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Autocross Springs

4675 Views 87 Replies 14 Participants Last post by  toonwarrior
My current setup:

Hotchkiss springs, bilstein shocks, spohn adjustable swaybar endlinks, BMR front and rear swaybars, BMR fixed extended length control arms upper and lower, spring perch relocated on axle adding like half an inch of ride height to the rear.

The car feels fairly planted street driving and what not, but when I took it to the course I was being thrown left and right with the roll. So it seems like the suggested advice is to go with a non-progressive spring which would be the global west 750#s.

But I've seen many mentions that if people could re-do it they would go with 800#+. I guess my question is where would I buy springs like that.

Then there's the question of ride height, what is the ideal ride height for these cars front and rear. Right now my current ride height is 27" inch rear and around 26" front. If I get the new springs for the front should I be aiming for 27"?

As for the rears, is keeping the progressive Hotchkiss rear springs ok?

Orrr do I just wait and save up for an adjustable setup.
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I went with 7268 and 5419 and the car is level. 91ss has the spread sheet with the numbers. Your front springs are very close to mine so consider the 5419. Other people and myself rightly or wrongly believe there is a front to back spring ratio and that is why I went with 173 lbs. I do not find my springs give me a hard ride but you hear more than feel the bumps if the tires and shocks match the springs.

If you want 5419 springs I have a NOS pair that never came out of the box.
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As you can see the two fronts are very close but my rear hub is closer to the body line.
The 5419 is the highest of your choices.

Both front and back are on spring isolators.

hopefully shipping isn't dumb expensive.
25 lbs
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Doing a quick search through my Moog spreadsheet.
These are Moog springs that get you close to an SS spring but only going by calculations. No actual experience.
The stock SS spring in my 91, with airbags fitted measures at about 10.5 inches. Might be around 10 with out bags. That's why the 5395 (HD for box style) has been at times referred to here as a close replacement.

SS is 10.5 inch installed(for me with bags) with a 154 lbs/in rate

First column is PN. Last 4th from the end column is calculated installed height into an SS based on it's weight and 3rd from the end is the spring rate. A box caprice is lighter in the back so actual would be higher.

5387 5.57 0.609 8.5 1089 9.5 157 15.42 Pigtail Ends
5395 5.54 0.609 10 901 9.9 167 15.52 Pigtail Ends
5415 5.57 0.61 9 950 9.1 170 14.6 Pigtail Ends
5417 5.562 0.61 8.5 1200 10.2 157 16.13 Pigtail Ends
8307 5.66 0.609 9.75 907 9.6 158 15.49 Pigtail Ends

Highlighted the 3rd and 4th columns as it wasn't previewing nicely
5419 10.6 173
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So I'd be aiming for a 10 inch installed height I guess since mines is already half an inch higher with the relocated spring perch. I'm thinking the 10.6 might cause it to be a bit too high,
With the relocated perch and axle I would suggest you use the "trim height diagnosis" chart (steering section).

Motortrend reported measuring 0.83g with a stock Impala and I thought I had seen a standard circle test reporting higher.

As I have said before my target was not autocross. If my back end was high it would be just about right with a full car of people or several hundred pounds of tongue weight.

What I find weird is my LS caprice which is supposed to be stock is also showing high in pictures. This is why I suggest you measure frame to ground (front and back) to get more data points. 91SS is clear his information is not perfect and is calculated, or colored by the fact he uses air bags and is a 1991 Caprice.

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As the modifications stack up comparisons to stock become more challenging.
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