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1
Tires, Brakes & Suspension / Coil Springs
« Last post by Mac on Today at 06:39:20 PM »
I’m going to totally rebuild the front end including upper and lower ball joints and control arm bushings. My question is what do you guys suggest for a coil spring compressor? I’m thinking of the inner springs compressor, I don’t think there’s room for the outer ones. I found this one on Amazon,

https://www.amazon.com/dp/B003A18KCQ/ref=cm_sw_em_r_mt_dp_F9JZC9BTVY7PJ2T35WK3?_encoding=UTF8&psc=1

Also this one

https://www.amazon.com/dp/B000GKEXP2/ref=cm_sw_em_r_mt_dp_EQCZGZQSM64BJT5DPGWF?_encoding=UTF8&psc=1

Any suggestions?
Thank You
2
Mechanical / Re: Deep Transmission Pan?
« Last post by NCBadBird1979 on Today at 05:48:40 PM »
Installed one yrs ago on my '78 with a th350 trans. Bottomed out & cracked.
It was a B&M aluminum, finned and with a drain plug. Nice part tho. PS, stock ride height.

Definitely don't want that to happen. I'll stick with the stock height.  8)
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by rkellerjr on Today at 05:15:02 PM »
So, this all looks fascinating but beyond my understanding, can someone explain to me what some of this means. I'm curious and wanting to be educated but I don't understand the math vs the car vs spring #'s, etc. Sorry to be an amateur and interested in what your talking about.
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by 79T/Aman on Today at 03:10:11 PM »
  "your preconceptions are blinding you here."

I guess it's a good thing that preconceptions win races.
Need to checkout the roads in In, Pa, Oh, Il sometime where the freezing and thawing turn roads into washboards.
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by scarebird on Today at 02:42:48 PM »
I am happy for you and Mike. 

800# springs would not fare well on New Mexico roads, or any roads in reality - pure track stuff.

I believe Herb Adam's approach is superior to Dick Guldstrand's.

"SORRY but your 275# springs are not holding up that car." 

Rubbish - your preconceptions are blinding you here.
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by 79T/Aman on Today at 02:34:17 PM »
  "Your experience has not driven/raced this car. "
Sorry but a second gen is a second gen, unless something DRASTIC was done to it it is not significantly different than any other, you have removed weight, so have we (a 77 T/A ) I posted the reading of the scale, explained what was done to it, it is still a street driven car, full interior, Hooker show bar full compliment of PTFB chassis bracing, fiberglass hood, inner fenders. Aluminum 461 Kauffman Pontiac, core support, radiator, manual master, hubs, shocks, TKO600 10 bolt rearend, PTFB Comp leafs, stock fuel tank, door beams removed, side lexan windows, "racing" seats, That car uses 800# front springs and we can bottom the suspension on the bump stops!!!
SORRY but your 275# springs are not holding up that car.
BTW we are going to 1000# springs for this year.
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by 79T/Aman on Today at 02:13:46 PM »
Not looking to have my thread turned into a one man rebuttal.
The blue Camaro I posted had 600# front springs when that picture was taken 3 years ago!! we are now at 800# and winning more races.
Picture below is Mike's blue Camaro after winning the Nashville good guys as well as the shout out not the 2 plaques on the windshield, the other Camaro came in second also with PTFB suspension.
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by scarebird on Today at 11:59:23 AM »
Cutting a spring down not change its rate.

Not true at all:



Where k=spring rate; d=diameter of the spring wire; G=shear modulus of elasticity of the spring material (11,500,000 for a steel spring); D=mean diameter of the spring's coils; and N=number of active coils.

The spring rate (k) is normally measured in pounds per inch of deflection; for example, 100 pounds per inch. A spring having this rate will compress one inch under a 100-pound load. Two hundred pounds will compress the spring two inches, three hundred pounds will compress the spring three inches, and soon. This relationship will also be exhibited when the spring is extended rather than compressed.



my experience spans 100s of cars, simple mat will show that a spring that light will bottom out.
"shaking the fillings out" tends to be an over the top abstract statement.

I don't buy loosing over 300# switching to an LS3 since the difference is only about 200#

Your experience has not driven/raced this car. 

The 300 pound difference is more than the engine; the previous drivetrain was a 403 with TH350, AC, PB, PDL, PW etc. and a much heavier bumper assembly vs. a much lighter AC compressor, manual brakes, lighter nose, battery in trunk. 

I drive this car hard - it has yet to bottom out that I have noticed.
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by 79T/Aman on Today at 10:14:47 AM »
Cutting a spring down not change its rate.

Yes but this is again something people wishfully focus on, rate increase can be estimated accurately in percentages, if you have a coil spring that is 10 coils and you remove one you will increase roughly 10% HOWEVER the first coil can be as much as 70% inactive therefore the rate increase from removing the first coil is between 3-5%
Now keep in mind that spring rate is not that relevant unless you calculate the WHEEL RATE !!! and on a second gen that is only about 30% !! (BTW this is where the 2:1 cut the spring 1/2 the amount of desired drop comes from but with 20% safety margined)
SO! lets use a 400# coil spring with 10 coils and you cut off the first coil it will shorten the spring about 3/4" to maybe 1" depending on the thickness of the wire and wire helix.
Back to our 400# spring with the first coil cut off, the spring is now 420# given 5% rate increase.
The wheel rate for our 400# is 30% =120#
Wheel rate for our 420# cut spring is = 126# as you can see 6# isn't going to do a darn thing to a car that weighs 3500-4000#

Now the softer the spring the longer it must be because it will need to be compressed more to support the weight put on it, as a result the number of coils is greater so if we go from a 400# spring with 10 coils to a 275 # spring with 12 coils you can see how removing the first coil nets about 4% increase at the coil, that is 11#  making the cut coil 286# with a wheel rate of 85# !!!!!
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Tires, Brakes & Suspension / Re: Spring rate misconception
« Last post by 79T/Aman on Today at 09:39:17 AM »
my experience spans 100s of cars, simple mat will show that a spring that light will bottom out.
"shaking the fillings out" tends to be an over the top abstract statement.

I don't buy loosing over 300# switching to an LS3 since the difference is only about 200#

Here is a customer's car with a Kaufman all aluminum Pontiac 461, it weighs about 404#, fiberglass hood, fiberglass inner fenders, aluminum hubs and calipers, lightened spindles, aluminum core support and radiator, aluminum bumpers and brackets, removed door bars, plastic door windows.
Granted it does have A/C full interior.
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