[jharris48]

Reserved

 

[jharris48]

I’m starting this thread by moving my journal over from another site that wasn’t as suited for the STi. So all the post up to the engine build occurred over the course of 2020. I’ll get this up to date quickly and then the timeline will make more sense, post the engine tune

I've been auto Xing my 2011 STi since I got it in 2014. Until now I've stayed in Street class, largely to work on driver skill. I've worked in some track days the last few years to include Button Willow, Willow Springs, and Laguna Seca. I finally hit the point that things were getting old and needing to be replaced. My plan is, once it needs to be replaced, replace it with something better. I dove in and started throwing parts at the car to compete in STU.

So here is where I'm at so far:
Whiteline Offset Top Hats
Braille 15lbs batter
Super Pro Front A-Arm Rear offset Bushings
Group N motor mounts, transmission mounts, pitch stop, differential mounts, front a arm forward pivot bushing, rear subframe bushings, and all rear end bushings that STi offers for group n replacements.
GTWORX Bilstein Trophy Cut Coilovers (Big thanks to Myles at Racecomp Engineering for answering the million questions I bugged him with. I can't overstate how happy I am with his customer service and the product I received.)
Proform Wireless scales are on their way and I will be corner weighting the car soon. After I got a quote from the only reasonably close shop, it seemed like a much better decision to buy the scales and learn how to do it myself. I'll be continuing to modify the car through the year and the scales will pay for themselves the second time I corner weight the car.
I run on Bridgestone RE-71s (well did until they have now discontinued them) for auto x
Anyway, here are some pics from some of the work.

 

[jharris48]

Proform scales showed up and I took them for a test run. Not that I have any experience with scales, but these seem like a really quality product. If there is anyone out there that is experienced doing corner weighting and see anything wrong with my home rigged set up let me know. I didn't bother adjusting anything yet, as I need to figure out a better slip plate plan. My first attempt at slip plates didn't work correctly, so the suspension wasn't settling. I could also drive the car on with some kind of ramp, but if I get slip plates working I figure it will be much easier to just lift the car and make adjustments and then lower it down again. Plus, as you can see there is a significant slant on the back half of the floor that requires a fairly tall stand for the scale, which could be problematic for the roll on and off technique even with ramps. I also need to get a better straight edge to triple check all the scales are as close to level as possible. I'd rather take my time and get this right the first time than have to do this several times trying to get it right.
I haven't done this before, so I'm not sure how bad 2.6% off of 50% cross weight is, but I certainly have some adjustments to make.

 

[Pault1]

I'm in SCCA STU in a 2006. While the bushings are all nice as is corner weighting, the big gains come from struts and alignment. And seat time, get as many runs as you can! And get faster people to show you what the car can really do and to give you advice.

The Bridgestones are still very competitive especially after having a few heat cycles. With your later chassis you might not need as much negative as I do, but if you're going for max handling you will get best handling from a setup that will give you more than -3 camber. Depends on your spring rates, bar sizes, etc. and how grippy a surface is at your racing site.

Get a cheap infrared temp reader (~$30 at HF, a little more elsewhere) and check your tire temps after you come in from your second run. Check outside, middle, inside, immediately on getting stopped, particularly on the front. If the outside edges remain consistently hotter, then you probably need more negative camber. Run zero toe front and rear if it's your daily so that you don't chew up the tires with the big camber.
I have heard positives about Racecomp. I am trying out another brand & builder to replace my less reliable than I'd like KW v3's, but they won't be in for a couple of weeks so I can't comment yet.

 

[jharris48]

After installing the coil overs, corner balancing and aligning, my rear tires have -2.0 degrees of camber. I only lowered the car 1/2" so I didn't think the rear camber would change too much, but it did. So I got the Super Pro rear camber kit. I looked at some other control arms that seemed easier to adjust, but they all replaced the inner control arm bushing with an all metal spherical bushing, which is not permitted in STU. I've had good experience with Super Pro in the past, so I look forward to getting these installed.
It seems unclear in the SCCA STU rules if I can use the tow links in this kit. I believe I can get the alignment I want with the OEM tow links, but I like having the super pro ones just in case. And if they are permitted then it wouldn't hurt to get a new ball joint to replace my 70k miles one.
After having done so much work already, I figure I might as well replace the last few things that aren't now new in the suspension such as the front ball joints and rear OEM top hats. While I'm at it I'm going to go back to OEM top hats on the front because it looks like I can get the camber I want up front (~1.8-2.0) with the OEM ones. Don't know that it will really make much of a difference, but I figure if I can maintain the factory strut alignment and get the same camber then that would be better. Once the other parts come in, and I'll do the alignment and corner balance all over again.

 

[jharris48]

I'm in SCCA STU in a 2006. While the bushings are all nice as is corner weighting, the big gains come from struts and alignment. And seat time, get as many runs as you can! And get faster people to show you what the car can really do and to give you advice.

The Bridgestones are still very competitive especially after having a few heat cycles. With your later chassis you might not need as much negative as I do, but if you're going for max handling you will get best handling from a setup that will give you more than -3 camber. Depends on your spring rates, bar sizes, etc. and how grippy a surface is at your racing site.

Get a cheap infrared temp reader (~$30 at HF, a little more elsewhere) and check your tire temps after you come in from your second run. Check outside, middle, inside, immediately on getting stopped, particularly on the front. If the outside edges remain consistently hotter, then you probably need more negative camber. Run zero toe front and rear if it's your daily so that you don't chew up the tires with the big camber.
I have heard positives about Racecomp. I am trying out another brand & builder to replace my less reliable than I'd like KW v3's, but they won't be in for a couple of weeks so I can't comment yet.

I’m transferring over these post from another forum/format and aren’t caught up to current events yet with my STi. I used a pyrometer to measure tire temps once I got the suspension where I wanted it and the temp is pretty even with the insides showing slightly higher with -2 degrees on the front. Which is contrary to what the corprate knowledge seems to be of -3 degrees. Maybe it’s something about my setup or perhaps the local autocross course, but I’ll test it more and make sure my measurements are accurate. I’ll get my post updated and you can tell me what I’m doing wrong haha.

 

[jharris48]

After installing the coil overs, corner balancing and aligning, my rear tires have -2.0 degrees of camber. I only lowered the car 1/2" so I didn't think the rear camber would change too much, but it did. So I got the Super Pro rear camber kit. I looked at some other control arms that seemed easier to adjust, but they all replaced the inner control arm bushing with an all metal spherical bushing, which is not permitted in STU. I've had good experience with Super Pro in the past, so I look forward to getting these installed.
It seems unclear in the SCCA STU rules if I can use the tow links in this kit. I believe I can get the alignment I want with the OEM tow links, but I like having the super pro ones just in case. And if they are permitted then it wouldn't hurt to get a new ball joint to replace my 70k miles one.
After having done so much work already, I figure I might as well replace the last few things that aren't now new in the suspension such as the front ball joints and rear OEM top hats. While I'm at it I'm going to go back to OEM top hats on the front because it looks like I can get the camber I want up front (~1.8-2.0) with the OEM ones. Don't know that it will really make much of a difference, but I figure if I can maintain the factory strut alignment and get the same camber then that would be better. It might be another week are two till the rest of the parts come in, and then I'll do the alignment and corner balance all over again.

 

[jharris48]

The Front/Rear Weight Ratio is 58.7%/41.3%. Based on that weight distribution I calculated the ideal weight at each wheel:

Front Left= ((% on front tires) x (total weight on both left tires))/100 = 1053 lbs
Front Right= ((% on front tires) x (total weight on both right tires))/100 = 983 lbs
Rear Left = ((% on rear tires) x (total weight on both left tires))/100 = 741 lbs
Rear Right = ((% on rear tires) x (total weight on both right tires))/100 = 692 lbs

If you compare that to what I was able to adjust too, I'm within 13 lbs of perfect weight on each corner. Considering I'm working from my own home made leveling platforms, I figure that's about as close as I can get. In the future I might look for some static weight I can move around to properly balance the car further.
Ride height at each corner measured from the center of the Hub to the fender post cross weighting:
Front Left: 355mm/14 inches Front Right: 355mm/14 inches Rear Left: 351mm/13 7/8" Rear Right: 352mm/ 13 7/8"
The rear heights were so slightly different I couldn't really differentiate in inches, hence the 1mm difference.

I also replaced all the lock nuts on the suspension, since they are only designed to be used once and I had loosened and tightened them at least three times each at this point. It was almost $70 of nuts from the dealer, but cheap insurance for the track. I also replaced the front lower ball joints since everything else is now new in the suspension. The old ball joints were a huge pain to get out, but I guess that's standard for ball joints.

Seat of the pants judgement is that the STi feels better than ever. Very flat in corners with much better roll resistance. Feels very balanced and controllable in corners. It felt like I got a little power on oversteer at one point, but it may have just happened from the undulations in the road causing the rear end to loose some grip. I guess I'll find out at autocross. I wish I had a place to do some objective testing, but I'll make due for now.
After nearly a month of the car spending most of it's time on the lift, it's great to have it back to drivable and feeling better than ever.

 

[Pault1]

The Front/Rear Weight Ratio is 58.7%/41.3%. Based on that weight distribution I calculated the ideal weight at each wheel:

Front Left= ((% on front tires) x (total weight on both left tires))/100 = 1053 lbs
Front Right= ((% on front tires) x (total weight on both right tires))/100 = 983 lbs
Rear Left = ((% on rear tires) x (total weight on both left tires))/100 = 741 lbs
Rear Right = ((% on rear tires) x (total weight on both right tires))/100 = 692 lbs

If you compare that to what I was able to adjust too, I'm within 13 lbs of perfect weight on each corner. Considering I'm working from my own home made leveling platforms, I figure that's about as close as I can get. In the future I might look for some static weight I can move around to properly balance the car further.
Ride height at each corner measured from the center of the Hub to the fender post cross weighting:
Front Left: 355mm/14 inches Front Right: 355mm/14 inches Rear Left: 351mm/13 7/8" Rear Right: 352mm/ 13 7/8"
The rear heights were so slightly different I couldn't really differentiate in inches, hence the 1mm difference.

I also replaced all the lock nuts on the suspension, since they are only designed to be used once and I had loosened and tightened them at least three times each at this point. It was almost $70 of nuts from the dealer, but cheap insurance for the track. I also replaced the front lower ball joints since everything else is now new in the suspension. The old ball joints were a huge pain to get out, but I guess that's standard for ball joints.
Seat of the pants judgement is that the STi feels better than ever. Very flat in corners with much better roll resistance. Feels very balanced and controllable in corners. It felt like I got a little power on oversteer at one point, but it may have just happened from the undulations in the road causing the rear end to loose some grip. I guess I'll find out at autocross. I wish I had a place to do some objective testing, but I'll make due for now.
After nearly a month of the car spending most of it's time on the lift, it's great to have it back to drivable and feeling better than ever.

It's better to NOT go all out on public roads. That's what race courses are for. And it's tough to tell exactly what happens at the limit unless you're somewhere you can exceed it slightly. Our local chapter sometimes hosts a "Test and Tune" day with a short course with a hard left, a hard right, and some slaloms, and more runs, so you can try things out and adjust better outside of competition. See if you can get people enthusiastic about that idea.

Replacing the locking nuts is a good idea. If I don't have the replacement locking nut I will add thread locker during re-assembly.

I don't have my alignment sheet handy but the rear is IIRC about -2. That is a result of the amount of lowering, plus the KW's have a slot in the top attachment point to the hub that allows some additional camber to be subtracted. The rear does not max out in the normal usage, cornering force wise, the front is still my limiting factor on my GD chassis. The fronts gather a lot more heat and pressure build at events, so they are obviously doing most of the work. With the new coilovers I'm going more radical on the rear spring rates and planning to drop the rear sway bar adjustment back. I get some oscillation in corners on throttle that I suspect is partly because the inside rear is lifting off the ground, spinning up a little, then upsetting the chassis when it comes down as I apply power. The new setup is /supposed/ to use the helper or tender springs to keep the tire on the ground more, and backing off the sway bar should allow the spring to set the tire down better. I'll see.

As I said the balancing is good for final trimming. I'm on the large side so getting the car corner weighted means more adjustment. My rears, sitting on my not really even driveway, are at 13" hub center to fender left and 13.5" right, but because of the pavement I'm not sure if that is really meaningful. It's lower than yours but I'm not sure if the numbers transfer between chassis families. For the new coilovers I'm obviously going to have to align and corner balance again. I may bump the front height up a little to increase clearance to the fenderwell liners because I keep destroying those, even with 255's which are about all that fits into a GD fenderwell. This loses me some negative but as I am also bumping the front bar size up on advice of a local suspension guru. That may limit the travel a little more and allow liners to survive, or even allow me to go to a slightly larger width as the RT-660's are available in 275.

 

[jharris48]

I got out to a few autocross events the last few months and I love the suspension. Overall I don't think it made me much faster, but it did allow me to be incredibly more consistent. Other than my first run, every run was withing .5" of the others. The coilovers have made the car much easier to drive at the limit and the feedback from the car is excellent with all the new Group N bushings. The rear end had previously felt vague and it was a bit of a guess as to what it would do when cornering, but that is no longer a problem.

On the way back from one of the events I popped at P0171 code for Bank 1 running lean. I had replaced my O2 sensors as a preventative measure, but after extensive trouble shooting it appears the problem was the forward O2 sensor being faulty. I swapped the old one in and I haven't had a problem in over 400 miles. I leak tested the intake and exhaust with a smoke machine. There was one small leak in the intake, but fixing that did not prevent the code. The only thing that has gotten the code to go out is putting the old O2 sensor back in, so I will continue to monitor.

 

[jharris48]

I found a leak in a broken weld on my SPT exhaust, so obviously I talked myself into buying a titanium exhaust to replace it with. I'd been looking for an excuse to get the exhaust and save 30 lbs. I went with the Tomei Extreme Ti since it is one of two options for a GR titanium exhaust. The other option is $500 more. It was a straight forward install.

So I think I over did it with this exhaust. It is only 15.2 lbs, but Woof is it loud! The rest of my power train is stock. It does sound good at WOT, but it sounds like I'm raising hell when I'm just putting around town. Personally the giant can exhaust isn't my style and neither is excessively loud exhaust. I like an aggressive sound, but this is a bit much for me. I prefer some subtly. I'll keep it on and see if I grow to like it. I doubt the 30 lbs of weight savings will truly manifest in dropping my run times. Or perhaps I'll swap the exhaust back and forth between periods autocross/track events.
My noise complaints aside, this is a really quality product. I was very impressed with the build quality and easy assembly. Although the joints do leak some air. I smoke checked the exhaust after install and no matter how I adjusted the slide over fittings, springs, and clamps some air leaked out of the two slide on joints.

There is an event coming up and I'll see what I think. Also a STi front upper strut bar is being delivered tomorrow. The front end of the car is a bit soft, so I'm hopping that the strut bar will help get the desired result.

 

[jharris48]

The strut bar showed up a couple days ago and it would not fit because of the COBB AOS. It sadly took me a day to figure come up with the idea, but with driling a couple holes and adding some spacers, I was able to lower the AOS and keep it clear of the brake lines and other hoses/harnesses in the area. Inital impression is that it gave me the increase in front end stiffness I was looking for. Also the benefit of the STi strut bar is that I didn't lose any ride quality.

 

[jharris48]

The STi comes with some stout brakes from the factory. I haven't had any issues of pad fade or brake fade while doing track days at Button Willow or the Streets of Willow tracks. However, at Laguna Seca I have had some brake fade which I believe was mostly the pads being overheated. I always flush my brake fluid with a racing fluid before every track day...and that's it. In stock trim the OEM pads hold up well. I did swap on a set of Hawk street/race 5.0 pads once for Button Willow. The bite was pretty incredible, but they were almost too aggressive for me and squealed real bad during street driving. I know there are trade offs, but the goal is to keep the car tolerable enough to street drive to the track and once or twice a week.
In what is probably the most unnecessary mod I've done so far, I swapped on AP Racing's front brake kit. This should increase thermal capacity a significant degree, but also shed 15 lbs off the front end. They are expensive, and the gain likely doesn't justify the cost for my use, but at the end of the day I just wanted them.
I weighed the pieces separately and all together. Ultimately I found the total savings to be 14 lbs, but given that my oem pads were worn out that likely accounts for the 1 lbs discrepancy of the advertised 15 (the new pads weighed one pound).

DBA 4000 Rotor: 20 lbs
Essex Rotor: 17lbs
AP Caliper: 6lbs (7lbs w/ pads)
STi OEM Caliper: 10lbs (with old worn pads and brake line attached)
AP Racing Kit all components total: 23lbs
OEM Caliper and Rotor: 30lbs

I got the Ferodo DS2500 pads with the kit and opted for the pre-burnised service. I put a set of the DS2500 pads on the rear and bedded them in. I haven't made it to the track yet, but so far the pads seem fairly mild. Slightly more bite than OEM, and mostly quite. They don't squel much on street driving. So far they seem like the right pairing for my goals.

Update: Got a track day at Laguna Seca on these brakes and all I can say is, “what’s brake fade? I wouldn’t know.” Laguna Seca is the only track that I experienced any kind of fade in the past on the OEM gear, and I had zero with this set up. The pads didn’t feel that dissimilar to the OEM in terms of release feel. I might look at going one step more aggressive in the future.

 

[jharris48]

Prior to getting underway with power mods I went down the Antspec in LA (Former LA COBB shop) to get a compression and leakdown test. Compression is good, but cylinder 2 is weak on leak down at 13%.

So, I've decided to bite the bullet and just build a motor with an IAG short block with Antspec doing the assembly and tuning. Seems like I will just grenade my motor doing mods on it now and it will end up being more expensive later. Since I'm going for it, I'm likely going to put a new turbo in and class myself out of STU. Figure I'll build the car I want and firgure out where to class it later.

 

[jharris48]

It's better to NOT go all out on public roads. That's what race courses are for. And it's tough to tell exactly what happens at the limit unless you're somewhere you can exceed it slightly. Our local chapter sometimes hosts a "Test and Tune" day with a short course with a hard left, a hard right, and some slaloms, and more runs, so you can try things out and adjust better outside of competition. See if you can get people enthusiastic about that idea.

Replacing the locking nuts is a good idea. If I don't have the replacement locking nut I will add thread locker during re-assembly.

I don't have my alignment sheet handy but the rear is IIRC about -2. That is a result of the amount of lowering, plus the KW's have a slot in the top attachment point to the hub that allows some additional camber to be subtracted. The rear does not max out in the normal usage, cornering force wise, the front is still my limiting factor on my GD chassis. The fronts gather a lot more heat and pressure build at events, so they are obviously doing most of the work. With the new coilovers I'm going more radical on the rear spring rates and planning to drop the rear sway bar adjustment back. I get some oscillation in corners on throttle that I suspect is partly because the inside rear is lifting off the ground, spinning up a little, then upsetting the chassis when it comes down as I apply power. The new setup is /supposed/ to use the helper or tender springs to keep the tire on the ground more, and backing off the sway bar should allow the spring to set the tire down better. I'll see.

As I said the balancing is good for final trimming. I'm on the large side so getting the car corner weighted means more adjustment. My rears, sitting on my not really even driveway, are at 13" hub center to fender left and 13.5" right, but because of the pavement I'm not sure if that is really meaningful. It's lower than yours but I'm not sure if the numbers transfer between chassis families. For the new coilovers I'm obviously going to have to align and corner balance again. I may bump the front height up a little to increase clearance to the fenderwell liners because I keep destroying those, even with 255's which are about all that fits into a GD fenderwell. This loses me some negative but as I am also bumping the front bar size up on advice of a local suspension guru. That may limit the travel a little more and allow liners to survive, or even allow me to go to a slightly larger width as the RT-660's are available in 275.

Not to fear, I’m a 35 year old man with the means for track days and all the autocross available. At not point do I drive “all out” on public roads. And desptie the interest and attempts, no my local region has not put together a test and tune day due to limited venues and other logistics. There is an ok way to take your car around the block after you install coil overs to check your work and there is a wrong way. I’m mature enough to do it the right way.

 

[jharris48]

It has begun!

 

[Pault1]

It's all good! It's your car and choices.
I've been really focused on staying in STU. I did need a new motor at 110000 mi. I put on Cobb access plus a tune with the CAI, and Perrin's downpipe that I already had, through Borla Touring cat-back. Not quite as annoying as the GReddy can that was on it before. It came out to ~300WHP on California's crummy 91 "premium", so I am happy there.

It's not a track day car, just focused on autocross, so I dialed back the pads to Carbotech 1521's when I had to replace the rotors anyway. Way less dust than the Hawk HP+, no squeaking. Autocross doesn't overheat pads and these give consistent grip without needing to be warmed up, street or track. It's my daily at the moment so that's a plus.

 

[Karlot]

Nice setup. I really dig those brakes. Following

 

[jharris48]

Here are some pictures of the motor assembly from the shop. I would have enjoyed doing some of this myself, but labor is free on all the parts while they are doing the short block rebuild.

 

[Jay11STI]

Nice to see another GR chassis car getting done right! Carry on good sir.