singledownloop
singledownloop Reader
5/27/17 11:46 a.m.

I want to improve the suspension on my volvo pv 544.I am going to put more performance oriented coil springs on it.The car weighs 2100 pounds and has coil springs on all 4 corners.What spring rates would you guys/girls recommend?I want to stiffen up the suspension but not to the point it beats me to death when I drive it.Thanks for any and all help.

APEowner
APEowner GRM+ Memberand Reader
5/27/17 11:58 a.m.

What's the predominant use of the car? Canyon carver, track toy, Autocross, daily driver...

singledownloop
singledownloop Reader
5/27/17 12:33 p.m.

Daily driver.I'd like a ride similar to the 99 miata s I used to have.

Ransom
Ransom GRM+ Memberand PowerDork
5/27/17 12:46 p.m.

Done any research into others who've done this before? IPD?

Beyond that, remember that you're after wheel rate, not spring rate, but I think keeping the wheel rate proportional to the car you liked makes sense. I'm not sure what to do re: adjusting for front/rear balance given that the Volvo is probably more nose-heavy than the Miata.

singledownloop
singledownloop Reader
5/27/17 1:00 p.m.

Ransom I have done some research.I've found that people use mustang II front springs for volvo front springs because they are a direct fit.Several people,including a pro race car driver,use the IPD front sway bar and said it completely transformed the car but said not to use the rear sway bar.Using the rear sway bar made their cars very uncomfortable to ride in.Thoughts?

KyAllroad
KyAllroad PowerDork
5/27/17 2:25 p.m.

It's light (like a Miata) but without knowing where you suspension points are it's tough to say what rate you want.

I can say that stock Miata springs are rotini noodles at 185/118 inch/lb. (Approximately). FM springs at 390/310 (ish) were a big improvement for me. I wouldn't go stiffer on a DD.

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
5/27/17 3:03 p.m.

Yeah ~300lb/in is a good ballpark for a firm ride without being too harsh, assuming the Volvo has a somewhat Miata-like motion ratio.

Stiffer sway bars means worse ride quality, period. I'd recommend trying the springs alone at first.

singledownloop
singledownloop Reader
5/27/17 4:11 p.m.

The pv544 weighs 2100 lbs and has 50/50 weight distribution.A 99 miata,like i had,weighs 2299 lbs and has 52/48 weight distribution.This is information off the internet not mine.

iceracer
iceracer UltimaDork
5/27/17 4:42 p.m.

I doubt the 50/50 distribution, most front engine, rwd sedans run closer to 54/46.

singledownloop
singledownloop Reader
5/27/17 7:28 p.m.

A member of another forum just sent me a pic out of a original volvo 544 repair manual.According to volvo the 544 has a 51.4/48.6 weight bias.I'm including a link in case anyone wants to check my math.

https://ibb.co/j2Z8Xa

Given this fact can you guys/gals tell me what coil springs I need for the ride/handling I want?

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
5/27/17 7:42 p.m.

Is this the same car that has the "whatever crap will fit" shocks?

We can't tell you much without knowing motion ratios. This is not being pedantic, it's a fundamental piece of info.

Stampie
Stampie GRM+ Memberand SuperDork
5/27/17 8:04 p.m.

I'm just a redneck hack but what I've done is find the factory rates and then keep the same ratio front to rear but increasing it of course. YMMV.

rslifkin
rslifkin Dork
5/27/17 8:40 p.m.

I'm glad Keith mentioned shocks. Those will play a BIG factor. Quality of the shocks and how well they're matched to the springs has a massive effect on ride quality.

Good, well-matched shocks can make some surprisingly stiff springs ride well. On the other hand, soft springs with crappy, poorly matched shocks can end up being harsh and riding like crap.

singledownloop
singledownloop Reader
5/27/17 8:43 p.m.

In reply to Keith Tanner:

Not quite sure about "whatever crap will fit" shocks.It is pretty hard to find replacement front shocks so i'm guessing that's not the case.I will measure the motion ratio tomorrow,thanks as always.

singledownloop
singledownloop Reader
5/28/17 1:24 p.m.

PV544 front suspension motion ratio is .63" the rear suspension motion ratio is .83",all help appreciated.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
5/28/17 2:21 p.m.
singledownloop wrote: Keith i'm looking for a shock I can walk into any parts store and purchase.I am looking at American compact cars as well as foreign cars that we have a lot of,datsun z,rx-7,etc.for a possible solution.I'm cheap so budget doesn't allow custom ones.

That says "whatever crap will fit", because damping was never a factor. The correct way to do suspension is to choose your spring rates first, then get shocks to control them. But if you don't care what the damping is, then you're probably pretty much screwed unless you get lucky.

Stampie's method is really good for a starting point. It'll keep you in the ballpark.

The rear appears to be a solid axle, which makes things interesting. If you want the equivalent of FM springs which should put you in the ballpark, you want about 415 lb front. In the rear, on one wheel bump, you're looking at 233. Because of the weight of the car and the unknown character of the shocks, I'd probably dial that back by 25%. Having a live axle on a car that light does make it difficult to get the same ride quality as an IRS car because of the relative mass of that rear end hopping up and down and the way they react to two wheel bumps - you'll get a much stiffer reaction to that than you will to one wheel bump. I've never been able to dial in the MG to my satisfaction.

rslifkin
rslifkin Dork
5/28/17 2:52 p.m.

Solid axles can be interesting to tune. The further outboard the springs and shocks sit, the better (less difference in rate between 1 and 2 wheel bumps).

And don't be afraid to experiment with sway bars. Some setups work well with a big bar and a moderate amount of spring (front of my Jeep, for example) while others work best with lots of spring and no sway bar (rear of my Jeep, for example).

singledownloop
singledownloop Reader
5/28/17 3:05 p.m.

Keith I can't remember if I ever mentioned I was a long time mgb guy.I've had a cb mgb,a cb mgbt,and 2 rb cars.I put a 215 bulck V8 with a camaro 5 speed in on of my rb cars.I spent a lot of money with D&D fabrication some years ago.

I'm going to take your advice and have AFCO make me a set of custom shocks.I've decided it makes no sense to half ass this and hope for the best.Does AFCO tell me what I need after I tell them my spring rate and desired ride?If not would you,and other forum members help me figure out what I nead?

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
5/28/17 3:15 p.m.

They should be able to get pretty close if you tell them what spring rates you're going to use. I ordered single adjustable twin tubes for the MG, which gave me decent tuneability to swap springs around. The shocks can always be revalved if they're way out, but better to get it right the first time.

Email me at keith@flyimiata.com and I'll put you in touch with my contact there. That'll get the conversation started at least.

singledownloop
singledownloop Reader
5/28/17 3:30 p.m.

In reply to Keith Tanner:

Email sent,thanks.

maschinenbau
maschinenbau GRM+ Memberand HalfDork
5/29/17 1:26 p.m.

Hijacking this thread for help with the Rice Rod spring rates. I could really use help picking springs.

  • Front is stock SC300 geometry, which has a MR of 0.619. Modified it to fit GSXR coilovers in the stock locaiton, so I can pick a spring rate between 300 and 575 lbs/in depending on what year bike they come off of. Stock Lexus springs are around 350 lbs/in, in a 3700 lb car.

  • Rear is a solid axle with 3-link and panhard bar. Flexible on mounting locations because I'm still building the frame. I am looking at older motorcycle coilovers, such as CB750 which are in the 100 lbs/in range.

  • Weight distribution is likely 50/50 or even rear biased, due to how back the engine is (completely behind front centerline).

  • Weight is likely between 2100 and 2400 lbs.

Any help would be appreciated!

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
5/29/17 7:22 p.m.

Since it's for autocross and you're on a tight budget, I'd say you should go with the 575lb/in springs in the front and try to get something that will give you a similar effective rate on the rear, or maybe a little harder.

singledownloop
singledownloop Reader
5/31/17 12:53 p.m.

Would I be money ahead to buy coilover's or separate coil springs and shocks?

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
5/31/17 12:56 p.m.
singledownloop wrote: Would I be money ahead to buy coilover's or separate coil springs and shocks?

I wouldn't say one way is generally cheaper than the other. I would shop for coilovers just for convenience.

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