What to do for a race car?

[ericsb210]

Back in the day, I raced avidly. Spent more time at the track than any where else. I swear I tried every trick in the book. Looked heavily into the tires, felt that they were would be where it is at, being the only contact to the track. Tried slicks, slitting, varying sizes, front to rear size modifications. That didn't seem to quite get the job done. I next looked into the power plant, tried every option out there still no love. Next I looked into body work, aerodynamics and the such. Looked at lift, drag, air flow...you name it. I also tried massive lightening, but that seems pretty strait forward. After a while started looking at centering, toe, camber. Damn, I would always loose!!!!!!.

 

An old friend stopped in on one of my racing sessions, he looked on thoughtfully, observed my actions and reactions. After a while he looked over to me and said "son, I believe that you have to have the little thingy hanging out from underneath your car in that slot right there" . I sat back a gassed and amazed, he had hit the nail right on the head.

 

 

 

 

 

 

 

 

 

 

 

 

 

[HRH]

Weak sauce.  Here's something more worthy.  Corner weights!  Not bad for wild ass guessing and getting lucky!

 

 

[datsunhead]

For the corner weights to be accurate, the sway bars need to be disconnected.

[HRH]

Ah hah, you are correct sir.  But for my very low-budget, this will suffice for the moment.  Plus it's a giant pain in the ass to disconnect those bars.

[Z chopper]

You know, I think I should just sell everything and buy an older Ferrari 308. :)  I like that idea.

no not a Ferrari 308, get the poor mans version a Pontiac Fiero GT with a 2.8 v6 and bw 5 spd. specifically a 1988 Fiero GT

[HRH]

^Lol, that's more rare than the Maxima!

[Z chopper]

true but read THIS before laughing too hard

[HRH]

Too funny, but the 308 definitely looks more badass!  Still, Fiero was a good thing until GM killed it.

 

Okay, last chance for autocross in the Spokane area tomorrow!  Spokane Raceway Park road course.  Last event of the season.  Octocross.  Who's going to be there?!  :)  This guy is.

[datzenmike]

It would seem to me that if you should normally have 500 pounds at each front corner and you properly install a sway bar, it's not going to change a thing if the car is weighed on a flat surface. The sway bar is neutral and transmits no weight whatever. It's only when the front (or rear) wheels are at differing heights caused by a bump or dip in the road on one side that each side affects the other. A sway bar has no effect when driving over a symmetrical speed bump across a lane because both tires move together up and down.

 

When cornering weight transfers to the outside and compresses the suspension while the inside lifts. This imbalance is resisted by the sway bar and if you could measure the four corners you would indeed find the outside tires carrying more weight, but traveling a hundred MPH on the level they would weigh the same as sitting still on the scales.

[HRH]

That's assuming the bar is exactly equal to the control arms, but it's not.  ;)  The bar is also not perfectly straight, one side is cocked a little farther down than the other.  Because it adds spring rate, even at static it still affects the weight totals.  Not that much, but a little.  That's why I'm not worried about it.  If I had a chassis dyno, it would be more apparent and the car could be set up uneven at static to reflect the characteristics of the bar under load at each side.  If I ever win the lottery...:D

 

In the meantime, I'm preparing for racing tomorrow.  Oh yes, she will dominate lesser vehicles!  Even though I haven't had time to solid mount the rear suspension.

[datzenmike]

Why would the bar be bent down on one side? It should be totally neutral at rest. Otherwise it's just like adding wedge to a stock car and favoring turns to one side more than the other. I assume auto cross isn't an oval track????

[HRH]

Most bars have some amount of twist to them.  Inevitable.  It's not perfectly straight.  Plus, even the slightest rise in one patch of pavement could raise one side or the other, and since they're connected, it affects the other side.  Regardless, it's hardly an issue given the level of competition I'm on.  And the corner weights are still pretty close to accurate.  Ideally, yes, you'd have nothing acting on the suspension other than the suspension, that way when you jack or lower one corner via the adjustable coilovers, you're getting accurate measurements.  Then you hook up the sway bar again and see where you stand.

 

http://farnorthracing.com/autocross_secrets11.html

 

 

 

Once the weights are set, reattach the sway bars and reweigh. Any major difference (more than a couple of pounds per corner) indicates preload in the sway bar - adjust the tension in the end links to eliminate it.

[datzenmike]

Right.

[LenRobertson]

The suspense if killing me, waiting to find out how Betty did at the autocross today. I'd hoped to make it there to see for myself, but too much to do here at home (including a bit of work on my 510).

 

Len

[HRH]

Here's the video from today.  Didn't do too badly.  Wasn't the fastest, but certainly wasn't the slowest.  We had a few offs on the track.  A black M3 at the tire wall and screwed up his car something wonderful.  A really nice WRX also hit the tire wall.  His was probably fixable, the Beemer was a salvage.  Tire walls are great for people, not for cars.

 

[Lockleaf]

Did your times/performance improve?

[paradime]

Nice run H. Looks like there's some body roll that could be stiffened up. but I'm shocked at how well the car handles. Betty looks like she's fun to drive.

[HRH]

Yeah, times were better, but still 4-5 seconds behind first place.  

[datzenmike]

Sounds like it revs slightly faster. :thumbup:

[ericsb210]

Apologize for the sins of my earlier post. 

 

I know for better MPG they fill in the gutters and plexi glass the front end for better airflow, remove the side mirrors and what ever else that can cause turbulence. Some go as far as putting a sheet of aluminum or such underneath the car so that the air does not boil.

 

Could this be worth a second?

[HRH]

Probably in real racing, in autocross the speeds are pretty low.  Still might help.  However, I may be going a different direction.  We shall see in the coming days.  Haven't committed yet.

[q-tip]

Lighter lighter lighter

[Datsunawi]

Well that was a fun run!  Pulls nicely in 2nd, I'm not an expert in autocross, though couldn't you go a little faster in taking curves?

[HRH]

You can, but you'll get out of line and go slower. ;)  It never looks fast in the video.  The rest of the curves were full throttle down until entry.

[HRH]

It's official.  I'll be racing something different come next autocross season.  Made the commitment to buy tonight after checking out the car.  Don't worry, I won't turn into a snob.  ;)  But it is a Z.  280 to be exact.  With a beautiful Joe-cage.  (My Datsun guru)  Love the Maxima, but she won't win autocross even if I throw a lot more hp at her.  I may still probably keep her for rallycross or something unless someone wants to give me $1500 for her.  (I'm keeping the wheels for the Z however.)

 

That said, I'll attempt to start cluttering up the classifieds, but suffice to say, I need to come up with some more dough sooner than later.  Just pm me if you have any needs.  I'll be putting an R160 4.11 LSD from my 510 for sale before too long, and a brand new rebuilt 300ZX VG30 transmission with hardbody tailshaft rear.  Ideal for 2wd D21 VG30 trucks, or Z car, probably need to swap the tailshaft for that, I think it's a bit shorter in the trucks, but don't quote me on that.

 

Sorry, no pics yet.  She has a few dings from chump car, but she's in pretty decent condition.