SPRING RATES & DROPS: ALL IN ONE THREAD!!

Gibbo205 · Feb 19, 2016

All updated, should be correct now.

Less Weight · Feb 19, 2016

Wow, this thread is a bit of a lesson in springs. So let me see if I get this right. Generally, rear springs are anywhere from 3 to 4 times stiffer than front springs?! This comes as a surprise to me as I always thought that front springs were much more stiff than rear springs as they had to support the oscilating mass of the engine. Can someone explain the significant disparity between the front and rear rates?

RockStang · Feb 20, 2016

Thanks OP for the post. I'm a suspension noob so this an eye opener and learning opportunity for me.

:cheers:

Sinub · Feb 20, 2016

Less Weight said:
Wow, this thread is a bit of a lesson in springs. So let me see if I get this right. Generally, rear springs are anywhere from 3 to 4 times stiffer than front springs?! This comes as a surprise to me as I always thought that front springs were much more stiff than rear springs as they had to support the oscilating mass of the engine. Can someone explain the significant disparity between the front and rear rates?

I too would like to know. Only thing I can think of is maybe the manufacturers of these springs kept drag racing in mind and general racing in mind. As you accelerate all your weight transfers to the rear causing more weight in the rear than the front during acceleration. Although that alone isn't enough to explain it.

Todd15Fastback · Feb 20, 2016

You guys are likely thinking of stick axle cars and those spring rates being somewhat close to the front spring rates.

IRS equipped cars, totally different story, hence the substantial difference in rates front to rear.

Sinub · Feb 20, 2016

Todd15Fastback said:
You guys are likely thinking of stick axle cars and those spring rates being somewhat close to the front spring rates.

IRS equipped cars, totally different story, hence the substantial difference in rates front to rear.

Please explain in detail rather than simply say its IRS rather than DRS.

Glex25 · Feb 20, 2016

All my cars have been IRS and the difference between front/rear has been around 2k. The front being stronger for engine support

It does seem weird that the front is softer than the back

Less Weight · Feb 20, 2016

Well, it nice to know that I'm not the only one who is perplexed regarding spring rates. Maybe one of the after market spring representitives on this forum can explain it it us. Perhaps the gentleman from Steeda may know.

BMR Tech · Feb 20, 2016

I'm at a race in Georgia right now, but will be happy to hop on here and share some rate info soon.

I won't quite share how we came to the rates we offer....but can address the questions about why the rates are so different etc.

MtnBiker · Feb 20, 2016

Less Weight said:
Can someone explain the significant disparity between the front and rear rates?

If you look at the rear suspension you'll notice the spring is pretty far inboard ... The control arm will have more leverage to compress the spring. Need higher spring rate.

Sinub · Feb 20, 2016

MtnBiker said:
If you look at the rear suspension you'll notice the spring is pretty far inboard ... The control arm will have more leverage to compress the spring. Need higher spring rate.

That actually makes sense.

Noize · Feb 20, 2016

Less Weight said:
Wow, this thread is a bit of a lesson in springs. So let me see if I get this right. Generally, rear springs are anywhere from 3 to 4 times stiffer than front springs?! This comes as a surprise to me as I always thought that front springs were much more stiff than rear springs as they had to support the oscilating mass of the engine. Can someone explain the significant disparity between the front and rear rates?

Yeah this is really weird to me, particularly since a greater percentage of weight is on the front wheels. Granted I haven't had RWD cars in years, and never lowered one.

It has nothing to do with independent rear suspension. My car is IRS too, but AWD. Stock, my rates are almost identical to each other. On the current coilovers, rates are 10k/10.2k (560/571).

MtnBiker said:
If you look at the rear suspension you'll notice the spring is pretty far inboard ... The control arm will have more leverage to compress the spring. Need higher spring rate.

This has to be why.

Simmons-Racing · Feb 20, 2016

Noize said:
Yeah this is really weird to me, particularly since a greater percentage of weight is on the front wheels. Granted I haven't had RWD cars in years, and never lowered one.

It has nothing to do with independent rear suspension. My car is IRS too, but AWD. Stock, my rates are almost identical to each other. On the current coilovers, rates are 10k/10.2k (560/571).

This has to be why.

The Motion ratio on the S550 is pretty bad compared to other cars. This is why you need so much more rear spring compared to the front.

For example,....I am going to be running 1,600-1,800lb rear springs and 650-750lb front spring for AutoX.

Simmons

GTP · Feb 23, 2016

Less Weight said:
Wow, this thread is a bit of a lesson in springs. So let me see if I get this right. Generally, rear springs are anywhere from 3 to 4 times stiffer than front springs?! This comes as a surprise to me as I always thought that front springs were much more stiff than rear springs as they had to support the oscilating mass of the engine. Can someone explain the significant disparity between the front and rear rates?

It is what [MENTION=16770]MtnBiker[/MENTION] said - leverage.

A coilover with the spring around the shock (and located on the LCA but much closer to the wheel) would have a spring rate closer to that used at the front.

Skrapmetal · Feb 23, 2016

BMR Tech said:
BMR SP089 Minimal Drop Front Springs: .875" Drop
170lb/in

Ordered myself a pair of these today. Hoping they help with the front end pogo stick bounce as well as the little bit of drop.

SPRING RATES & DROPS: ALL IN ONE THREAD!!

Gibbo205

Well-Known Member

Less Weight

Well-Known Member

RockStang

Well-Known Member

Sinub

Active Member

Todd15Fastback

Well-Known Member

Sinub

Active Member

Glex25

Well-Known Member

Less Weight

Well-Known Member

BMR Tech

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MtnBiker

Well-Known Member

Sinub

Active Member

Noize

Ricer

Simmons-Racing

Well-Known Member

GTP

Deutsche Pony

Skrapmetal

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