So I Autocrossed My Silverado This Weekend........
I have this thread posted on other sites, but I have some suspension specific questions so I am posting here to hopefully add some enthusiasm from the group to the questions I am going to be asking..
I gotta tell you.. It's been a long time since I have autocrossed or for that matter, competed in any SCCA event. The last time I did it was in a BMW e30 that was 50/50 weight distribution from the factory. Clearly a full size 4WD Silverado doesn't share this luxury. When I bought this silly truck with this crazy idea (take a full size 4x4 Silverado and autocross it competitively) in mind like 5 years ago and it's been on hold ever since.
Here's what the truck looked like when I bought it ...
Well over the winter, I started by converting the front end to Atomic's coil over suspension (deleting the torsion bars) and installing McGaughy's drop spindles on the truck. A lot of work, but pretty straight forward. Richard (Atomic) was great, I ended up changing my mind a couple of times during the process and he was great to deal with, and quick to get the parts out.
After I completed that installation, I turned to the rear of the truck. Last winter I chose to deliver the truck to Jeff and Mike at JSM and asked that they build a bad-ass 4 Link that can withstand the rigors of an autocross and tolerate future HP mods in mind, specifically stand up to a forced induction LS motor. Jeff and Mike have been extremely helpful, communicative and very willing to offer advice as I try to dial the truck in further. They are also a Viking dealer so I get parts quick as I try to get shocks/springs working together to support this big gal. Couldn't be more happy with this kit!
This is what was installed, my truck was the prototype installation for this kit, but I am very happy with how things turned out.
About a month or so ago, I got the truck back from JSM and have been tweaking on it to get the ride dialed into my liking. Playing with the Viking coil overs on all 4 corners can be a bit overwhelming, but I am making progress as I understand how it all ties together and works.
Here is what the truck looks like after the front coil overs and rear 4 link is installed:
I still have some changes to make regarding spring rates and dialing it in, it will be lower than pictured above. While I still have a ways to go in that department, I can not tell you how delighted I was to autocross the truck. I started off in RWD only and ran a few laps. Then switched to Auto 4WD and the truck responded amazingly! Not more sideways drifting action, I have to tell you, it is very very neutral. Over-steer is available if you dial in a little more pedal in RWD mode, but I ran most of my runs in Auto 4WD. While even in Auto 4WD it is possible to overdrive the truck, for the most part it goes exactly where you point it and responds quickly to steering inputs. During these runs, was there never any time I was worried it was going to roll or I was going to run out of luck and end up in the weeds or wall.
Arguably this truck will never rival a Corvette or a Viper in terms of handling, but I guarantee you, as it sits right now it will get the attention of many performance cars. The 4 link really woke up the handling, ditching the torsion bars and leaf springs is the best mod I've ever done.
I still have a little work to do sorting out the spring rates and ultimately adding a rear sway bar (not equipped from GM on these 4x4 trucks). When I get this work completed, well lets just say I'm very excited to get it done and see what she has..
Here is how the truck looked during the SCCA event (Not too shabby for a 4WD):
The last run I had the tech guy from our local SCCA chapter approach me asking for a ride. I let him ride the first round and then drive the next.. As a self proclaimed Miata/Volvo guy he walked away from the truck amazed. He just couldn't believe that he had rode and drove a Silverado that quick around the course. Commenting how well the truck drove and relatively neutral it was.
I still need to make some minor changes in spring rates front and rear, as well as add a rear sway bar, then most of the suspension work will be complete. (Spoiler Alert) Big CTS-V brakes are coming for the front..
Anyhow, I have a bunch of videos up from this weekend, but here's a few of the good ones:
Very soon I plan on going with a budget front brake setup..
The 14" Summit rotors and CTS-V calipers/pads I already have.. In fact I had a machine shop make me brackets a few years ago to adapt them to the sprindles around the 14" summit rotors.. I think I will have $450-500 into rotors/calipers/pads + machine shop building the brackets.. I just need to figure out the stainless lines to the Brembo calipers.. Definitely not as cheap as you mentioned, but waaaaaaaaay cheaper than the big brake kit.
Good news ! Just got the notification my personalized plate from TN has been approved, that will be going on when I get it, no handling improvement, but hey..
I am very familar with Hydroboost, it just hasn't been installed yet.. It eventually will, but the stock brake system wasn't going to deal well with repeated stops from high(er) speeds ..... brake fade..... the CTS-V caliper/rotor setup was actually intended for my Avalanche that was a heavy bitch.. I designed it for that, and actually had 2 sets of brackets made and never installed either set.. So one is going on this truck.
I was surprised at how flawless it was in Auto 4WD. The truck was very stable and it was seemless power with virtually no slipping other than off the line until the front axle engaged. No creaks, groans or complaints.. I have a Silverado SS TCase (NP149) to install but damn.. This will let me push that off a bit until it starts to complain.
In other news, today I ordered 2 sets of Eibach coils (one set each for the front and one set for the rear). The rear spring rate was waaaay high, like 150# too much, and the front springs are supposed to be around 1100-1300, I have 650# springs currently installed (my mistake ordering them). So I am righting my wrong on the coils and hopefully going to be able to dial this thing in a whole lot better and level it out.
I honestly can't believe that it drove so well at the autocross. With my luck, I probably hit on some stupid offbeat combo that worked well.. Putting the recommended springs in on all four corners will make it handle like ass.. :bash:
Apparently spring rate coils that high are a bit of a unicorn..Nobody had the 1200# rate springs in a pair. Most didnt even stock it, or they didnt have a pair.. Amazon says 1-3 month delivery, Summit was backordered until first week of March.. Jegs didn't even show they knew what a coil spring was Ugh.. I found a vendor in CA that actually picked up the phone and verified stock with Eibach, and at $64/ea it wasn't too awfully bad. Hopefully they should be here within a week as they are being drop shipped direct from Eibach. I'll be sure to update when I get them installed...
So while parts are still trickling in.. I decided I'll post up some pics from last Sunday's autocross event. The local SCCA group has a gal that likes to come out and snap some photos for us. She posts 'em up for us to download... Anyhow I got some good 'action' shots of Diabla doing work.....
I have parts coming to do the eFans conversion, that will probably get started this weekend and I received notification that the springs have been shipped from Eibach so it's probably going to be the following weekend for the spring swappero...
It figures, the parts that I want to show up the fastest just got shipped Friday (my heavier rate springs).. Looks like I am going to tear into the cooling system this weekend and start replacing all the hoses, the thermostat and 34" radiator. Then it's eFan install and PCM reflash with the EFILive.. I started to think that my cooling system is 14 years old and I want to beat the piss out of this truck this year, better do some preventative maintenance.
LOL. I guess by dumb luck I managed to hit on a very balanced combo in terms of tire sizing.. I have 275/55/18s on an 18x9 wheel. I was playing with tire pressure a little when I was a the autocross.. I went down 6 psi in the front and 8 in the rear.. I was in fear of rolling the bead off the tires.. As you can see in this video, it gave the sidewalls a workout, but it never rolled over on to the sidewalls like I have had happen on my BMW.
Sadly, I don't have enough power for a bigger course, I can get the fury that a 4.8L can dish out to the ground as it currently sits.. About 3 years ago I installed a TruTrac in the rear, in 2WD it can put enough throttle in to break the rear end loose, once I go 4WD, it all changes. To be honest, I was dumbfounded how much it changed the trucks characteristics, at least on this course. It added a huge amount of stability entering and exiting the corners and virtually all the tirespin was gone unless I drove it in waaaay too hard and thats just driver error that no vehicle can make up for.
As far as moving things around, in all honesty I don't plan to do much. This truck isn't going to go full race mode. I will probably borrow a page out of Steve-O-08's playbook and move the battery when the current one expires, and I'd like to borrow his idea about the half height rollbar that would let me install 4 point harnesses. I mean it's always going to be a fat lady at the track, you can move the weight around, but she'll never hang with a Miata or Mini on a tight course.
My goals for this truck are: street truck first, race truck second. I still want to use the truck as a truck so I can't fill the bed up with all the underhood bits. Unless I lose my mind, this truck will probably retain the full interior as GM delivered it.
However, with that said I do see mods coming for the engine and transmission. I'd like a built 6L with a turbo or LSA blower, and I eventually will switch over to the Silverado SS AWD (NP149) T-case I have in the shed.... Dammit.. gotta add researching an Accusump system to the list...:hmmm:
Hydroboost, CTS-V brakes up front and SUV brakes in the rear will come too, probably sooner than the engine/transmission .
And I already have a quick ratio steering box that I keep forgetting about... Damn need to get that in place.. LOL
All these things take money and patience.. Getting the truck setup as it currently is hasn't been cheap.. I'm not complaining, I just need to settle down a bit on the spending :-D
Alright guys, I've been busy though I looked at all of the events I want to participate this year and I questioned whether or not the 14 year old cooling system was upto the task of keeping me on the road. So I started to research parts and I wanted to upgrade the radiator anyhow since I have had an e-fan harness and some chinese e-fans now for like 2+ years..
Anyhow, I ordered the following:
every rubber hose under the hood that contained coolant including upper/lower rad hose, heater hoses and throttle body coolant hoses.
160* Lingenfelter Thermostat (nothing more than a re-boxed MOTORAD unit).
New Coolant Recovery tank and Cap.
New temp sensor for the driver's side cylinder head.
34" AC Delco Radiator.
Anyhow, I started ripping parts off last weekend, and finished it up this weekend complete with an PCM reflash to set the efans settings so the PCM controls them.
I finished up the coolant system yesterday, and turned my attention to the spring issue.. For those of you who have been paying attention, you probably remember I was rolling on 650# springs on the front, which are, ironically, about half of what they should be.. I ran the first event (above) with those springs but the ride was miserable and there was less than 2" of travel before the truck rolled onto the bump stops. I got under the truck and measured the clearance between the lowest point on the front end and the ground.. LOL WOW !! It was the front crossmember and it was less than 4" off the pavement, probably in part why it drove well around the track, but rode like ass !!
As you can imagine this spells bad news for CV Shaft angles in the front, this is event with McGaughy's 2" drop spindles... :EEK:
So I started the hunt for the correct (better) spring rate springs.. As it turns out, not every vendor has +1000# or higher springs on the shelf. LOL I guess not everyone is racing a fat bitch 4WD Silverado, who knew ??
Anyhow I did find a place in Cali that could actually access Eibach's inventory and tell me for certain that they could get and drop ship 1200# springs, so I ordered them and some softer springs (225#) for the rear as well.. Purple Santa brought me these:
So today, I got to switching the 650# springs over (left side) for the bigger stiffer beefier Eibach 1200# springs (right side):
So with all those swapped in place, the truck is done and I am a lot happier with the spring situation:
Here's the truck at the current ride height, I ~think~ the front is pretty well sorted in terms of ride height, we'll see.. I still need to put the softer springs in the rear and lower it to match the front and I'll be ready for the next event:
Next weekend, I plan on a transmission flush/fill, replace the smurf juice in the transfer case and top off all the fluids.
Maybe a trip to the local scrapyard to hunt down a set of SUV brakes for the rear and maybe a hydroboost setup? Who knows.
The next autocross is set for the weekend of 3-11 / 3-12 and I plan on introducing the truck to the Misssissippi SCCA crew, I'm hopeful they will be as accepting as the Tennessee guys are, I'll follow it up with more video for sure.
The SCCA club here has a gal that goes to the events and takes professional pics of the event, pretty neat to get action shots of your ride in action.....
I have a couple pics from the last SCCA event I attended, the next event is Sunday I plan on attending it.
Punishing the RF tire:
Look at this lean, this is why I need bigger bars:
Back in the day, I installed a rear swaybar on my Typhoon and considered it the best mod I ever did to that truck, so I am not opposed to adding a rear bar. My bigger concern is that with the 4 link in the rear it is very busy back there in terms of mounting a swaybar. Between the 4-Link, gas tank, spare tire, driveshaft and misc brake lines, there's a lot of 'confusion' back there. If I decide to add a rear bar, I'll need to make a concentrated effort to get something that fits well without hitting other components. Not impossible, but not just an order & install affair. I want to get a better setup in the front and resolve that first before I start on the rear.
I placed a few calls today, one to Speedway Engineering, they said they are the manufacturer, and have limited application data available (read NONE). They recommended that I contact a chassis shop because with all the angles, and dimensions they don't really have any idea what I'd need.. Fair enough, they have their market, and it's manufacturing, not spec'ing out rides. Very friendly and positive people to talk to, just not their bag.
I called another chassis shop here in Tennessee and basically got the brush off, not certain but it felt like it was because my truck is too new. Must be nice to be able to pick and chose what customers you want to work with.
So I finally called Ron Sutton, he was heading back from a show in Vegas and was very accomodating on the phone. Even though he was trailering back a display trailer from his show he took the time out to talk to me and laid out my options. Damn.. I need to start plasma donation or something to support my hobby. LOL I'll follow up with more details as they get finalized.
In other news, I did another SCCA points event autocross yesterday, overall everything went well (relatively speaking anyhow). While I was doing corner-worker duty the skies opened up and it started to rain, sort of sucks when its only 50* ambient air temp and the wind is blowing. I was hoping for a full on rain as it would level the playing field in my favor significantly.
At this event there was 2 other cars in my class this weekend (that's a first).. A 4th Gen WS6 Trans Am and 5th Gen Camaro. The Trans Am was a purpose built vehicle that was impressive to watch, the driver was very talented. The 5th Gen Camaro was a nice piece as well but leaned a little more towards the street than track/course built ride of the T/A. The Camaro had a nice lumpy cam in it and was rolling on ZL1 wheels. Both cars were running sticky rubber (opposed to my street tires).
Anyhow I had hoped for a full-on rain, SCCA runs in the rain, only stopping for storms involving lightning. With my truck in Auto 4WD and on street tires it would have levelled the playing field exponentially in my favor vs. the RWD race tire guys.. Sadly, this would NOT be the case, by the time it was my turn to run the track was at best, damp. By the 2nd run, I couldnt even tell it had rained. However, on my first run, while it was damp, I was able to pull a giant Petter Solberg style drift around one of the corners. The back end broke loose under braking and began to rotate around pointing the truck into the direction of the corner. I slammed the throttle WOT and the front end just pulled it straight forward and into the corner in a slingshot manner.. Pretty damn cool and by far my highlight of the day..
Sadly the rest of the day didn't end well for me, I need to learn to slow down and stop trying to hammer the F#_%* out of the course. I continually over drove the course.. I'm am attaching my 5th run of the day for your viewing pleasure/laughter. It was set to be the best run of my day until I over-baked the last corner (intended to slow people down, which I didn't), and I clipped the last cone and blasted through the finish gate cones, taking out at least 3-4 of them and causing the two guys behind me to get re-runs as they were setting up the cones I destroyed.. Fortunately I didn't hit any timing equipment.
One thing I did find myself doing was I was 'hugging' the center console in preparation for turns!! I didn't realize that I was doing this before, and I am certain it isn't helping my technique. So I believe I will be working towards a harness of some sort or at the very least, a competition lap belt to help hold my butt in place!!!! In the mean time, in an attempt to compensate, I moved my seat forward about 3-4 clicks to help wedge me in place, at 6'5" tall it's not uncommon for me to get wedged in a car/truck anyhow. This did wonders for my technique and I actually felt better on my last 3 runs.. I can't believe I didn't do this before, I used to back when I autocrossed my BMW back in 2008-2010. I believe a 4 point harness is in my future if I can figure out a way to mount it in place without losing too much recline room on the seat, being 6'5" tall I don't always want to feel 'wedged' in place. I do use the truck for other daily usages. Anyhow, more to come.
Quote:
Originally Posted by Sieg
I'm guessing a splined bar setup on that truck with tuning insight would money well spent.
Call Ron Sutton and hopefully you'll get along and end up throwing some money his way.
I concur 100%... I called Ron earlier today and I am in the early stages of getting a 3 piece splined bar in place.. Most likely it will be a weld in place 'bar in a tube' setup.. The bad news is, I think I just blew my harness money on a sway bar.. Great, more traction adding stuff to throw me around in the truck and less restraining devices in the truck !! Perfect !!
Nice job!!!! just went through it and love it. I'm doing something similar to my '16 Chev 4x4 rcsb. I wont be autocrossing it but i'm in sales/estimates and spend hours in it everyday and WANT better handling. I've been intouch with McGaughy's and there doing a new spindle as these a arms are a little different than yours.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
So I Autocrossed My Silverado This Weekend........
Must be nice to be able to pick and chose what customers you want to work with.
LOL I'll follow up with more details as they get finalized.
Fortunately I didn't hit any timing equipment.
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