than the Teins, but I feel like they also give the front wheels better traction.

The only real downside to the Mugens (vs. Tein) is the lack of front camber plates, but eventually, I may try and see if the Hotchkiss camber plates work with the Mugens. Since they were designed for the stock suspension, I assume they would fit because the Mugens look physically the same as stock. The hotchkiss plates are pretty expensive, though, around $400, I think.
Thanks.. very informative. I'm in the same boat. I want descent ride comfort and will only auto X very little. I would only lower the car about as it is now (about 1.6" drop around) and the mugens are really close to that. I'm not one for adjusting much either.

So you want more front camber with the mugens over what you can adjust them to standard? I have the Ingals front camber kit for the front (well, rear too) and would want a very little negative camber up front. Are you saying that the camber kit won't work and that I would need camber plates, or that the mugens camber can be adjusted, just not as much as you want? Sorry, the "camber plates" are new to me.
 

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The only reason I would want front camber plates is that I think they are a better method of setting camber than adjustable cam-bolts (like the ingalls kit), easier to adjust with precision.

I'm sure the ingalls kit would work fine with the Mugens, though. Just as well as with the stocks.
 

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BlackNite said:
Sorry, the "camber plates" are new to me.
Same here. It would be great if you could elaborate on this Jeff.
Great reviews from everyone! Its been a great help!
-Jalal
 

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That is a great post, with a boat looad of information. I have been back and forth for the past two months about the Tein Coilovers or the Mugen Susp Kit. And thanks to you I have made up my mind. Mugen it is....

Thanks again:)
 

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Arjayness,

I'm still trying to make my chassis stiffer :) It's a really weird obsession I have with this car.

I e-mailed EM Racing about their C-Pillar bar. They said the prototype was done, but they were not going to sell it because it required cutting the plastic interior trim a bit. They thought most RSX owners wouldn't want to do that because their cars are still relatively new.

I told them that wasn't an issue (i.e. look at all the people who have Mugen rear strut tower bars), but did not get a response.

Honestly, the J's Racing bar is good, but the end brackets are kind of weak. I've been considering making my own end brackets, should be pretty easy, just haven't put the thought into it yet. Also, I got my J's Racing C-Pillar bar powdercoated flat black, and it looks better...a lot more stealth and less ricey.
 

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Everybody else-

camber plates are usually those aluminum things on the top of coilovers for macpherson struts, where they mount to the shock towers. They have longitudal slots so you can slide the top of the strut in or out to adjust camber. They're the gold-colored things in this pic below.

Many coilovers come with them, i.e. Tein SS and better, JIC's, etc.
 

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On my C-Pillar bar, I just adjusted it so it was as tight as possible in Tension. Trying to spread to similar amounts of compression just bent the brackets down too much.

I'm not sure how much the brackets effect things, though, because the bar is probably only good for transferring loads straight accross, even super-solid mountings might not really change that.

arjayness said:
yea, i've noticed that the current c-pillar bars have weak ends, j's and alex. i wonder how their setup is if you have to cut interior panels. [/B]
 

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conradb212: Let me guess, Kragen torque wrench? Haha, ask me how i know. By the way, awesome thread. :thumbsup: Now i expect no more new threads started about this Showa Kit. haha.

arjayness: In that picture you posted comparing the two strut arms, the Mugen arm looks to be angled more towards the outer fender (if you can imagine how the struts would look like installed) compared to the stock strut. From that, it would increase toe-out, but i don't see how that resolves the bumpsteer issue. I have CRAZY bumpsteer with my setup right now using the stock strut housings.
jeffbatt said:
Arjayness,

I'm still trying to make my chassis stiffer :) It's a really weird obsession I have with this car.
Then get a 4pt race roll bar. No need for all those extra "monkey bars" in your car.
 

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Discussion Starter · #19 ·
sjracer said:
conradb212: Let me guess, Kragen torque wrench? Haha, ask me how i know. By the way, awesome thread. :thumbsup: Now i expect no more new threads started about this Showa Kit. haha.

arjayness: In that picture you posted comparing the two strut arms, the Mugen arm looks to be angled more towards the outer fender (if you can imagine how the struts would look like installed) compared to the stock strut. From that, it would increase toe-out, but i don't see how that resolves the bumpsteer issue. I have CRAZY bumpsteer with my setup right now using the stock strut housings.
Yup, Kragen torque wrench. Now how did you guess? :) I took that pic of the two strut arms, and I examined and compared those two struts pretty carefully. The Mugen does not angle any differently from the stock strut. However, the springs are quite different.

As for bump steer, I am definitely not an expert on suspension technology or terminology, but if bumpsteer is defined as a change in toe caused by suspension travel or unintended steering input caused by that change, with a resulting need for steering correction, then I, at least through fast curves, now clearly have considerably less bumpsteer with the Mugens.
 

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conradb212 said:
Yup, Kragen torque wrench. Now how did you guess? :) I took that pic of the two strut arms, and I examined and compared those two struts pretty carefully. The Mugen does not angle any differently from the stock strut. However, the springs are quite different.

As for bump steer, I am definitely not an expert on suspension technology or terminology, but if bumpsteer is defined as a change in toe caused by suspension travel or unintended steering input caused by that change, with a resulting need for steering correction, then I, at least through fast curves, now clearly have considerably less bumpsteer with the Mugens.
I have the same exact torque wrench in 3/8" and 1/2". I use to work at Kragens 2 years ago.

Bumpsteer is not the change in toe, but the change in steering when you hit a bump or dip on the road. So if you ever enter a corner and hit a little dip, which turns your steering wheel sideways sending you off the road, that's bumpsteer saying "Hi." haha. If Mugen did not change the arm angle at all, more important the arm height, then you will have the same amount of bumpsteer on this Mugen kit as on stock struts with the same amount of drop.

If you have ever driven a front double-wisbone honda, you'll know this wasn't the case. Just another side effect of having a MacPherson front strut setup on a FWD.
 
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