suspension upgrades?

[TurboCajun]

my car has been 1.49 60ft with the stock rear with home made boxes upper and lower and air bags on both sides and this was on drag radials
since I have change to the 9" rear my best 60ft is 1.57 with slicks, I cant get the DRs to hook and even have trouble getting the slicks to hook.


What would be the first think to upgrade?

[good2win22]

Get a nice sway bar

[wmsonta]

Not enough info for me.What else did you change?
If the pinion angle and the instant center didn't change, it should hook the same. A 9" will eat a small amount more hp but not enough to count.
Is the mph at the stripe the same? RT the same?

[nocooler]

Are the uppers down hill to the rear? My guess is the mounting points on the uppers and lowers have moved a few degrees
Talk to Kevin at baseline suspension.
If you have time, plot out the suspension on his site.

[Steve Wood]

I assume you went with the 3.25 gear ratio in the Ford?  If so, you may need to add a little more timing in low gear on the chip and see if you can leave with a bit more boost.

I don't know who installed it, but, I agree as suggested above, to measure the instant center location and see where it is located.  Kevin Slaby shows you how to do it and I suspect you will need to lower the front mounting points of the upper control arms.  Kevin sells some G-body relocating pieces that make it pretty easy to do.

Main thing you need when taking the measurements is a level rack, or floor so you get the correct heights.  It's not a complicated process and a plumb bob makes it easy to be accurate.

If the IC is off a fair bit, you may not be loading the rear tires enough on launch.

I used to use this http://www.performancetrends.com/4link.htm

They have jacked the price way up, tho.  I think it was $39.95 when I bought it. LOL

[OwenOwelty]

Nice! Thanks for the tip, Steve!

[TurboCajun]

nothing else has changed. I purchased the 9" from checkered racing which the mounts for g-body were done by them. the gear ratio is 3.50 , the mph has pretty much stayed the same. I did install it myself but it was very easy. but I have never check the pinion angle as I have no way of adjusting them at this point.

[Steve Wood]

Next time,  go 3.25 on the gears.  With an engine like yours, you don't need that much multiplication to launch it.  That will give you more usable rpm at the top end.

Pinion angle is not a big thing on a four link like it is on leaf springs but you can check it any way.

I would certainly check the IC and see if it is way off, or not.

If the car wants to spin the tires off the line if you launch at higher boost, then more timing in low is not going to help, I suspect.  If they are not spinning, then try more timing in low and/or a little leaner on the O2s.

[wmsonta]

nothing else has changed. .............. ...... the mph has pretty much stayed the same.......... .......... I have never check the pinion angle

Like Mr Woods stated, pinion angle operates fine within a range. With oem style rear control arm bushings you will probably use most of that range at your power level. If the mph stayed but the short time increased, the pinion would probably be going too high. IF that is the cause. The pinion would almost have to look off.
The pinion is a shaft with a gear on one end. You will need to be able to mentally visualize the centerline of the pinion shaft. With a floor jack and the trans in park, jack up the rear wheels barely off the floor. Get close to the U joint but not the pinion seal. The whole rear weight of the car is then pushing up on the pinion.
If the pinion centerline is pointing higher than the driveshaft centerline, the pinion angle is too high.With the jack out and the rear tires on the floor, the pinion angle should be pointing higher than parallel with the floor.If one of these is off, we will need to get technical, but gains will be made.
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Apples to apples. You are trying to find 7 hundreds in a world where reaction times can make 1 1/2 tenths difference. Staging deep vs shallow can make a tenth or more. When track tuning a car, it is best to eliminate driver variables as much as possible. I try to get the guy's to stage as shallow as possible and leave on a 'hard' green. After the light goes green, you can just set there and get the rpm/boost exactly the same. You must make the car set still. The time slip will read the same no matter the reaction time.
This is enough.