soft loc or advanced launch question

[L79racer]

Joe, I'm going to send you an email.

Jeff, I ran the car twice leaving at 4000 because it was the first time to the track with a 4 link that I put in myself. I didnt really know how the car would react so I thought I should take it easy fot the first couple of passes. I had a set of 28x11.5 M/T slicks on the car. both passes were 10.50 at 132.After the two passes I noticed the were growing more than I thought and were starting to rub the front of the quarter panels. So, I switched to a set of 28x10 Hoosier slicks which are actually about an inch shorter than the M/T's. With the hoosiers I left at 5000 but they spun a little and werent lifting the wheels off the ground. The car ran the same 60' but went 10.44 at 133. I tried lowering the air but I think the hoosiers compound is too soft for a stick car. I posted a video so you can see how the car left with the 28x11.5 M/T slicks. Check out the light I cut, not bad for a amateur.
Mustang has a 427 small block ford in it. I hope the link works!!

http://www.metacafe.com/watch/910263/vega_vs_mustang/

[Jeff Lee]

Most definetly pulls the engine WAY down on launch. The fact your laying rubber on the gear changes should tell you something...
I have no experience with a 4-link. Maybe somebody will want to chime in on that issue seperately. But it doesn't look like it's right either...My guess is the IC is to short?

[L79racer]

I/C is about 44" Tires were set at 12.5 lbs cold so, after the burnout they were problably at about 15 lbs. Shifting at 7200 got a little spin as apposed to the 4000 launch which spun a little before the engine pulled down. I think I was leaving at too low of a rpm. I'm thinking I should try a 6000 launch with the 28x11.5 slicks at 10 lbs and see what happens.

[Joe Sprint Bros]

L79, I think you would going in the right direction to leave higher and less air (9.5-10.5 lbs). I would also pull over to side at end of track(return road) and measure each tire immediately.If they are different psi (assuming same at starting line) then you need to look at chassis preload, tire circumference,etc. Are you using the Alum wheel and 900 series disc? Joe.

[L79racer]

Joe, so if the tire pressure is different at the end of the track the preload is not right and heating the tires unequally?? Am I understanding that correctly? Yes, I am using Rams aluminum flywheel and a 900 series disc. I did speak to Rob at advanced and he said he could change my springs, add the counter weigh levers and give me a new disc and chance the heat shields on the flywheel. The clutch I have is an 11" and Rob said it was way too big for what I need. At the most a 10". He recommends going to a 7". Vinny

[LNorton]

I talked with Rob about a clutch for our V6 car a while back. He is pretty keen about going to as small a disc as you can. He was thinking a 6'' unit for us. But when I told him I would put close to 400 runs on it in a year if I got to race as much as we can in these parts, he said to go with a 9'' for mileage.

After talking with him a few times, I can say that Rob is pretty slick.

Just cant afford it for now...

[Joe Sprint Bros]

L79, that's right, tires should be same +or-1/4lbs. If they are 2-3 lbs higher then you are hazing them long ways down track.I think they should only increase 3/4-1 1/2 bls once the cae is working properly. Measured circumference at starting line pressure should not be more than 1/4-3/8" on short tire. If you need new tires, make sure buy matched pair. From the video it looks like it is spinning most of the 330, and I think some of that is chassis. If the idea is to make the car launch better on a budget, I think I would be trying different bar settings, shock settings, maybe loosen the front some, since that doesn't cost much money.Adjustable shocks would allow you to tighten up for street use. Sometimes weight in the right place makes a car quicker and more consistent on the launch. Maybe retard 1st gear with microswitch on shifter? I sucessfully ran the same clutch you have(with some mods) before moving on to ADV. Since you already own this clutch, use it up while you sort out chassis, the maintenance on any of the centrif clutches is more intense and expensive. Then go buy ADV when you have the money. Joe.