This article came out of a conversation I had with Dan here at Professional Awesome Racing. I was in need of help as I was using upper control arms for an EK Civic on an SUV. Why? Because I’m a crazy person who’s building a track Honda CR-V, that’s why. The CR-V has longer control arms and with Professional Awesome’s help, a slick solution was devised. While talking with Dan, we realized this could make a really useful article; so many Honda suspension components are interchangeable, it leads to unique builds and options for other adventurous souls, so here we are.
What is a widebody and why do I want one?
Usually when the term “widebody” gets thrown around it’s regarding a cosmetic body kit with different offset wheels or wheel spacers to go with. It can look killer, especially with some added ground effects and other bits, but looking good is one thing that doesn’t always translate to better performance. What this article covers is the functional end of a widebody setup, or put another way: widening track width. Why should you care? Because better handling. A wider track width leads to increased stability and better chassis and suspension responsiveness. To top it off, you can have more available grip when cornering. I bet I have some track junkies’ attention now.
The cheap and easy way to widen track width is to change your wheel offset, either with a less- positive-offset wheel or the addition of wheel spacers. In the rear, this isn’t much of an issue, but in the front this changes the scrub radius in a way that is usually counter productive. That and you lose out on certain advantages you get from doing it the right way. What’s the right way? Increasing control arm length.
A bit on Suspension Geometry
Always read the directions right? It’s best to have some understanding before making changes. I’ll cover some basics with this short, quick, and over-simplified explanation of suspension theory but I encourage you to read more about the following topics: scrub radius (click here, here, and here) roll center (here), center of gravity (here and here), weight transfer (here and here), and for further reading, get yourself a copy of Tune to Win by Carroll Smith. Tune to win is an extremely valuable guide to the fundamentals of setting up a car, so I would recommend getting that anyway.
One more topic you may want to brush up on is understanding wheel rate and motion ratio of your springs and suspension. What is that? Well your suspension arms act as levers on your springs, so the spring rate of your springs isn’t the effective spring rate applied to your chassis, or in other words your unsprung mass. There are multiple ways to measure it, so to give you a basic but comprehensive start click here and here. For a calculator and good glossary of terms, click here.
Your car’s roll center (RC) is an imaginary point somewhere above the suspension that is the rotational axis upon which your car’s chassis rolls (leans). The RC is calculated using the control arm angles and the tire track width. (How do you measure your roll center? Click here.) The front and rear have a different RC with the rear usually higher. Because the RC is based on control arm angle, the RC moves when your suspension moves.
Your car’s center of gravity (CG) is its singular point of center mass. However, you have different RCs front and rear, so you need to imagine your CG points at both the front and rear suspensions. Doing so you will come up with a mass axis that the vehicle rotates around, see here. The distance between the CG and the RC determines how much body roll your car experiences. Body roll is your car leaning on its suspension; this is applied on top of normal load transfer in a corner. This is why bigger/taller/heavier vehicles usually have far more body roll than an NSX, Miata, GT40, etc. It’s worth noting that this acts like a lever; the farther they are apart, the more torque your chassis applies across the RC, which means you need higher spring rates to counter it. In most cases, it’s best to keep spring rates as low as possible, so reducing the distance between the RC and CG is a good place to start.
As you turn, load (commonly referred to as weight) is transferred from your inside tires to the outside tires. This affects available traction. Explaining this properly is worth its own article (see recommended reading above), so I will leave it at this: the more evenly your car’s load is distributed across all four tires, the more available traction you’ll have. One automotive trend that’s based on this is the pursuit of a 50/50 front/rear weight distribution. That is a static example; it doesn’t move. This idea also applies to your car when you drive it. In our case, it’s the load transferred from the inside tire to the outside tire when cornering, which can oversaturate the available grip of one tire while underutilizing another. A wider track reduces the transferred load, which improves available grip.
With that covered, let’s discuss what happens when you apply that:
- Widening your track width by lengthening the control arms gives you the benefits of:
- More stable roll center, due to less extreme control arm angles, meaning it moves around less when your suspension compresses.
- Less lateral load transfer, which increases available grip.
- If your car already has a positive scrub radius, this keeps it from going too positive, which can be detrimental.
- If you don’t have power steering, you’ll want to keep a small scrub radius. The more positive it is, the more steering effort is required. (Additionally, this can reduce torque steer on FWD/AWD vehicles as the tire has a smaller moment to the steering axis.)
- Longer control arms should, in most cases, lower your RC, which you may want to address with RC correction parts. (Some suggestions for Honda chassis are below.)
- Using longer control arms also changes your steering geometry. Ackerman steering geometry can be a messy subject and has far less information available to explain it than does suspension geometry. You’ll have to tackle that one on your own, but if it’s kept close to stock it shouldn’t be an issue.
- By definition, lowering your car also changes its suspension geometry. On every car I’ve seen, this lowers your RC. Again, longer control arms usually lowers this farther, so you’ll want to consider RC correction parts.
- Less positive wheel offset, while adding to positive scrub radius, will also slightly raise your roll center. And I mean very slightly.
Honda Chassis’ – Background Information:
Phew! If you’re still with me, let’s dive into some chassis information. The rest of this article is based around Hondas, so here are some basics:
- All the ‘90’s Hondas referenced in this article use roughly the same suspension design; Short/Long Arms double wishbone (SLA) front and multi-link, trailing arm rear
- General purpose chassis codes will be used in reference to the majority of model ranges to keep things clean:
- EF – 88-91 Civic and CRX
- DA – 90-93 Integra
- EG – 92-95 Civic and 93-97 Del Sol
- DC – 94-01 Integra
- EK – 96-00 Civic
- “CR-V” refers to the 97-01 Generation
- EF and DA cars share front Lower Control Arms (LCA)
- EG and DC cars share the same suspension parts, but for the purposes of clarity I will list both separately
- The EK front steering knuckles are 11/32” shorter than the DC steering knuckles
- The Civic EK has 2 different front LCAs (see main suspension parts pic)
- Forged for all trim levels except Si
- Stamped for the Si trim level
- Both share the same overall measurements, the only differences are the construction and placement of the sway bar end link
- EG and DC cars share rear toe links, and the CR-V and EK share rear toe links
- Every car listed above shares rear upper links/UCAs
- None of this takes into account fender well and strut tower clearance, that will have to be modified on your own.
***Every measurement taken for this article was done in inches and taken as accurately as possible.***
Control Arms – OEM and Aftermarket:
Since the key to this setup is the control arm length, some creativity might be needed. The table below shows the different upper control arm (UCA) and lower control arm (LCA) lengths of each chassis, and therefore which ones can be swapped to widen your track width. You can use stock LCAs in stock form, swap in poly bushings, or you can buy aftermarket ones with spherical bearings instead of bushings. PCI and Skunk2 are two places to start with aftermarket arms. There are also UCAs that offer caster adjustment; I have a set from PCI that do just that.
|Front -> Back||7.3125”||7.4275”||6.875”||7”||7”|
|Front LCAs||5th Gen Accord/1st Gen Acura CL***||EF/DA||EG/DC||EK||CR-V|
|In -> Shock||11.25”||10.625”||10.8125”||10.8125”||10.8125”|
|Front -> Back||N/A||N/A||10.75”||10.75”||10.75”|
- ***The 5th Gen Accord and 1st Gen Acura CL share the same basic LCA design as the EF chassis cars. While I have not had these arms side by side with the EF ones, I have taken the measurements of the Accord/CL arms and they may be a viable option on an EF chassis. This is even more uncharted territory, so it may take more work than otherwise.
- 4th and 5th Gen Prelude front LCAs are also similar, so they may be worth looking at as well.
- Both upper and lower control arm length is important; and as I found out with my CR-V, if improperly matched you have camber issues.
- The EK UCA is exactly 1” shorter than the CR-V, but the LCA is 1 ¼”. This is almost certainly due to the increased arm angle on a stock CR-V.
- The DA/EF LCA is the same, and the reason it doesn’t have a rear compliance bushing is because that arm is coupled with a traction bar/radius rod that is the second mounting point on the chassis.
- The EG, DC, EK, and CR-V LCAs all have the same front->back measurement. The shock mount width is the only difference in making it work, so as long as you get a shock fork that matches, it should bolt in.
- The EG, DC, EK, and CR-V LCAs also share the same in->shock measurement, so the shock angle is unchanged and there’s no headache there.
- If you know anything about calculating motion ratios for spring rates, you’ll notice the CR-V has a different (lower) ratio, so remember that if you want to match spring rates properly.
Since you’ll be mismatching arm lengths, you may very well run into the same situation I did; unwanted camber changes from the arms not being the right lengths. One solution may be a setup like I used, if you’re alright for paying for it. I extended the length of my UCAs by having a larger block machined. It wasn’t cheap, but it solved my problem perfectly. (Thanks again Dan.)
Axles and Hubs – Next Steps
Of course it can’t be THAT easy; on top of swapping arms out, you’ll also need to match axle lengths. What good is it if the wheels won’t turn, or worse, the axles break while driving. Good news! There are many stock axles that may work for your setup, in both the smaller and larger stock axle sizes. The smaller axles have a 26 spline outer and the larger have a 28 spline outer, however most of the Honda community goes by the axle nut size, which is 32mm and 36mm respectively.
|Axles||EF/DA||EG, DC, EK||RSX Base*||RSX Type S*||4th Gen Prelude||5th Gen Prelude Type SH||5the Gen Prelude Base||CR-V|
|Outer Spline Count||26||26||26||28||28||28||28||28|
|Cable or Hydro Half-shaft||Cable||Hydro||Hydro||Hydro||Hydro||Hydro||Hydro||Hydro|
- Some of you may have caught this already, but there are some K Series engine axles on this list (the RSX). K series engines sit on the opposite side of the engine bay (in front of the passenger) but for ease of interpretation, I’ve listed them on here as they would appear installed on a B series engine.
- Thankfully, Honda axles follow the same basic design principle, so If you have a K swapped car, *ALL* of the axles listed above will work, assuming you’ve got the right hubs and type of half shaft to match.
- Cable half shafts do not work with hydro axles as the half shaft end is different:
- Cable half shafts have a female end, and hydro half shafts have a male end
- That in mind, you’ll have to swap the CV axle joint over to get axles of different lengths to work
- *ALL* of these axles use a 27 spline inner stub, which means as long as you are using the appropriate half shaft, they should work.
This chart has been organized to try and make comparison easier. Outer joint spline counts, and general length goes from smaller to larger as you move from left to right across it. The CR-V axles are by far the longest, and this is again due to the CR-V’s ride height and track width increase. As a reminder, you may need to play around with axle length to get things to fit properly. Too long of an axle and things can bind, too short and things can come apart. Axle angle also plays into length requirements, which differs between cars.
If you’re pushing any kind of reasonable HP numbers, the larger spline-count axles are the way to go. If you want to switch to the larger axles while you’re doing the widebody, Karcepts.com is about the only source for the hubs you’ll need. In stock form, the larger axles use a different hub that won’t fit into the smaller wheel bearing. Karcepts hubs are designed to fit and offer both 4×100 and 5×114.3 lug patterns. They also come with ARP extended wheel lugs, which is great for anyone with aftermarket wheels.
For those of you who would prefer to try and find a budget route for the hubs, good luck because I haven’t found a solution! Before getting the Karcepts hubs I tried finding a cheap way with my EK knuckles. I asked a machine shop to turn down the larger hubs; unfortunately, this would cause runout and the wheels would always have a slight bit of wobble. Wobble on a car going around a track at 80+mph? I don’t think so. Then I looked at boring out the knuckle to fit the larger bearing; that doesn’t work either as the knuckle design doesn’t allow it. After that I searched for hours to find wheel bearings that would fit the larger hub into the smaller knuckle bore. Even got a rep from Timkin to help me search for an hour and half on the phone. No dice. If you find an alternate solution, I’d love to know. I’ll even add it to this article.
Something else to know is that the EG, DC, EK, and CR-V front knuckles are somewhat interchangeable, but you’ll have to do some research on which ones are best to use. What I do know is this:
- CR-V knuckles are almost identical to DC knuckles, but come with a 5 lug hub that also uses the larger axles
- Knuckles from an EX or Si EK car are the ones you want to use from that generation of Civic, as the other versions’ knuckles can’t accept larger brakes.
- Knuckles from an EX or Si EG are the same as DC knuckles, the other EG knuckles don’t accept larger brakes
- You can use DA front knuckles on an EF to upgrade the brakes
- You should not use EG, DC, EK, or CR-V front knuckles on an EF or DA because they are a different size and you will have clearance and camber issues
- Like I have done on my CR-V, you can use EK knuckles in place of DC or EG knuckles to help correct your roll center
Tie Rods and Misc.
Now that the front control arms, axles, and hubs are out of the way, we turn to the steering. (Sorry for the pun, had to.) The good news on tie rods is that they’re already adjustable in length, so with any luck you won’t have to swap these, but just in case here’s all the tie rod lengths and info you’ll ever need.
I wasn’t able to get my hands on a DA tie rod, but suffice to say it’s within the same length range as the EF, DC, EG, and EK tie rods. The only noticeable outlier here is the CR-V, at a whopping 1 ?” longer than the next longest. Again it’s that CR-V ride height and track width at play.
To add more to this suspension parts mish mash the EK front steering knuckles are 11/32” shorter than the EG/DC and CR-V steering knuckles. The upper ball joint location seems to be ?” inboard on the EK knuckle as well, but that measurement was taken between a CR-V knuckle and an EK knuckle with Karcepts hubs, so it may be slightly different stock. This is useful information to know if, like me, you’ve decided to get some extended lower front ball joints for RC correction on your lowered car. Adding “height” to the knuckle with an extended ball joint is best paired with a shorter knuckle, if possible, to keep overall height as close to stock as possible. Again, RC correction.
If you want to take your handling advantage farther, get some adjustable height tie rods from Honed Developments. Yes, you heard correctly, “height” adjustable. They’re an Australian company that specializes in (mainly) Honda suspension parts. They sell extended lower front ball joints, rear trailing arms extensions, and rear upper links that are all designed to correct suspension geometry, specifically RC and bump steer. Their parts offer more adjustment than anything else I’ve seen on the market, and they have track tested their parts with lap time data to prove it. I have their rear upper links and tie rods on my CR-V.
The Rear – Why stop at the front?
In many cases, on a FWD car it actually makes sense to stagger the front wider but solutions do exist if you want to also widen the rear track width (maybe you’re doing an AWD setup?). By far the easiest way to address this is with wheel offset, but if you want to use longer control arms, that’s also possible.
|In -> Shock||10.1875||12.125||15.875|
As you can see the DA, EF, EG, and DC chassis all use the same rear lower control arm. The DA chassis uses a straight arm, whereas the DC/EG one has a kink in it, but all the measurements and mounting points are the same and people have been using them on all of those cars for years. Keep in mind that the EK shock mount point is also wider on the arm itself. The CR-V rear LCA has an “interior” shock mounting style, like the Integra Type R. The CR-V rear LCA is also by far the longest, and may be too long to use without modification.
Please note that if you do use longer rear control arms, you will need to look out for toe link clearance and trailing arm to chassis clearance. Moving the trailing arm outboard, and therefore the wheel outboard, may present some issues with fender clearance as well.
Some Suggestions – Final Notes
If this is something you want to do, you’ll be dipping into fairly untested waters, so be prepared for troubleshooting and problem solving when issues inevitably arise. You may run into issues with fender well and strut tower clearance, or axle and strut fork clearance, or something else. Whatever it is, I’ve learned there’s almost always something unaccounted for when it comes to modifying cars.
Before you get to wrenching, here are some suggestions on possible combinations of parts, based on my measurements:
- The EK chassis seems to be the easiest to do this on, as both the front UCA and LCA from the CR-V are a direct bolt on, and the LCA shock mount width is the same
- The EG and DC cars can use the CR-V front LCA, but you’ll need to use EK or CR-V strut forks and have a UCA intended for an EG or DC be lengthened to work.
- The EF and DA cars are kind of on their own as their front LCA design is incompatible with the others, so you’ll have to find a way around that.
- Perhaps try contacting a company who makes aftermarket arms.
One interesting combination to notice is that the CR-V LCA is 1 ¼” longer than the Civic or Integra LCA, but to closely match that with axle length you may choose to use CR-V driver’s side axle mixed with a 5th gen Prelude passenger side axle.
Mismatching all these parts can be a game in and of itself, so take your time setting up your build. This is a hefty undertaking, so plan on it being a lot of time and a hit to your wallet.
I hope this article serves you well, and good luck out on the grid!
Neil Rawlings is an optimist, aspiring automotive journalist, passionate car enthusiast, and builder. Check out his YouTube and Instagram, GoStickOrGoHome, showcasing his build projects as well as some how-to installs.