Roadracer's #997 build

[RoadRacer]

Installed brake pressure gauges in the dash so I can log data as I change f/r bias. My version of datalogging ��
The pressures I measured at the calipers in January (see here) were 750psi/1500psi - these still show the same.

https://youtube.com/shorts/dunQsxBcS...NUXiA3e9UeQ0Qx

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[RoadRacer]

Did another autocross yesterday, I missed one while on vacation so it's been a while.

It rained heavily in first session, dried in second and I was luckily running in third session. So it's hard to judge improvements against others who may have been running in worse sessions. But I did get 24th fastest (and the R class was running third session too). Car felt good!

[RoadRacer]

Following on from this post about 3-link panhard bar mounts, I braced mine - for no other reason than it's a quick fix

panhard-fix.png

[RoadRacer]

Following on from my thread "Has anyone built headers for side pipes on hot rod?" - the headers are an easy fit (with one caveat)!

They bolted up just fine to my SBC, with loads of space around the chassis. This opens up space for potential easier steering routes too.

And remember, these headers (Schoenfeld part #1346) are just $469.95

Take a look:

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Now here's the caveat.. it touches the 'glass body here. Tight.

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So I'll talk to them about attaching the collector at a slightly different angle - they may want to send me another set to test. We'll see. Otherwise I'll modify these myself. Now onto the side pipe/muffler investigation.

BTW, I did measure dB at 50ft to the side just to compare. The current FFR w/borla muffler was at ~89db at ~6000.

The new open headers were ~108db. They sound great! But would get me kicked out of any autocross I tried to go to.

[progmgr1]

Considering that 6 dB is a doubling of loudness, I can see the issue. However, this will look wicked cool when its done.

I always appreciate builders who "color outside the lines" to make their cars unique.

Keith HR #894

[RoadRacer]

Considering that 6 dB is a doubling of loudness, I can see the issue. However, this will look wicked cool when its done.

I always appreciate builders who "color outside the lines" to make their cars unique.

Keith HR #894

Yeah it’s fun. This was driven by two things.. 1. The gen1 floor touches the exhaust throughout so is a rattly mess. 2. I wanted bigger primaries for my motor. Now 1.75 up from 1.5.

[GoDadGo]

Great News!

[RoadRacer]

I never mentioned it here, but I went to a hub dyno at the weekend. They only gave me wheel speed, not rpm, but luckily you can calculate it given 4th gear (1:1) and rear ratio (3.73). From there I could calculate torque using t = hp / (rpm/5252)

So here's the result, I've adjusted this by 115% to account (somewhat) for wheel hp vs motor hp, but of course that's a complete guess.

peak hp 5500-6000, peak torque 4200-4800 - both pretty flat at their peak.

Dyno (motor) _100524_-_Google_Sheets.png 2024-10-05 11.16.40.jpg

[RoadRacer]

Having discussed with Schoenfeld, we decided to send mine back, and they'll send a new set out (I did move to 3" from 3.5" though, after noticing 3.5" is far less supported for mufflers).

This new set will be sent fully welded up, except for the collector which will be loose in the box. That will allow me to adjust the angle and space from the bodywork.

[Just 1 More]

Having discussed with Schoenfeld, we decided to send mine back, and they'll send a new set out (I did move to 3" from 3.5" though, after noticing 3.5" is far less supported for mufflers).

This new set will be sent fully welded up, except for the collector which will be loose in the box. That will allow me to adjust the angle and space from the bodywork.

https://youtu.be/Z0YIJQ1jgEI

[RoadRacer]

Haha well the exhaust is on. It’s been a journey and I’m not quite there yet. A friend and I spent all day yesterday getting it on and it’s not bolt on.. but it could/will be. Schoenfeld need to make a little tweak to give more body clearance and I’ll talk to them about that.

We spent most of the time heating and bending the headers with oxy-acetylene torch - had to put a lot of heat into them to bend them out. Heated along the top curve of the header. The angled bend I bought from collector to muffler was wrong angle too - hard to estimate off the car. So more heat and bending. But that’s going to be replaced with a proper and removable piece soon.

Ultimately we had to get it all on, hung and tacked together so I could drive home. Our first step in morning was to cut the old stuff off

Most parts leak (not fully welded), the old header gaskets got damaged (will put my new set on, but I saved them until final fit) and currently it’s rigidly welded to the car. No rubber mounts. So this is very much in proof-of-concept mode.

Worse, for most people anyway, is that the body curve is pretty significant. I decided to lose the bottom of the door completely, and cut the corner. Better to have close to body (much less chance of burns). I have so far found that the way I get in and out does still work.


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[Just 1 More]

Looking good James

[RoadRacer]

My latest autocross.. pretty tricky and car felt loose even though I was trying to tune it between runs. So I was too timid this time.



Everyone loved how the car sounded though, I had all the seams welded during the week. It was right at the sound limit though.. the sound check guys were alternating between "just under" and "just over" the limit. I still got all 6 runs, but I'm going to rotate the end pipe to point down rather than sideways which usually helps.

The 200 mile drive though.. this is the first time in thousands of miles that I felt beaten by the sound. It's too loud honestly. But sounds amazing LOL. This morning I drove to home depot and got some 26db corded ear plugs and it makes a huge difference. At least for longer drives.

[GoDadGo]

Thanks For Taking Us For A Ride!
.....Also, I Love The Headers!

[RoadRacer]

Exciting! Since I want to do a lot more circuit running in 2025 I just ordered some big brakes from Gordon Levy

Basically this setup: https://a.co/d/3uSAT1t

Aero6 14” and superlite 4 13”

IMG_2646.jpeg

[Just 1 More]

Exciting! Since I want to do a lot more circuit running in 2025 I just ordered some big brakes from Gordon Levy

Basically this setup: https://a.co/d/3uSAT1t

Aero6 14” and superlite 4 13”

IMG_2646.jpeg

We talked about brakes a while back and you seemed pretty happy with the factory brakes with the upgraded pads...... I'm Looking forward to hearing the amount of improvement.

[RoadRacer]

We talked about brakes a while back and you seemed pretty happy with the factory brakes with the upgraded pads...... I'm Looking forward to hearing the amount of improvement.

Yeah I am happy with stock for road and autocross.. but will run out of brakes at the track. A lot more sustained heat.

[RoadRacer]

Just realized that I hadnt posted my latest video from our club's "track sprint" - basically a 2/3 lap of a lap private track called Harris Hill.

I hadn't done any laps here since this event a year ago, so I really need to get more practice and get quicker at this track. Unlike autocross, this track doesn't change!

In 2025, this is one of my focuses: knocking 6-7s a lap off this (quite timid) lap. Part of that is the reason to upgrade the brakes above. 6-7s sounds like a LOT (and it is) but others in corvettes are hitting 8-9s quicker than me, and that must be stopped

[RoadRacer]

My last official autocross of the year, although I hope to get some more track time to get a base time for my push at much-improved track time in 2025.

I was very happy with this run. I had 5 clean runs, and each one improved on the last by at least 1s.

[RoadRacer]

These were some basic runs to give me a baseline time around Harris Hill Raceway in Austin to use as I aim to improve my time throughout 2025. I didn't even change gear out of third in any of these runs. These were with the OG Mustang brakes, which will be replaced in Q1.

My best lap was 1.32.888

[GoDadGo]

James,

How has your new header and exhaust system worked out for you.
I know it looks totally Bad A--, but what is your takeaway on this recent change.

Steve

[RoadRacer]

James,

How has your new header and exhaust system worked out for you.
I know it looks totally Bad A--, but what is your takeaway on this recent change.

Steve

Oh it was definitely the way to go for me and my car. I can’t imagine anyone would do it.. the body shape means that you have to cut the bottom of the doors off.. and live with the hole. In reality there was no filling the hole left because you need the straight line for the pipes.

I love it, but it requires a no paint, GSD car. The engine is much happier and I have more flexibility for tuning. Plus.. it removes a lot of interior heat from an old Gen1 hot rod. I don’t think I’d need to do it with a gen2.. very different floor that I could have run an exhaust through and no heat problems.

[RoadRacer]

My upgraded Wilwood brakes arrived from Gordon Levy, so I wanted to make a quick update on progress so far. I use my car a lot and I have a autox on 3/1, so minimizing downtime is important. I've taken a staged approach so I can complete parts of the upgrade while I wait for parts or helpers to be available.

1. install front brakes
2. install rear brakes
3. install new MCs, flush fluid, and bleed
4. install parking brake

Why? I can do the front brakes on my own, no helpers, and I have all the parts. And fitting bigger front brakes doesn't affect balance for a few days. (Putting wilwoods on the back first would have). The rears need helpers, as does the brake flush/bleed.

I did step 1 last night, so I now have the aero6 14" setup at the front and the 10.5 stock setup on the back On Saturday I'm visiting friends to help with the rear.

Firstly, the Wilwood instructions are great. Very easy to understand and covered everything. Gordon told me I'd have to grind some of the upright to fit the front brakes, but you'll see it was easy.

Here's a before picture!

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The day before I'd spent an evening safety wiring the rotors and hats. Considerably easier on the front rotors! The rears put the bolts in a narrow valley so I compromised the safety wire a little by choosing a more direct line since you couldn't do the s-shape that you really need and can see below on the fronts.

rotor-safety-wire.jpg

On the car I removed the wheel, caliper and rotor, and left the caliper hanging from an S hook on the sway bar.

Then I modified the upright to allow the caliper bracket to fit. I used a dremel disc of the same curve as I needed to cut into the upright (see pic 1 below). It's tricky to get a nice clean cut without touching other parts around it, but now the bracket fits. I also took some off the bracket.

front-upright-mod1.jpg front-upright-mod.jpg front-caliper-bracket.jpg

The shims they get you to start with didn't need changing - the caliper lined up with the rotor centered and the pads flush without any other shims.

I had to drill out the rotors to fit over the shoulder on the wheels studs, and that required a 5/8" drill bit - way larger than you probably have in your toolbox.

drill-rotors.jpg

I did have to buy a bigger INCH/lbs torque wrench, my small one didn't go up to the 155 In/lbs you'll need. But this did the trick for $33

The last step was to fit the included hose - no banjo fitting this time - I found the best direction was to aim the fitting at the center line of the suspension.

brake-fitting.jpg

As always, the second one took a fraction of the time because no thought required. And this is where I ended up that evening.. and drove it the next day!

new-front-brakes.jpg

[RoadRacer]

I fitted the rear brakes on Saturday, but it was a bit more involved. It shouldn't have been, but I made a few mistakes early on. First, make sure your vendor (Gordon Levy in my case) knows exactly which rear end you have and, more importantly, which axle shafts. I had replaced mine with some from Summit when I found my junkyard axles were bent.

It's a bit of a story, but posted to save someone else the pain. I had bought SUM-700128 which are 30.63" long. They are theoretically the correct ones for my 2002 GT, but you can buy shorter ones (since Wilwood removes the backing plate). If you're using Wilwood (and only then), then you can buy SUMN-700126 which are 29.94" long. 0.69" shorter.

Wilwood's kit relies on a 2.5" offset, but I had a ~3.2". But here we are on Saturday morning at my friend's machine shop, so we push on. I always think we can find/build a solution.. and we did - but it took a 10-hour day without breaks.

Picture so you can follow along.

wilwood-instr.jpg

The first step is to remove all the old stuff, easy.

Then, measure the slop in your axles using a dial indicator. We had 0.020 on one side and 0.013" on the other. We want to make this zero or close to it. Otherwise any axle sideways movement in corners can push the pad away from the rotor. And you'll have extra pedal travel to take that up before you get braking.

Then drain the rear, pull the c-clips, and slide out the axles (don't rest on, or damage the seals).

To take up the slop, use shims behind the c-clips. Sounds easy, but.. I'd forgotten to look for shims in the box and there weren't any. Check for this stuff! Ask your vendor if anything is missing! Anyway, it's the day of installation, and no local shops have any. Luckily my friend has shim stock. a box of thin metal sheets that you can cut any shim from!

We used the C-clip as a template, cut them slightly larger, sandwiched the shims between the C-clips, and made the perfect size on the belt sander. It worked great! We made two 0.013" shims, installed them, and measured again.

This time, we measured 0.006 and 0.004 slop (yeah, the math doesn't add up, I know), and we left it there. This is barely detectable movement.

DO NOT FORGET to put the drum brakes (the parking brake) on before the axle goes in. We installed the axles, glued the cover back on and everything before realizing this, so it all came off again.

Installed the drum brakes, and mocked everything up. This is where we found that the rotor was 0.69" away from centered in the caliper.

So we removed the spacer (#12 in picture) which is 0.48" so that got us closer. But we were still 0.21" off, so we got on the lathe and made 8 x 0.21" spacers from stainless steel stock and placed them behind the drum assembly. That got us to a perfect spot again. (The original bolts still worked, I have 0.25" longer bolts coming today to give us some extra thread)

brake-spacer.jpg

The rest of the installation went great - super easy to bolt bits on, and if I had the correct axles in there (and checked for shims beforehand) none of this would have been necessary. But hey, it was kinda fun.

I may still buy the shorter axles; it's the "right thing to do," and then I can use the kit as-is. But that will pull the wheels in 0.69", and it'll be close to the bodywork and narrow my track. So I'm still deciding.

finishedrearbrakes.jpg finishedrearbrakes2.jpg

One last comment about Gordon Levy—he's been very responsive and took calls on Saturday when I had questions. Although he couldn't help directly, I'm still very glad that I got the brakes from him and had direct-line support. He knows what he's doing!

[RoadRacer]

One last thing for now.. the master cylinders. I bought new ones, but they are slightly different design nowadays. The supplied ones are 0.75" for front and rear, but I still have the 0.62" rear installed today.

I flushed the old fluid on Sunday and installed a much better fluid (Castrol SRF) which has a much higher boiling point. Also installed 6 speed bleeders to help with bleeding.

Once I had a hard pedal I went and bedded in using the Wilwood process - basically stop, cool, stop, cool at higher and higher speeds to get a good temp in the brakes.

Then did the 40mph balance test.. this is where I was concerned I'd need to 0.75" rear MC. But the balance bar adjusted the bias perfectly, so at least in my case I dont need the 0.75 MC. The rears locked up first initially, but I quickly adjusted to fronts locking first.

First impressions are great btw, so I'm looking forward to putting some miles (and especially track miles) on them to get a feel for them.

[RoadRacer]

Here's my first autox run since the new Wilwood brakes were installed. I had a ~2.5% increase against the rest of the pack - probably due to the increased confidence than the brakes themselves - but whatever works!

My fastest run (49.352s) didn't record, so here's my second fastest 49.707s.

[RoadRacer]

Got some track time yesterday in Track Night in America event at Harris Hill Raceway.

[RoadRacer]

Not been posting much here for a while, but I'm always tweaking and improving the car.

The most recent thing was to stiffen my front sway bar. As you know, driving a car faster is a journey. You start off (hopefully) with an understeering car, because it's safer and easier to drive. But it's slow, so over time as you get to know your car you want to remove the understeer (the 'push') and have an oversteering car ('loose'). So over the last year, I've made my front sway bar stiffer, and eventually had to disconnect my rear sway bar entirely in the search for a faster car.

But the front bar was full stiff, and the rear bar disconnected... so what next? A stiffer front bar. Then I can add the rear sway bar back, and start tuning over again.

FYI I run 3.5º camber and 10º caster (so there's a fair bit of dynamic camber too), and the tires (currently vitour P1, 315/345) show perfect wear patterns, so no real gains to be made there.

My front sway bar was from VPM, documented earlier in my build thread, but it was pretty soft - we measured it as 137lb/in, even though the calculators show ~230lb/in. As we measure sway bars on the bench we notice roughly a 1.5x discrepancy - no idea why. But it doesn't matter relatively, you can still compare in the calculators to get a 2x or 3x stiffer setup, and it will be in real life.

ASIDE: Here are the measured and calulated numbers for old and new setup:

Calculator says: old one 230lbs/in, new one 584lbs/in (2.5x stiffer)
Measurement says: old one 137lbs/in, new one 392lbs/in (2.9x stiffer)
measured with a dial indicator to measure deflection and 65.5lbs weight.

I bought a Rhodes Race Cars Sportsman Series Anti-Roll Bar. Stiffer because of the bigger bar, but also because of the shorter arm. More importantly for the 33, I needed to support it much further outboard from the chassis. The VPM setup suffered because the 33 chassis is so narrow.

So we built a support bar out of angle and bolted the sway bar to it, then welded it all up. Here are some final pics:

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The funny part - I decided to test it without the rear bar attached at today's autocross. It's always better to test one thing at a time, and I wanted to know if I'd even feel the difference of the stiffer bar. In theory it should push, but I have NEVER understeered with this car, it's been loose since Day 1.

Well, today was the day!

In the first run, it was astonishingly bad - the car felt like it wouldn't steer at all. Just went straight on! I had to unwind so much lock just to get around. On subsequent runs, I softened the front shocks and lowered rear tire pressures to try and counter this as much as possible, but it was just too far out of balance. I even left before the last two runs!

Next event is a track sprint at Harris Hill Raceway, so I'll take at least one day at the track ahead of that to tune in the rear sway bar which has a lot of adjustment.

[RoadRacer]

Today's lesson kids: Problems are always related. Remember that. If you do X, and then a week or do later Y happens.. look again at X.

As I write this out, it'll be obvious to everyone where I went wrong, but hindsight is 50:50 Come along for the ride!

The last time I removed my radiator (when I fitted my new front sway bar) my thermostat switch in the bottom of the radiator broke. It's about the 4th time one has, so I got fed up and fitted a bung, and moved my thermostat switch to the intake manifold, where it's less exposed to road debris. Great! While I was there, I fitted a fan override switch, so I never have to worry about broken thermostat switches again.. if the engine gets too hot, knock on the switch.

[one week later]

I go out and park up at the track. My car starts, but the starter is slow.. uh-oh. My battery is failing. In Texas heat, this happens, and batteries don't last long. In fact, I've had warranty replacements when mine has failed "early". So I test it - I have a massive truck battery in the trunk - and it's perfect. Passes the load test. Hmm.

I check the alternator cable, seems ok. Voltmeter shows 14v running.

A few days later I go out again, and this time it really doesn't start. I bump start it down a slight gradient in the parking lot. Then later, I get some kind guys to push me.

The battery health is still perfect (literally, 90-100% by the tester). So I get onto chatgpt (much better since 5.1 if you gave up on 4.0 like I did). Had a long conversation about possibilities and it came to battery cable.. I said that 4 years ago I used 4AWG and a cheap kill switch and hammer-on crimps and no dielectric grease. All of which SUCK in hindsight, but it was a long time ago.

Apparently all of that is sub-par, at best. And over 4 years, every connection gets worse, and the voltage drop gets larger, until.. it's just not up to it.

I tested the voltage drop a few different ways.

First, I measured the voltage (all while cranking) at the battery, and at the starter. The difference should be 0.5-0.8v.
I saw 12.5 not cranking, 11.8 cranking (so a good strong battery), and ~10.4v at starter (bad)

To diagnose further, you measure the voltage drop on positive, and ground.

To measure ground, voltage meter red on starter housing, black on battery ground. Crank. Reading should be 0.2-0.4v. Mine was 0.3v
To measure positive, voltage meter red on battery positive, black on starter positive terminal. Reading should be 0.4-0.6v. Mine was ~1.7v

So all/most of my error was on the positive cable, and the ground side is good. Could still be the cheap kill switch, but I decided to change it all.

[NOW, before too many people jump in here and tell me all sorts of ways that I'm wrong, that's ok. I've been through the wringer on FB, and I've heard it all. But just keep reading for a second on where I end up]


I ask for recommendations, and go through a few product options, and ended up (with a trunk mounted battery, 10:1 SBC) that I should be using:

- 1/0 OFC (oxygen free copper) welding cable - specifically not CCA (copper clad aluminum)
- 10 ton hydraulic pressed crimper
- tinned, closed, copper crimps
- a good quality kill switch (ie not $20)
- dielectric grease on everything

For quick fix, I did use some 1/0 CCA that my son had laying around, removed my cheap kill switch, and hammer crimped it together, and it did help. Then ordered all these parts ^

I included the links above on the parts I ordered.

I've yet to final fit the new stuff, but I expect it will stop any problems that I have with low quality parts.

===

Now to loop back to the beginning. I did need to do all this stuff, but why, after 4 years did it suddenly start failing? The thermostat fan switch!

I used to run a switch in the radiator, and after turning off the car, the fan would run on until the radiator cooled - pretty quickly actually. I never gave this any thought at all.

When I moved it to the motor, the fan ran until the motor got cool enough, which the fan wasnt even helping. The fan ran for many minutes, and drained the battery. All this happened because when building the car I wasnt paying attention and did not snip/replace the red loop wire on the fan relay that you are clearly told to do "if you have a computer". I don't have a computer, but I should have paid attention! Because the fan did not have switched power, it had always-on power.

Snip the red loop and connect switched power to 86, and the problem goes away. The fan stops when ignition is off. No more running the battery down. Here are some diagrams that will help (found one on another thread here)

IMG_20241122_180020209~2.jpg fan relay.jpg