K-series OEM Axle Setup & Measurements

K-series Axles

When it comes to a K-swapping a legacy chassis (ie. golden era Honda’s: 88-00 civic/90-01 integra), there are many axle companies on the market with tons of axle stage choices (DSS, Hasport, ProFab, etc). It can get quite convoluted and frustrating. For those looking for an ‘OEM axle’ setup you’re in luck! I personally went the OEM axle route a years ago (2009 or so) after researching on K20A.org along  with help from Brian Karwan (Karcepts.com). Some quick back story… When I dropped in my EP3 K20A-R engine  (summer ’04), I used a set of axles from a company by the name of ‘Pro Fab’. I don’t think they exist anymore but their axles held up just fine for the period of time I used them. Except they had one seriously annoying flaw. Upon acceleration, in the lower sub 4000rpm range, they would shudder (ie. shake/wobble sensation during acceleration) from 1000rpm to about 4000rpm. That shuddering drove me f**king insane over time. Made my car feel like an EF w/B16 swap from the early days. As it turns out, these ProFab axles didn’t have a dynamic damper on either axle unlike factory Honda axles (the black donut on the center of the axle shaft – this helps eat up or dampen vibrations). So, I looked for alternatives which brought me to the OEM axle setup. Once I switched to OEM axles, car life was renewed – no more shuddering on acceleration and my civic felt normal.

Note: All axle measurements were taken when ‘fully compressed’. (photo soon)

  • EP3/Civic Si:
    Driver: 24″ / Passenger: currently unavailable / 25.3mm thick shaft
  • 06-11 Civic Si:
    Driver: currently unavailable / Passenger: currently unavailable / 26.3mm thick shaft (assumed)
  • RSX Base model:
    Driver: 24-1/8″ / Passenger: 22-5/8″ / 25.3mm thick shaft
  • RSX Base model (w/swapped inner joints):
    Driver: 24″ / Passenger: 22-3/4″ / 25.3mm thick shaft
  • RSX Type-S:
    Driver: 23-5/8″ / Passenger: 22-5/8″ / 26.3mm thick shaft
  • RSX Type-R:
    Driver: 25-1/4″ / Passenger: 23-3/8″ / 26.3mm thick shaft
  • ProFab:
    Driver: 23-7/8″ / Passenger: 23-1/8″
  • Hasport (EGKAX):
    Driver: 24-1/4 / Passenger: 23-1/2″

The ‘OEM’ axle setup consists of the following ingredients:

  1. Using a pair of factory Acura RSX axles (Base,Type-S, or JDM Type-R model).
    Depending if your vehicle was originally 4-lug or 5-lug converted will help dictate which RSX model you need to use. Note: there are 32mm 5 lug & 36mm 5 lug conversions!
  2. Swapping the inner joints are key!
    Doing this forces the use of the whole driver side axle onto the passenger side of the vehicle & the passenger side axle onto the driver side of the vehicle. The point of this is to gain maximum axle length on the passenger side of the vehicle – getting it as closer to 23″ inch length as possible. The RSX passenger side axle, specifically Base model, in its unmodified stock form, is a bit too short for a K-series swap into 88-00 civic / 90-01 integra chassis’s. Once the inner joints are swapped the driver side axle becomes the passenger side axle and is at its closest to 23″ total length.
    Though some have said they’ve used RSX Base axles with unswapped inners and say they haven’t ran into any issues.

Application Scenarios:

  • 4×100 with 32mm axles
    If your vehicle is 4-lug like most civic/integra’s are (excl. Type-R), you will want to use a pair of factory RSX Base model axles. Base model axles, by default, have the the 32mm splined outer joints. Base axles will plug n’ play into any legacy chassis with 4-lug front wheel hubs. Simply swap the inner joints, install axles, and you’re done. EP3 axles can be used but with caution, see below in the Alternative axle section.
    Note: I’ve found that swapping inner joints is not even really necessary for Base axle use. It’s more of a peace of mind thing. I’ll leave the joint swapping choice up to you.
  • 5 Lug 32mm axles
    If you have converted to US Integra Type-R or JDM CTR EK9 5 lug (aka 32mm 5 lug) on your legacy chassis, RSX Base model axles are usable as well. The US Type-R 5-lug front wheel hubs cater to the outer axle spline joints that utilize a 32mm axle nut-outboard joint. Simply swap the inner axle joints, install axles, and you’re done.
    UPDATE: If you find that your passenger side axle does not seem to have enough length or you’re experiencing passenger side axle issues, you should quickly upgrade to an 06-11 Civic Si passenger side axle and swapping your 32mm outboard joint onto the Si axle.
  • 5 Lug 36mm axles
    If your vehicle has been converted to JDM ITR 5-lug w/36mm splined outboard joint, the RSX Type-S or RSX Type-R axles are the ones for you. 98+ JDM ITR 5-lug front wheel hubs use a larger outer splined joint by default using a 36mm axle nut.  RSX Type-S & Type-R axles share the same larger outer spline joint & 36mm nut. So, Type-S/R axles will basically plug ‘n play into these hubs. Swapping of the inner joints is NOT REQUIRED as the axle lengths are perfect for this application (especially with RSX Type-R axles)

     I’ve found out (through others and a close friend) that using 36mm RSX-S axles unmodified w/36mm 5 lugged swapped EG/EK/DC2’s doesn’t always work for some. Especially with EK’s using EKK2 Hasport K-swap mount kit and even DC2’s with an EGK1 swap mount kit. This happened with a close friend of mine. The result is the Type-S passenger side axle falls short by an inch or so. The fix for this is switching over to an unmodified 06-11 Civic Si / K20Z3 passenger side axle and retaining the Type-S driver side axle. Turns out the Z3 passenger side axle is the perfect length for 36mm 5-lug users. You don’t want to use a Z3 driver side axle as it is too long and will likely bind. So retain your Type-S driver side axle!

Alternate ‘Hybrid’ and Aftermarket Axle Scenarios:

  • Type-S axles w/B-series 32mm outboard joints (4 Lug)
    Some are forced into this scenario for lack of parts or finding RSX Base model axles. This setup consist of using Type-S inner joints and axle shafts but using 94-01 Integra or 92-00 Civic SiR (B-series) outer joints in order to get the 32mm axle spline use for vehicles with 4×100 wheel hubs. I’ve tried this scenario before and I found it works perfectly fine for street use (and possibly drag race use) but will fail big time for road racing conditions. Binding occurs within the outer joint creating friction. This friction eventually boils the axle grease and creates air within the axle boot, ballooning the axle boot to the point of almost popping! Now, the axle place that I had put these together for me, might have used 90-93 integra outer joints rather than 94-01 integra outer joints. So, I’m not going to fully throw this axle setup under the bus. So, if you go this route make sure you use 94-01 integra outer axle joints! Otherwise stick with RSX base model axles from the get go.
  • EP3 Civic Si Axle Use
    The 02-05 EP3 civic Si axles are almost identical to RSX base axles in relation to being “32mm axles”. The length is where the difference is, mainly with the passenger side axle. EP3 passenger side axle is way too short for use on a K-swapped legacy chassis. In fact, I think its the shortest factory K-series axle Honda makes. I know this from personal experience.  With an EP3 passenger axle in place on a K-swapped EG, the inner boot is noticeably stretched out and you can see some of the tripod bearings pushing on the inner boot from coming out of the inner cup. Lets just say a spirited pull on a freeway on ramp made a mess under my hood because the axle pulled apart. However, th EP3 driver side axle is perfectly fine to use as-is unswapped. Just stay away from using the passenger side EP3 axle. It’s only usable for its inner and outer joint parts or swapping a RSX base shaft over to it and then disregarding the EP3 shaft. You could possibly re-purpose the EP3 passenger side shaft for driver side use. 
  • Hasport EGKAX Axles
    If you want to go aftermarket axles, these are the ones to get. Brian@Karcepts informed me these are the best aftermarket axles he’s used outside of the OEM axle setup and have held up great for him (he autocrosses btw). Hasport has made these the perfect length as well, so no matter how high or low your car is, the length of these axles will do the job.
  • Stage 1234878654785&#^@# Axles
    Sorry to disappoint, but I have zero experience with the aftermarket stages 1-5000 axles. OEM axles can handle up to about 350whp which is absolutely fine for me as I’m barely crackalatin’ 228whp vtack to the tire. If I get more information on higher horsepower axle applications I will definitely update this section.

10 thoughts on “K-series OEM Axle Setup & Measurements

  1. i have a integ with a jdm b18c n with the jdm itr 5 lug conv and my driver side axle went what im askin is will the rsx type r fit into the half shaft?

  2. travis,
    I’m not sure if a K-series RSX-S axle will work w/your B-series. I would highly suggest using another B-series axle, or just rebuilt your JDM ITR axle (36mm outter hub nut).

  3. I originally had a K20A2 with the type s tranny and EKK1 mounts on my 2000 SI and I never had any axle problems at all. It turns out that I blew my K20 Type S and decided to go with a K24A2 (TSX Motor) with the EKK2 (Hasport) mounts so I had to swicth over to the EG subframe but my mechanic took it upon himself to install the EK lower control arms and tie rods on the car. When my car was supposedly fully done from the mechanic shop and paint shop I was a happy but my happiness only lasted 2 days.

    My RSX Base axles snapped out of the boot on the passenger side n I almost blew my motor because it hit my engine oil filter so imagine what a mess that was(WORD OF ADVISE IF YOUR AXLE BREAKS SHUT OFF YOUR CAR IMIDIATELY) , I was not a happy camper that night with a freshly painted blue 2000 honda civic SI with oil all over the place. I started doing some reading the next morning as to why this would happen and I read all kinds of stuff. My first thought was to replace the axle which I did the next day and pulling out of my driveway the new axle snapped out again which made me realize the axle was too short, then I did some more research and I needed the lower control arms and inner tie rods from EG which I replaced and then installed a second axle and it got me to the stop sign on my block and it snapped out of the boot again….. At this point I was furious and frustrated at the same time, and didnt know what to do. I did some interesting reading which was all on your post so I went to my local auto parts store last night and bought 2 new axles for a 2004 rsx base model axles since I dont have a 36MM hub on my US ITR 5 lug conversion and you recomended to switch the inners on the axles which I tried to do with my brand new axles once I took the boot clamps off and remove the inner joints it turns out that they were not interchangable because the shaft and the bearings were bigger on the driver side so once again I was dead in the water…..

    Here is the problem I have with my options.
    1. buying hasport axles for $350 / these axles only hold 200HP and thats not gonna cut it on my K24.
    2. buying 36MM hubs for $300.00 plus I would have to buy 2 axles and its required to swap the axle inner joints and god only knows if they are interchangable n I dont wanna go through it again……

    I find it hard to believe that I'm the only person having this issue, a friend of mine had a EK hatch with my same exact k24 setup and he was using ep3 axles and he never broke an axle. The whole mystery here is why did I drive the car for two days after I got it out of the shop and now its snapping the axle right out by pulling it out of my driveway.


  4. Hey guys, just wondering I have the shuddering problem as well.  Does hasport axles eliminate that or have some kind of vibration damper?  I'm sick of these napa remans…

  5. I know of people who are K swapped that are running their stock B series axles temporarily without problems, some ive heard the axles have popped out and some say no issues. im just opposite of that. i have a B series motor in my integra and i have 36mm hubs. Can I run RSX type S axles in my car?

  6. Hello FFS-Tech/Katman, I'm dong a Type R 5 Lug Conversion and debating of which size mm axle nut conversion to use on my 93 Civic DX Hatch.  I have a K20Z1 swap with Hasport mounts, and currently using oem 32mm RSX base model axles which fits perfectly fine and drives good.  Though, I was wondering if I would have any issues running the JDM Type R 36mm conversion? Or should I just stick to the 32mm 5 lug conversion?
    Anyhow, this is what I've concluded, let me know if I'm correct? 
    1) If I go with 36mm Type R 5 Lug conversion, then I would have to use RSX Type S/R 36mm axles? 
    2) If I go with 32mm Type R 5 Lug conversion, then I can use my current (32mm RSX Base Model) axles? 
    The whole point of this topic, is to stay on a budget and not buy any extra parts that I don't need; like the axles, etc. 

  7. So I have a 2000 Acura Integra with a k20 swap, with 36mm 5lug hub from a crv. Close to two years now I've been running with stock RSX type S axles with no problem at all. I started getting vibration issues whenever I'd hit gears hard. It sounded like a buzzing noise. I thought maybe the motor was just vibrating up on the hood. I searched up and down for the source of the noise and could not figure it out. Checked the mounts and the suspension and everything was tight.
    So I put the car back on the ground and took it out for a test drive. I was at a light with no one around at 10:30 at night and decided to rev it up and launched at 4k. The axle broke immediately. I swapped my OEM one for one at auto zone, and didn't even make it out of my driveway before that one broke. I had an old B series axle with the outer swapped for a 36mm and that broke on me before getting out of my garage..
    according to your article, my setup should be plug-n-play with type-S axles. But everyone that broke so for has broken on the inbd passenger boot. I'm stumped. Is it the incorrect length axles that I have? My tranny took a dump? I don't know what to think.
    Hopefully you have an answer for me Katman! 

  8. Sorry for the late late laaaaaate reply. Which axle side kept breakin on you (passenger?). The proper axle combo for 36mm 5 lug is running a Type-S driver side and 06-11 Civic Si passenger side.

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