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 Post subject: Re: Suspension Dynamics.
 Post Posted: Mon Apr 06, 2009 6:44 pm 
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Scott Smith wrote:
Barry can you push the back of the car down? Maybe you have a frozen shock or a bound up anti roll.




Scott, I just checked everything back there and everything looks goods....

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Mon Apr 06, 2009 8:25 pm 
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Well Barry we only moved it one degree. It might need one more.

Video would be nice. ;-)


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 Post subject: Re: Suspension Dynamics.
 Post Posted: Mon Apr 06, 2009 8:27 pm 
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One more thing,
What is your rear gear ratio?


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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 5:18 am 
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Scott Smith wrote:
One more thing,
What is your rear gear ratio?





4.30.......

shrinker, long day yesterday so i will try tonight to get you then#s....

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 6:31 am 
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Quote:
4.30


Wow is that a diesel motor in there?

You don't have enough motor for a 4.30 gear. That gives you a starting line ratio of 7.56.
4.56 would be 8.02
4.86 would be 8.55

Even if you had a 1.92 fist you would only be 8.25 with a 4.30 gear.

Rear gear x fist gear gives starting line ratio.

Bottom line Barry you not working the tire.
Granted mine is a small block with only a 3.875 arm but my SLR is 9.00
Ken's is even higher.

This is old school but I have found it to be pretty much dead on.

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 7:05 am 
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I think Barry made his gear and possibly convertor choices based on a higher HP motor that he will eventually go to. If I'm not wrong about that I guess maybe those choices are preventing the car from doing what it should with what he is using now.

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 8:14 am 
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Quote:
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That chart doesn't take tire diameter/rollout into play or how much power the engine makes. My Camaro weighed ~2375# had a 4.56 rear gear and 1.76 low with a 383 making about 525-550hp. 8.0SLR when the chart shows it should be a 9.75. The engine was at 7k at the finish at 140mph, best 60' 1.32 and very consistent. When I ran the 360ci 18º engine with a 3.48" stroke it had a 6.17 gear with a 1.82 low for 11.2SLR and the tires were shorter at 31.5". It had a 1.19 60'. Depends on what your doing and the engine TQ/HP curve.

I've found raising or lowering the car (especially in front) helps get the amount of transfer for the power being applied. Not enough transfer and you can raise it up, too much and lower it (if you can). But the bottom line is the ideal height of the C/G will change as the power level changes.

I switched from the 750hp engine to 550hp engine and the ladder bars stayed the same, I raised the front up about an inch or two. I tried changing the ladder bar mount position up or down and had almost no effect.

Rick


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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 9:06 am 
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With the gear of 4.30 and a 1.76 trans gear and a 33 inch tire it crosses the 1/4 mile at 6900 rpm........With the 4.56 gear the rpm was 7400 rpm more in good air...

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 11:18 am 
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Beretta wrote:
With the gear of 4.30 and a 1.76 trans gear and a 33 inch tire it crosses the 1/4 mile at 6900 rpm........With the 4.56 gear the rpm was 7400 rpm more in good air...


Hey I know, put a 5 speed in it =;

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 11:32 am 
 
I'm lost on all this stuff i run a 5.14 gear with 33.5 tires go thru the traps in the 1/4 mile at 7800


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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 12:35 pm 
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ron owens wrote:
I'm lost on all this stuff i run a 5.14 gear with 33.5 tires go thru the traps in the 1/4 mile at 7800




Your car also weighs 2000lbs more than mine does O:) O:) O:) O:)

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 4:16 pm 
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Gettin back to the rear springs.......I measured the spring length, the 110lb spring is compressed to 10 inches from it's free length of 14 inches

I then put the 125lb springs on and it is compressed only 12 inches from it's 14 inch free length.......

So will it take more pressure to compress the 110 lb spring a 1/2 inch or the 125 lb spring???????

The rear seems to be softer in the rear with the 125lb spring :-k

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 5:28 pm 
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Too many cooks in this stew. I'm out of it.


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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 5:53 pm 
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shrinker wrote:
This is the info i need to calculate it if you wish too. With some example numbers.

diff ratio= 4.30
rear tyre circ= 104

gear box first gear ratio = 1.76
rear spring rate 125
front spring rate at wheel 275
tyre press psi 7.00

The four link geometry measured with car sitting on ground.
chassis end attachment upper forward of axle C/L x= ??
chassis end upper above ground y= 13.75
chassis end lower forward of axle C/L x= ??
chassis end lower above ground y= 6.75
axle end upper forward of axle C/L x= ??
axle end upper above ground y= 16.00
axle end lower forward of axle C/L x= ??
axle end lower above ground y= 13.00
scaled weight's
left rear= 526
right rear= 527
left front= 572
right front= 536
static cgh= ??
rear axle assembly weight= ford 9" with a Iron housing
wheelbase= 110
FRONT tyre dia= 25
rear tyre press= 7.0
front tyre press= 30
rear tyre tread width in contact with ground when static on start line 17
max tread width= ???
[code][/code]



This is about the best I can answer these question and some I can't?????? O:) O:)

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 Post subject: Re: Suspension Dynamics.
 Post Posted: Tue Apr 07, 2009 5:53 pm 
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Scott Smith wrote:
Too many cooks in this stew. I'm out of it.





Come on Scott stay in it......

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