heavy85

Thanks Cary. Earlier you said "Hillclimbs are probably the most fun thing I have done in a car" and I can fully attest to that. I've spent somewhere north of 40 days competing on variety of midwest track plus autox plus a couple years of w-w karts but nothing compares to a fast hill run. Quick side story. My first event I was thinking maybe break 2 min. Was still on street tires and ended up mid 121s but happy and hooked. Second event switched to the R6's and finally broke the 2 min mark on the last run on Sunday with a 119.4. That felt sooo good. I couldnt believe the feeling at the top if the hill. Now this last event and my third hill climb on same R6 tires. Third run on Saturday I broke into 117 sec almost two seconds faster than ever before. When I reached the top I seriously was scared to death and seriously contemplated putting in on ths trailer for the weekend. I've never felt anything like that driving a car before. I got over it and went three or four more laps in the 117s and each one scared me just about the same but what a rush. Ended up spinning at the top of third gear over a crest trying to break into the 116s. Luckily stayed on pavement and only damage was no longer round tires. These are all 500 miles from home but am actually contemplated running all three events next year despite the distance because its that good. Back to car set-up ...... The class I run 'SU' which requires DOT tires otherwise I would be on Avons. I'll have to ask if there is another class I could run on the more readily available slicks but I'm still on a rollbar instead of cage so that may limit classing. Im still on 425/350 springs and do bottom the exhaust ina couple spots. Seems like I may want to go higher but was worried it would make the car less predictable? Seat is all the way back and battery is in the front of the hatch - could move it to the back I guess. With just enough fuel Im at about 51/49 weight distribution and just under 2700 lb. Its been on the list for a while but still dont have droop limiters. The fronts have helper springs and at full droop othe main springs are a good 1 to 1.5 inches slack. Should I get on this already?

Back from the past. So I've been to three of these now and am over 4 seconds faster than the discussion above. http://www.dragonhillclimb.com/records/ (I'm fifth overall all time) http://m.youtube.com/watch?v=zZ8AulTJH7g <- 117.3 sec run Now am starting the 6 month off season and planning for the next Dragon hill climb at the end of march. This surface is very abrasive yet I'm struggling for forward traction. My rear tires wear fast and look like cheese gratered on what feels like .1 grit sandpaper asphault. I'm also spinning the tires all the way through third gear at the launch and elsewhere. Do not have nearly as much problem on other tracks. So question is how to maximize forward traction without other unmanagable compromises? As discusses in another thread Im making heim joint rear control arms to help stiffen the rear and reduce friction but what else should I be doing to be better out of the hole? Overall the car turns in well, generally puts down power OK outside of here with these tires, but tends to chase the rear mid corner. I'm confortable where it's at but always looking to go faster. Second question is I run used Hoosiers. Last year I ran 275 R15 R6 since I couldnt find any A6's used. I'm still not able to find A6's for next year in that size to fit my 15x10 rims. Other potential option is 245 R17 R6 to fit my street tire 17x9 rims which John Berget has available. So 275/15 R6 or 245/17 A6 if thats the only options available? Last general question, for a bumpy humpy track like a hill where you are going back and forth across the crown and dealing with old asphault is a big spring / little bar or a soft spring / big bar setup better and why? Cameron

Thanks for all the info. Change of plans - after more searching I came across Cary's pic of his modified stock arm. http://forums.hybridz.org/topic/62776-yet-another-rear-control-arm-design/page-5 I'm still curious about comments to lower the inner pivot. Seems that would be the same as lowering the rear of the car? I would have though it would be better to raise the rear roll center on a lowered car and therefore would want to raise the inner pivots? Whats the thinking here? Thanks Cameron

Old thread but this design is the best one I've seen IMO and making a set is going to be one of my off season project. Several questions on material specs. - Assume 1" x 0.095 tubing? - The treaded tube where the rod ends attach - is that solid bar that was drilled and tapped or can you buy pretapped thickwall tube somewhere? - I've never seen one before so where can you get that bolt on clevis? - Seems 3/4 is overkill - has anyone successfully used 5/8 rod ends? - I really like the inner pivot rod ends that bolt in to the factory mount idea - is that a threaded tube in the middle between the rod ends and the outer piece with the ears that bolt to the chassis just has a through hole? - Going through the effort of making these, is there any geometry changes that would be usefull to build into them? Thanks Cameron

True and what I currently run for Hillclimb only. Problem with 15 is other than these Hoosier 275 Race tires or 9.5" slicks there is nothing bigger than 225. Especially true for street tires. 17" opens up lots of 245/255 options in all kinds of tires. The reason at the time for my 17's was rotor clearance for street driving. I have since been using thise rims with street tires but for racing in classes that requires 140/200 treadwear tires. 15 Diamonds steel race rims barely clear the caliper but the al street rims dont. Also need to consider 15's are typically 23" diameter where the 17's are about 25" so gearing, ground clearance (I bottom a lot on hillclimb with the 15's), etc also come into play.

Lots and lots of variables to make a conclusion on tire size especially for hillclimbs. It been my experience that hillclimb times are HIGHLY dependant on how hard the driver is willing to push. For example, my first hillclimb I beat a former Daytone 24 winner with him in his purpose built hillclimb special complete with big wings, low weight, turbo, huge slicks, etc and me in my LS1 Z on 245 STREET tires. Im not that great a driver either. Then you need to pick a tire and venue. Hillclimb need tires that work now so if your tire needs a lot of heat then smaller can be better to get them up to temp faster. If you want to put some ZG flares on, I've had much success with 245 17's. RS3's

My current race Z while never finished is about there with not a lot to do without spending big $$. Looking for next project and came across this in a <$3k car search on Craiglist. Wasnt even looking for a Z just looked like a potential interesting new daily driver. If I would ever do it, speed events would be limited to the paved mile relatively low speed version not a full boat deal. Bucket list thing I want to do someday. I have a complete low mile stock brake setup from my 240, swaybars, old Tokico's (assuming ones from 240 fit), decent rims w/ nice tires, etc. Was thinking if I could grab for a couple hundred and spend a couple grand could have a much better than family minivan driver. Maybe interesting enging swap? Afraid the little crap may ruin budget like hatch seals, misc missing whatever, bolts and stuff. Dunno looks like a lot of work .....

http://decatur.craigslist.org/cto/4054326502.html Dont know why but it caught my eye and has been for sale for a while so guessing could get for next to nothing. Its maybe 1.5 hrs drive away otherwise I would have taken a peek already. Back seat could be handy for occassional kids haulage but seeing its been without a rear window for who knows how long may be too far gone? Can you even gets stuff for 2+2's or are they mostly the same? Not sure what would use it for. Maybe turn into daily driver or land speed racer or something?

Sounds like you need a different sized spacer between the bearings. Ive fought this before and it's quite frustrating. Either shorter to bring the inner races together or longer one to move the inner races appart either way to take the play out. I ended up getting shims from McMaster-Carr and trial amd error shimmed it until it was tight. I've read procedure where you take a fish scale and pull on a wheel stud and tighten the nut until you get to a certain full force. I found that the nut torque doesnt impact rotation torque at all. You have to keep trying shims until you get the torque preload. The first time I shimmed it, the shim was so thin it basically fell appart. Luckily I found this before the bearing was damaged. I assume this happened because the nut wasnt tight enough? Now after every race I wiggle the tires to make sure the bearing are staying tight.

Camaro studs and lug nuts here. You can press them in with a press or a vice and a deep socket or run them down with a nut.

"and lowered the car significantly more" Not sure what that means but you may want to undo that. IME those springs can still be relatively fast. Yes Jon is right once you are getting really serious you will want more but those should work for what you are doing. Rear toe in is good, very good. Swap springs. As light as those springs are I think you need the bars. I dont run a rear bar but use 425/375 springs. Get the camber where the tires are happy and I wouldn't use camber to adjust balance.

It goes back to just in front of the swaybar

Jon - how much weight you think could be saved by converting the shaft to race stuff? Seems like a meaning amount but never weighed a column before.

I would mount it maybe an inch or so off the rad. Need some room for the air to move from the oil cooler fins/tubes over to the radiator fins/tubes since the dont line up. Cant comment on the vents but they cant hurt. My splitter hurt cooling a lot - if you are in a pinch remove splitter and see if that helps. Im curious why your shroud is a funnel - seems it would force lots of air into the radiator and without a way to get the air out the backside may be hurting cooling. I ended up with off the shelf Ron Davis dual pass that works great.

Yep all blocked off. You think there is actually tangible low pressure in the rest of the engine compartment?

The cavity on the other side of the far panel is a stagnant area sealed off from everything. Im thinking you need to open that area up to a low pressure source otherwise how do you get any low pressure in there? Where is the low pressure coming from since its basically a sealed box?

The near side in the pic seals off the (hopefully) high pressure area for the airbox. The far side could be cut out to make a single bigger area but then it's still basically just one bigger sealed off areas instead of two. That area is connected to the interior through the fresh air vents that run through the front frame horns. Should I open that vent to the interior? Should I take out the duct so this area is open to the engine bay? Cut the floor out so it's connected above the splitter? What's the nearest low pressure area to feed it?

Hey Jon - this look any better Now I'm not sure how to get low pressure into that cavity. It's sort of sealed off so not sure any downforce can be made without connecting it to a low pressure area?

I may try that Jon - thanks for the idea. More I play with this, the Z is front aero limited and I think the big bottleneck is the blunt radiator opening. One related issue Im trying to wrestle with is the front edge of the hood dips down as the hood opens. This means you need either a lift off hood which is a PITA as big as it is or are forced to recess the block off plate back into the grill as I did which has to hurt both downforce and drag. Anyone tested dive planes on the front of a Z to see what they do?

I'll take some more pics. The upper left grill area is the air filter inlet. The rad is boxed in with the inlet just above the aid dam. Edit here they are The taped off area above the bumper was a test opening to see if it helped cooling.

Someone say hood vents? These are working well for me. Also on the topic of fender vents. Just did this but haven't had a good test to understand effectiveness.

Heading to a hillclimb on Friday. Going to be starting with some new 245/45R17 Rival street tires. Never ran them before so starting with the RS3 set-up. Long story why Im doing this but on day 2 plan is to swap to some used 275/35R15 R6's I just picked up used just for this event. Would of liked A6's but couldnt find some. I've also never ran R-comp Hoosiers before so any suggestions on pressures or quick set-up tweaks I need to be aware of? Diameters are 23" vs 25" so theres that but otherwise from what I can tell pressures should actually be about the same, low 30's hot. Thanks Cameron

This has prevented a lot of issues as you often find little issues and can fix before they become a problem. This has also resulted in zero DNFs in about 40 track days.

What tires? Things to consider - tracks around here are all clockwise so the front left takes a beating. Lots of camber there. Right side doesnt need as much. Lots of camber hurts braking and with a big bar leads to flat spots IME - its a trade-off to play with. Rear gains camber in bump so you dont need as much static camber. Watch tire wear and adjust accordingly or until lap times go the wrong way. IMO start high in camber and work your way down as tire wear can go bad fast with too little (ask me how I know ...). Cameron

Where would this happen?