Vorshlag Build Thread - 67 Mustang Pro Touring/Track Car

Discussion in 'Corner Carver Racing Tech Discussion' started by Vorshlag-Fair, Nov 8, 2019 at 11:25 AM.

  1. Vorshlag-Fair

    Vorshlag-Fair Official Site Vendor Official Vendor

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    Project Kickoff - November 3rd, 2019: We get a lot of customers asking us to tackle their "big project" builds, and sadly we don't have the time or room to take all of these on. Prior commitments and a finite amount of manpower limit what we can take on as new builds or significant projects. In the last few years we have been turning down more and more requests, but when this one came across my desk it was a hard one to turn down.

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    Many classic domestic muscle car owners want to do "show car" things, which doesn't really pique my interest. Sure, this car looks good but the owner Adam wanted to take an already track prepped car to the next level. He had followed some of our other Pro Touring builds and wanted to do similar things to this 1967 Mustang Coupe. Some of that Ricky Bobby theory "I wanna go fast!" Also posted on these forums:

    BRING IT BY FOR A LOOK

    We talked a bit about his car in 2018, but we kept telling him we were too backed up and couldn't even look at the car until sometime in 2019. Adam kept checking in - persistence is key here - and we kept nicely pushing back. We can't see it until "sometime in the Fall" I told him early in the year. We needed a day to look at it in person, as there is only so much we can see from photographs and email. Not to sound snobbish, but we have to see a car in person to see if its worth the time, effort, and cost of a build up that we feel is to our standards - and to see if the customer has the budget to do what we feel is necessary for track worthiness.

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    We had some projects wrap up and cars leave so in late October 2019 we had him bring the car by for a quick look. It wasn't running well, and the exhaust and a fender were removed, so I was a little worried at first sight.

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    We could see right away that the car has been tracked (notice the flat spot on the tire above right), but it has real potential. Some Total Control Products front control arms, Bilstein shocks, but still the original front geometry for the most part. Knowing what we do, improvements could be made here.

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    Underhood was a '85-93 era Mustang 5.0L HO engine, with a carb and some mid length headers. A Griffin aluminum radiator, a cowl induction hood and the owner built air box, some other bits. The customer wanted more power, and more importantly, he was willing to listen "to our suggestions" for how to get there the easiest way possible. #TriggerWarning

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    Inside were a pair of Corbeau fixed back seats, a 4-point roll bar, racing style steering wheel, and the remote shifter for a T5 5-speed, which had a hydraulic TOB. Not bad, could always be improved.

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    The gauges were done well, as were some other aspects. The 4-point roll bar could use some work, and Adam really wanted a full roll cage, for added safety.

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  2. Vorshlag-Fair

    Vorshlag-Fair Official Site Vendor Official Vendor

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    continued from above

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    For once, we were pleasantly surprised by the condition of a car that someone dropped off, and unlike other instances, we did NOT ask him to load it up and leave (that happens more than you'd think)

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    After about a 90 minute discussion with Adam in the shop - showing him features from other cars inside we could adapt to his car - he left and we got to work on a more detailed evaluation and some estimates.

    TAKING A CLOSER LOOK & NUMBERS

    At this stage we have not committed to anything other than taking a closer look at the car, then making some upgrade suggestions (powertrain, braking, safety), putting together some price estimates, and then seeing where it goes from here.

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    A number of potential projects stall out here, after we've spent a couple dozen hours taking pictures and measurements, doing research on the parts in place as well as an upgrade path, and putting together estimates.

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    Once we had the car on the lift we could see some things we liked, and some things we didn't. The Wilwood brand of brakes always gives me the shivers, as do the small spindles we noticed on the front. The brakes, front wheel bearings and the front spindle design were going to be questionable if we added a lot more tire width - which we always try to do if lap times are of even the slightest import. This customer had modern Boss302 and GT350 Mustangs in the past, so we had a target we needed to beat.

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    I've owned a couple of 1965-73 "classic" Mustangs but they were way before I started Vorshlag.

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  3. Vorshlag-Fair

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    continued from above

    On my 69 Mustang we changed the entire front suspension, added a modern rack and pinion, so when he said it had a Woodward rack conversion I held some hope... right until I saw the actual installation. The front crossmember was simple gone - it gets removed in this brand's version of a rack conversion. Yikes, yikes, yikes... to be track worthy in my eyes, all of this had to go.

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    Out back I breathed a sigh of relief. The "Street or Track" brand Watts Link + 3-link rear suspension conversion was a big step up from the leaf springs, so I felt we wouldn't need to "burn budget" back here. A modern style 3 link is the best way to manage a solid axle RWD chassis, and the Currie 9" rear looked beefy - it should easily withstand the modern V8 power we want to install.

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    This style of "chaiss mounted Watts" axle clamps can be problematic (we've seen them slip - a lot) but we can mitigate that. The axle side control arm mounts might get some additional welding, but overall it looked like a nice setup with some inverted Bilstein monotubes.

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    The radiator was upgrade but the front grill opening is limited by the radiator support on these cars - which is setup for a narrow radiator and blocks off about 1/2 of the engine bay opening for airflow. For the modest horsepower targets we talked about (something north of 400 whp) this shouldn't be a limitation. We will likely add an oil cooler right where Shelby did - in the lower grill opening shown above left. The customer wants to ditch the air con and interior - which we warned him would be a negative come resell time - but he wants to keep this as a forever car, and a real cage was higher on his list than street driving.

    CAN WE FIT A LOT MORE TIRE?

    The tire is the ONLY thing connecting your car the track surface. Period. There is NO BIGGER improvement we can make on a track car than increasing tread width on the ground + compound. So this is often the first thing we push customers to look at, whether or not they understand or want this.

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    Most of the time the most room available for adding tire is inboard. On the rear we saw a little room, but the front was massively limited inboard. The car is 17x9" rear and 17x8" front tires with a 245/40ZR17 Michelin Pilot Sport (300TW) tires. While these are light years better than the tires in 1967, the diminutive size and 300 treadwear are definitely the "low hanging fruit" we can improve lap times - and fun levels - drastically.

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    "But I have fun sliding!" Look, I get it - skinny tires can be fun to push to the limits, but being the rolling chicane that has to constantly give point-bys to Miatas at a track day is both frustrating and nerve racking for fast drivers. Watch the video linked above of this Fox Mustang with 375 whp on 275mm tires. He is having fun because he can pick off modern ZL1 1LEs and other $50-75K pony cars on this lighter, LS powered, 275mm tire clad fun buggy. another example of "wider is faster and more fun" was my wife's '13 FR-S, which we ran for 2 years on 215mm rubber - then switched to 315mm Rival-S tires. WOW! The biggest single lap time drop (2.6 sec on 90 sec road course) in 7 different track tests there using the stock 2.0L engine. And it was FUN AF on the wider rubber. #BigTiresMatter

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  4. Vorshlag-Fair

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    continued from above

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    We cannot always "flare our way" to a 315mm tire, but it does become part of the equation. Luckily Adam already had acquired Maier carbon front fenders which have integrated flares. So we mocked those up and took some measurements to the outboard edge of the existing 245mm tire...

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    Not super encouraging - we might gain 1.5" of tire here, in a best case scenario. That might get us to a 275mm tire, or if we tweak every millimeter on the wheel offset maybe a 285/30/18. There are some good 200TW choices in this size - which was something the customer wanted to stick with, for longevity and fun factor. No Hoosier craziness. Which makes sense on a "fun buggy" track build, where there is no class rules to build around.

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    Another easy way to drop lap times - and lower consumable costs - is to lower weight. The Maier carbon flares were about a third of the weight, so that's a net drop of about 25.6 pounds when these get installed. Dropping air con, some interior bits, the pushrod engine we will use has an aluminum block (*hint*), and other changes should net some weight losses. The cage upgrade over the 4-point could negate some of that, of course.

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    How will we get 315mm tires on the front? Its going to take some significant changes to the front suspension. The entire spring and shock are housed in a tower structure that is right where we want the inside of the tire to be. That's all coming out.

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    After significant research into various options that exist for the 1965-73 Mustang chassis we felt the costs for the parts and massive surgery required to install them did not fit our client's budget and overall goals. Instead we picked a hybrid approach - some off the shelf bits with some custom bits. All will be revealed next time, and I'm sure many won't agree with our choices.

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  5. Vorshlag-Fair

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    continued from above

    The only thing I can say is that we have confidence in the type of suspension we will use in our design, and it will net us a better spindle, hub, and brake options - with an easy, modern ABS option in there, too.

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    Once we finalize the front suspension we will move out back - where the 9" wide wheel has some rolled fenders to make it fit. The inboard wheel room is also tight, so we will likely "flare outwards" to fit the same tire width as we use up front. I'm hoping for a 315/30/18 Rival-S at all four corners, but 285/30/18 is the fall back number. There are surprisingly few 315mm clad classic Mustangs out there that don't have MASSIVE flares - and we want to keep the Maier carbon fenders unmolested, if possible.

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    A racer friend of mine that has a 67 fastback bought some Maier 3.25" flares for the back of his car to clear a 315/30/18 on an 18x11" wheel - my kind tire and wheel sizes!

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    It was the right size to clear a wheel pushed inboard as far as possible on his suspension, but he is going to go metal flare on his car and spend more money. But his measurements and pictures are some I can trust, since he's an engineer type and a real racer. We will use these same integrated flares on Adam's 67, having the bodywork and paint done to match the existing paint color.

    WHAT'S NEXT?

    I hope you liked this "project intro" - I've been wanting to write this and kick off this project, and after a couple of weeks of emails, estimates, and a little arm twisting - we just got sign off from the car's owner to start.

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    The front and rear Maier flares are shipping and and a "new front crossmember" we are using is already on order. We might not use the front flares, but in a pinch these will make a 315mm tire fit up front, too. Then the old carbed 5.0L + T5 drivetrain comes out for the last time and a mock-up drivetrain goes in, then the carbon front fenders get properly fitted for initial suspension testing.

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    After we install the front crossmember, we will take a lot of measurements (possibly using a CMM or 3D scanner like the one above), and design the control arms and suspension geometry in software. Then we can fabricate the control arms, add the spindles we want to use, and then mock-up a wheel and tire package to get wheels coming. Once we have the front suspension in place I will make another post, but that might take a number of weeks.

    Thanks for reading,