Great info!! I'll try that. However, I highly doubt that I get more than 1/2 inch travel in the rear.and 1/2 inch unloading won't cause the car to break loose... I watched several videos of launches of my car and there basically is no noticable travel at the rear suspension. All the travel and weight transfer happens in front..

 

just checking i haven't been able to keep up with all the mods

 

You may find when you lower the front that you lose some of that traction oyu have. I raised my front end 1-1/2" (I ran HAL QA1 adjustables front and rear so I could raise and lower the car in addition to changing the shock settings) and I picked up a hair over 0.1 sec in the quarter mile. Much better weight transfer to the rear tires. If you do lower the front try and do it after a baseline run so you can really tell if it makes a difference.

 

Lowering the front with coil springs isn't something that you can do at the track.. Coils will have to be cut off to lower the car...

 

*IF* the front end is coming down and then back up bouncing, that is exactly what is happpening, the rear is unloading and not keeping the front end up. Shock abosrbers on Vette's are major tuning aids.

If you do the snubbers and let it come down hard against them, you can keep things planted. You might even want to try 60/40 setting on the front to slow down front end rise and keep nose down some so it doesn't lift and allow rear to unload.

Either way, I don't think it's costing you much either at this point..it's relatively mild, but as power goes up it could become a handful later on.

BTW..was that the 2-3 shift I head on that short video? Sounded like it made two shifts very quickly.

You gotta get that thing over 7000 rpm in each of the lower gears.

BTW- I've still got VBP 550 lb short fat little springs on the front of mine!

JIM

 

Jim, the 2 - 3 shift occurs shortly before the 1/8 mile and I shift at 6600... The engine is still pulling at 6600 but not hard enough to keep pushing it..
You can see the shifting RPM in this video

http://www.corvetteforum.net/c3/gran...desoto1114.wmv

If you run 550 lbs/inch front springs, you are getting all the weight transfer from the rear.. You have enough power to lift the front end up without needing soft front springs. I have a lot less power and I really want to get 95% of the weight transfer in front to reduce stress to the rear end component... I've seen too many C3 rear end components break due to squatting... The tight rear also keeps the front from twisting.. Both front wheels are off the ground by about the same height which is good.. With softer rear springs, the left side usually comes up higher than the right side...
I'm gonna try the transbrake soon and if the bouncing doesn't cause any issues for me, I'll just leave everything the way it is right now. I'm sure that I'm not loosing traction during the bounce..so for now, I'm ok..but we will see what is going to happen with the transbrake...

 

I still don't see the relationship between the spring rate of the front springs and weight transfer. Granted, the softer the front springs the more the front end will pick up. However, that does not mean it is transferring more weight. A softer spring will allow for more travel. Once the front end is off the ground the front springs don't mean a thing, they're not being used.

 

soft, long extending springs will assist in getting the wheels off the ground. In combination with drag shocks, the restistence of going up is minimized. The more the springs extend, the less power is needed to get the front wheels off the ground.. If the front wheels are off the ground means that the weight is on the rear wheels where it should be to get the best possible traction.
Just check any catalog that sells drag race springs.. You won't find a stiffer spring than 275 lbs/inch.. Most of them are 250 lbs/inch or less.. There's a reason for that.. Moroso Trick front springs are one example..
I'm getting 60' times in the low 1.50's right now... I doubt that I'd get those with stiff front springs...

 

If you have not traction problems why do you want the front end in the air?? Looks?? I ran into handling problems off the line with 90-10 shocks. Your car will have a minimum of 1 1/4 inch toe in on launch. I know your front end is in the air but it has to come down , that's when the toe and your inability to settle will really screw up your alignment.
I would think that getting the front end settled down ,and again you are not having a traction problem, that settling the front end down would be better for top end.
A few years ago I posted alot on out of the hole problems with 90-10 shocks. Going to a stiffer street friendly set really help out of the hole handling.

I know you have the video Got Traction. Look at the handling problems he ran into with his loose front end.

 

I have no traction problems at all right now.. I'd just like to get rid of the bounce because I'm concerned that the bounce will be worse with the transbrake due to the wheels higher off the ground. I think that front-bump-stops will help to eliminate the second bounce.. For my setup, I need the front to come up because I don't get any weight transfer in the rear... Teenagerwith74vettes issue was with his rear suspension.. He lost traction when the rear suspension bottomed out and broke the tires loose when the rear suspension reboundeded... That's why I went with a very stiff rear spring so that the rear suspension won't bottom out.. Like I said before... I don't have any traction issues, especially since I decreased the tire pressure in my slicks.. I'm now running 12 lbs of pressure compared to 14 - 16 lbs before... I haven't spun a single time with 12 lbs of pressure...
I also got a new best 60' time without using the transbrake.. (1.539)

 

The front spring rate is used in racing to help the 'rate of rise" during the launch. If you compress a relatively tall smaller wire spring a whole lot, then it has more stored energy and will "unload" quicker and help front end lift. That's what the Moroso style stuff does.

But often, the rate of rise is too quick and you end up hitting tires too hard and causing the unload situation. It can even be a case of converter stall/flash not being optimum and after initial flash/hit, it can't maintain the rpm and the engine isn't in peak power which allows car to unload and bounce. Happens to me when I try to bog motor on launch..it pulls rpm low and I can get some wild stuff going on as it loads and unloads tires.

The amount of travel or lift has nothing to do with front springs..it's all about the snubbers or limiters on the frame under the upper control arms, and how low you started with. Once they contact the arm, all front end lift is over other than the ability to completely lift the front end off the ground. If you keep front tires just barely kissing the ground, you have all the weight on the rear tires and anymore won't gain much.

But hey, I love pics of mine with daylight showing too!

You can try to stiffen front shocks to control rebound and see if it helps. There are no hard fast rules...that's why everything is adjustable.

Norval has a good point. I've yet to go through it all on my Vette yet, but I can tell you that spending a couple of weekends working out camber change and toe-in issues during launch gave me almost .2 on my old Camaro. No other changes and it really helped things. The tires were going the right direction finally!

I also know if a high 8 sec NMCA Malibu that went from Moroso style springs to stock 305 A/C springs, which jacked front of car up a lot compared to Moroso's and it really helped. All the bad boy street race guys told him to try it even if it didn't make sense...and wham..instant quickest 60's ever. Who'd of thought it...

The point is to keep trying new stuff.

"If you always do what you've always done...you always get what you always got"

See ya,

JIM

 

I think that pulling the wheels off the ground is cool, even if it doesn't give you a better ET... My main concern is to do it safely... Right now, the bounce is not an issue, but it might be if the wheels will come off the ground by a foot...

I believe that my 60' time would be difficult to improve with any change
considering that I'm hooking perfectly right now..
On a car that has traction issues, it can make a huge difference indeed....