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.

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[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”

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[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.

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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.

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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)

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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.

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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.