Wednesday, March 25, 2015

STU Build Phase 2, Part 2

Couple more things to cover before we get to the first events of the season.  Control arms are a big one- the stock bushings seem to have been tuned for the stiff sidewalls of the run-flat tires the C5 came with originally, which means they had to add some compliance into the suspension somewhere besides tires.  I think the bushings were a big part of that, and when you put on tires that aren't crappy 90s run-flats and crank up the roll stiffness with a big front bar you really notice the bushings deflecting every time the steering wheel is turned.  I decided to send my front arms off to Van Steel in Florida for their Delrin bushing install since they quoted a 1-2 week turnaround and they also replace the lower ball joints with new ones.  Phoenix Performance out of Pennsylvania is another company that does Delrin bushing installs but they don't replace the ball joints.  Both of those outfits press out your old bushings, clean the arms, and then jig them up and ream the bushing bores to precise diameters to install the new Delrin pieces.  I was very happy with how the Van Steel arms turned out, let's take a look:


Niceeeee.  Pretty easy install too, everything lined up well.  

Next up, Sparco Evo install.  Another big negative with the stock C5 is how crappy the stock seats are for driving around corners.  They might as well be bench seats for how much lateral support there is, so a new seat was required for serious driving.  The Sparco Evo seems pretty ubiquitous so I figured it was hard to go wrong with it.  I paired it with a set of Marrad machined aluminum fixed brackets to bolt it to the floor as low as possible with as little weight as possible.  Adding sliders and those huge bent sheet metal side mount brackets can add 10-15 lbs on top of the seat weight, and when the typical fiberglass bucket weighs 18-20 lbs you can quickly get way over the 25lb minimum ST-class seat+bracket weight.  I ended up at 27 lbs with the seat+brackets and also I am very happy with the seating position.  Only took a couple tries at seating position before I came up with one that worked.  I also replaced the hardware that came with the brackets with some nicer stuff from McMaster- now I only need one wrench size to pull the seat out instead of 3 and the nuts are nylocs for vibration resistance instead of normal nuts. 




Stock seat with electric motors was 40 lbs, so 13 lb weight savings. Passenger seat has manual controls so less weight to be lost there, might get around to that at some point... Lower priority since I don't sit in the passenger seat while I'm driving.

Speaking of weight saving, one other big area that is popular in ST classes is the battery.  C5s have 32lb AGM batteries stock so there isn't a 50 lb battery to remove like in some other cars but still that is some low hanging fruit.  I went with a 14lb Deka ETX-18l AGM powersports battery for now, it was $80 or something.  I found out later that Battery Tender sells 3lb LiFePO4 batteries for $250, so if I want another 10 lbs out of the car I know how much it will cost me.
Mounted it flat for a lower CoG.  Also added a tie-down later, don't freak out.

Also added an SLP Blackwing intake.  Supposed to be good for 15hp, I couldn't tell a difference really but every bit helps I guess.  The stock LS1 filter housing is definitely restrictive so it has to be better than that, and it looks cooler to have that big filter sitting there.



That's really it for Phase 2- HPT front spring, Delrin front CA bushings, seat, battery, intake.  Next we will have impressions from the first round of events.

Meanwhile, some more pictures from the front suspension overhaul:






No comments:

Post a Comment