Hey Arvaxx you are thinking in the right direction, but have the wrong idea here I think.

Dropping the front low will actually add more weight to the rear. But dropping the rear will just counter act that.

Think of a suspension as 4 guys holding up a pallet full of dirt on all 4 corners.

FL FR
RL RR

If Mr. FL bends his legs and lowers down. It is going to get "heavier" for everyone else. Especially Mr. RR-his cross partner.

Now imagine that instead, Mr RL and Mr. RR both lift their hands and press the whole thing up. There is now a ton of weight on the rear.

Now imagine that while they have the rear raised in the air. FL and FR in turn both raise, their hands above their head. It's now equally distributed again.

(I am assuming of course these 4 men are clones with equal strength height and arm length.)

The point is you can add weight to the rear, by either lowering the front, or raising the back.

Lower too much, and it's just like doing a squat where you put your a$$ all the way to the floor-it becomes very hard to stand up- and, if your back is bent to much(camber out), you are going to lose the leverage of your legs.


The "Correct" height(if there is one) is this:
Street car-60% of shock travel length exposed(the silver piston thingy) and usable for compression. (makes nice smooth ride)
Road race-50/50 of shock travel length exposed used for compression/Bump (handles a variety of unknowns)
Drag car-40% of shock travel length xposed 40 for compression 60 for rebound (not worried about bumps in the road or ride quality, just want to put the power back on the ground.)

Don't flame me it's not a hard rule, but a good guideline.

That doesnt make sense... if Mr FR bends his legs and lowers down, its going to put more weight on FR and RL and take weight off RR. The weight will pivot off FR and RL and lower down on FL, raising up on RR. Just like when you are carrying a couch up or down the stairs.. the guy on the bottom is holding most of the weight.

Lowering the front of your car will take static weight off the rear.

This car isnt like a solid rear axle dragster. We want static rear weight high, but rear load/compression low to avoid camber.

Just thinking about basic physics with simple objects (as in your earlier example with 4 guys), this doesn't seem right? I realize with a suspension system there's a lot more going on, but think of the extremes with a simple static object: if the rear two guys kept their end 2 feet off the ground, and the front guys raised their end way up in the air (so that the object is now getting close to vertical, but not quite), wouldn't almost all of the weight be in the rear guys' hands at that point?

with all this talk of 4 guys bending over i may have to leave the room.....

:yum:

:wtf2:

Phunk you are right as well. And maybe my model of the 4 guys holding the pallet is not good.

Instead. Let's image 4 girls from the Swedish Bikini team holding you up standing on top of the Ark Of The covenant from Raiders of the Lost Ark. IT IS THEIR JOB TO MAKE SURE THE ARK STAYS PERFECTLY LEVEL!

The swimsuit model on the front left corner, is getting tired,so she bends her knees just a little bit. She stops pushing up just a little bit. the weight on the other corners is going to increase a little bit.-but mostly is going to affect her cross weight-the rear right corner.

Now that is much different than if both of the two Bikine Models holding up the front, just let go completely. In that case-theoretically, all weight would have to be transferred to the two rear set of tits(if they don't want the friggin Ark to touch the ground).

However what could also happen, is that when the FL bikini model stops pushing up and bends over, the other girls sense this, and they stop pushing up too. Eventually they all just give up and the focking Ark of the Covenant is laying in the middle of the road.

Fortunately we have a frame on the car. So if the FL is lowered say 1/4" what really ends up happening is that corner sort of becomes a Bikini model and that 15-20 extra pounds gets distributed to the other 3 b1tches because they all are secured with metal beams to each other.

I really don't think so. I think as the front left girl bends her knees, a percentage of the total weight of the object (which was previously evenly split 4 ways) shifts from all of the other 3 (in varying amounts) to her. The lowest side/corner carries more static weight.

Damn I actually laughed out loud:nutswinger: that is some fun shik:roflpuke2:

Really? That easy? Win.

Any idea what the widest you can go without tsking off the stocks?

Also, you bring up another item i was wonering about...18 or 19s? I would think 19s are harder to spin but not sure if they hurt your time for other reasons.

Yes and I hope my previous post made you laugh hehe. Keep in mind the goal, the car stays perfectly level.

Yes if you lower the front end 12" and raise the rear end 12", then all the weight is going to be on the front. It will be physically impossible for the two rear people to hold up the weight(unless there are giant springs back there with and incredibly stiff frame). This is why just a little bit of preload is good as well, allowing you to adjust corner weights without actually moving the ride height too much. With 50 lbs of preload on the spring when you load it on the perch, you can first set the ride height, then balance. Lot of guys will do the back first, and then tune in the front. The heavier side(our front) will make more dramatic changes throughout.

When you lower one end of the car too far, it's pretty obvious because an unusual amount of weight will be transferred. That's when your roll moment goes out of whack. so you can use that as a measurement or baseline point. It's just like when you take 400 lbs and don't bend your knees on a squat rack. Sure anyone can suspend 400 lbs on their shoulders if they don't dig too deep. Try doing it with with a full knee bend.

Think of the frame of a house, it's job is to distribute equal weight to all four corners. Even if the earth sinks 1" on one side, the frame transfers this weight around. Same with a car. However, if you completely knock out one corner of the house, then you have a real problem.

be careful...you might make all these changes to get it to hook, and when it does hook... something will break lol

If you lower the front left coil of your car, that "missing" 20 lbs of force, is going to get distributed to the other 3 points. Of course, this will end at some point(when your suspension geometry fails/springs give up). And then yes, what you are saying will be correct.

I hate to subject you to this level of nerd but this video is pretty solid: corner balance a car - Bing Videos

Haha. That's ok. She likes it rough. Besides scars make everything sexier. :)

But good thing to bring up. Luckily for me I would not be stck with a garage paperweight if something went wrong. But not everyone can afford to take risks with their cars so words of caution much appreciated.

I am not sure how wide of tires the stock wheels fit. Just remember that with all the camber, the extra tire isnt on the pavement anyway. A car with a better suspension could go 9s on my 315 drag radials.

More sidewall is better for drag racing... that means smaller wheels or taller tires or ideally both. 19s will spin easier and also more likely to bust your axles.

agreed. this is one of my fears with going with sticky DR's on my car even being just N/A.

my luck the extra grip will end up blowing out my diff or a axle :shakes head:

i was at one point buying 315 19" mickey thompsons to go on my OEM rays but then thought about this exact thing lol :shakes head:

What you want the car to do coming out of the hole is weight transfer to the rear. If you have adjustable shocks in the front. You want them set full soft on rebound, and full stiff on compression. What this does is let the front come up quicker, and keeps it from settling down too soon. And a stiff springs helps too.

On the Z. You want to have the compression full stiff. This keeps it from squating, and changing camber. Stiffer springs here too.


When I used to drag raced my 440 Dart. I ran 90/10 shocks in the front, and 50/50 shocks in the rear. The front would pop up like right now. :D

I honestly dont think you need to worry about anything except your axles and rear differential mount. The 3rd gear on some of the older trans used to separate but I have not not yet heard of that happening since the CD009 trans or any of the 370z trans (and it was only the high HP TT cars that I ever heard of it happen to). Our driveshaft and differential is in the category of "bulletproof" as in nearly unheard of failures.

The diff mounts are cheap and a couple hours of work to change out. The axles arent hard but expensive if you replace with upgraded ones. Just preload the drivetrain before launch and dont stay in it during wheel hop and you probably wont break an axle.

solid info.

sadly i will not tell you how i ran my fastest 2 ET's and other 1/4 mile runs then lol my technique probably wouldnt fall into ideal for most.

also idk if it's the 7AT but i'm never had any wheel hop issues ever. i've spun on lesser prepped tracks, bald tires, or airport run ways but never any hop.

plus i think i have the only Z that will left me light up the rearsfor full burnouts with just VDC off and none of that pulling the brake fuse stuff that i see everyone say you "need" to do lol

I had Fast Intentions put in Whiteline diff bushings after they tore theirs up during their test runs (video's on youtube).

I also have the whiteline diff bushings. I busted my rear-most mount the time I went to the track, so I swapped them in.

The only time I ever really get wheel hop is in the rain. I think I got some in 1 of my passes at the track. I only brought up wheel hop because its an axle buster... I dont think its a regular problem, just wanted to mention to let off if you happen to get it.

with an auto trans car it is far easier to preload the drivetrain before launch without even thinking about it.

anytime i've ever pre-loaded the throttle all i got was wheel spin. even only at low rpm's just spins and spins.

best time i ever had was 12.89 @ 111 and that was just holding the brake until mashing the gas when i wanted to leave the line.

only preload would maybe be whatever delay that could come from when i hit the gas with my right foot as i am releasing the brake with my left foot lol

i would still preload, just not go full throttle immediately when letting off the brake. start lower and ease into full throttle. an auto car doesnt need to worry as much about preloading though... your not dumping a clutch from higher rpm. You are either brake torque launching which is already full preloaded or doing your throttle mash which isnt going to shock the drivetrain like dropping a racing clutch. ultimately it doesnt sound like you dont need to worry about your drivetrain much at all since your 7AT, i dont really imagine anything breaking from occasional drag use.

what it really sounds like is you need some better tires and alignment. you shouldnt really be having issues with wheel spin on a prepped track with a bolt-on NA setup!

:iagree: but still with any track use there's always a chance of failure on some stock parts not designed for it. so i worry sometimes since i really enjoy runnin the car. its a good time.

car has never been aligned nor have i ever had a problem with alignment.

this year i've had no wheel spin issues on the tracks even though one i dont think is well prepped lol

but i am running RE-11s this year over last year running PSS's. however last year the PSS's delivered my best time. that was also spring running vs summer running. conditions have not been too favorable this season when i've ran. typically higher humidity any night i have time to go lol it's like mother nature knows.

sure, but your car doesnt know the difference between the track and street. so it just depends on what kind of driver you are. if you rarely floor it anywhere, then I can understand staying off the track because you dont like abusing the car. but if you floor it everywhere anyway, then its all the same. Especially in a bolt-on NA car.. because in that case, the parts on your car absolutely *were* designed for it.

you dont have to have a problem with an alignment to get better traction out of a different alignment. there are a few ways to get better rear traction in your car, alignment is just one of them. if you were able to solve your traction issues with new tires, than it sounds like you dont need to worry about it. I was just addressing the fact that you said your car is nothing but wheel spin if you try and launch it. i guess you were referring to a previous setup though.

yea i think the PSS's ran a much harder compound than the RE-11's. the RE-11's feel much softer and proven by the fact i never found rubber around my wheel wells like now lol

but i do drive my car a bit harder than most and it's my DD.

for the alignment part i just never seen a want to have it adjusted for drag specific use considering i DD it and as i said before i love driving it hard and corners are plentiful in western PA. same goes for all the other "tricks" people do for ET time. my best time was full weight and full gas with 32psi in the tires. was good enough for the #5 spot but sadly i've been dropped to #7 or 8 now :shakes head: this is why i'm getting the itch again to reclaim what is mine lol

i also see no reason to change your alignment if you have adequate traction now. but on that topic, to just remove some of the negative camber doesnt hurt DD use at all. You wont notice the difference on the street to just remove some of the negative camber. But again, no reason to if you have no wheel spin issues.

Those of us with higher HP have to change our alignments, and full time. Its not just a drag specific alignment adjustment... its a full time adjustment to make the car more usable in all environments. The factory alignment with over 500rwhp makes the car pretty much useless!

That is a good point...and I am finding it to be very true.

bear in mind the issues I'm running into with most big name, and properly prepped tracks here in Ohio. I just don't want you to get heart broken when you're on the verge of breaking out of the 11s, and the track advisor escorts you off because you're not NHRA compliant. Unfortunately now a days its more than just building a power plant and shooting for the desired times like I was expecting going into this.

13.99 1/4-mile (8.59 1/8-mile) or quicker:

-A driveshaft safety loop is required when you run slicks (not drag radials or street tires). With street tires or drag radials, no loop is required until 11.49 1/4-mile (7.35 1/8-mile) and faster.

-A helmet (closed face or open) is required with a minimum Snell K98 or M2000/SA2000 rating. Helmets last 12 years from their rating date (example a Snell 2005 would be good until 2017). Shield is not required.

11.99 1/4-mile ( 1/8-mile) or quicker:

-Metal screw-in valve stems required on tubeless tires on all wheels.

11.49 1/4-mile (7.35 1/8-mile) or quicker:

-A 5-point minimum roll bar on a fixed roof car (t-tops okay as well if in place while racing) from 11.49 to 11.00 (7.00 1/8-mile). If the hardtop / t-top car has un-altered floors, firewall and frame rails (wheel tubs are okay), then the 5-point roll bar is good til 10.00 1/4 mile (6.40 1/8-mile). Convertibles require the 5-point bar from 13.49 (8.25 1/8-mile to 11.00 (7.00 1/8-mile).
The rollbar must be constructed of a minimum o.d. mild steel or chrome moly tubing (moly can be a smaller o.d and is lighter but more expensive), see diagram below for specs.
The roll bar can be bolted or welded to the floor, see diagram below for specs.
Roll bar must be padded anywhere the driver's helmet may contact it while in the driving position, see diagram below for specs.
The 5-points are:
Main hoop; 2 "down bars" (bars that go from the main hoop rearward to the trunk floor/hatch area. These can be straight or bent like a "package tray" style, search for photos); Welded crossbar for belts (can't be removable), see rulebook for exact location. Driver side door bar (can be a swing-out. Many put a passenger's side bar in as well (6-point) because it strengthens the car on both sides, but if you have subframe connectors the difference may be minimal).

-Protective Clothing (SFI jacket with a 3.2A/1 rating, no expiration date)

-5 point harness (up to date, they must be replaced or re-certified every 2 years; You can re-cert by shipping the belts to the manufacturer, or buy new ones. I usually buy new ones and sell the old ones on EBay (street racers and dune buggies buy 'em).

for space reasons i shortened your post but where in Ohio are you racing? i race in PA OH and MD. i may be able to help find you a track with some leeser attention to "details".

i run low 13's at a OH track and never have been told to wear a helmet and they also allow passengers if you're at a 11.99 or slower i believe cant remember. sadly the end of the run seems to go slightly uphill to start the shut down part of the run. so you may see a little bit slower times there.

We have a event at our track every friday that is essentially if your car is street legal you can run it down the truck (however they usually run others in between as well which is a pissoff but another story).

For us up here the rules differ from the ones posted above, for example.

"11.50 Roll Bar Rule Update: This group is limited to any unaltered 2008 or newer foreign or domestic, production type automobile or truck that is street driven with proof of registration, vehicle insurance with valid license plates. These vehicles are limited to street events, test & tune and select import events. Competition in the facilities normal weekly ET bracket series under these parameters is prohibited. These vehicles may run provided all of the criteria listed within this section is verified prior to participation. Unaltered 2008 OEM model year and newer production cars running slower than 10.00 and 135 mph do not have to meet the requirements and specifications for the Summit Sportsman ET safety rules except for the following: Convertibles and T-top entries must meet the minimum specifications listed in ET Bracket section for roll bar and roll cage requirements."

Essentially they had include this because there are some factory cars that would fail these NHRA rules.

we have street night at my local track every friday too.

when i tech'd in the guy just checked my drivers license, insurance papers, and registration. didnt even look at my car and put a number on my windows. sooooo yea if you guys wanna come run without any limitations i know a palce lol

but yes convertibles need roll bars still.

You can often get away with bypassing the safety regs, because yeah, most sup-pro-level events don't have the staff to check every car thoroughly anyways. So long as they've at least told you what you're supposed to be doing, it gives them a little liability coverage in court if you get hurt and your car wasn't up to spec.

But keep in mind those safety recommendations are there for a reason. It's probably better in practice to be doing more than your time strictly requires, if you don't want to be a drag-strip statistic someday.

i think i just get passed over for a full insepction since its a newer car, not comin in on a trailer, state inspected, etc..

now my one buddy with a older civic who comes sometimes yea he gets inspected lol

Seriously? Did I read that correctly? A 5 point roll bar...at 11.49? Holy crap! That seems a bit, no a LOT, excessive. How far are you from the state border and other options?

I have a track run by a group of older men about 45 minutes north of me that are pretty lax on the rules of inspection my biggest worry is that the stopping distance is far too short. Never the less NHRA rules are NHRA rules. The track I would like to do my 9 second test runs is Kilkare speedway south of Dayton but they are VERY strict about their rules(or at least any time I've gone they are)

if your car is a 2009 and up . it can run 10's and not require the above.
but you have to convince them that the car is stock .
eg. the GTR 's can run with no cage as long as it does not go 9.99's.
nhra rule's

Z

guess my tracks dont care then lol

my buddy ran 9.82 in his GT-R about 2 weeks ago with no cage.

EDIT: changed the ET i was slightly off but still under 9.99

Current Setup
9.82 @ 146.53mph

That's impressive as hell I hope I can dial in the Z that good. It ain't to hard with a GTR it doesn't seem it's just the cost to get it there haha