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GKR IS300 Racecar

16K views 49 replies 15 participants last post by  OptionalZero 
#1 · (Edited)
Chapter One
(I)S Club 7: Bring It On Back

*EDIT*
To follow along with up to date posting on the car and the race season, follow me on Instagram @nikromanoracing

Hello My.IS!

I just made an into thread a few nights ago. My name is Nik, and I recently decided to start doing IS things.

The goal is to build the car for NASA wheel to wheel racing in the PTD class. I'll also bring it out to other events like the SpeedSF challenge (a grassroots time attack event and track day organization), and maybe some TRD Cup events.

My history with IS300s started with one Mr. Joe McGuigan, an SF Bay local ProAm drifter and one of my best friends. Over the years I helped him with his car as it changed form over and over, from a GE to a 1UZ, to a 1J-GTE. I always liked the car, but I was happy playing around with Miatas and didn't need another project. Here's that car in its final guise, on one of two laps I got to do some skids in it:



At some point, I got involved with a Hayward-based tuning shop, and I helped them to build this:



It ran at the 25 Hours of Thunderhill, and despite some major braking issues early on and not really having time to tune the car to its potential, it finished the race in 7th place. It would have been neat to see what it could have done when the power to weight was up to spec and the suspension was dailed. Alas, it was not to be.

Fast forward to last year, I decided one day that I wanted to build a first-gen racer, and that same day I called up a guy with a Craigslist posting, drove to see the car, then bought it and drove home. I had to take an Uber to get my other car back home. #planning

That very day:







The photos hide the bad clear coat well. It had a cold-start rough idle, what is likely the top-o-tha-fuel tank leaky valve, and a slushbox...but at $2500, the price was right, and I'd be disassembling the entire thing anyway. I DD'd the car for a few months, immediately began regretting my plans to take my only practical car with an auto, AC, 4 doors, useful trunk, power windows, and comfortable suspension...and using THAT one to gut and cage. Seriously, the whole thing is a totally dumb idea. Why am I doing this. Halp.



The first order of business was engine maintenance. There was some oil dripping off the front end, so I decided to tear all that mumbo jumbo out and replace the oil seals. Turns out, the crank bolt in these cars is good fun to take off. It must have taken 1000lbs of force to get it to budge. Two dudes both pushing on a breaker bar with a cheater pipe on it, and we almost couldn't get it done. I can get my Miata's crank bolt off with a stern glance.

The leak ended up being the VVT cam gear, so I bought one of those handy do-it-yourself kits consisting of a sheet of printer paper and an o-ring, and went to town. Half of this job was to fix the leak, half was to familiarize myself with a new (to me) car and engine. Once you get the hang of this car, it's not so bad.

With everything all buttoned back up, it was time to actually do some racecar things.
 
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#2 · (Edited)
Chapter Two
The Opening of the Start of Preliminary Beginnings

Before making any modifications, I wanted to get a baseline for the car's weight and balance. This "before" measurement is with me in it, 100% stock with the full interior and the automatic transmission.



The "base weight" for my class is 3255lbs, which is a measure of the minimum weight the car is allowed to be on track, with driver and at the end of the race after fuel has been burned off. So ~250lbs need to come off. Should be doable, between the sunroof, seats, interior panels, carpet, windows, sound deadening tar, etc. I'm also allowed to use carbon body panels and a lexan windshield if necessary.

The seats and the carpet were the first to go.



Maybe I'm just used to dealing with older cars, but it seemed remarkably clean under there. No nasty liquids, grunge, or poo stains, just a single, solitary, presumably stale Goldfish. I'm also liking how all of the plastic bits come apart without much of a fuss. On 25+ year old Mazdas, the interior parts will break if you look at them wrong, sometimes even if you look at them right and they are just in a dodgy mood.

Plenty more stripping to be done, but then I moved on to do some suspension work. I'm using a fair number of FIGS Engineering parts on this car. I've had some experience with Mike's parts before, on Joe's drift car and on the 3IS endurance car so I'm already intimately familiar with how well designed and built they are. Mike is a hell of a guy too, and I couldn't be happier to have his stuff on the car.

First up, the rear toe links:



Using these does a few things; the length is adjustable, which means we can set the factory eccentric bolt to the furthest inboard position and lengthen the rod out. That will make the rod follow a larger arc, reducing the amount of bump steer for a given amount of suspension travel. Of course, the rubber bushing is also eliminated in favor of a spherical joint. On a track with sticky race tires, the forces applied to the bushings are a good bit higher than the factory ones were designed for. One place you certainly don't want a lot of deflection is on the bushing that determines the direction the wheels are steering. This should be a nice improvement to stability and predictability.

Next, it was the MEGAarms.



These do even more. First, they are lighter and stronger than stock. The factory arms aren't boxed, so they will twist from the torque of the engine and, essentially, not put that power through the wheels. These are boxed, so they don't have that problem. Next, the lower shock mount is slotted. This means you can make small adjustments to the motion ratio of the rear suspension. The farther out you push it, the stiffer the spring (and shock) act. Ultimately it would awesome if the motion ratio was higher from the factory, but this will have to do. There are three choices for the sway bar end link mount, which means you can get them closer to being perpendicular to the bar itself (or farther, depending on how much leverage you'd like). Just like the toe rods, these eliminate the rubber bushing and replace it with a spherical joint. The lower arm will be the most stressed member during lateral load, so this will play a big part in making sure the wheels are pointed where you want them while cornering. And of course, these are length-adjustmable, which means you get way more camber adjustment than stock.

I've done some more work on the front end and interior, but I don't have any photos yet, so those will have to wait for next time :smile2:
 
#7 · (Edited)
Chapter Three
Stop the World and Sabelt With You

HOKAY. It's been a bit over a week, and progress has been made.

First, I got to work installing my race seat. I went with a Sabelt GT-160. I got this seat for a few reasons:
-It's full containment, and as someone who used to be an open wheel dirt racer...I know the benefits of a containment seat.
-It's a quality brand, with FIA certification
-It's looks cool
-I got an absolutely ridiculous deal on it. Seriously, this is very much a ballin-on-a-budget build so I'm always on the lookout for deals, and this was one. It fit what I was looking for (and fit me) so that was an easy trigger to pull.



There doesn't seem to be much in the way of options for rails on this car. The Planted rail looks to be pretty solid, and it came recommended from McG, so that's what I got. On the brackets, I don't really have any real preference, so long as they are strong and let me lean the seat back enough. I got some Sparcos.







I want to be low, and I want to be centralized. This is as far to the right as I could get the seat. If you look closely, it's slightly off center to the steering wheel. Turing the seat minimally anticlockwise makes it so you don't even notice while driving. I mocked everything up and drilled some new holes in the rail to mount it. I'll put it in permanently soon, but for now the stock seat goes back in. I'll be doing a long trip in the car on Saturday, so I'd like it to at least reasonably comfortable on I5 for 6 hours.



Back to the suspension. One of the biggest sources of mushiness in the front end of this car is the caster bushing on the lower control arm. It's big, rubbery, and has sizable airgaps. The whole point is for it to be squishy and comfortable, but I want neither of those things. Furthermore, mine happened to be torn.



I opted to use FIGS replacements, in spherical flavor.



Like any bushing these are a bit of a PITA to install, but very worth it. I'll be doing more (all?) bushings on the car over time. Next on the list are the front and rear upper control arm bushings, but those are saved for a later date.

I went back to stripping the interior out to get it ready for the cage. I'm taking it up to a friend of mine in NorCal to git r' done. Not only is he a hell of a fabricator, he's also a NASA champ. Who better to build a cage for NASA? And you know, trailers are a hassle and costly, so I'm just gonna drive it there. I have family in the area and I can mostly work remotely, so I'll be staying there until it's done, then driving it back home. #yolo , or something. More on the cage process next week. Remember the photo of the car "stripped" from before? Well, here's all the stuff that I took out after that. There's a ridiculous amount of stuff inside this car. Guess it makes weight reduction easy?



(Seriously though Toyota, screw you for RIVETING the front speakers in. Why.)

Once the weight was out and the arms and bushings in, I threw the car onto the alignment rack to get it reasonably drive-able for the weekend. I had to put the stock springs and shocks back on since my coilovers aren't ready yet, so I'm not going for perfection yet. I happy with the amount of camber I could get up front with the factory adjusters. With all the weight out, plus the adjusted geometry in the rear, plus the stock springs, she's in 4x4 mode right now. Granted, I'll be about doubling that number later on, but for now this is not bad.



That's all for now. Next on the list is a solution for the sunroof hole. I wrote this while sitting at my fabricator's shop while he finishes up the plug, so more on that later. :approve:
 
#9 ·
Check out the "Race Related" section. There's a PTD or PTE build in there. He hasn't updated the thread in a while.

Keep in mind that PTE and PTD are rumored to get phased out next year and got to the ST format.

My biggest quam with the IS is lack of front fender space for tire. I'm running a 275 out back, but limited to a 245/255 up front. With a big iron straight six, the thing understeers when pushed.

Mine is lowered a bit; want to try the RCA and see if that improves my roll stiffness.
 
#10 ·
Are you talking about mbmillig's car? I had a read through and watched his videos. Funny (but not surprising) to see him dealing with the same issues I'm dealing with, like the silly spring rates and the P/W. His is a PTE car, I'm going up to PTD. I'll definitely be doing a dyno reclass, it would be nearly impossible to get the P/W where you need it and stay within points without a cheeky zero-points engine build. I don't have the cash for that sort of thing though.

So far, it's looking like ST will slot the PT cars in fairly well. They use power under the curve too, which IMHO is a WAY better system for keeping cars' effective output closer. I like it.

With such a big split in your tire sizes, I think you'd have a hard time getting that understeer out no matter what you do with the suspension settings. I'll be running the same tire size front and rear (either 235/17 or 245/17). You could even argue that in a front heavy car, you'd want more front tire than rear, but I've never seen anyone actually do that on anything that wasn't FWD.

As my car sat when I weighed it, it was 54% front weight. Sure, that's a little front heavy...but not too much. A typical Miata is 52%, I've even seen 53%, so the ol' IS isn't too far off, and certainly not as bad as many other FR cars. (Makes me wonder how good it would have been with the BEAMS in it...)

With square tire sizes, a nice alignment with ~3* camber up front, and some science'd out spring rates we can all but eliminate the mid-corner understeer. Remember, the weights you see on scales are static numbers. When you are actually in the middle of a corner you are experiencing a much different balance. Biasing the springs heavier up front will equal out the forces applied to the tires. Sure, the inertia of the front end will always be higher, but that's the case for a whole lot of very successful racecars.

Regarding the roll stiffness of the IS, it's mostly a problem with the motion ratio. Sorry to keep referencing Miatas, but they provide good data points. The Miata's motion ratio is roundabout 0.7. A strut car has nearly 1.0. Our ISs have 0.5. What that means is, we need ludicrously stiff springs to get anywhere near the bounce frequency and roll stiffness we'd want for a race car. Of course, the roll center is a factor too and can be used to help, but the real problem lies in the motion ratio. I'd be really curious to see where the RC sweep is. Has anyone made a computer model of the suspension in this car yet? We could go old-school on it and just draft it out, but if someone has or can do it digitally that would be even better.
 
#13 · (Edited)
Chapter Four
Next Time Baby, I'll Beeeee....Without A...Sunrooooof

Alrighty folks, I mentioned earlier that I'd be eighty sixing the sunroof. It's heavy, and it's literally the highest point in the car. The IS is already roll-stiffness-challenged, so this should be a pretty big help. I took it out weeks ago, since the car was sitting in a garage. For competition, I need a plug to replace it. I drove it over to my local fab guy's shop for him to whip something up. On that drive, I learned a few things about the aerodynamics of the IS and the about the thickness of the sheet metal.

1, the air flow coming off the top of the windshield sticks to the roof really well.
2, the opening to the sunroof is directly below that air's path and creates a massive zone of negative pressure.
3, holy crap the roof is made of tin foil.
4, oh god, why

Basically what happened was, as soon as I got above 35mph, the wind would grab the leading edge of the rear of the sunroof hole and absolutely thrash it. Like, the roof skin itself flapping wildly in the dirty air making horrific noises and doing so with such force that I'm CERTAIN it would have started doing some actual damage to itself if I let it. I had to hold the roof up with my right hand while I was driving down the freeway to get to the fab shop.

Pro tip: Don't drive an IS with the sunroof removed.

But, I got there safe and with the car in one piece. Now it was time for him to do his thing. The most obvious solution would be to just rivet a piece of sheet aluminum onto the roof, but we can do better than that.

Instead, he made these brackets out of steel box and rolled them to match the curvature of the roof. These will give it some extra strength and make the metal sit nicely.



Next, the plug itself, with nice rounded edges.



A little bit of caulk (insert your own jokes here)



A whole bunch of rivets



Aaand, alaka-presto, we have a plug.



I think I'll put a rivet into the corners later on just to make me feel better. As it is, there were no holes drilled into the roof at all.

Looks pretty clean from the inside too. I may go and cut that extra sheet metal off, as well as the studs for mounting the sunroof.

 
#20 ·
Pics? I've always loved 86s, crappy suspension and wheezy engine be damned. I am a very firm believer in the slow car fast ideology, and I'll take it a step further and say that cars that drive and handle too well are boring. I guess that's why I'm making a racecar out of an IS instead of an E46. Everyone does that, it's too easy.
 
#21 · (Edited)
Chapter 5
Like a Bridge over a Troubled Water Pump

Oh, My.IS.

I have no one to blame but myself.

You see, I broke the Golden Rule. I did the timing belt on this car basically right after I got it. Guess what I didn't do?

I'm not sure why I didn't. It's not like I haven't told people countless times in the past to always do everything all together. A slip in judgment, I guess. Oh well.

So here's how it went down; In the last chapter, I mentioned that I'd be driving the car from LA(ish) to SF(ish). And that happened, no issues there, I made it safe and sound (though perhaps a bit less sane from making the trip with no stereo. Apparently, unplugging the rear speakers shuts the whole thing down. Who knew?) It was the next day, while driving from Redwood City(ish) to San Jose(ish) that the pump's gasket kicked the proverbial bucket.

See, I was headed to a friend's house for the next round of interior strippage, and to remove the dash in preparation for the roll cage. I even made it there OK and without noticing anything wrong. It was about an hour later that I got a whiff of eau de bmw and saw the puddle growing under the engine. I'm getting a little ahead of myself, so let me back up and cover what I did prior to settling in for a crappy night of wrenching.

Basically the plan was, remove the dash, remove that large piece of foamy rubber behind the dash, figure out what to do with the large bits of wiring harness by the kick panels (right where the legs of the cage will go), and remove the tar mats from the floorboards with the assistance of dry ice.



The dash is a pretty simple affair in this car. There aren't a whole lot of bolts, and it's pretty easy to find the ones that do exist. The stereo/HVAC combo is pretty damn heavy, too. I'll be keeping HVAC, at least for the time being, but the stereo will be replaced with some sort of switch panel methinks.



Obviously the air bag has got to go.



How nice of Toyota to make the cover clip right back in.



Then the dash basically just pops right out.



There's no way I was getting that foam rubber stuff out in one piece, so it came out in many.



It basically filled up a plastic trash bag on its own, and it's surprisingly heavy. I'm happy to get as much front weight out as possible, since there's a 6 cylinder boat anchor between the front tires.



Next up was supposed to be the tar mat, but this is when I noticed the pump problem, and the tune of the night changed. Now we had to swap a pump without the proper tools and have it working for my appointment at the fab shop the next day, two hours farther north. It was also 5pm on a Sunday, and everything was either closed or soon to be closed. I left immediately to pick up the only water pump available in town, while McG started pulling everything apart.

There are not enough middle fingers in the world.



Bonus content: The 90% badass track IS seen here was getting some hood vents installed. We're more or less doing a bunch of testing on that car, then applying the results to mine.



Being that my car is still an automatic, we had to get clever with removing the crank bolt. I've made fun of the ridiculous lengths and sketchy methods people go to to get that thing off, but with no options I had to try something dumb. We went for the "breaker bar butted up against the frame rail and bump the starter motor" trick, and wouldn't cha know, it actually worked! And nothing broke!

At that point I stopped taking pictures, because it was getting dark and I didn't want to waste time. Also, it's just a water pump, y'all have seen it before. I think I got home around 2am after decompressing over a Denny's dinner. Didn't get to the tar mats, so I'd have to deal with it at the fab shop the next day.

Blah blah sleep blah blah driving blah HEYYYYY Sacramento. Made it with no issues to Total Kontrolle Engineering, where I'd be leaving the car in the capable hands of one Mr. Trux and his crack team of engineers and fab dudes, including many time NASA champ Justin Ross. Justin and I have known each other for a long time from tracking/racing Miatas, and it was a no-brainer to bring the IS to them. They put together some seriously nice cars, and I'm more than a little excited to see how she turns out.



Since there was still that pesky tar mat in the way, I had to deal with it at their shop. Nothing a chisel and a torch can't handle. Dry ice is for wussies.





I had them mark where they needed to weld, so I could just remove those spots for now. I'm glad that's how it shook out though. Once I get the car back on the scales, I may end up leaving some of it in there. It's as low as the weight can get, and I can be strategic in what I remove and what I leave.
 
#22 · (Edited)
Chapter 6
Welcome to the New Cage, to the New Cage

I'm a little behind on posting updates. It's been hectic trying to go to work, thrash on the IS, go to my weekend job, and take on contract work all while fitting in sleep and a few meals. I'll do my best to keep everything in order :smile2:

When we left off, I had dropped the car off at Kontrolle Engineering in Sacramento to get the cage designed and built. They are well known in the BMW race community, especially for Spec E30, Spec E46, and many classic race cars as well. This car is sort of like a Japanese 330i, so I put a roundel on the car and hoped nobody would notice. Sure enough, after complimenting me on my rare dual A-arm trim level and strangely non-broken Vanos, they got to work.

That was dumb, I apologize. Kontrolle will cage anything. Moving on.

Here are some photos Justin sent me of the progress:

















And then, I drove it home to SoCal.



The cage came out better than I had hoped. It's well thought out, the welds are fantastic, and I can't think of a car I'd rather have a horrifying crash in. Or something like that.

Next up: finishing up the insides.
 
#25 · (Edited)
Chapter 7
Indotech Yo Self Before You Wreck Yo Self

Now that I was back in SoCal, it was time to bring the car over to Indotech Motorsports to do the next round of work. Up to this point, I had done work in my driveway, in my friend's driveway, and in an Extra Space Storage unit. Obviously, none of that is exactly ideal...Also, I have no idea what I'm doing, so some guidance and extra hands were in order.

That's where this dude comes in.



This is Alex. Alex owns Indotech, and he's been a big part of all the racing I did last year. I competed in a time attack series called Vtec Club in his car, a Mazda Miata.



A Miata, equipped with some sauce of the Extra Special variety.



We've also worked together with Gears Racing to develop a pretty serious off-the-shelf Miata coilover, which is what we used in that car. Together we've done lots of stuff at the shop and at the track in many different cars. Now, he's helping out with the IS.

Alright...keep in mind here, I'm pretty behind on these posts, so I can't really remember the exact time line...but I do have a photo from this HOD track day I coached at. For varios (dumb) reasons, I couldn't bring the Miata with me, so I just commuted there in the caged Lexus. It's by no means fit to track yet, but that didn't stop me from just doing a few lead/follow parade laps.



And also at some point I put on this Longacre mirror.



Anyway, at IMS I got to work on the first steps of the manual swap.

Two bad.



Three good.







Yes, that hole is massive. Blunder on my part, I don't think it will cause me any issues though.

Now I started to get into a few issues with compatibility. My car is an 01. Apparently, the pedals I got came from something newer. The upper bolt doesn't line up on the clutch pedal bracket. That's a simple fix, we cut off the upper part of the bracket and will just weld on our own. Easy.

The brake pedal is a bit of a faff though. Apparently, the ABS system changed around on the 02+ cars. Mine has no electronics on the pedal itself, where the others do. For whatever brilliant reason, they decided that warrants a change in the pushrod mount. (WHY, TOYOTA......WHY....) I saw earlier that abj ran into this same issue. He bought a new pedal for an 01, which I very well may end up doing. Until then, I did two things:

I ordered a new one of these doohikies for the 02+. It might work, it might not, but at $7 I'm willing to find out.



Aaaaand, well...a brake pedal in a vise with a line drawn on it explains itself.



Temporary solution only. The pedal spacing isn't ideal for heel/toe shifting, and it would just feel unfinished to leave it like this.

Rather than deal with the factory hard line for the clutch, I instead had a braided line made to ease installation. It wasn't ready at the time, so I moved on to stripping more interior junk. Since then it has indeed been made though, and here it is:



I can't help but think it looks way too short...I did measure though, so...hopefully? We'll see once I get to that step.

We finished off by draining the AC, looping off the heater core lines, and taking everything out from under the dash. Starting to look a bit more proper now.



Up next: Everyone's favorite thing to do ever, removing sound deadening!!!!1!2!!!!
 
#30 · (Edited)
Chapter 8
I See A Bare Cage and I Want It Painted Silver

I'm back my.is! It's been a month since the last update. There's been a trip to NY, a work trip to Vegas, and many many hours of 9ish to 5ish preventing me from posting. There has indeed been work done to the car, however. Tonight's composition will cover the completion of the coating of the cage, with the contents of compressed canned chemicals.

Good ol' spray paint.

But first, I got myself some frozen carbon dioxide and got to work removing the remainder of the tar mat.



I wasn't really sure exactly how you're supposed to do this, so I tried breaking it up as well as just setting a chunk down on the trans tunnel. ¯\_(ツ)_/¯



After taking hammer and prybar to the situation for a few hours, it was time to prep for paint. As if that last step wasn't miserable enough, here's a project that takes hours and hours and you literally rip it off as soon as you're done painting.



Luckily, I had help.



Alex's kids have taken a liking to the project (and to sticking blue tape to me while I'm working), and helped get the thing all masked up.



I did the painting myself though. I'll let them decide what exciting variety of chemicals they'd like to inhale once they turn 18. Until then, Uncle Nik will take that bullet.

The weapon of choice was this particular Rustoleum, since it looked potentially the closest to the body color while not actually bringing a sample into The Home Depot. Which, admittedly, is a bit silly since I'm changing the color of the car anyway. Buuut, I figure it will at least sort of match the interior until such a day comes that I see fit to have the interior professionally painted.





Several cans of clearcoat later, and it's looking rather nice.



You will ride eternal, shiny and chrome.



WITNESS ME, MY.IS!!!
 
#32 · (Edited)
Chapter 9
I've Been DriveLine'n All Night, My Hands Wet On The Tools

It was time.

The automatic had to go, the manual had to go in. I've done two manual swaps in my day, one on an AW11 and one on an NA Miata. I understand the concept well, and I understand that I hate doing it. With the amount of work piling up, I decided to take the easy road and fork over some cash to have Alex and co. do it while I was away. Here are the photos they sent me during the process.

The first spot they hit was t̶h̶e̶ ̶l̶i̶q̶u̶o̶r̶ ̶s̶t̶o̶r̶e̶ the AC pump. We already drained the system when we removed the bits under the dash, so this was just a few bolts and a shorter belt.





This is JR. His role in the project is to make this face.



All of the exhaust, including the stock manifold came out.



Out with the old.



*Deep inhale*

Mmmm...Type T-IV.



We don't need no stinkin' flex plates.



Funky phresh rear main seal.



I was originally just going to use a stock clutch and flywheel to save some $$$. On further inspection, the ones I got in my full swap purchase were pretty well worn out. So, I got this instead. I can't remember the exact weight, but compared to stock it's basically nothing. It's aluminum, with a steel friction surface that can be unbolted and replaced. The replacements are roughly $60. They also made me a race clutch to match.



The new hotness.



All bolted up.



The differential got some love too. The stock open diff came out, and this FRS Torsen went in, with a set of new FIGS Engineering poly mounts. This takes the final drive up to 4.1:1.







Alex used to be into IS300s back around 2006, and he still had some parts left over, including this header that was apparently built for a factory race car. Pretty beefy, pretty long tubes.



As well as this midpipe and muffler.



A little dusty, but substantial nonetheless.



Aaaaand, a nice pile of unnecessary parts.



We're getting close to caught up now! Up next, in a much shorter entry, the process of putting the wiring back together in a way that jives with the cage.
 
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