Mikey 97Z M6

iTrader: (37)

OK, so I had some big plans for this coming race season, but I got layed off a couple weeks ago so now I'm stuck with a half-completed car and a very limited budget. I would like to know where to spend the least amount of money to get the car to HOOK better than a 1.92 60' time. Here is where I'm at with the car and the current mods. It's a 6 speed btw.

97 Z28 with LS1 swap
-387 All-Bore (Darton MID Sleeved)
-L92 Heads (self ported)
-Stock L76 Manifold
-NW 90
-36lb SVO's
-236/236 .595/.595 112lsa
-Monster Level III Clutch Billet Steel Fly


Suspension Setup:
-QP 9" Rearend w/3.89 Gears and 31 Spline Detroit Locker
-Weld-in LCA Relocation brackets (mounted on bottom hole)
-Boxed stock LCA with poly bushings
-Adj Panhard Rod
-Rear Shocks = Stock worn out 12 years old
-Stock cut rear springs
-Stock Torque Arm but the QP 9" has a little bit of pinion angle adjustment similar to a MidWest Chassis 9"
-BMR Kmember
-!ABS
-!Cruise
-Front Shocks = Billstiens
-No front sway bar
-Rear Tires = Nitto DR's 315/35/17 on chrome 17x11 ZR1's
-Front Tires = Nitto 555 on 17x9 chrome ZR1's

-No roll bar
-No subframe connectors

I was at the track a couple weekends ago, and ran (3) 11.7X's @ 123mph. My best 60' was a 1.92 and averaged around 1.97. I was playing with launch rpm and tire pressure and it didn't really help much. Just doesn't seem to be transferring any weight to the rear at all.

Here is a vid of my best pass of the night. FWIW, track prep wasn't very good either. Stats of this pass: 1.974 60', 1/8 = 7.689 @ 96.68mph, 1/4 = 11.700 @ 123.30mph

http://www.youtube.com/watch?v=Je2jIGFBGSE

There are some things I'd really like to buy but I just can't afford at the moment. Things like dedicated drag wheels/slicks, and an adjustable torque arm are gonna have to wait. I'd just like to know if there are some cheap things I can do to make the car hook up better? I did order some new adjustable CE drag shocks for the rear, as the worn out stockers were causing wheel hop on a few passes. Should I bother moving the LCA's to the next higher hole (car is lowered)? What about an airbag?

So what do you guys think? Right now I feel the car should be running at least a couple tenths quicker even as it sits.

Mike

joblo1978

iTrader: (14)

Well, your video isn't very good for seeing what your car is doing on launch, obviously spinning though and Nitto's aren't regarded as the best for traction.

First I would check your lower control arm angle. You said you have them mounted on the bottom hole which may be giving them too much of a downward angle causing your rear to unload too fast. Switch that to the middle hole and I guarantee you'll feel the car push forward harder. You want about a -1 degree angle so that when your rear loads, you get closer to 0 degrees. That is free!

From the side it looks like your car has a good bit of rake to it as well. If you have the rear isolators in, take them out and replace it with some heater hose to lower the rear even more. It looks like you're really going to be slammed, but you should transfer weight a little bit better. Cheap mod right there too.

But I'm not sure about that either. Your short, cut, and soft rear springs could be absorbing all of your weight transfer and compressing the rear springs instead of putting weight on the tires.

Those are just some cheap things you can try.

An airbag is really a band aid for getting to much weight transfer to the right rear causing the car to launch crooked. A drag sway is a better fix for that. Since you're not hooking, that won't really help you.

I'm not doing THAT much better than you.

Mikey 97Z M6

iTrader: (37)

Thanks for the suggestions. I'll take an angle measurment on the lca and see where it's at. So the angle should be about -1 degree for the lca when all the weight is on the car? What about the pinion angle?

The pic in my sig is an old picture. It sits pretty even now but it is still lowered.

Nitto's aren't the best track tire for sure. Those were supposed to be my street tire and my plans were to get some dedicated slicks/skinnies for the track. But hey, that's just one portion of the "plan" that is now scrapped because of this shitty economy lol.....

Ya, I know the airbag is a band-aid fix, but I'm all about band-aids at this point lol.... If it will help hook the car, I'm game, and they're cheap. Has anyone here used one with success?

Mike

Mikey 97Z M6

iTrader: (37)

Well I checked the lca and there was a 4 degree difference between the body and the lca. I'm going to try the heater hose mod on the spring first and see how the lca sits. If that doesn't work I'll raise the lca bolt hole to the next highest spot and try it with and without the isolator to try get the correct angle. Also, the CE drag shocks should show up today so those are going on too.

I'm trying to get some tires (MT bias ply ET streets) lined up for the next track day.

So nobody in here has used an airbag with success?

Thanks for the help and suggestions so far!!

Mike

cambirdracing

iTrader: (4)

I have this S&W stuff for sale. It will help you out.

http://www.cambirdracing.com/photo_a...76844/54150/1/

tomcowle

iTrader: (5)

Summit drag shocks, cheap.

Mikey 97Z M6

iTrader: (37)

Probably more money than I want to spend right now, but can you send me a PM with a price for the torque arm and subframe connectors.

Mike

BlackScreaminMachine

iTrader: (17)

99% of your issue is tire compound, especially since your flying on a 6 speed. But with being laid off, you do not have a choice, just enjoy the car or borrow some bias plys

tektrans

iTrader: (23)

Launch that car with bias plys, stock torque arm and no subrames or roll bar/ swaybar and you'll likely be staring at the wall 10 feet outta the hole. That's after you twist a t top off. The guys trapping 123mph, that's no joke.
Get yourself some subrames and a torque arm/control arms and an airbag before you go back to the track. DO NOT put slicks on it the way it sits please.

To answer your question I do use 2 airbags in the rear and they work quite well for me.

joblo1978

iTrader: (14)

I don't know all about this. Seems that me that if his car isn't transferring weight properly it's not very likely that he's going to get everything out of a bias ply anyway. He also never mentioned whether he was looking at a DOT or drag slick. But from your 60' you probably know better than me.

Wanna cheap torque arm fix? I've heard of guys welding two stock ones together with decent results. Your pinion angle should be at -2 degrees. An adjustable torque arm may help you, but I didn't see really big gain with mine, and they're not cheap.

I have seen lots of guys cut 60 foots that I'm sure you would be happy with at this point with completely stock suspensions. Was it safe? I don't know, I wasn't driving.

But if you can get it to hook, and the car isn't staying level because of getting good weight transfer, than an airbag would help you. At this point, I would say don't waste your money on an airbag. Maximize what you got before you start throwing **** at it. When you can do what tektrans does, than you may need one. You need some other things first.

tittan1500

iTrader: (8)

....What was the tire pressure? did you play with it at all..beacuse it can make a huge diff

Mikey 97Z M6

iTrader: (37)

Yes, I really need to stiffen the car up and I honestly had a budgeted plan to do so until the layoff. Subframes would be a cheap fix but I really want a weld-in rollbar. I'm right on the edge of needing one for NHRA requirements anyway, so if I get weld-in subframes, then later get a rollbar it's just added weight having both IMO.

The tires I'm borrowing are a M/T ET Street (bias) 26" 10.50 on a 15x8prostar. Also borrowing the 4" front runners so I should be removing close to 80lbs of weight in the process. I just weighed one of the rear 17x11 ZR1's with the Nitto and it was 56.6lbs. Compared to the rear prostar with ET Street at just over 24lbs.

The LCA's I have are indeed stock, but they have been welded/boxed-up for strength, and do have poly bushings at both ends. Again, if I had the cash flow, I'd invest in some adjustables.

Thanks for answering my question about the airbags. I'll probably be investing in one or two before I try the ET Streets.

As for the T-top twisting off, I guess I could safety-wire them to the car just in case, lol.....

Adjustability is kind of a secondary thing, as I mostly wanted the aftermarket torque arm to get the load off the back of the trans. I don't want to be replacing a broken tailshaft housing at this point. Even if the ET streets do grip like a ****, I'm not going to be doing any 6k rpm clutch dumps until I can get that load off the tailshaft.

Like I mentioned before, there are many things I wished I could get for the car as it desperately needs certain items.

Oh, and I did play with tire pressure on the Nitto's before, started at 22lbs and I think I ended up at 16-17lbs. Didn't feel comfortable going lower than that and lowering the pressure wasn't really doing much.

Thanks again for all the suggestions from everyone. I have a decent game plan at this point:

-Adjust LCA angle (done)
-Adjust pinion angle
-Competition Engineering Drag Shocks (done)
-ET Streets and skinny front runners (done)
-Airbags
-Subframe connectors

Mike

tektrans

iTrader: (23)

If you decide to install 2 airbags make sure you don't T the lines together, you'll want to run separate lines so they don't share air under load. Good luck Mike!

Mikey 97Z M6

iTrader: (37)

Good advice again, thanks. Do you have any air pressure suggestions to start off with? The passenger side bag should get more pressure to help level out the car under launch,,,, correct?

Mike

Gen414

iTrader: (38)

Every car is different, but you can start @ 10PSI and work up/down from there. I ended up running an air bag in just the PS coil spring, as when I had teh DS in, I ended up lowering it and lowering it, until I had no pressure in it. So, I just removed it, and just ran the PS bag. If I remember correctly, I ended up @ 12 PSI in teh one bag. (this was on a Fox Body Mustang).

Also, if you are just doing a cage (and not a full chassis car) I highly recommend subframe connectors and the cage. (and not just the cage). I believe there was thread recently on that topic, and some said no need for both, I just don't agree with that. Especially on a TTop car that needs ALL the help it can get.

And then tires. You can throw ALL the suspension tricks in teh world at it, but if you don't have good tires, you are gonna spin. A good set of sticky tires are the single most important traction device on a car.


I like to call that teh KISS method

BlackScreaminMachine

iTrader: (17)

With the right driver, anything is possible. To be honest, I want the car tied up and stiffened up too. I just got a new set of QA1 rears, but I really do not have the $$$ for fronts so as much as I want to throw them on and go racing, I might just have to suck it up and wait.

I pulled both wheels last fall and as of right now, my most proudest moment in my drag racing career, and there will be more. BUT right now I have things that I need to do personally and honestly, racing is not the priority, and with that. DO what you can, borrow what parts you can and have fun.

Just do not go out expecting to turn the world on fire. Also, it sucks when your borrowing parts and have to give them back and now your slower again.....

Mikey 97Z M6

iTrader: (37)

OK I have some more questions about chassis flex. I had the t-tops out the other day and I went for a ride in the car. I noticed that the chassis seemed to be flexing when taking off from a stop light. The car felt very unsettled, like I could feel the car twisting and this was just light acceleration from a stop. It was almost like the car was rolling on a cross axis to the ps side rear.

I hadn't noticed it so much with the t-tops installed, is this normal? I still don't have subframes or rollbar installed. Just curious if anyone else has noticed this kind of unsettled chassis twisting feeling? Also, I did some quick measurements on the length of the rear lca's, and the passenger side seems to be just a hair shorter, ie closer to the front of the car. Would this explain why the car wants to walk to the left a bit (not dramatic) when spinning?

If this is in fact chassis twist, I had no idea how badly it was until I had the t-tops out.

Mike

tektrans

iTrader: (23)

don't forget the frame is separate from the front to the rear, just basically sheetmetal tying the 2 together, nothing boxed or tubed-it's gonna flex. That's why everyone's t tops leak, because of the the flex the seal is compromised. I put subframes on the car like the first week I bought the car (new) and mine have never leaked. It's a '98.

Mikey 97Z M6

iTrader: (37)

Looks like those changes made a difference at the track, so thanks to everyone for their suggestions/advice etc. I really appreciate that.

The air-bag I ordered didn't show up on Friday like it was supposed to though. Couple improvements were obviously the 60' time got down there a bit. I launched around 4000rpm on this pass. Chassis still wouldn't hold anything over that. The ET dropped almost 3/10th's and the MPH increased. I was also testing different shift rpm's so I'm happy to see the car respond with a higher trap speed, although the lighter wheels and tires could attribute that also. I had one run that was over 98mph in the 1/8th.

Changes that were made:
-CE shocks on 50/50 setting
-LCA's @ -2.5 degrees (best I could get)
-Adjusted pinion angle as best I could -1 degree
-26x10.50 ET Streets @ 17psi
-Skinnies on the front
-Shift rpm

RT - 0.004 <--- Best ever R/T
60' - 1.815
1/8 ET - 7.459
1/8 mph - 97.83
1/4 ET - 11.434
1/4 mph - 124.67

Sorry, no video this time.

Mike

tektrans

iTrader: (23)

New best mph and et, Nice day at the track
btw, I run my airbags at 30psi in both but my set up is way different than yours right now.
I would start out with 10psi on the driver side and 15psi on the pass side and take it from there. Without a good swaybar once you start hooking her good if you're making enough power she's gonna roll over to the pass side anyway, then it gets interesting, hehe-ask me how I know.
You get a little outta shape out of the gate just lift and go make your adjustments and come around again-cheaper that way.