Havin a launch issue...car leaves too violently initially looking at the tapes of it from the weekend. Car specs...86 Camaro 406 (dished pistons and flat tappet cam)w/TH350 Southside Suspension with 3.90 gears. 29.5X10.5 M/Ts Best run so far is 10.61@129 w/ 1.47 60'. Car "hops" bad when leaving...looks like the front is jumpin up too quickly and causing the tires to unload momentarily, they spin 2 or 3 turns and then when the front tires slam back down it does the same thing.(tires only comin up 3 or 4 inches not wheelstanding or anything) I have CE 90/10 struts on it now...thinkin they are lettin the front rise too quickly then are too stiff when it comes back down? Considering coughing for set of Koni adjustable struts and/ or limiting the front end travel for this weekend. This is a weekly bracket basher and I need to get it calmed down a bit for consistency...also thinking about swapping the current 750 for an 850 to take away some of the initial hit? Would welcome any thoughts, suggestions or experience anyone can share?

 

sounds undergeared for that tall of a tire, but anyways I would look into the rear suspension unloading too quickly not the front. What rear shocks are you running, are you running aftermarket rear suspension? Does the rear lift or squat then unload?

 

Yeah ATI told me the same thing about the gears when I ordered my converter...LOL(they want 4.10...car is already taching 6200 through the traps tho) ) I have new 29X11 Hoosiers I am putting on this week which may help that a lil anyhow...the circumference on the MTs makes tham closer to 30 than 29.5...
If I still frame the vids the tires appear to get hit HARD when I first hit it...wrinkle HARD, tail squats slightly, and the car pitch rotates well(although it seems to rotate TOO quickly...car seems to jump up before rolling forward if that makes sense?) then as soon as the front tires clear the track they unload for a few turns, plant again then unload and spin slightly again when the front tires come back down goin past the tree...car also "bounces" when the front tires come back down. After the intial squat the rear seems to be doing its job? I have Southside Bars (basically like a crude non-adjustable ladder bar for anyone not familiar with them) set at about 3.5 degrees pinion angle, along with QA1 coil overs with the shocks set at 3 clicks from fully loose. I am staging at about 3500, if I drop down to about 3000 the car calms down quite a bit...consistent 1.51 60' times BUT my reaction times suck(.060-.080 range..at 3500 .015-.035) At 3000 the tires barely clear the track and the tires stay planted very well with slight squat through the entire launch.
Lookin at the vids it seems to be an issue with what the front end is doing upsetting the balance if the car somehow? It is CE 90/10's with a coilover conversion on the struts and tubular k-member and a-arms. I had a similar problems with a ladder bar cars over the years and tighter front shocks usually solved those....I have very limited experience with strut cars however...and shocks were MUCH cheaper to play with than swapping struts..LOL

 

I feel your pain. The S-10 in my sig is/has the same problem, it is a ladder bar set-up that we've played with the 3 moutning holes, numerious settings on the rear shocks (front is still stock with trick springs and 90/10's) and I forward a tape of it leaving and the guy told me it's not pitch rotating enough and we need more gear. Currently we run a glide with the 1.76 first gear, 4.33 gears, and a 31" tire.....so you know the obvious, and we only trap at 5900...but on the dyno we made peak hp at 6800....but my uncle refuses to swap gears to 4.88 or idieally 5.13's (he's an avid Hot Rod magazine reader with no clue on the real world of racing) but ours is doing exactly what your is.

I did try chaining the front end down and that did abssolutely nothing since front end travel is limited already.

Wish I had some first hand info to be able to help out in this situation, but I have'nt dealt with this one yet personally on my F body. Maybe Stephen can give you some ideas since he runs the same SSM bars out back too.

 

Sounds like the rear of the car is bouncing back up too quick and not staying squatted long enough to keep the tires planted. Mine started doing that with stock shocks as I made more power. I'm not familiar with coil overs and the spring rates. I just don't think its in your front suspension since its not wheel standing. Those 90/10's on the front are suppose to jump up real quick, then slowly let back down as you go down the track. I'd play with your pinion angle and rear coil overs.

 

i run the koni spa-1's front and rear. fronts stay on full firm, rears are 50/50. stock rear springs, moroso trick front springs.
thats a pretty big tire your running, strange your having problems like that.

 

I would suggest that you work on your rear suspension and gear it up. You should go thru the numbers with your motor guy and see what the calculated trap rpm's would be. If only 2-300, then go for the swap.

 

I have qa1 rear coilovers and have them set at 8 to prevent the shudder you are talking about. The looser I got the more squat and shudder I got. The firmer the better for me. When I leave I have both tires coming off the ground though. I had the probelms you speak of last year and found stiffening up the rear the best.

 

stiffen the rear definitely or try out some air bags, I bought a set and they really helped out my launch, running 5/10 on the drivers side and 25/30 on the passenger side.

 

Just wait till up step into a dedicated anti roll bar like Wolfe Crafts....makes dem bags look ghetto

 

OK....update... Went all over the car just to check for anything that may have changed...preload is still good, both front and rear suspensions are both totally bind free. Car has nearly 8" of front suspension travel however! My QA1's are set at 3...anything tighter seemed to make it want to not just bounce but spin. One possible problem we did notice was the wear pattern on the slicks, they were a used set off a buddy's 440 Cuda that I just threw on to start out the season. There is about 4-5" of slick total that look like it is being absolutely tortured while the rest in the center and outside edges look nearly perfect?? Thinking maybe his leaf spring car started an odd wear pattern that my car is making worse?

I appreciate all the input, I wish I was computer savvy enough to post the vids...the spin definitely seems tied to the front peaking then coming back down. The car jumps up before moving forward like the fornt is almost rising TOO easily. Gonna put on the new slicks this week and the Boss Lady has given me the go ahead to get a set of Konis!...LOL Seriously considering a gear swap in the next few weeks also.

Headin for a test and tune at Beaver Springs this weekend....hopefully it will give me a chance to iron everything out. I'll keep ya posted on the progress... Was planning on backhalving the car this coming winter and building a better motor...figured this mild motor would prolly only run low 11's...gotta love an over acheiver!!!!

 

In this car we have spa 1s in front and at a real track (dragstrip) we are running them almost full stiff soon it will need limiters the car usually sets the front tires down right before the 60 foot beam, best 60 is 1.35 by the way and its a 350 cube small block with a small shot of spray (150 hp jets in bigger plate so maybe 175 or so) and a trans brake turbo 350 , it has a weird rear in it not stock not a true 9 inch, but has stock lower arm pickups and a random technology torque arm that connects to a custom cross member between the frame connectors, and the pinion angle is 1 degree, and the rear shocks are konis also and they are as stiff as we can get them without bouncing over bumps down track , it has m/t 28 x 10.5 slicks and has never shaken them on launch with either of two setups.. airbags with diffrent pressures or with the anti roll bar that is in it now (custom made by me along with the fuel cell to make it fit ) ..now for the opinions 90/10 s are old technology, and the konis are newer thinking when they are adjusted (spa 1 konis im refering to) they adjust both bounce and rebound at the same time one thing i do notice is not much change in the first 1.5 turns of adjustment in your case i would start out full stiff on them and work twords looser

 

OK...between the new slicks and the Koni's the car calmed down and hooks up fantastic! Played all day at the test and tune and ended up with the Koni's set 1/2 turn from full firm and the rear QA1's set 4 clicks from loose for the most consistent 60' and reactions. 4 passes Sunday were 1.478, 1.476, 1.481 and 1.480 60' times. 10.656@127.91 10.658@127.89 10.708@127.13 and 10.722@126.93(first 2 time runs were in the morning...temp went up 10 degress and barometer dropped .05 by first round) Even got the first round bye with a .000 light! LOL Hopefully I can lean it out a bit and make it less sensitive to air changes and start goin some rounds!!!

Thanks to everyone for their suggestions! My g/f drove her stinkin Sonoma in the Mother's Day race and is HOOKED....looks like I will be draggin the old project IROC out of the weeds and droppin in last years 11.80 350!

 

Excellent news!! 60's are right there consistency wise for you to do some damage

Funny you updated, friend of ours with a 66 stang did'nt change anything from lst year, and the first two races they went to the car was just wheeliing out of control, ended up finding the shocks they had up front were completely gone, he said he could push them in/pull them out like they were empty. They put some new stockers back on the front and said now the car only lifts the tires about 2" and carries them out nicely, with a gentl touch down.....she ended up going to the Box/No Box final Saturday....nothing else changed but front shocks!!! amazing how important each piece of the puzzle is for consistency.