mid 60's b bodies ( 330/sport fury/satellite/etc)

what coil over spring rates are you guys usually using on 34- 3500 hundred lbs cars that are running 10.0 or so?

I will 4 corner weight thus one next week and then call Strange /Comp etc to get their data but would like to hear from others.

My research says- lightest spring we can run without coil binding and then tune spring control return from compression with shock ( duh), tire hit with front location of ladder bar.

I know manufactures are going to give me data based on 4 corner weights, what else do we need to factor in?

Are some of you using staggered spring rates?
Staggered shock settings?
How much front end travel do you like to see before hitting the limiters?

Personally - it seems to me the faster we can get the hit to move the car forward- the better- hello!, thus too much time spent with suspension movement is counter productive as well.
right now this car has zero- nada rear of car compression.
I filmed it and have studied it to death, i don't believe the springs compressed a 1/2 inch.
Shock travel appears to be very little as well.
My hypotheses is simply the suspension isnt working and thus the tire spin on launch and second gear.
I think rear springs are 200 lbs .
Can i depend on Strange data sets based on 4 corner weights of car with driver in it, fuel cell full and tune from there?

Back in the good ole days ( grin ) we just made the rear stiff as we could and put 90/10"s up front, but we didn't go as fast as you guys are today either- grin.

Thanks guys.

Ladder bars tend to add stiffness to the suspension and keep the car from rotating the front end. Maybe it's just because they also act as an anti roll bar, but I have set up multiple cars where the car seems to be less active on launch, even though it bites harder. 200 sounds about right for the weight, but if you can swing it, it's never a bad idea to experiment with +/- pressure springs. Just like playing with shock settings. No reason to stagger spring rates. If it's necessary, then something is wrong in the car or suspension. I had problems with tire spin on shifts. It ends up my tires went away. Would still launch fine, but I have videos of tire smoke on gear changes.

The lighter the better. My 63/64 B Bodys have been 120-130 on the rear. You need a rate that puts the shock in the correct range of travel. That would be in the the middle or slightly compressed. These rates will do that. Track only you might even get away with 110, but it would be tight on compression travel. My Belvedere ran a string of 1.25-1.26 last Saturday foot braking on 10.5x31.
Doug

DVW: Would you mind sharing a little more data on car?
HP/TQ
727?
Stall?

This car is 675 hp at flywheel 511 stroker.
5400 stall
727 Rollerized- build, bolt in sprag etc
Race only car.

only 60 footing 146-148
weight transfer is basically non-existent
90/10 front shocks/travel limiters.

Its my opinion the 200 lbs are just too tight for the car and thats why there isn't any rear travel to help plant the car i don't think the shocks get a chance to do blooming thing.
Ladder bars were set in center hole ( neutral )
I would like to see some compression and the shock controlling rebound long enough to carry the car on the tire so it stays planted.
just my thoughts.
Am i nuts?

I have never ran more than 140lbs springs on a b-body with ladder bars - like Doug said 120-130 is usually about right for keeping the shock in the middle of it's range. Depending on the body style hard top or post the bias will be different - hardtops usually will carry more weight up front

Never been on a dyno. Best ever 9.00@150@3340lbs.572, guessing 900+, 727, 6100 flash. A 200 lb in my opinion is way to stiff. Rear will have very little help with rear seperation as the springs are barely compressed at ride height. Be aware power affects 60 ft. My bet is your combo has at least .05-.10 left in 60ft. Once the rear is scienced out chances are the 90/10 will be too loose. Just had my front Afco doubles tightened about 50%
Doug

What size torsion bars and what ride height in the front now? How much front end travel before the suspension limiters work?
I would lower the torsion bars to the bottom hole and see how much that helps your sixty foot times
My old ladder bar coil over Duster(3450Lbs. with me in it) started out with 175 lbs. springs, I switched to a set 150 and that helped, I should have tried a set of 130 Lbs. but I didn't
On your deal not knowing on how much weight is on the front and rear I would probably try a set of 140 Lbs. springs next

Its not my car, just one we are helping to get where it needs to be.
Agreed on front shocks- needs adjustable's.

Im thinking it should 60 ft in the mid to high 1.30's if car is right.
Im also wondering is his tires are toast even though wear indicators show tires to still be good.
My reasoning here is they are several seasons old and breaking loose pretty hard in second, wondering if age has just hardened the compound.

I will get 4 corner weights next week, make some phone calls and may reach out to you as well if you don't mind.

I'm going to assume 3400# with maybe 54% on the nose. That's about 1550 on the rear.

What shock/spring combination is on this? If it's a typical 17" extended length shock, like a 3850 AFCO, or S5206 or S5006 Strange with a 12" spring, a 200# spring has to be holding that shock at full or almost full extended length. It's can't separate without topping the shock. Plus it has to about as stiff as a solid suspension.

So, the shock installed length needs to be correct, about 13 3/4" or so. I would try a 150 if my assumptions are correct. This spring will need to be compressed a bit to hold the shock at the correct length @ ride height. Then a good shock can be used to control the separation at the hit. With that horsepower level, it won't need a lot of separation. You don't want to crush the tire.

90/10s are probably not the best choice for this car. A good adjustable shock, so you can control separation, with a bit smaller than stock torsion bar is where I would start.

Again, this is all based on assumption of what's under that car.

Cm: Thanks.
Stock front suspension other than wilwood drag brakes
I would like to see lighter torsion bars and two way adjustable shocks as well.

ladder bars and coil overs in rear- no leaf springs.
8.75 braced, 4.30 gear/spool

Car went 9.80"s on the bottle with cal-tracs - no issues when stock stroked, stroked it and its torn up everything from tranny to driveshafts to rear end housing - made a horseshoe out of it.

Im trying to help him get car sorted as he had ladder bars, coil over installed.

we did an chassis dyno at end of season last year and then took engine to engine dyno- huge chassis loss showed up.
New converter based on dyno info , chassis was twisted- put it on a chassis table and had that straightened out, stiffened chassis.

went to test and tune and, car doesn't want to hook, i shot video of the pulls he got before throwing the shaft out - u-joint clamp failure.

rear of chassis has zero movement , front try's to come up but, tire unloads , cant hold separation /rotation.
My guess is you are correct- too much spring, shock cannot work.
rear of car didn't move up or down- locked out like rear is welded to chassis.
Tire bits, lets go, bites, lets go- porpoising the car.

we just had through tranny- it was fine, i then found the tail-shaft bushing was bad, had that changed , sent converter to be checked and should have it back this week and we can get 4 corner weights then.

The rear shocks are probably topping out and unloading the rear. Lighter spring's and set the shocks up to the manufacturer's ride height.
Mines a e-body that weighs 3490 and I'm using 130 qa1. Different brands have different rates too. Strange 110's work on my car too.

a correction CM: He does have lighter spring tension torsion bars , runs travel limiters.

1. I think the 90/10's are worn smooth out- people forget they are still in use on the trailer so, however many miles one travels to races- suspension has that many miles on it too.

2. Ladder bar front point has 4 holes, he is in second from bottom.

3. Agreed, I think shock is topped out.

4. I think corner weights are going to show a max spring rate of 150, i'm thinking 130 will probably be correct.
My understanding is to use the lightest spring you can without coil bind and use a good shock- is this correct/factual?

Thanks

Im going to weight it next week Cab.
Im thinking 130-140 is going to be correct.
I have the empty weights- just driver in car, no engine/tranny/fluids and i know what those weigh, but not the distribution factors.

Im thinking the ladder bars need to be on bottom hole or 1 up.
New adjustable front shocks and the right rear springs/shock settings.

We get it close we can start playing with tire pressures vs shock settings front and rear.

i really wish i was able to get driveshaft speed readings and g forces would be really cool as well for chassis tuning- even on these old cars .
being able to see the results of "fine" adjustments would be really cool as well as beneficial.

just my thoughts

Correct shock installed length at ride height and good shocks on a ladder bar car with some power are critical. Without those, nothing else matters.

I agree fix this issue and try it. It may not need anything else.

Ok Guys, I 4 cornered the car this evening :

3363 with driver and all fluids.

50.7 percent of weight on drivers side.

47.0 percent on rear of car

LF - 973
RF- 809
LR- 737
RR- 845

Car was pretty well level.

Ladder bars:
Drivers side down in front 2 degrees.
Passenger side was dead level

Checked rear for square to car and it’s out 1/16 inch .

Current springs compressed almost an inch , shocks being held almost fully open .

What springs rate would you reccomend ?
Springs/ shocks mounted to rear of axel housing .

Thanks guys .

I reread your first post real quickly looking for your current coil over spring rating, if it is a 200 lb. rate I would try either a 130, 140 or maybe a 150 lb. spring
Did your shocks come with instructions to shoot for 2/3 compress height for the ride height ready to race? If so I have heard those same instructions from 4 different coil over companies It works well
The first coil over ladder bar drag race car I worked on and raced had 3.0 inch travel AVO on the rear, it would top them out against the foot brake staging
The first street and strip car I built with ladder bars and coil overs got a set of single adjustable Strange coil overs with 7.0 inches of travel, 15.0 inches fully extended with either 200 or 170 Lb. springs CRS
I switch the rear springs to a set of 150 Lb. springs later on and changed the shocks to a set of Strange double adjustable and that help a lot on the 60 ft. times, especially on bad tracks

Don't forget, the rear scaled weight includes unsprung weight. This must be removed from the equation. My car has never hooked as good it has this year. Just went from 130lb to 125lb. It weighs 3340 ready to race, 1830F/1510R.
Doug

Can’t get a consistent answer from places I call- screen readers, not racers/ engineers, frustrating doesn’t even begin to cover it.
No consensus- this should be math , geometry etc.

I never saw how much shock/spring travel you have. More travel should lend to a lower rate spring. For my $.01 (can't afford $.02), here's my calculations.

LR- 737
RR- 845

Total rear weight is 1582 pounds. As stated above, deduct the unsprung weight of the rear axle, wheels and tires, etc. I subtracted 250 pounds here and ended up with 1332 pounds rear sprung weight. Divide that by two (two tires) and I get 666 pounds to be supported per side.

If you have seven inches of total travel, maybe you would want to compress the spring four inches per Cab's 2/3 rule-of-thumb. 666 pounds/4 inches = 166.5 pounds/inch spring rate.

If you have ten inches of total travel, maybe you would want to compress the spring six inches. 666 pounds/6 inches = 111 pounds/inch spring rate.

Q.E.D.

That's my theory anyway. Check some of the chassis books and see what they say. You may have to test a few spring rates and shock settings to find a good setup? Hopefully this can get you in the ballpark.