Launch Suspension

[3ponyshow]

You may have the same car, but don't think you will get the same traction on the street as on the strip.

no, of course not. I'm saying I don't want to put my car through a transformation to go from one to the other. Did that once early on...never again.

So I heard back from several vendors including UPR and Maximum Motorsports. Both agree that I needed to focus on the rear setup first. I was able to put together a very attractive MM setup but unfortunately, it was too expensive for me to ever become reality. I opted to pick up some UPR upper & lower control arms. Knowing what I know now, I should've done that a long time ago. I went with the UPR's because the MM setup called for eliminating the uppers by adding a torque-arm and pan hard bar. Attractive as that was, combined with their lowers, it's what drove the price beyond what I can reasonably afford.

I looked at quite a few K-members, but focused mainly on UPR, QA1 and MM. (Once I select a vendor, I prefer to stay with them since like components tend to work better together). All 3 appear to do a very reputable job of what they're intended to do and have confirmed my Koni's are more than adequate with their setups. The QA1 is the most adaptable to my current setup and least expensive, but the UPR seems to be the lightest (-78 lbs ttl)at only a slightly higher cost. I'm a big fan of MM and apparently, so are a lot of other people as they seem to be the most popular. They're just out of my price range.

I'll get control arms installed in a few weeks and get out to the track. I'm also going to remove the front sway bar and see how it feels. If I don't like it on the street, it goes back on. As many people prefer as hate it, so it seems to be something I have to just try for myself. Lastly, I'll stiffen up my rear adjustables which have been on their softest setting due to some previous bad advise. We'll see if we can't brake the 2.0 demon.

 

[Maxpowers]

275's and I launch anywhere between 3000 and 4500 rpm's, again, depending on the track prep for the night. Orlando speed world really sucks. Once I can afford to start driving my car again the Nitto's are going to be used for street use and I am going to get some better tires. I find that they are really inconsistent.

Do your tires "skip" when launching at this RPM? I started out my psi at 25 for the night and kept lowering it. Do you advise with going to the street psi on the track with hoosier DR?

I'll get control arms installed in a few weeks and get out to the track. I'm also going to remove the front sway bar and see how it feels. If I don't like it on the street, it goes back on. As many people prefer as hate it, so it seems to be something I have to just try for myself. Lastly, I'll stiffen up my rear adjustables which have been on their softest setting due to some previous bad advise. We'll see if we can't brake the 2.0 demon.

Front sway bar is easy enough to put on an off that it's not that big of a deal. I personally wouldn't take if off if you still plan on dd the car.

 

[3ponyshow]

x2

Start with a good set of drags and a line lock, and then go from there.

Do you both run a stock 4r70w? I would think launching that high would put a serious amount of stress on both the tranny and a stock 28 spline axle.

My best 60' is 2.00 flat that I ran on 275's.

I stand corrected. While reponding to another thread, I looked at my ticket and apparently ran a 1.937 60'. I guess I don't suck as bad as I thought, but I can still do better.

 

[Flghtmstr1]

You should be able to cut at least a 1.8 60' time with your setup. Heck, I was able to cut 1.8s with C-springs, MM LCAs, 3.73s, and Sumitomo HTRZ-IIs! I was putting about 400 to the tires back then.

Now, I'm putting about 0 to the tires

 

[sneaky98gt]

What kind of blower do you have and how much torque are you making down low? (<3000 rpm?) What gears are you running? If you were blowing the 275 555Rs off, then either you have a positive displacement blower making 400+ ft-lbs of torque down low, or you have shorter rear gears. Or the track sucks.

My car, which makes 330+ ft-lbs of torque off idle up to 3500 rpm and has the stock stall and 3.27 rear gears, has gone a best 60' of 1.91. And this is leaving at 2100 rpm, dead hooking with 275/40-17 Nitto 555Rs on 8 inch rims (I don't have all of the tire on the pavement). I played around a lot with it, and leaving at a lower rpm just resulted in a slower 60', and any higher and the car bogged. With cooler air (making more power), I think I could go 1.8s, but that's about it. My tires and suspension are definitely more than sufficient for the torque I'm making on the stock stall and gears.

With the stock stall (and I am assuming stock gears), and a centri set-up, you will NOT get out of maybe high 1.8x 60's. With gears or a PD blower making more torque than I am, you may could go lower on the stock stall. Basically what I'm saying is that your tires/suspension isn't going to hold you back right now; your stall converter and low-end torque is.

So my advice:
A. Put a higher stall in.
B. Make more power down low.
C. Put shorter rear gears in.
D. Go to a track with decent prep.

Until A, B, and/or C are done, your stock suspension and current tires should be more than enough.

 

[3ponyshow]

Real good input. Thank you!

I have a centri (vortech) blower and 3.73 gears. The strip where I run is prepped second to none. I'll have to look at what tq I'm running at 2300 rpm where I launch. Launching higher is possible, but until I know how that will affect my stock tranny and axle, I'm inclined to keep it safe.

Two points that are relevant to time that haven't been discussed are the fact that even though Las Vegas International Speedway is a state-of-the-art strip, it's also at 2000' altitude. Also, when I made my best pass, the temp was still 97 degrees. Pretty common out here. Those factors make it pretty difficult to compare to others that run in better conditions, which is why I kept the questions focused on what's best for my application and not "who's best".

To your point, what made my 275's break loose was when I switched from ambient air to ice in my intercooler. Not only did I break my 275's loose, I did it 4 times and ran a 16 something. My point being apparently, I have plenty of power down low. I just need a setup to transfer it better to the rear tires and not through the rear tires.

 

[3ponyshow]

So I made the following changes.
1. Swapped the Nitto 555r 275's for 315's
2. Switched the Koni's to their hardest setting to transfer weight to the tires.
3. Replaced the stock upper and lower control arms with UPR's.

My passes sucked because I hit the rev limiter (you can hear it from 1st to 2nd in the vid) on every pass. Don't know why that just started, but anyway...

Even though I hooked well, with all these changes, my 60' didn't decrease at all! Still 1.9
LVMS 8-20-10

 

[Dark04GT]

So I made the following changes.
1. Swapped the Nitto 555r 275's for 315's
2. Switched the Koni's to their hardest setting to transfer weight to the tires.
3. Replaced the stock upper and lower control arms with UPR's.

My passes sucked because I hit the rev limiter (you can hear it from 1st to 2nd in the vid) on every pass. Don't know why that just started, but anyway...

Even though I hooked well, with all these changes, my 60' didn't decrease at all! Still 1.9
LVMS 8-20-10

1. More important than the width is the type/stickiness of the tire you use. Going from a 275 to a 315 will help a little but not because the tire is actually stickier, rather because you can get better heat transfer, rigidity, and wear in a larger tire. All are relatively minor factors in sticking to the ground. Friction can be generalized by this equation- F=μN (friction force = coefficient of friction x normal force, the μ is dimensionless and does not depend on tire width). Moving to a stickier radial sounds like your solution. I moved up to 275's because they look better not because they will give me more grip. It was the move to the sticker 555's that made the difference (much stickier over the stockers).
2. Drag suspensions are usually softer for better weight transfer, dial it in for what works
3. control arms are always a good call- hopefully you have subframes too
4. Keep practicing if you want those 1.6's (I'm happy enough with 1.9's )

 

[3ponyshow]

Moving to a stickier radial sounds like your solution.

I think I'm missing something. The tires stuck well, so I'm not sure why I would go with a stickier tire.

2. Drag suspensions are usually softer for better weight transfer, dial it in for what works

That's originally what I was told also, which is why my shocks had previously been on their softest setting. But the current popular opinion seems to be to have the rears set hard to allow the weight transfer to go through the shocks to the tires instead of being obsorbed by them. Same concept as adding SFC's.

3. control arms are always a good call- hopefully you have subframes too

Yes, I have SFC's. And yes, I thought with adding CA's I'd see a noticable difference. I was shocked to find they had no effect whatsoever.

The only other thing I can think of is that I'm running at a >5000' DA. I knew that would affect the ET, but I didn't think it would affect the launch.