Spring Rates

Trunk Monkey

Staff member
Sep 12, 2023
Charlotte, NC
Vehicle Details
'95 Thunderbird with '18 TF 5.3L - SVO Engine
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See the spring rates in the technical articles at this link:

I also found this information on spring rates over at SCCOA. In this thread. Post #8.

Also see this thread here:

For background info, I have three Thunderbirds:

A rustbucket 96 (PI heads) with sport springs and tokico blues a stock front sway bar and 1-1/8" addco rear bar.

A new to me 96 sport with a stock suspension.

A Vortech supercharged PI motored 97 with Eibachs, Tokicos and 1-1/4" Addco bars front and rear.

I have a set of 1" drop Vogtlands Springs I had purchased for the rustbucket when I broke a spring but I didn't use them because I found a replacement spring. I also have a new set of tokico blues for the 96 sport and a 1-1/8" Addco rear bar.

My plan was to use the 1" drop Vogtland springs on the 96 Sport but I have never really thought the Eibachs were great on the 97. They always felt kind of soft so I thought about putting the Vogtlands on the 97 but I like that car lower for the looks and handling increase. So I had the thought of buying 1.6" drop Vogtlands for the 97 and selling the Eibachs. Has anyone every directly compared these springs? Would this be worth time and money? Is there a better choice for 1.5" drop springs? Does anybody know the spring rate of the 1.6" drop Vogtlands. I created a chart below for the spring rates for all the springs I could find. I guessed at a 7.5% increase in rate of the 1.6" Vogtlands over the 1" drop spring.

I have the 1.6" Vogtlands on my car and am very happy with them.

I found this information on spring rates over at SCCOA. In this thread. Post #8.

These numbers vary from slightly to dramatically from what you have in your table for the Vogtland springs.

I'd trust these numbers since they're directly from Vogtland; and I'm certain that these numbers will be the same for all MN12's regardless if they're V6 SC, LX V6 or LX V8's.

RedFox at SCCOA said:
September 27, 2008

Getting information on these springs is like pulling teeth...

I read a review on a Mustang install and spoke to a vendor and all comments were very positive. This is a quality product!

Spoke to an SC vendor but he didn't know spring rate, so I e-mailed Vogtland and will post info. when I get it. So I posted my questions on the technical forum.

You can read the replies @: http://www.sccoa.com/forums/showthread.php?t=102772

1" Vogtland: 315-412 front / 530-650 rear

1.6" Vogtland: 365-400 front / 600-713 rear

1.5" Eibachs: 286-411 front / 514-714 rear

1.5" Suspension Techniques: 432/631 Linear

From the measurements from those who have Vogtland, the drop on the 1" springs is right around 1" (maybe just under) and the 1.6 give the exact same drop as the Eibachs.

So what does this all mean?

The initial rates on both Vogtland springs is higher than the Eibachs. In my books, this is a good thing as I find the Eibachs a little mushy on smooth surfaces and because of that, the rate quickly climbs on sharp bumps. So IMO, based on these numbers and without having tested a car with Vogtland springs, both Vogtland springs should provide a better ride on rough surfaces. The 1" Vogtland should provide a ride quality very similar to stock while giving you the handling benefits of the drop.

Other factors to keep in mind:

Good springs are only 1 part of the equation. Condition and quality of your shocks will also play a big role in ride quality and handling.
Polyurethane spring isolators and sway bar bushings will give you better road feel and a tighter steering feel but will transmit some of the irregularities from the road. The density of the poly also varies, so not all are created equal.
Larger sway bars will work similar to increasing spring rates without giving you such a harsh ride.

The rule that I like is "as soft as possible and as stiff as necessary". It really depends what your expectations are and what you want to do with the car.

There appears to be allot of interest for these springs. Maybe we should set-up a group buy for our club. What is the procedure?

Hope this helps.

Denis :)

Here's an additonal review/comparision of the Eibachs vs Vogtland that I found very helpful.

RedFox at SCCOA said:
December 20, 2009

A few people had asked me about these springs and to comment on the ride.

I got them installed late September and I'm very happy that they performed exactly as expected. Refer to my comparison on page 1 of this thread. They sit exactly 1/2" higher than the Eibachs (which may not seem like much) but the effect on ride quality is significant. As I pointed out earlier, maybe most of the improvement may come from the higher initial spring rate compared to the Eibachs. This provides a much smoother transition when hitting a harsh bump. That low initial rate may also have been responsible for a high speed oscillation on the highway, which is now completely gone. The car doesn't have a slammed look and appears very natural with 17" wheels and low profile 35 and 40 series tires. Obviously when it comes to looks this is entirely a personal thing. I'm running Koni adjustable shocks on all four corners and this is a great combination.

I met a guy at Mosport who was running the 1.6" version on a V8 T-Bird and he was very pleased with them.

These springs may not be that well known in North America but they are a high quality German product.


Before we go live, do you think it's a good idea to leave that Eibach info with the link to the other site up?


Before we go live, do you think it's a good idea to leave that Eibach info with the link to the other site up?


I don't see any problem with cross linking to their site. That way the content remains theirs but we can reference it. Cross linking happens all the time online.

Does anyone else have any thoughts on this?

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