In our last article with the Dead To Shred C5 Corvette, we took out the D2S C5 Corvette and track tested it with five different drivers. While all the drivers had fun and had some general positive takes on the C5 Corvette, the complaints that were consistent across all drivers was that they all lamented the lack of ABS, and the vibration on the car was clearly an issue that needed to be sorted. These were all pretty attainable goals, so we focused on knocking them out and then finding our next event to test the car out at!
First: We tackled the EBCM (ABS)
For those unfamiliar, the EBCM on the C5 Corvette is the "Electronic Brake Control Module", which covers ABS and traction control. The Dead to Shred EBCM was showing a "No comm" error code, which wasn't exactly a surprise given that the EBCM's on the C5 Corvette are known for failing. This meant that we didn't have ABS on the C5 Corvette, which caused us to flat spot a set of not exactly cheap 315/30R18 tires Shred Jesse had been kind enough to loan us. While some folks will say you don't need ABS... the first time accidentally overdo it and flat spot a set of tires, having ABS will have paid for itself. The good news for the Dead to Shred C5 is that 01+ EBCM is generally repairable!!
We're going to save you the full writeup on these and instead link you over to the article we wrote in tandem about C5 Corvette EBCM Repair with ABS Fixer. Suffice it to say, the EBCM can be repaired, it's about $200 plus shipping which also includes an upgrade that will improve the reliability of the EBCM. We sent our unit out, got it back with a lengthy list of all the repairs needed to sort out our very neglected EBCM, and with it reinstalled we were in business!
Next Up: We found the Vibration Source and sorted it out.
Now if you buy a clapped out C5 Corvette like ours, the odds are pretty good that something on it is going to be incorrect, clapped out, or in or case just flat out installed wrong. There's been no shortage of that on the Dead to Shred C5 Corvette, and one area we had an issue was that the car would start to vibrate at the upper end of highway speeds.
Troubleshooting this is easy enough, starting with just grabbing each wheel and giving a shake in and out both on the vertical and horziontal axis. Generally you won't find any play... but when you do the next step becomes a two person job. You'll want to get the car in the air and make sure it's safe to be under, and then have a helper grab the troublesome wheel and give it a good shake. Looking up from underneath the car you should be able to identify the problematic part.
In the picture above you can see the inner tied rod attachment, which has a bolt through it. Nothing exciting to see there... except that is where the play was on our car. Slight maybe 1.5mm of play existed in this connection, and surely the source of our wobble. Hmm, what could be causing that?
Should you find yourself in our shoes, we recommend you compare the problematic side to a known good corner of the car, assuming you are not so unlucky that both sides are the issue (which is a rarity). Pictured directly above for us is the way the correct inner tie rod looks, and I'm betting you can see a difference compared to the first. That main difference is that instead of a through bolt, there was an actual bolt that was the correct size for the threads which are in the body of the tierod connectors. Perhaps a previous owner at some point lost the bolt and just jammed a nut and bolt in there to get it over the finish line. Whatever. the story may be... we're the last ones with the hot potato so it's time to fix it right!
Fortunately for us, we were just a few short blocks from Parkrose Hardware, which is an amazing hardware store that features an sprawling selection of DIY hardware. Not only were we able to source the bolts we needed, but we were able to get some improved bolts for our inner tie rods, which were about 5mm longer than what was already on the car. This allowed us to get the full thread engagement on the rear of the car. Match the improved thread engagement with some purple loctite (which Shred Jesse wouldn't shut up about and recommends over blue Loctite), we now had our chassis free of any clunks, clanks, or other such imperfections. Surely it will track smoothly now!
Lastly, We Made Some Minor Tuning Changes
So the C5 Corvette as a platform is pretty darn good, but a few things on it haven't aged well, or weren't setup right, or were designed for a situation that may never apply to you. For all of these situations it's worth investing in working with a knowledgable tuner for your C5 Corvette to make at least a few changes. Alternatively you can get an HP Tuners MPVI4 setup and make the basic adjustments yourself for not that much more... all while learning the more advanced bits of tuning if you so choose courtesy of various tutorials or entities like HP Academy.
The Adjustments We Made:
- Adjusted fan temperatures to come on at lower temperatures than OEM. This is a pretty common tuning choice on C5 Corvette as the factory settings are pretty excessive. The second fan essentially only coming on as the car is approaching engine failure by many accounts, which for a car that's going to see intermittent stress, why start with a high temperature to begin with? We went with both fans coming on at 189 degrees and turning off at 182 degrees, which with our 160 degree thermostat only really comes on when the car is hanging out in the pits or in traffic. We also made a slight adjustment to the fan off speed, raising it a bit specifically. While for street going C5 Corvettes we don't recommend this, we find that low speed travel on an autocross or track car generally means cornering and off axis airflow, which is reduced versus straight light airflow. Thus for AX and track oriented folks the fans are still useful until a bit higher of a speed than on the street.
- Adjusted for E10 Stoichiometric Ratio. At this point the entire country is pretty much using E10 for everything, but when the C5 Corvette came out ethanol wasn't common, so the C5 ships with a stoichiometric ratio target of 14.63, which is incorrect for E10. We adjusted the number to 14.14, a slightly "fatter" ratio that works a bit better with ethanol mixed fuels. The car is just that little bit happier with this configuration change.
- Tuned out Troublesome and/or Irrelevant Engine codes. There is no generic information to include here, but suffice it to say that your car may have a few trouble codes that don't really apply to you. Perhaps your AIS went kaput and a replacement didn't exist so you deleted it, or your modified thermostat means the car runs a bit cooler than expected at times. You can just tune those codes out as you really don't need a check engine light for problems you know are inconsequential. We removed a few pesky codes that were causing the CEL to show on the Dead to Shred but really just weren't an actual concern.
Putting the Fixes to the Test: D2S's Second Autocross Event
So we can fix up a car all we want and then just tell you it's good, or that it was fine on the lame commute to and from a cars and coffee... but if you want to genuinely test out a car, you need to take it somewhere it can shred. For us, the most recent modifications aligned really well with the Northwest Autosports Association May 2nd event at Portland International Raceway. We polled the available drivers, and found our author Shred Jesse and his wife (Mrs. Shred?) had the day free to see just what the Dead to Shred Corvette could do!
The even started fairly early with a rather mild outside temperature around 52 or so degrees. The initial course layout was quite tight, featuring a lot of slalom cones and tight turns. The early course layout was a bit of a struggle for the D2S, where it sat at about 25th place overall. The cool morning temperatures and the Vitour P01R tires unfortunately didn't combine terribly well, making the car an oversteering mess out there... but did make for some fun full sweeper drifts on track!
What really matters though is that the improvements made to the car helped. The newly revised ABS was surely put to task out there with a lot of trail braking into and through some of the gates. The repairs to the tie rod also kept the car smooth all day, and the newly revised fan temperatures kept the car cool and happy all day long in the pits. Solid successes!
For the afternoon the course designers opened things up after receiving a lot of complaints from drivers. Our drivers weren't the complainers, but did find the revised layout a lot more friendly, jumping up from 25th to 15th place overall with a 5 second improvement, while the previous top 10 cars only improved about a half second on track.
Above is Shred Jesse's best run from the onboard GoPro. The rear end of the car definitely wanted to come around, but with some precision throttle application and fast hands the Dead to Shred C5 stayed in place without issue, though a slight step out right before the finish line likely cost the D2S C5 a few places... but that's just how it is with Autocross!
In the end the Dead to Shred Corvette get an admirable 15th place out of 62 entries with our author Shred Jesse behind the wheel. We're calling this a victory because not only did the car behave admirably, but this is only the second event we've ever taken it out to so there's room to improve! The Dead to Shred C5 also smoked the other C6 and C8 Corvettes that entered, quite handily in fact... and all of this was on a set of loaner Vitour P01R tires (not an AX competitive tire like the P01X) with his wife in the passenger seat!
So for this episode, we took a beater C5 Corvette, fixed the ABS, found some chassis bugs and sorted them out, adjusted the tune... and went and kicked the butts of some far newer Corvettes worth 200-600% more. If that's not a win... we don't know what is!
What's Next for the Dead to Shred Corvette?
The car runs, drives, shreds, stops on a dime, doesn't vibrate and doesn't have a dash lit up like a Christmas tree. Where's a person to go from here?
One area that remains a problem on the D2S Corvette is rear traction, which isn't exactly a unique problem to the C5 platform. The front of the car can still step out, and it still tends to oversteer at the limit. The common solution for that is nearly always adding rear aero, but such installs can get pretty spendy or often require a custom fabricator to be involved. They're also against the BST classing rules... but if you go with a wing that's removable in 5 minutes... you can have it all: On track stability, remove for AX and street.
Lucky us, our author Shred Jesse designed a DIY chassis mounted wing for his C5 Corvette. He's since that article gone on to take a bunch of race wins and records with that configuration, but that dude just never seems to sleep, as he recently designed up a "no weld" version of the chassis mount. His intentions there were that such a design should be far more reasonable for the at home DIY enthusiast to mount up to their car... and we've got just the test platform to try this out on!
