What spring rate ?

[Sheck44]

Ok guys, just checking to see what you guys are using for front and rear spring rates for a street driven car with an LS based engine with performance in mind. Reason I am asking is my setup with 600Lb springs in combination with Viking DA's up front seem to be quite harsh. Just an FYI, I also have a speedtech torque arm in the rear.

I know there are calculations for this, but I'm just interested to see what others are using with their LS setups.

Cheers
Steve

[frojoe]

I presume you're using the coilover-conversion Vikings that use the upper spring cup in the subrframe (identical to the QA1 design)? These have a long spring, so 600lb/in is pretty huge. On my iron block turbo LS motor I used 450 lb/in springs for a bit on QA1 conversion coilovers, and they worked well but were a bit squishy. I would've changed to 500 or even 550's if I decided to track my car on a regular basis.

I see you are running a N/A aluminum block LS7 I would suggest 450 for a fun street car, 500 for street/track car.

[Sheck44]

Thanks Joe, appreciate the feedback yes you are correct on my setup (with the exception of NA) and That's kind of what I was thinking.

Steve

[Rod P]

I run 750lb 8" hyperco front springs and 250lb 12" hyperco rears.....6.0 LS car

[Sheck44]

Talked to Roger at Speedtech yesterday, he reconfirms I should stick with the 600's and play with them a bit ... there seems to be a large variant on what guys are using from 450 to 750.

Cheers
Steve

[Gscherer78ta]

I am running 750# springs on 2" drop for my 2nd gen TA with stock control arms/bushings right now and some PTFB "racing shocks". I am finding that these shocks can't handle that spring rate and am about to pull the trigger on the Viking DA 19 position shocks for this set up. Anyone have any comments on the Viking DA 19 position shocks?

[frojoe]

Just to avoid misinformation, there are essentially 3 lengths of springs available for our cars and all have vastly different spring rates:

1) Stock spring (uses spring pockets on subframe as well as LCA's) I believe is in a 12"-14" range (changes depending if OEM vs aftermarket vs aftermarket lowering, etc) and are generally quite soft (200-300lb/in?)

2) Traditional design "conversion coilovers" like QA1/Viking that re-use the subframe spring pocket however have a threaded collar on the shock body to support the bottom of the spring. These are in the 10-11" uncompressed length if I remember correctly, and usually have spring rates available in the 350-550 range (for our cars 400lb/in is quite soft and 350lb/in would almost be undriveable)

3) Newer "coilover conversion" design like the Ridetech, where the spring is entirely captured by collars on the shock body and the shock itself has a Tbar mount on the bottom and a pillow ball like upper stud mount. Because the spring is entirely captured on the shock body, and has to clear the subframe as well as the LCA, the spring has to be a much shorter uncompressed length of 8" in order to clear everything (spring rates available from 500-800lb/in)

The shorter the spring gets, the higher the spring stiffness needs to be to get the same ride quality (obviously as the spring gets shorter, then available travel also decreases).

When I switched from QA1's with 10" 450lb/in springs to the same control arm setup but with 8" 700lb/in Ridetechs, for curiousity sake I calc'd that the equivalent rate of the new springs would've equalled ~430lb/in if in the length needed to fit the old QA1's.

Rod P's setup of 750lb/in 8" springs is now what I'm running, and that should have an equivalent ride feel to maybe a 475lb/in spring that is the proper length to fit a QA1/Viking conversion coilover, or maybe a rate of ~325lb/in for a stock-suspension length spring.

When you ask what peoples' spring rates are you have to take into account the length of the shock they're using, for stroke as well as uncompressed overall spring length.

-Joe

[frojoe]

I still say that 600lb/in is extremely stiff for a car with an aluminum block (even if it does have a blower).. even for a highly-tracked street car you would be sacrificing a lot of ride comfort as well as exntension travel and ride height, since the stiffer springs would make you ride higher and potentially run out of extension travel on really uneven terrain, and worse case scenario you would lose grip. However this last point isn't teribly relevant since all of the coilover conversion systems still allow our cars to have tons of wheel travel, and I doubt yours would be riding high enough for this traction loss to be a real concern.

[z28cp]

Originally Posted by frojoe

Just to avoid misinformation, there are essentially 3 lengths of springs available for our cars and all have vastly different spring rates:

1) Stock spring (uses spring pockets on subframe as well as LCA's) I believe is in a 12"-14" range (changes depending if OEM vs aftermarket vs aftermarket lowering, etc) and are generally quite soft (200-300lb/in?)

2) Traditional design "conversion coilovers" like QA1/Viking that re-use the subframe spring pocket however have a threaded collar on the shock body to support the bottom of the spring. These are in the 10-11" uncompressed length if I remember correctly, and usually have spring rates available in the 350-550 range (for our cars 400lb/in is quite soft and 350lb/in would almost be undriveable)

3) Newer "coilover conversion" design like the Ridetech, where the spring is entirely captured by collars on the shock body and the shock itself has a Tbar mount on the bottom and a pillow ball like upper stud mount. Because the spring is entirely captured on the shock body, and has to clear the subframe as well as the LCA, the spring has to be a much shorter uncompressed length of 8" in order to clear everything (spring rates available from 500-800lb/in)

The shorter the spring gets, the higher the spring stiffness needs to be to get the same ride quality (obviously as the spring gets shorter, then available travel also decreases).

When I switched from QA1's with 10" 450lb/in springs to the same control arm setup but with 8" 700lb/in Ridetechs, for curiousity sake I calc'd that the equivalent rate of the new springs would've equalled ~430lb/in if in the length needed to fit the old QA1's.

Rod P's setup of 750lb/in 8" springs is now what I'm running, and that should have an equivalent ride feel to maybe a 475lb/in spring that is the proper length to fit a QA1/Viking conversion coilover, or maybe a rate of ~325lb/in for a stock-suspension length spring.

When you ask what peoples' spring rates are you have to take into account the length of the shock they're using, for stroke as well as uncompressed overall spring length.

-Joe

Um, spring rate is spring rate, regardless of spring length. It still takes 'x' pounds to compress the spring 1 inch.

However, the wheel rate can be affected if the top and/or bottom of coilover 'x' is mounted in a different spot than coilover 'y'.

[Vince@Meanstreets]

Originally Posted by z28cp

Um, spring rate is spring rate, regardless of spring length. It still takes 'x' pounds to compress the spring 1 inch.

However, the wheel rate can be affected if the top and/or bottom of coilover 'x' is mounted in a different spot than coilover 'y'.

exactly. The cosine between the DSE quadralink and a Ridetech airbar are night and day which is why Rod is up there at 250.



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