F body drag racing suspension questions

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LS14gezr
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F body drag racing suspension questions

Post by LS14gezr » Sun May 12, 2013 5:37 pm

On a points day prepped track my car is very consistent (thousandths) for incremental and split times. It's when the track is less than good I have issues. Also it doesn't take much to provoke wheelspin downtrack on a suspect track. After having the same car as mine go by me on the bumper during time trials I thought it might be a good idea to seek guidance/info from S/SS racers. First my combo: 2001 camaro LS1, mid 12 second bracket car,t400,ati mrt 8" converter, 3200 stall(not optimized to my combo. Ati says it's as tight as they can make it.). Moser 9" w/4:10 w/locker. S&W sfc, adj tq arm, bmr anti roll bar, bmr rear lower control arm relocating brackets, tubular panhard bar and tubular lower control arms w/rod ends. LCA located in bottom hole(only 2 holes are available),8 pt. roll bar, Afco DA rear shocks w/V6 springs, QA1 SA front shocks(full soft) w/QA1 300# front springs. I have some preload on front springs. 53% frt / 47% rear weight distribution. M&H 26x12x15 slicks. 3650# w/driver. A modest effort, still street legal but I've had success (pts championship,runner up following year, 2012 NED 1 Bracket Finals Pro - 5 rounds w/bye).

My questions are chassis/suspension related. I am looking for a real, working suspension.

1. my pinion angle may be too negative. At 60 mph there is a vibration at light cruise/decel. Goes away on accel. What affect would a too negative pinion angle have related to drag racing?

2. While bringing up launch rpm, the car rises about 3" in rear. It's quite noticeable. I believe this relates to the rear lower control arm bottom mounting position but w/low hp I thought a high
instant center would be best. But aren't I transferring weight to the front? I' m getting good chassis separation though.

3. Front suspension: stock except for above. Using the search here I see bushings and such need upgrade. Recommendations?

4. 1.80 60'. Pretty slow. Car has never 60 footed.

5. Does the fact that I have a low hp car affect the workings of the suspension? I sometimes think that on launch the car pitches back but doesn't have enough power to keep from pitching back forward again. Afco rear DA are set: full soft extension ( have been 8 clicks up
from full soft) 16 clicks from full stiff compression.

6. My converter was setup for a bbc 468/550 hp and a lot more torque than I have.I felt that a converter that didn't hit the tire hard would provide a softer launch and make for more consistent times. Opinions?

7. The camshaft provides a very flat torque curve. 30,40 ft/lbs tops from 2500 to 6000 rpm. 371 rwtq / 354 rwhp.

I want to compete at different tracks and for instance at the bracket finals last year the track conditions deteriorated over the event. I was .1 off my 60' at the end but dialable. With a low hp combo I feel I should never have a traction issue.

I have many different chassis/suspension books for drag racing. If you need to
reference something I may have it.

I've gone on long enough. Just wanted you to have as much info as possible. Thank you in advance for any insight, recommendations, info you can provide.

E103 Ed Knodler

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nhrastocker
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Re: F body drag racing suspension questions

Post by nhrastocker » Wed May 15, 2013 9:16 am

LS14gezr wrote:On a points day prepped track my car is very consistent (thousandths) for incremental and split times. It's when the track is less than good I have issues. Also it doesn't take much to provoke wheelspin downtrack on a suspect track. After having the same car as mine go by me on the bumper during time trials I thought it might be a good idea to seek guidance/info from S/SS racers. First my combo: 2001 camaro LS1, mid 12 second bracket car,t400,ati mrt 8" converter, 3200 stall(not optimized to my combo. Ati says it's as tight as they can make it.). Moser 9" w/4:10 w/locker. S&W sfc, adj tq arm, bmr anti roll bar, bmr rear lower control arm relocating brackets, tubular panhard bar and tubular lower control arms w/rod ends. LCA located in bottom hole(only 2 holes are available),8 pt. roll bar, Afco DA rear shocks w/V6 springs, QA1 SA front shocks(full soft) w/QA1 300# front springs. I have some preload on front springs. 53% frt / 47% rear weight distribution. M&H 26x12x15 slicks. 3650# w/driver. A modest effort, still street legal but I've had success (pts championship,runner up following year, 2012 NED 1 Bracket Finals Pro - 5 rounds w/bye).

My questions are chassis/suspension related. I am looking for a real, working suspension.

1. my pinion angle may be too negative. At 60 mph there is a vibration at light cruise/decel. Goes away on accel. What affect would a too negative pinion angle have related to drag racing?

2. While bringing up launch rpm, the car rises about 3" in rear. It's quite noticeable. I believe this relates to the rear lower control arm bottom mounting position but w/low hp I thought a high
instant center would be best. But aren't I transferring weight to the front? I' m getting good chassis separation though.

3. Front suspension: stock except for above. Using the search here I see bushings and such need upgrade. Recommendations?

4. 1.80 60'. Pretty slow. Car has never 60 footed.

5. Does the fact that I have a low hp car affect the workings of the suspension? I sometimes think that on launch the car pitches back but doesn't have enough power to keep from pitching back forward again. Afco rear DA are set: full soft extension ( have been 8 clicks up
from full soft) 16 clicks from full stiff compression.

6. My converter was setup for a bbc 468/550 hp and a lot more torque than I have.I felt that a converter that didn't hit the tire hard would provide a softer launch and make for more consistent times. Opinions?

7. The camshaft provides a very flat torque curve. 30,40 ft/lbs tops from 2500 to 6000 rpm. 371 rwtq / 354 rwhp.

I want to compete at different tracks and for instance at the bracket finals last year the track conditions deteriorated over the event. I was .1 off my 60' at the end but dialable. With a low hp combo I feel I should never have a traction issue.

I have many different chassis/suspension books for drag racing. If you need to
reference something I may have it.

I've gone on long enough. Just wanted you to have as much info as possible. Thank you in advance for any insight, recommendations, info you can provide.

E103 Ed Knodler

You have to post this question in Class Racer.
There are many Stock and Super Stock racers with F Body cars that will be able to address your issues.

http://www.classracer.com

LS14gezr
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Re: F body drag racing suspension questions

Post by LS14gezr » Wed May 15, 2013 10:21 pm

I have. I was hoping for something more than I received. I realize S/SS racers work hard for their results and just don't give away their secrets. I was looking more for direction/recomendations/education on the 4th gen 3 link from guys who have been there.

Is Bill Shope still contributing on Speed Talk?

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Re: F body drag racing suspension questions

Post by nhrastocker » Thu May 16, 2013 9:12 am

LS14gezr wrote:I have. I was hoping for something more than I received. I realize S/SS racers work hard for their results and just don't give away their secrets. I was looking more for direction/recomendations/education on the 4th gen 3 link from guys who have been there.

Is Bill Shope still contributing on Speed Talk?
Just go to Class Racer and do a search; although we S/SS racers have secrets, many of us like to help and share just like in this site.

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Re: F body drag racing suspension questions

Post by John Wallace » Thu May 16, 2013 9:34 am

Why such a 'tight' converter especially from an 8" one?

The body rising in the back I would think is from not enough 'stall'.
(or leave at a lower RPM)
You're wasting most of your launch when it does that.
Too much pinion angle can hurt the launch as can not enough.

Sounds like a lot of mods without knowing what they do?

I'm no guru on suspension/chassis so my 2 cents worth I guess.

:)
John Wallace
Pontiac Power RULES !
www.wallaceracing.com

LS14gezr
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Re: F body drag racing suspension questions

Post by LS14gezr » Thu May 16, 2013 12:13 pm

Re: why a tight converter? Basically it's what I had. I had success with it and that was the bottom line. Now that I can compete at higher levels, I see that converter selection should be my next area to address.

Re: lots of mods. Yes, lots of mods. The stock suspension requires alot of mods IMO to acheive my end goals, which is a competitive, consistent bracket car. I have tried to educate myself through reading all available published materials. I experiment through small changes and extensive note taking. I was hoping by laying out everything I've done someone might spot something I've missed and/or offer advise from their own experience.

Are you the Wallace of Wallace Racing.com? If so, thank you very much for providing the calculator section. I use it frequently and recommend it to people all the time. Thank you for your response.

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Re: F body drag racing suspension questions

Post by John Wallace » Thu May 16, 2013 2:52 pm

Are you the Wallace of Wallace Racing.com?
Yes.
Is Bill Shope still contributing on Speed Talk?
He was having some problems a year or so ago.
Haven't heard from him lately.

Billy Shope's site may still be up.
Not sure.

:)
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Pontiac Power RULES !
www.wallaceracing.com

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Re: F body drag racing suspension questions

Post by LS14gezr » Sun Apr 20, 2014 12:38 am

Found the problem. The design of the aftermarket torque arm, from a well respected manufacturer, put the rear suspension into severe bind. So I made my own based on a slider link. First time out today with this setup - 3 passes 60' foot within .003. Finally a working suspension. My confidence going into the points season is high.'

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Re: F body drag racing suspension questions

Post by noice » Sun Apr 20, 2014 12:56 am

I hope it wasn't a Spohn unit. I bought some of their stuff for a F-Body and it failed me. They didn't stand by their product one bit, snapped a bolt off in my Moser 12bolt rear end that I had to damage threads to get out. I also had issues with BMR, but they stood behind their product and sorted it out for me. UMI I had no issues with.

That sucks that you spent so long trying to make a bad setup work. 1.8 60ft should have been giveaway that something was way wrong. I like to take high speed video of my car on the line and usually I can see things on the video that I didn't see in person watching the car leave.

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Re: F body drag racing suspension questions

Post by LS14gezr » Sun Apr 20, 2014 1:39 am

No, it wasn't Spohn, BMR or UMI. I've learned quite a lot during this quest. I've come to understand the engineering relationships relating to instant centers and anti-squat, setting the pinion angle with a driveshaft inclinometer and the satisfaction of solving a vexing problem by my own means which is extremely gratifying. It did take a long time to arrive at this understanding but at least the inefficiency of the aftermarket design did not prevent me from some successes.

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