Honda K24 Swapped 2015 BRZ Ship of Thesus (NASA TT5)

[Ace23_BRZ]

Nice build! Clean and well documented.

[jflogerzi]

So much win in this thread! Subbed!

[RedReplicant]

In efforts of keeping this thread up to date...

To reduce some of the drivetrain vibration I decided to have my stock driveshaft shortened 5.5" (do your own measuring) and spaced the carrier bearing down.

2x M10 15mm spacers
2x M10x1.25-60 bolts
2x M10 split washers
2x M10 fender washers




This actually worked out really well, there is pretty much no vibration from the driveshaft any longer and it is overall much quieter. Super happy with it.

This brings us to the first event with the car, so have some S-Tier (shit tier) driving. Track is brand new so I was lost as hell and the AIM data is pretty wrong due to some kind of weird GPS issue.

We ran the outer configuration CCW with the chicane added in. Track is private and has only been opened a few months so there are no real times out there yet, I did a 48 in the heat / not knowing which way I was going. One or two other local TT guys have been there and from the times they've done without the chicane I think the car will be competitive locally.

In the marked stuff below:
Esses were a mess
Hillcrest is deceptive because it crests and then drops away but there is still more track than you'd think out there
I want to try taking the sweeper flat, I'm guessing it won't work with my aero but at least there is nothing to hit
'T3' wtf is even going on here
'T1' should probably be taken wider and turned into later



Anyway, I was actually super happy with how the car worked its first time out, I had very few real issues and the car ran great. I wanted more rear grip out of the car, the front grip is what really surprised me.

1. Initial throttle tip-in needs some help, it can be kind of snatchy. Easily fixed in Haltech

2. I let my friend (instructor for the private track) drive the car and he managed to overtravel the DBW pedal twice and put the car into limp mode. Didn't happen to me, but I am going to add some kind of stop and recalibrate the throttle.

3. Oil was blowing straight through the catch can. It turns out that the baffled (as it is advertised) Vibrant catch can doesn't actually have any real baffling or media in it. They want you to pay $100 for their drop-in baffle.

Scotchbrite stainless steel scouring pads to the rescue.




I also have another thing planned to help with the blow-through - I talked to the guy that did my valve cover and it turns out he was looking for someone with a RWD K to test a CNC cut breather baffle. He also trimmed the front of the cover a tiny bit so I don't need to clearance the hood. Should be here soon and I'll post a picture of the inside of it.



This is what his S2000 baffle looks like:



Stock:



4. Transmission rear seal is still leaking even after replacement. I ordered another OEM rear seal, not real sure what to do here. Driveshaft input shaft looks weird because there is no dust cover on the driveshaft or transmission.



5. I noticed that oil pressure drops under braking, Miata experience tells me there is nothing to be concerned about here since it is off throttle / low load.



Uhhh, yeah, where does this leave us? Pretty happy with the car so far. Tentative schedule of upcoming events if the car stays together:

10/8 - NASA AZ Attessa Motorsports
10/9 - NASA AZ Attessa Motorsports
10/29 - NASA AZ Arizona Motorsports Park
10/30 - NASA AZ Arizona Motorsports Park
11/12 - NASA AZ Chuckwalla
11/13 - NASA AZ Chuckwalla
11/25 - Speedventures Buttonwillow (NorCal 86CUP day)
12/3 - NASA AZ Arizona Motorsports Park
12/11 - Club Racer VTEC Club Chuckwalla

[jflogerzi]

Damn that's alot of track time. I wish I could be there on the 11/25 day..... By then my car should have full aero and new suspension from Annex with there club sports on Swift 9K/12K Springs. Would be a good comparison as the car should be mostly gutted by then as well.

[RedReplicant]

Originally Posted by jflogerzi

Damn that's alot of track time. I wish I could be there on the 11/25 day..... By then my car should have full aero and new suspension from Annex with there club sports on Switch 9K/12K Springs. Would be a good comparison as the car should be mostly gutted by then as well.

It'll actually be my first time at Buttonwillow, figured I'd make the trip for 86Cup.

I also haven't run any of the Willow tracks, do you run the 86Cup days with them or which orgs do you frequent?

I hadn't planned on posting about it until they showed up, but I ended up buying Shaftworks single adjustables with 7K/11K (400lb/620lb-ish) as a temporary TT5 thing until I get ahold of a set of Xidas, at which point they will go to my Hyperblue car. During that install I'll also be putting in Superpro FLCA bushings and the Whiteline roll center correcting front lower balljoint / tie rod ends.



The ProParts Megans with 7K/7K (400lb/400lb) in the Hyperblue are terrible and it makes no sense to put the JRZs in a street car that I drive once a week. I think I've said it before, but the JRZs with 10.7K/12.5K (600lb/750lb) ride leaps and bounds better than Megans, which is half surprising due to the spring rate difference and half not given what they cost.

edit: Oh, I was cleaning the car up the other day and figured I'd hardwire the Beastronix to CAN. I was not expecting to find a straight up Arduino and CAN shield in the box. If I wasn't feeling incredibly lazy about figuring out exactly what CAN messages it is spamming I'd replace it with a Teensy and a CAN transceiver. Maybe I will anyway.

[jflogerzi]

I tend to run only open HPDE days vs the cups cause my budget does not allow that many track days. Run with Speed Vetures, SoCal Driving Club (low car counts and no run groups, 100% open track)

BTW you will love BW. Its my favorite track that's close.

[RedReplicant]

To illustrate the transmission tail shaft leak:



I have no idea what is going on here, it is coming out between the seal and driveshaft yoke somehow. Three different driveshafts, two different OEM seals, two different fluid fills. Breather isn't clogged.

I don't see anything abnormal with the seal removed



Tossed in another OEM seal



No idea what else to do, what a pain in the ass.

Running Attessa with NASA this weekend, I'm classed for TT5 but that is based on the Shaftworks I ordered showing up by Thursday so I can slap them in and send it without a corner balance or alignment. If they don't show up I've got a TT4 classing sheet where I will be running effectively 750lb overweight based on current mods/weight/power.

It'll be fun either way.

[gt5759]

Originally Posted by RedReplicant

To illustrate the transmission tail shaft leak:

You need to check tail shaft play, run out and the tail housing id. In my opinion it can only be one of three things - tail shaft has movement, tail shaft is not perfectly straight or the housing ID is out of round. 30 minutes and a dial indicator will tell you the story.

[RedReplicant]

Originally Posted by gt5759

You need to check tail shaft play, run out and the tail housing id. In my opinion it can only be one of three things - tail shaft has movement, tail shaft is not perfectly straight or the housing ID is out of round. 30 minutes and a dial indicator will tell you the story.

Thank you, those are good thoughts, I'll see what I can figure out. I wish I'd kept the transmission that I blew up since the housing was still good and would have been useful as a reference.

[RedReplicant]

Pulled the JRZs today



Shaftworks showed up with some shock dyno plots and a knob starting point, so I tossed them in and maxed out the camber plates. 100% going to need some eccentric bolts, hopefully someone sells some lockouts like Professional Awesome sells?

https://professionalawesome.com/prod...-camber-locks/





Set the ride height to 130mm / 135mm at the pinches as a starting point and I'll do a quick toe plate check tomorrow. I'll have to wait to do the front roll center correction and bushings until after this weekend, so it'll be a bit of a suboptimal setup for now.

Loading the car up first thing in the morning, I'd like to run a test session or two on Friday but I'm somewhat worried about breaking the car early. Meh.

[RedReplicant]

Alright, so the weekend turned out decent, all things considered.

On Friday I had the car W2W teched for NASA and I tossed it on the scales to verify I'd be fine. I also played with the tire templates a bit and found the 255/35/18 AR1 on a 18x9.5 fits into the 257mm template, so I updated my sheet for that. It let me drop min weight to 2820lb from 2850lb.

This is with a completely full tank and me in the car, so I'm going to pull a bit of weight back out.



On Saturday the car started out feeling super vague and low on grip so I ended up going the wrong direction on the dampers like an idiot, tried adding wing, etc all day. Finished 4th of 10 in TT5, top 5 were within 8 tenths on Saturday.

At the end of the day I was like alright, let's go the other direction, changed a few things, and left the car for the night.

Sunday morning the car felt pretty loud on the out lap of the first session and I realized the exhaust had probably cracked since it is a common issue with the KPower header, so I came in before starting my first flying lap rather than melt everything under the car.

It really sucked to eat the fastest session of the day (by far). This turned out to be the session that most people in class set their fastest lap, rip, and also meant that I had to grid at the very back for the second session. I left a 15 second gap and got a single clean lap.

Found this:




Cobbled together some bolts and put it back together with minimal melting, though I did notice at this time that the transmission is no longer leaking, which was a really nice surprise.

Played with the knobs and the car started feeling really great. I also noticed that if I maxed out the wing the car would start pushing heavily in almost every corner, which was kind of surprising since I haven't had a wing make an in-your-face difference back to back.

Last session of the day was super greasy, but the car felt great and I had fun, which was a nice change from where I've been with tracking for a while. Finished 5 of 9 for the day, meh.

Quickest lap for me, not super happy with my driving.

Post event stuff over the last week or so...

Adding the steel wool to the can helped, but it was still misting out a bit. Nothing major, this is what it looked like after a full day



A while ago I talked to Charlie / Doryoku LLC who does a lot of the powdercoated AN valve covers floating around, he told me that he was working a CNC cut baffle that he wanted to test in a RWD swap car. Unfortunately, it didn't show up in time for the event but I just tossed that on. It is also trimmed down in the front so there is no more hood contact, which is a nice touch.

You can see that the AN ports are just open on the normal valve covers.







While I was in there I put on the K24Z upper timing chain guide for a little bit of added security.





On the suspension end of things, I finally got around to doing the Whiteline bumpsteer kit. While I was in there I replaced the rack boot that got torched by the Ace A350 from when the car still had the Harrop'd FA20.

Since I was pulling the arm off anyway I figured I'd do the SuperPro LCA bushings at the same time. That was kind of a pain in the ass, balljoint and front bushing pressed right out. For the rear one I had to push out the rubber, cut a slit out of the bushing casing with a hacksaw, and hammer the case out.







Ended up doing SPC offset lower bolts in the coil overs to try and run a bit less camber at the plate, we will see if that works out with the pyrometer.




I tried ordering 255/35/18 Toyo RR since I am not a fan of the AR1 and I'd like contingency Toyo Bucks, but they are currently nationally backordered with no ETA. I ended up buying another set of AR1s.

Need to get an alignment sorted real quick, next weekend I'll be at Arizona Motorsports Park both days for TT5.

[RedReplicant]

Oh, I guess something to add is that NASA is cracking down on splitter length this season. Apparently there was some kind of loophole until a couple of weeks ago where max splitter length was technically 4.5" due to the 1/2" variation in measuring allowed elsewhere in the rulebook.

My splitter looked like it was hand cut by a drunk sailor, because it partially was, and ended up slightly over 4" in certain spots, but not over 4.5" so I wasn't DQ'd at Attessa.

Ended up sanding the stupid thing down 1/8-1/4" in the blue spots with a harbor freight belt sander.

Just throwing it out there since I'd guess other regions will make it a point to check.

[gt5759]

Glad to see the leak was just a seal install issue of some sort.

Couple questions Why not install an accusump to control pressure and for added insurance?
Why did you choose such a large spread front to rear on spring rate? 7kg front/11kg rear, if I see correctly? You mention its rather loose in the engine swap section.

[RedReplicant]

Originally Posted by gt5759

Glad to see the leak was just a seal install issue of some sort.

Couple questions Why not install an accusump to control pressure and for added insurance?
Why did you choose such a large spread front to rear on spring rate? 7kg front/11kg rear, if I see correctly? You mention its rather loose in the engine swap section.

Yeah, I was pretty relieved when I popped under there and it was bone dry.

I'm probably going to end up accusumping the thing, KPower told me that the these need to be overfilled by a quart when I posted in the Facebook group. I had success with that on a BMW in the past, but it is still pretty irritating and we will see if it solves the issue (I think not).

As far as spring rates, that is what Jon Lugod recommended when I bought them, so I felt I should follow his recommendation to start out.

I hadn't bothered writing up how the weekend went, but yeah, the car is super loose from when you get on throttle mid corner to exit. We're talking straight up and down steering wheel and driving the car with the rear from mid corner for a 3rd/4th gear corner and will roast the tires in a 2nd gear exit corner, which to me more or less points to the rake being way off or the rear spring rate being way too high.

I think basically what happened is that my pinch welds in the front were actually a lot more smashed up by the previous owner than I realized. I straightened them out but I guess the floor is actually pushed up.

The numbers I had were originally based off pinch to ground, but here I will add fender to ground and wheel lip (18") to fender:

Front: 24 3/4 fender to ground, 22 1/4" fender to lip, 5" pinch to ground
Rear: 25 7/16 fender to ground, 23" fender to lip, 5 3/16" pinch to ground

Basically, the rear is dead on and the front is 3/4" low, so the car had 3/4" of rake in it, which would explain a lot. Based on recommendation from Jon I went 23" fender to lip in the front and rear. We will see how that goes.

Front went from 0 toe to 9mm toe in when raising it so I need to fix that.

Anyway, that is a lot of typing to say I screwed up. Here is a pic from the weekend.

Chuckwalla with NASA SoCal next weekend.



Oh, yeah, for my TT5 people - that A-arm penalty isn't going away for next year.