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Recommendations for Spring rates?

Dan820

Dan820

Member
Joined
Nov 24, 2008
Location
Willamette Valley, Or
I'm going to be running 8" springs in my 142 (out front) and wondered what the opinion was about ideal spring rate.

Driving style for this is aggressive daily driver, with occasional autocross fun.

Was thinking 600#, but not sure.

Any input?
 
Spring rates have to be matched to strut/shock rates and also with rear spring rates. Don't pick them in isolation. 600 seems high for your intended application.
 
pwschuh said:
Spring rates have to be matched to strut/shock rates and also with rear spring rates. Don't pick them in isolation. 600 seems high for your intended application.
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There are no struts in a 140, but I know you knew that. :-P

600 isn't that high with the 140 motion ratio. You probably want something closer to 900-1000 in the front.
 
blkaplan said:
There are no struts in a 140, but I know you knew that. :-P
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The advice was intended to be general, that's why it said "struts/shocks." ;-)


blkaplan said:
600 isn't that high with the 140 motion ratio. You probably want something closer to 900-1000 in the front.
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Regardless of whether or not he is using leaking, 275,000 mile OE shocks? (Which I have to presume is the case because TBricks.)
 
pwschuh said:
Regardless of whether or not he is using leaking, 275,000 mile OE shocks? (Which I have to presume is the case because TBricks.)
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Low mileage Bilstein Tourings (Eventually HDs)

A reasonable assumption though, could have been blown KYBs (although, are there ANY kyb that aren't blown?)
 
pwschuh said:
The advice was intended to be general, that's why it said "struts/shocks." ;-)




Regardless of whether or not he is using leaking, 275,000 mile OE shocks? (Which I have to presume is the case because TBricks.)
Click to expand...

Typically you pick your spring rates and match dampers to that.
 
600lbs is about right for the front for a daily or if you prefer the ride firmer 700-1000lbs would not be unreasonable. Rear end 200-250lbs works well.

You will either need to replace your dampers or have them revalved to match the springs. If you are lowering depending on by how much you will probably also want a shortened version of the dampers.
 
OE is 300 -or about 306 if you use exact conversion from metric.

You might do well to ignore the above advice to double it.

John Parker lists progressives which might be worth considering. Just don't order them from him! I'm not sure if they are true custom, or if he matches through spring suppliers. Several suppliers have something dimesionally *very* similar (they have some specific use- 3rd rear springs on modifieds, IRRC?)

On mine, I cut only less than a turn off a pair of OE springs, had the lowest coil torched to lay flatter, ground it with an anglegrinder, then when that wasn't enough and it was still going to be likely to damage the spring seat in the lower arm, I grabbed an Energy Suspension urethane spring seat for an early Golf to even out spring-to-spring seat contact. It's an excellent street stance and rides relatively firm when combined with the IPD front bar & a hacked-on OE bar (both), a 240turbo rear bar, and 45series 17 tires.

From there, I'm not happy with two things- front shocks (I used aftermarket S10), and camber gain. I'm looking at doing an inner upper arm mount position mod for more camber gain and more caster (for active camber gain). For me, to be happy with more caster, that means I have to install the 164E PS set up I pulled at a wrecker many years ago.
 
As a point of comparison, the Volvo R-Sport progressive rate springs with 5/8 wire size are (were) 475 lb and nicely mated to the R-Sport DeCarbon shocks. I have run them with Bil HD's and stock valving on the HD's is softer than the R-Sport springs needed. The R-Sport suspension w/22 front bar and an IPD 19 mm rear bar made it a very solid tight car, very little compliance even with the progressive springs, would lean into a corner about 1/2" and stop.
I think running 600 lb springs would be far too stiff with a street car. And then re-valved Bil's will make it so rough you'd get kidney failure. A good match for the stock springs is the Bil Touring, and even then it's a pretty solid ride.
 
Dan820 said:
Driving style for this is aggressive daily driver, with occasional autocross fun.

Was thinking 600#, but not sure.
Click to expand...


blkaplan said:
600 isn't that high with the 140 motion ratio. You probably want something closer to 900-1000 in the front.
Click to expand...

I think when I looked at Fidel's car it was a little under 0.50 MR, maybe .45:1.
So the MR^2 on a broad guess is under 0.25:1, but I would really want to check. It makes a big difference.
At .25, 600lb/in becomes 150lb/in at the wheel. That's not bad for a daily sporty ride, 200-300 would be great for beating on it hard. So 800-1200 springs, which will greatly alter your free height. I don't know the free height or rate of a stock spring.

While the wheel rate is determined by using the MR squared, to get the free height you scale it using just the MR, the stock height, and the desidred height.
Beware the online calculators for this part. Some of the rate calculators are OK, but the hot rod sites can be way off with height and rate calcs. esp with shocks..
 
vvpete said:
As a point of comparison, the Volvo R-Sport progressive rate springs with 5/8 wire size are (were) 475 lb and nicely mated to the R-Sport DeCarbon shocks. I have run them with Bil HD's and stock valving on the HD's is softer than the R-Sport springs needed. The R-Sport suspension w/22 front bar and an IPD 19 mm rear bar made it a very solid tight car, very little compliance even with the progressive springs, would lean into a corner about 1/2" and stop.
I think running 600 lb springs would be far too stiff with a street car. And then re-valved Bil's will make it so rough you'd get kidney failure. A good match for the stock springs is the Bil Touring, and even then it's a pretty solid ride.
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^ This.

500# is too much.
 
ok guys the wheel rate of the spring is a third.

the factory 300# =133# at the wheel its 10" long (40 years old springs, never had a new one to test)


i ran 700#-750#-800# and 900# in my 142 (gutted) they were all 9.25 long , they were all run with the r-sport decarbons.

the 800# and 900# were too much for street, great for auto-x

the 9.25 springs in those rates only lower the car about 0.5-1"

the 700# were perfect with the r-sport shocks for street and did good at auto-x

i'm going to go to a 8.75 spring to get the front a bit lower when i put it back on the road (health allowing)

i have tried 600# 8" springs in my old 145, it gave it 2 inches of travel (were the bumo stop is) before it was on a metal to metal bump stop, ( factory ones were cut , then removed)

with a 8" spring i would go with at least a 7-800# spring unless you plan on using the bump stops like a miata. and please get shocks to match, otherwise its gonna feel like :-P

lets say we go with the mike p approach, double the factory rate as a starting point #600 (200 wheel) depending on ride height desired 7-9 inch.
 
For my daily 145 I'm running 600lbs x 8" open length springs with a set of my adjustable dampers. The roads here a very rough but the ride is nice and comfortable and better than many modern sporty cars. I've been tempted to go a little stiffer and possibly a bit shorter but I know I will loose ride quality.
Soft springs give a worse ride then hard springs! I'd rather the odd jolt rather than be in a sailing boat while the sea is choppy!
 
blkaplan said:
#oldmanride
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I drove the 144 w/R-sport springs and DeCarbon for 18 yrs, 385k miles, and that was only one of the 17 or so 140's I've had with various suspensions. I used 205/60-14 Pirelli P600 summer tires and that car could stick like glue to the road, needed some compliance from the tires just to save my kidneys.

It was so far from an oldman ride it's not even laughable.

Sometimes I think the ideas for what it takes for handling these Volvo's is way too complicated, 90% is driving and tires, and just throwing a ungodly harsh cut-spring, go-lo, skinny tire, suspension at it isn't gonna get you there. Too stiff and you loose the compliance to track through a corner and oversteer, forget about ride quality.
 
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