Need suspension help badly!

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nitro520 · #1 Post by **nitro520** » Mon Apr 30, 2007 8:49 am

I finally got to the track with my 77 f150. Motor has great power, but no traction at all. I had to leave at 1/4 throttle and shift immediatly to 2nd gear and feather the throttle in for about 3 seconds. Best 60' was a 1.96 at 116 mph in 12.07 at 3500' ft of alttitude.
My question is regarding the rear suspension I have the stock springs with the overload removed and rs 9000 shocks with home made cal-trac bars. The bushings are poly and I have -4 wedges in. The front has qa1 off a bb chevelle with extensions and small block springs. The front is plenty loose and has good travel.
When I leave off of footbrake at 1/4 to 1/3 throttle the pickup leaps slightly, tires barely wrinkle(30x12.5 et streets) and front and rear of vehicle raise slightly, maybe 2" and that is it. It does not transfer weight even with the front loose and the rear shocks set at 1. I am sure it has to be in the rear springs. I know the cal-tracs are working, because there is so much force that the front of the spings are bending down slightly.
I really need help to sort this mess out, debating what to do, new mono leafs that are softer and keep adjusting, or ladder or a 4-link setup. I really would like to stay with the stock setup and make it work.

#2 Post by **John_Heard** » Mon Apr 30, 2007 10:39 am

I don't really have any great ideas at the moment, but I'm just wondering how bad the weight bias is? What percentage do you have on the nose of that beast?

nitro520 · #3 Post by **nitro520** » Mon Apr 30, 2007 2:11 pm

I can't quite remember, total weight with driver is 4150#, I will try to go to the scale tonight and check again, I know it is very light in the back. I am currently trying to remove as much weight as possible off of the front, i.e. fiberglass bumper, aluminum radiator and considering moving the battery.

#4 Post by **John_Heard** » Mon Apr 30, 2007 2:33 pm

How much travel does the front end have?

bbc68nova · #5 Post by **bbc68nova** » Mon Apr 30, 2007 3:29 pm

i helped build a 80s f150 SHORTBED with a 408
and it would do the same thing it would shock the suspension so hard that it would bounce the back tires off the ground
we had home made caltracks with stock leafsprings
and we went with C\E ADJUSTABLE SHOCKS AND SPRINGS AND IT HELPED ABIT( I THINK IT WAS MORE OF THE WAY THE STOCK SHOCK PLACEMENT THAT WAS THE COULPRET BUT THAT IS ABOUT AS FAR AS HE GOT COULD BE WRONG
IT SITS RIGHT KNOW HE HAS OTHER THINGS ON HIS MIND (HOUSE ,WIFE)
BUT THE BEST HE EVER GOT WAS 12.08 ON PUMP GAS
LUKE

bbc68nova · #6 Post by **bbc68nova** » Mon Apr 30, 2007 3:44 pm

FORGOT TO SAY IN THE LAST POST WE WERE GOING TO THE DIRECTION OF THE HALF LEAF SPRING WITH COIL OVER SHOCKS AND SPRINGS
ON HIS BEST PASS THE BODY WAS SEATING AT EQUAL RIDE HEIGTH
AND I THINK THE STOCK LEAF SPRINGS ARE NOT STIFF ENOUGH

BADGMC · #7 Post by **BADGMC** » Mon Apr 30, 2007 7:19 pm

Well I had to sign up to help after reading this one. I have been fighting with the same situation for a long time. I have a 85 GMC half ton longbox that I have a twin turbo 383 in. With a suspension just like yours it has been 10.91@ 123 with a 1.54 60ft. at 4125 lbs on drag radials.

Before I went to the turbo setup I had a 177 weiand blower on it which bested a 12.29@111 with no suspension mods. It would pop the rear end up so bad it would top out the shocks and spin. I then flipped my rear end on top of the springs and lowered the front spring mount 3 inches eliminating most of the drop from the flip. This made the biggest impact out of all the things I tried. It immediately went to 12.00's besting out at 11.94@ 112 with 1.66 60ft. with the newly installed caltracs and rancho shocks on #1. However, it was still erratic and would never do the same thing twice off the line.

The current time was with the same suspension setup just a lot more power and getting lucky with a great track however it was still inconsistent in the 60ft times. I have figured out a few more things since that should make it even better.

My springs were so stiff that the shocks really didn't do anything so I took two leaves out of the spring pack. Now the difference between #1 and #9 is easily noticable where as before there was no difference. I then flipped my rear shackles over so they're like a car now with the spring eye below the mount. Now when the shackle moves forward upon launch it won't move down and lift the rear like it did. Also I mounted my shocks vertically behind the rear end housing. My initial driveway testing shows that it picks the front up way better now and the rear end separation is very limited compared to what it was before. We'll see what happens hopefully in a few weeks.

I can't promise anything but maybe some of this will help you out.

nitro520 · #8 Post by **nitro520** » Mon Apr 30, 2007 9:30 pm

Badgmc, many thanks for signing up to help me out. I think you have some ideas that will get me in the right direction. One question, what do you think made putting the rear end on top of the springs so much better, just curios. I have thought and now I am going to pull some leafs out so it will squat in the rear. I will probably follow exactly what you did.
I really need to get this sorted out before the new motor is finished. I am hoping to get in the high 10's.
For those that were asking about weight and travel. I weighed the beast tonight and had 2440# on the front and 1700# on the rear, with 5.5" inches of front end travel.

BADGMC · #9 Post by **BADGMC** » Tue May 01, 2007 12:15 am

My main reason was that all cars with leafs are this way and with lowering the front hanger I had to to avoid raising the rear end up. It ended up 2" lower than before which made it sit level which I also wanted. If you draw a line from the contact patch of your rear tire through the front spring eye it should go through the center of gravity or about the transmission area of the vehicle. The caltracs are supposed to improve this as well as the front of the bar becomes the lift point instead which is lower yet. Look at how this line would go on your stock setup and you will see why its not a good thing. All the things I did improved this situation as I changed things.

nitro520 · #10 Post by **nitro520** » Tue May 01, 2007 2:53 pm

One more question badgmc. Did you have the caltrac bars on before lowering the front leaf spring mount?

BADGMC · #11 Post by **BADGMC** » Tue May 01, 2007 5:29 pm

No, I did however try it with just the lowered spring hangers and that by itself helped a bit.

Need suspension help badly!

Need suspension help badly!

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