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Vorshlag Build Thread - 69 Camaro Pro Touring/Track Car

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  • #31
    continued from above

    ECM TUNING ISSUE: SOLVED

    One of the challenges of building a car from scratch is we have no OEM parts to start with. One mistake I made on this car early on was how I purchased the E38 "LS3" style GM engine computer module or ECM. After learning this and hope to pass along this painful lesson here.



    In the last post I talked about us firing up the engine for the first time in late August 2019. Well it would start and run, but it would not stay running for more than a few seconds. Evan managed to get it running by adding a jumper to the fuel relay, but the E38 ECM was not sending a steady signal to run the fuel pump. Why?

    Junkyard sourced vs New ECM: When you buy a used ECM that came out of a running OEM setup, it will already have some "base" programming loaded, including some body module aspects that you cannot load with tuning software like HP Tuners. With a new ECM (like the two I bought for this project) it is MISSING those other aspects, and you need a specialized GM technicians computer OR a fully functional car like a 2010-15 Camaro to plug the ECM into, THEN it will "talk" to these other modules and THEN you can put it in the actual car you are building for and reprogram it to your custom tuning.



    When the first one had an issue, I bought another new one. When both new ECMs had the same issue, we had someone come by who said he could fix it - he didn't. We flashed both new ECMs with HP Tuners software to add a start-up tune and bypass the VATS key security system, but without some of the GM base tune aspects, the fuel pump trigger would go away after a few seconds. A silly mistake that cost me thousands of dollars in wasted man hours and months of wasted time. Luckily a tuner friend found someone with the right hardware to add the GM base tune, we sent one off to be flashed, then loaded the start-up tune, then it ran and drove without any jumper wires or other tricks.

    HOOD VENT FINISHED

    We had fabricated this crazy hood vent system out of aluminum and it tied into the main radiator, then the engine oil cooler and power steering coolers on the sides. Lots of swooping curves that flowed up to the surface of the hood. It has only been held in with Clecos - it was time to mount that with real nut and bolt hardware ... and finish one glaring pair of errors.



    The rear corners of this duct were strangely missing some material on the mounting flanges - and nobody knew why it was left that way. I didn't catch it when the last round of work was done to this, but I couldn't let it go this way. Once Evan had a day to work on this I had him remove the vent and fix this - on my dime - and get the bolts and floating nut plates installed to mount the duct.



    Once the assembly was off the car the missing corner of the upper mounting flange is painfully visible. The missing puzzle piece was made from cardboard then transferred and cut from aluminum sheet, with two mirror image parts cut.



    Evan TIG welded these corner flanges in place, then smoothed the welds with a sanding roll and orbital sander, and when completed you would never know they weren't in the original flange.



    With that detail completed he could add the floating nut plates to the bottom side of the flange, then some stainless button head 10-32 bolts were put in place, holding the upper duct assembly to the hood.



    We will likely use 3M panel bod to attach this during paint work, but for now the ducting is complete enough for track testing. The customer might choose to keep visible hardware here, to make it easier to work on down the road if the hood were ever damaged. We will see, but now at least I don't see ANY more damn Clecos on this car, or the two gaps in the corner of this hood duct.

    TRANSMISSION ISSUES + FIX

    While bleeding the clutch system, Evan found some things that were not completed in the past, which meant we had to remove the transmission (at my expense) to get access to some fittings that were only trial fitted.



    I will cover all of that next time, plus some other "fun" things that happened as he was unbolting the shift arms on the side...



    Evan was loosening the shift rods at the three shift forks (1-2 / 3-4 / 5-R) on this 5 speed G-Force GF-5R 5 speed manual. And one of the shift cams just... broke. He was shocked as he was using hand tools and was just removing a Nylock nut, but the shaft on the 3-4 shift form cam just sheared clean off. FFFFFFFFFF! A call to G-Force was made, then to the customer.



    While we were trying to figure WTF happened to that, the transmission was pulled and some detail work that was missed earlier could finally be completed.



    These tunnel details were completed and the shift rods were finish TIG welded (they were only tack welded), so those would be ready to go back in when the replacement parts arrived to fix this G-Force.



    The folks at G-Force admitted that this early GF-5R model trans had some wonky shift cam issues, and while they never admitted fault, they did have an upgrade kit of about $535 in parts ready to fix this issue. That was ordered in late April 2020 and arrived within days, and we didn't mark it up one penny. The upgrade parts they strongly suggested included the 1-2 and 3-4 shift cams (one of which is what broke), the 5th-Reverse shift cam, and an updated 5th-Reverse shift fork.



    That meant that in May of 2020 we had to crack open a new transmission we didn't supply and completely tear it down to fix it. Luckily these straight cut gear race boxes are made to be serviced quickly and easily.



    It kind of sucked to have to tear into a new transmission that had zero miles on it, but I get their point - at what time frame does an old part no longer have any "warranty period". In the case of most race parts, it is on day zero. While the revised shift cam is much thicker and should provide years of hard use, it should not have sheared off.



    The upgraded 5-reverse shift fork was also visibly thicker, and stronger. After getting all of these shift cams and forks in place it was time to put the main and intermediate shaft and gear stacks back in.



    Myles helped Evan get everything lined up and the stacks were reinstalled. Once everything checked out the split case was reassembled with the correct gasket sealant between them, then bolted up.



    It took a little file fitting to make the shift arms fit the new, thicker shift cams' shafts, but that was worked out and the arms were clocked and bolted down.



    Once the transmission was back in, fresh Motul 75W140 went back into this box and we were almost ready for test drives. Frustrating to have to fix something new that shouldn't have broken, but the revised parts have proven effective on the test drives I have made since.

    WEIGHT CHECK MAY 2020

    A quick weight check - and yes, these are almost meaningless. This was with a running car and all fluids, but no doors or door bars, no seats and much of the front aero removed. It kept gaining weight, but this was a "feel good" picture opportunity.



    MCS SHOCKS DESIGNED AND ORDERED

    It was apparent that the RideTech dampers ordered years before this car came to our shop, where we made major changes to the ride heights and mounting, that the dampers needed to be replaced with something of a special length and travel.



    We convinced the customer to let us - a shock design shop - order a custom set of MCS remote triples made for this exact custom car. Jason took a bunch of measurements in April of 2020 and made two drawings for MCS to go by for body length and stroke as well as the end types already on the car. The rear is an "eye to eye" shock and the front is an "eye to T-bar", since the front suspension is all C6 Corvette.

    TRUNK INSTALLATION AND "SLOTS"

    This is one of my least favorite details of this entire build - the rear wing uprights. They are mounted at the rear frame rail, which makes them very sturdy, but there was an argument I lost on getting them through the trunk.



    The customer provided a rare aluminum OEM style rear trunk lid, but it had not been installed since the rear wing uprights were installed. And it couldn't be, because those items occupied the same space. Now I was in favor of a trunk mounted wing upright with separate bracing underneath to the frame, which would allow the trunk to swing up with the wing attached, like we have done many times - see these two cars below:



    The customer didn't want to pursue that design, so now we had to make the trunk and frame-mounted uprights fit together. Many suggestions were discussed but nothing elegant came up. It was time to hack two giant slots in the trunk, and the customer was on board.



    There was no rear trunk latch anymore and that part of the trunk had been cut out. The uprights were installed and so was the trunk, and it was time to mark where the slots would be...



    As you can see this was an iterative process, with the trunk swung down, the slots extended, and on and on. Care was taken to keep the slots as tight as possible, to prevent a giant gash from appearing once the trunk was able to be closed fully.



    Evan did an admirable job here, sneaking up on the cut until the trunk closed. But this isn't a laser perfect set of uprights - they are very square to the centerline of the chassis but not so precise that they don't require a little margin for error. So the slots grew in width more than I had hoped, and we had some work cut out for ourselves to cover up this pair of slots - on the now weakened trunk lid, which had no latch. We solved it in 2022...

    INSTALL CUSTOM BUILT MCS RR3 TRIPLES

    The dampers that Jason designed arrived in mid June 2020 and they looked really good. He had ordered up some Hyperco springs for this car in 700 lb-in front and 450 lb-in rear spring rates. These were photographed then Evan got down to the install .


    The remote reservoirs give additional travel and a more substantial compression curve, with both low and high speed compression adjustment.



    The front shocks mount at the bottom like any C6 Corvette damper, with the "T-bar" lower mount that attaches to the lower arm. The "eye" upper installed to a mount on the frame we had added before and built towards. The reservoirs are mounted under the hood - I will show more of that in a later write up.



    The "eye to eye" rears mount to brackets at the rear axle (bottom) and chassis (top) with bushings and bolts on the spherical ends. The reservoirs were very temporarily mounted to the Watts Link lateral arms, but the car was never driven like this. I will show those reservoir mounts in a later post as well.



    Even got the wheels back on and set ride heights, with input from engineer Jason. This was the last task he tackled on this '69 Camaro before he left to start his own business in September of 2020. We still work with Evan on projects even today and wish him the best!

    WHAT'S NEXT?

    I wrote for the better part of a day and only got us through June 2020, dang! We still have a lot of work to cover to catch us up to "it runs and drives and is ready for dyno!" Next time I will cover several big tasks that took both heavy fab and some engineering wizardry to complete.



    Also, the first of two Racetech front seats was also mounted - you can see that I'm sitting where the back seat would normally be! That's the driver setback that we designed in from the beginning, which allowed for so much engine setback.

    Tune in next time for more on this build.
    Terry Fair - www.vorshlag.com
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev

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