heavy85
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Posts posted by heavy85
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8 years of racing LS and couldnt be happier with it.
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On the Sanderson headers I dont use any gasket and they dont leak.
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I am not sure how you would measure bump steer with just two dial indicators.
What are they attached to for a stable reference, and how do you track wheel height displacement from nominal ride height?
Attached to something heavy like jack stand - dial indicators have magnetic base. Measure height with ruler. Get static ride height from LCA angle then jack up and down with spring removed.
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I just use two dial indicators on the brake rotors.
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No desire for a vette. Its fun to be fast in a traditionally not that fast car. Its also fun to keep progressing and lowering lap times - something that I havent done in two years and why Im searching for a step change. Also fun to push others. Two best comments I ever received was a guy in an tube frame, lighter, higher power car come up and thank me for pushing him to go faster than he ever would have otherwise (we were in same class) and a guy in a high downforce formula car at a hillclimb say he put me on his dartboard as the target
. You wont get those by getting good lap times in a vette. -
Already use 25" tires so that's not and issue for me. Yes lots of tire options in 18". However, more I look at it and to do it most efficiently one would want to cut out most of fhe front end. Moving the load path from the strut tower down lower to basically part way up the side of thd strut tower would need a lot of reinforcement. Not sure Im ready yet to lop off the front end and completely rebuild it.
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Not sure I have it in me to go through the effort but other than the upper coilover mount doesnt look too hard. FYI Z front suspension is 46 lb (big brakes) and the C5 is 52 lb with a shock but without a coilover. Think the strut is a limiting performance factor - lap times - and I need to replace (again ... worn out two sets now) Konis and other maintenance so it's tempting. So would it be worth it over a well set-up Z strut? It wouldnt be cheap but biggest fear is new learning curve setting it up.
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That would be great Cary. Im to the point that rules are typically unlimited for suspension so will move things around to get the best performance. Look forward to your results.
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Stock LS1 (at the time). Ran the factory 240Z rad for a couple years. Worked fine on interstate right at thermostat setting. On track (road course) would get hot after a couple laps so had to manage temps. Went to Champion ebay deal and temps were much better on track. Then added splitter and temps went up. Managing airflow is as or more important than the core itself. Hood vents, ducting, etc. Round 3 went with an off the shelf Ron Davis Racing dual pass and it works awesome.
PS: I used to manage on track temps to try not to exceed 230 deg as measured in the passenger head port. Now dont ever see over maybe 210 on track.
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Thats a problem. Car is currently dissasembled on jackstands for the winter work. The lca pivot is about 1/4 higher than stock and points down ~3 deg. R comps are ~23" diameter and 200 'street' tires (race on both for different events) are 25" diameter although Im contemplating buying another set of 17" wheels and going up to the ~25" R comps.
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If you aren't constrained by the rules why not move it to in front of the LCA to put the rod in tension?
Why?
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Edit: sorry to hear about your wife. Hope recovery goes well!
The LCA point front the center down towards the tire by ~3 deg if that helps with ride height? Will have to take the strut off to measure but the strut top us currently about 1/2" rear and 1/2 inboard of stock location. Also have 3/4" spacers between struts and steering arm.
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You could move it to mount on your k-member. That would be slightly forward of the TC mount but allow it to align. That said a long time ago a friend measured all this and used wingeo to see the curves. While it did change it wasn't some major issue. When you pushed the front wheels forward for more caster the curves were very close again. If you want to do the measurements I'll put it in susprog and then we can share the plots so you can decide.
Cary I'll bite. Measurements are close but may be off 1/16" here or there.
- Stock arms 11.5" from pivot to ball joint
- Ball joints 3/8" forward of the lca pivot
- TC pivot 7/16" outboard of lca pivot
- TC pivot 5/16" lower than lca pivot
- 14 3/16" between TC pivot and lca pivot
- 240 struts sectioned 2"
- If I just add a bolt in rod end the TC rod would shorten about 1 1/4"
I'm thinking as already mentioned to put the lca and TC mount in line. It's got a bit of pro dive in now but don't really have a clue where to go vertically. Can put it just about anywhere that would get the best performance. I'm also thinking of pushing the upper strut mount forward 1" and lengthen the TC rod accordingly to lengthen the wheelbase - should move 0.5% weight towards the rear and I want as much as possible.
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Quickly realizing its going to be a PITA to locate accurately relative to the LCA mount.
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Finally converting the TC rod to rod ends. Have run the Gman aluminum cup / nylon ball w/rubber bushing on the back side set-up for a long time. Something that becomes immediately noticed is that by adding a bracket to hold the rod end on the frame side you effectively shorten the TC rod. Since rules are open, Im free to remocate the mount location. Has anyone mapped the suspension and determined a) the impact of a shorter TC rod and b.) if you could move the frame mount where is a good target location?
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I will postulate that the lifting of the inside rear wheel is caused by the combination of the following:
1. The 14 degree SAI and ~ 7 degree caster cause the outside tire to rise relative to the body and the inside tire to drop relative to the body. This takes weight off the inside rear.
You can see how much this de-wedges the car in even a static situation if you have some turn-plates and wheel scales.
2. Large scrub radius. This exacerbates the problems caused by problem 1. The larger the scrub radius, the more the outside wheel will rise and the more the inside tire will drop.
3. Super stiff springs. This magnifies the problems caused by 1 and 2 above.
So what is happening is that you are entering the corner and transferring weight to the outside front tire, which as you turn is rising relative to the body. Meanwhile, the inside front tire is dropping relative to the body. Essentially, the car tips about the diagonal line connecting the inside front to the outside rear. If the rear tire does not have much droop available, then it will be lifted off the ground.
I know from your build that you have super stiff springs, lots of caster, and HUGE scrub radius.
So basically it works like a solid axle gokart - use front geometry to lift the inside rear tire so it will actually turn.
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Nice run. What time you were hoping to get? Sorry to hear that PP is looking less likely to happen. It would be great to see it come together.
Cary
Thanks. Class record is 117.1, my previous best was 117.3 weekend only got down to 117.5. Was hoping to beat the class record. Kicker is previously I was on used R6 and upgraded to A6 specifically just to beat the class record but not to be. On subsequent runs kept slowing down and eventually found both rear tires showing cords so maybe the tires were gone. Only had about 20ish runs by then.
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King of the Hill at the 'Chasing the Dragon' hill climb a few weeks back. Didnt get the laptime I was looking for but able to FTD for the weekend and get the sweetest trophy ever - a full size sword. Company cutbacks and according plummet of stock prices has PP in question for next year. We'll see over the next couple months. Regardless plans for update to fuel cell and rebuild the trans w/ faceplated gears over the winter. Last race of the year next weekend so will get torn down soon.
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You can also bolt angle iron to the ST bar and run the rod end from it. Heavy85 has a nice piece he built here, http://i1150.photobucket.com/albums/o618/ls240z/Mobile%20Uploads/image_zps6017f710.jpg
Cary
Also allows adjustment to make the legs of the bar shorter or longer depending which direction you orient the bracket.
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I started with the ultra light rotors for track car to try to keep weight down. They lasted OK but one eventually cracked. Luckily on the cool down lap of last session on Sunday. I replaced with the heavier version and immediately noticed more consistent stopping performance due to the extra heat capacity. Have not cracked one of those yet either and have run the same pair for the last several years.
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Here is a pic from the last race. Its in photobucket so can scroll through if you want.
Yes lateral. Braking is I think around 1g but dont have it in front of me now.
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Really? That is some serious downforce. That's much more than any of the cars I've worked with.
Those are peak numbers (1.38 and 1.62 from last races), steady state is about 0.15 g's lower but from a strut perspective it will see the peaks. All based on Aim Solo datalogger and yes reasonable downforce.
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I added caster by adding shims between the end of the step in the TC rod and the theads to add 1-2 deg of caster. 2 was too much and kept spinning in slow, heavy braking turns so back to one. There is enough slop in the factory TC mount to the control arm there is no bind. The inner control arm has a spherical too. The TC bushing is Gman nylon cone style with factory rubber on the back side. One of next mods is to change the mount out for likely one of those ball cup style (repurposed tie rods).
Cameron
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Im at about 2730 lb all in with me but Im guessing the killer is 1.4 g on 200TW street tires and 1.6 g on race tires. Depending on which series I race on both.
Now if you could just replace that strut bushing it wouldnt be a problem but a rebuild is about same cost as a new strut.
. You wont get those by getting good lap times in a vette.
TrackZpeeds CXRacing LS1 T56 240z
in Gen III & IV Chevy V8Z Tech Board
Posted
When mine started howling, it progressively got worse over the year (several years ago). Got so bad had to wear earplugs on long distant drives to the track. Ended up being input pinion bearings. Easy enough to change those bearings.