K SWAP GUIDE (PART THR33) ACT clutch/flywheel, SPEEDFACTORY Detent springs, and Drag spec Shifter Spring kit

K SWAP GUIDE (PART THR33) ACT clutch/flywheel, SPEEDFACTORY Detent springs, and Drag spec Shifter Spring kit

Thanks for following our K swap guide series, as we highlight the most often left out details or unanswered questions about installing a K swap. This marks our fourth installment of the series, with the first one just being a prologue and backstory to why we are installing another K20 on Pats car. Below are links to the previous posts:




Now keep in mind all of these posts aren’t meant to deter or scare you away from doing a K swap. No, no, these are merely meant to educate you on everything that you should do, and how to go about doing it all when doing a K swap in your car. When most people get the idea about doing a K swap, their first thought is to look up either how much it costs, or how cheaply they can do it for. Well quite simply, if you’re going to do a “proper” “reliable” K swap then… Yes its going to cost money, A LOT.  You shouldn’t speculate the cost, just go into he project knowing that it’s going to be pricey. Im not here to argue, I’m only her to delivery facts and help guide you. Remember at the end of it all, it’s ultimately your choice if you’re going to do any of this or not. If you’re plan is to have a K swap just to show up to meets trying to deceive people by passing you’re K20A3 or beat down A2 as an actual K swap, then just stop reading this now. These posts are here to guide an actual enthusiast in what is really necessary for k swapping, and help guide them to see if a K swap is really for them, or if they should just stay B series (which is totally fine). Yes we have all seen “boosted boys” and how they make a million horsepower on stock motors… Is that reliable though? NOPE, there is no way you are going to be able to use and abuse motors like that for tens of thousands of miles. Or you’ve watched That dude in blue, or Zosh and seen that they have stock K24 swaps that work well. Do you think they did it relatively cheap? Or did their sponsors help them out?  Enough, like I said I’m not here to argue. I Just want to help educate you on some K swap stuff. Yes there are plenty of people with ghetto  K swaps that run okay, but cmon… have some integrity or pride in what you’re doing. I would rather have a nice B series than a crappy K series any day of the week. Just look at the JDM B18C (type r swap) it makes just as much horse power most K swaps. (with the exception of the JDM Type R K20’s) and almost as much toque. Its cheaper to install, easier to work on (since a B series was designed to be in the EF/EG/EK/DC chassis) parts are much cheaper, readily available, and the transmissions are stronger. Don’t get me wrong, I LOVE my K20, but its a proper one, done properly.

The first part of this article will go over Installing a new clutch and flywheel. This should always be a MUST DO for anytime you’re swapping any motor into your car. Flywheel not as important (just at-least get it resurfaced) Even if the motor comes with a “slightly used” clutch don’t take anyones world for it. It will be much easier to replace it all while everything is all out of the car. Sure you can just drop the trans and leave the motor bolted in the bay, but this can be cumbersome.

If you’ve spent any time researching K series you will know that the transmissions are very fragile, and prone to break easily. Some would even say this is the achilles heel of a K swap, and for this reason many drag racers will go with the 5 speed k series gear box as opposed to the 6 speed. Getting a crazy Unsprung clutch with a heavy duty pressure plate is a no, no, and will only end up putting more stress, and wear on the transmission/drivetrain. So for all K swap stuff I usually recommend people getting a Sprung clutch. Of course this is just based purely off my experiences with K swaps I have done or been around. The springs in the pressure plate will allow some force to be absorbed so you don’t shock the trans when aggressively shifting. In both my brother and I’s K swaps we run an Exedy 3 puck sprung clutch, and both of us are making over 240 hp to the wheels. Even through countless track days of incredibly hard driving I have never had any slipping what so ever.


Make sure while you’re doing the clutch you also replace the throwout bearing, and Pilot bearing. Worn out ones can cause driveline noise, and the throwout bearing can actually explode preventing you from being able to get your trans into gear. If you’re staying NA, there most likely isn’t going to be a need for you to get a really aggressive clutch. Keep in mind that the car that this motor came out of is much heavier, and having a NA K20/24 above 300 HP is pretty rare.

Next is the flywheel, and there are very many opinions about what weight you should get. Let me just tell you my thoughts on it real quick. First of all the JDM K20a type r swaps (only the DC5,FD2) come with the best OEM flywheel you can use. It’s what I currently use and in fact what most track racers will choose as well. Its the lightest of all K20 flywheels yet still offers enough weight so that the power your motor is making isn’t spent on trying to spin the flywheel. There is a point when a flywheel will be too light and can actually rob some power by not having enough inertia to keep it moving. There are SOOOO many arguments about this, and what point any of these numbers become relevant. Patrick decided to go with a really light ACT one because he would rather have a rev happy motor since this will help some of his corner exit speeds, and “blip ability” or throttle response for rev matching down shifts. A light flywheel wont harm any mechanical part of your engine or trans, but it can alter power bands, and how quickly you get in and out of them.


If you’re following along with the build process, you might be asking yourself… “Wait, I through Patrick got a JDM K20A motor from a DC5, which is the motor that comes with the best flywheel. Why isn’t he using that one?” Well as it turns out when you buy a “long block” from HMO (Honda Motors Online) you don’t get the “good” flywheel, You actually don’t even get a flywheel at all. Patrick didn’t want to use the OEM Euro R flywheel off his blown motor because that one is heavier than the DC5/FD2 type r one, and remember he wants a “rev happy” motor.

He also bought all BRAND NEW OEM clutch and flywheel hardware.


(yes he bought extra)

I would love to give a huge shout out to Vein Engine Stands for making such an awesome product. That is the engine stand that the motor is currently on, and it makes installing everything super easy (including the transmission)

Here is how the new motor looks sitting on the stand, without a flywheel.


First thing is removing the old pilot bearing (bushing) and installing the new one. On K series its not actually a bearing, but more of a ring (bushing). B and D series have an actual bearing that looks almost like one you would find on a skateboard that will press into the flywheel, where as the K series Pilot bearing (bushing) will go into the actual crankshaft.


Use a specific “remover” tool to extract the old pilot bushing. Then gently tap the new one in, making sure you’re keeping it even as you tap it in. I used a socket that fit into the crankshaft.


Next, Don’t forget to use Loctite on all bolts.


Manually thread in each flywheel bolt.


I then use a small impact to gently snug down all of them, going in a crisscross pattern to help ensure the flywheel has properly seated. This gun is just a screw gun so there isn’t really much torque being applied.


This is what it should look like with all bolts properly seated.


Now you are going to torque the Flywheel bolts to 87 lb/ft and tighten in a crisscross pattern, doing so in a few different steps. (like 30 lb/ft for all, then 55 lb/ft for all, and ending on 87 lb/ft for all) Im a little confused because in my manual it says 87 lb/ft, then in the clutch section it says torque the flywheel bolts to 76 lb/ft for the 5 speed, and 90 lb/ft for the 6 speed. Honestly there isn’t much of a difference in the 6 speed specs so either way I’m sure is fine, and I bet if you did the 5 speed one at 87 lb/ft it wouldn’t be bad. Shit there is people out there that just tighten the crap out of them with a 1/2 impact and call it good.

Below is a trick I use to keep the motor from spinning while trying to tighten the flywheel bolts. I manually thread a clutch bolt in until it pokes out the back of the flywheel (this will prevent stripping out the flywheel) Then take a bolt that holds the trans on and thread it thru the closed end of the wrench until its stops.(this will prevent you from stripping out the block) Now just leave the wrench in that one position while you tighten all 8 flywheel bolts.


As you will notice the clutch and flywheel bolts are all 10 point bolts, and you must use a 10 point socket to tighten. This will prevent striping of the bolt heads.


Now use brake cleaner, or alcohol to completely clean off all the oils that are sprayed on the surface to prevent rust during shipping and storage. If this isn’t cleaned off, it can cause many issues… slipping clutch, heat spots, excess noise, inconsistent clutch engagement, or prematurely worn clutch.


Do this until there is no longer any residue coming off on the towel.


Installing the clutch.

First off, make sure you clean all the oils off the pressure plate. Just like you did for the flywheel.


Now (not pictured) take the clutch alignment tool and slide it thru the clutch disc, then insert the alignment tool into the crank shaft.

Now you can take the pressure plate and use the X6 clutch bolts to bolt it on. (don’t forget the loctite)

There will be X3 alignment dowels that are in the flywheel and those will line up with the pressure pate. This can be tricky because they only fit one way. so you will have to rotate around the pressure plate until they all line up properly.


Due to the “spring” of the pressure plate the dowels will barley stick through the plate. Once you tighten the clutch bolts the dowels will become more visible.


After using loctite manually thread in each clutch bolt.


Then tighten in a crisscross pattern. tighten the bolts in a several step process to prevent warping of the diaphragm spring. final torque spec of 19 lb/ft

Make sure that the clutch alignment tool can move in and out freely. If not, it will be incredibly difficult to get the trans input shaft to slide in, or it might not even go in at all.


Once you’re confident in the mounting of the pressure plate. Take the supplied grease, and lube the clutch disc splines. This will help stop any binding in the clutch while in use.


Don’t go crazy with he lube. if you do, it will fling off under higher rpms and get on to the surfaces you’ve just cleaned with brake clean. This will instantly cause issues, and you might have to pull the trans back off or you will damage your new clutch/flywheel.


And now you’re all done. One clutch and flywheel have been installed. Now you must install the new throwout bearing, which is located on the transmission.


Remove the clutch fork from the trans (its just held in with fork set spring) use pliers to squeeze the spring together and you will see how it unlocks it from the pivot ball. It is not necessary to remove the spring as you can see below I still have it on the fork, but if its your first time it might be easier to just remove it.

Put a small amount of grease not he two tips that rest on the throwout bearing. This will not only help silence rattles or any other unwanted noises, but will also allow the fork and throwout bearing to slide with out friction. This will allow again for proper clutch engagement and pedal feel. It will also prevent premature failure of any components


Below is what the fork set spring looks like.


Throughly clean the output shaft housing to ensure no debris is on it. Then lightly grease to again allow for the bearing to easily slide. The bearing is what presses up against the pressure plate face. It disengages the clutch disc away from the flywheel allowing no transfer of power from the Engine (flywheel) to the transmission, this allows you to shift gears. Again too much grease will fling off under higher RPM’s and get places you don’t want.


clean the pivot ball and reapply new grease.


Then reinstall the fork and throwout bearing making sure they move freely. (make sure the spring is fully clipped around the pivot ball)

Yes I run the rubber boot that goes around the shift fork. I just remove it because it makes the install of the fork go smoother. then reinstall after I bolt the trans on.


Everything above is what I would call mandatory. Now the below stuff is not necessarily mandatory, but while everything is out of the car its very easy to do, and the upgrades are rather cheap.

SPEEDFACTORY Detent springs, and drag spec shifter springs:

Ive just got to say that just installing these and using my hand to shift the trans manually you can instantly notice a difference in how much better it locks into gears, and removes all slop.


On a K series, the three bolts you need access to are under the trans mount. You must remove it.


Below are the X3 bolts you will need to remove.


Each one will have a spring, and a small ball bearing (inside the hole)


Below is a comparison of the stock (OEM) spring on the right and the Speedfactiry spring on the left. Each bolt will have the same size spring in it, and you will just simply pull the old spring out of each hole (leaving the ball bearing in) then drop the new Speedfactory one in.


The bolt will go in like this, and you will be able to manually thread almost all the way in.  (the spring isn’t that strong) Do this for each individual bolt X3 and you’re all done.


This is a super easy install! Even if you already have the motor in the car, you can simply put a jack under the motor and then just take the trans mount off to gain access. If you have a D series you can access all the bolts without having to remove anything (its super easy) and I’m pretty sure that a B series is just as easy. This modification is very inexpensive, and will give your shifter that “notchy” feel that everyone likes.  IM going to be doing this on my personal K20, and my D series.

The last thing we did was the Drag spec shift spring kit. This maybe a little confusing because it says drag spec and Pats going to be tracking his car. But what this heavy duty spring kit does is…  I’ll just let Speedfactory explain. (copied from their site)

At SpeedFactory Racing we understand the frustration of the common 2-3-2 and dreaded 1-2-1 K-Series transmission mis-shifts, and we have the solution.

The SpeedFactory Racing K-Series Drag Spec Shifter Spring Kit is the strongest available (over 200% stronger than OEM springs) and gives your shifter a firm, positive feel and returns the shifter to the center position with authority which improves shift accuracy and speed while rowing through the gears.

This kit will help improve shifting on all K-Series transmissions, from stock transmissions to dogbox racing applications- especially the 2-3 shift. Just push the shifter forward, and it will automatically drop into the 3rd gear position.

Installation is very simple and can be done with the transmission in the car. Simply remove the shift mechanism from the top of the transmission (one hex head interlock bolt and four 10mm bolts), remove the shift piece and interlock assembly (retained with a single 12mm bolt), and remove the factory springs and replace them with your new springs. Reassemble and re-install the shift mechanism.

This installation isn’t quite as simple as the detent springs, but if you take your time its still pretty easy.

Start by removing the Hex bolt on the side of the trans. This is what actually locks the mechanism in, so if you don’t remove it the mechanism wont come out.



Next remove the X4 10mm bolts holding the mechanism to the top of the trans. There is Hondabond or similar sealing this, so you will need to break that seal to remove.


The trans will need to be in neutral to easily remove the mechanism.


Below is what the complete mechanism looks like removed.

Now remove this bolt, it’s what locks the shift selector in place.


Below is what each piece looks like all taken apart.


Slide off the OEM springs.


This is the threaded hole that you must line up the shift selector with when you reassemble all pieces so that the bolt can easily be reinstalled.



Slide the new Speedfactory ones on.


Reinstall the spring cup.


Lastly, slide the shift selector back on, making sure the hole lines up and then thread the bolt back in.


Now it’s all ready to go back in the transmission.

Clean off the old Hondabond, then reapply a small layer around the square hole. this will ensure no oil leaks out.


Take the X4 10mm bolts, notice that two are short and two are long. They will only fit one way, and they go diagonal across from each other.


Below you can see the X2 longer ones are in.


Then the X2 shorter ones.


Now you can see how there is some Hondabond that gets squeezed out once tightened back down. These are only 10mm bolts so they don’t need much torque to be tight. Im sorry but I don’t want to look up the exact specs. my manual is VERY BIG!


Lastly, put some Hondabond on the Hex bolt to completely seal so no oil leaks out.


The final product.


If you’re doing this while the motor is in the car, you will need to remove the shifter cables, and some of the wiring. Depending on what chassis you are doing this on you might need to remove the air box/intake pipe. However you can leave the trans mount bolted in.

Heres a sneak peak of the new motor sitting in the car, I’m assuming the next installment of the K swap guide will be the final one. We will be going over wiring, cooling, and firing up the car.


Thanks so much for coming to visit the blog, Please don’t take any of the negative things too personally. I just want people to know that not all K swaps are good, created equal, or should be lusted after. You can have plenty of fun with a B series and spend much less. As always there’s exceptions to all rules and there will be people that “daily” their K swap that don’t do any of these upgrades. It will probably work for them too, but why risk it. You are saving up all your hard earned money to get a motor swap, you might as well make it reliable so you can enjoy it or years to come. Remember, the people you see on social media only make up a small percentage of enthusiasts, and most of them don’t show you the bad times. Don’t just assume because someone says they have a trouble free K swap that it truly is. K swaps can be very moody, and unless you’re sponsored or have friends (like me) willing to work on it, then it’s going to be expensive.

As always, please feel free contact me about anything relating to this post. Email me at Billy@functiontheory.com, or DM me on Instagram @functiontheory, or just comment on the post below.





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