Bad idea.
You remove the variable rate portion of the spring, have less coils, loose the pigtail, not enough rate...

Google it, been discussed, dont go there.

 

Thank you for the response but I know this is a procedure that many people have done. I should have clarified that I have searched this forum for "cutting rear springs" to find that people cut anywhere from .5-1.5 coils from their stock rear springs for performance and visual gains. I guess my question is for those people who have done it, how much is too much to cut? My car seems to be a lot different in the rear than others' because the Steeda Competitions I have in the rear still sit too high and I have already tried cutting 1 coil out of a set of stock V8's and it sits even higher :livid:

Not too be mean, but there are also some inconsistencies with what you wrote. Stock V8 prings are linear (specific) and not progressive. While it is true that I will increase spring rate by removing coils, there is not a "variable rate portion" that I am removing. Nor would I ever consider cutting the pigtail portion of the spring. I am only asking if there are differences in ride height or performance that can be achieved by twisting the position of the pig tail end?

Cutting springs seems to get a bad wrap because people are thought of as being too cheap to buy the "right" springs or complain about ride quality after they throw them back on with worn out shocks, but there is a formula behind cutting that it can be done correctly and that is all I am trying to figure out.

I guess I should stop typing and start cutting. I have a set of backups if I mess up and I can always save for the coilover route and end this thread entirely. But, for those interested in following my trial and error I will keep yu updated. This is where I got the idea of cutting in the first place. http://www.mustangmotorsport.com/springs.html

Using the formula I made these calcs for spring rate after the following cuts:
1 coil = 213lbs/in
1.5 coils = 231lbs/in
2 coils = 252lbs/in (which is equal to aftermarket springs, but I fear too
much bump travel)

Thanks,
John

 

if you were going to cut them anyway, why did you bother asking?

 

Because I have not cut them past one coil yet.

 

The key here is spring rate. What rate do you want? Figure that out and you can calculate how much to cut (for those of tyou who don't have the formula, it can be found here.)

Now you know what the rate is, what about the ride height or the spring's free length? Doesn't matter because any changes here (short of heating the spring, pulling it or re-winding it, and then re-tempring the steel) are impossible. You get what you get. And if your spring rate needs to be fairly high, chances are good that you'll be cutting so many coils off, that the spring is now too short for the car to sit where you want it, or in extreme cases, is so short that when the rear suspension unloads, the spring falls out -- how embarassing!

There's a reason folks buy aftermarket springs instead of cutting their own -- the aftermarket manufacturers have designed springs that not only have the higher rates needed for different applications, they also have wound the spring so that its free length and the associated ride height are both in the ballpark for most customers.

Now, if you're fighting oversteer in a Fox or SN95 Mustang, you need to do a LOT more than get the spring rates right. However, if you're tryong to do this on the cheap -- get rid of the rear anti-roll bar. That will soften up the rear suspension a bit and give it a little more grip. A rule of thumb is if you need more grip at one end of the car, SOFTEN that end of the car, either by going to softer springs or less anti-roll bar. (Dampers can help too, but only during transient situations -- once the car takes a set, the dampers are largely out of the equation.)

 

Stock 87-93 rear springs are NOT linear-rate. They are progressive. And the only way to trim them so they'll stay located is to trim the top, softer-rated part. People trim rear springs all the time, but not too many trim the STOCK ones, which are pretty light to begin with.

 

MFE,
I know you are pretty much 100% right on the suspension stuff, but I must ask why stock 87-93 rear springs are not linear or specific rate? They don't look like the traditional progressive rate spring with the close coils up top and the big gaps towards the bottom. Maybe for 185lbs/in the softer coils at the top don't need to be that close?

Again, this is where I got my info. I know 87-93 is not outlined but I assumed the same linear nature. Maybe when I ASSUME.....:idunno:
http://www.stangsuspension.com/store/springratesarticle.asp

Thanks,
John

 

I just noticed something:

I have read that some autocross guys like to cut stock rear fox V8 springs to achieve a better stance yet softer spring rate to prevent oversteer?

Cutting the springs raises the rate, it doesn't make it softer.

Perhaps we should start back at square 1. What setup are you running right now, front and rear?

 

I just noticed something:



Cutting the springs raises the rate, it doesn't make it softer.

Perhaps we should start back at square 1. What setup are you running right now, front and rear?

Sure, thank you for helping.
I understand that cutting springs increase the rate, yet when you start with a stock 185lbs/in rear coil, cutting one coil off still keeps you below the stiff aftermarket 250-300lbs/in range. Please see my calculations above.

My car is an 1981 Mercury Capri with an 8.8 and MAC lower control arms. I currently have Steeda Competition rear springs and it looks like this. Front is 250lbs/in coilovers (no problem here)

From the mustangmotorsport.com site that I posted above the author makes the claim that autocross guys cut stock rear springs for a better ride height and feel. So instead of cutting the "dead coil" off my Steeda and hoping for the best I wanted to experiment with a set of stock springs.
Well, I cut off 1 coil last night (which made the stock spring the same physical height as the Steeda) but the car sits even higher. I know I only have a 12 gal gas tank, but is my car really that much lighter in the back? Maybe the control arm perches are higher than other aftermarket ones?

I am just looking for help.

Thanks
John

 

I don't know WHY they're not linear, I just know they aren't. Notice stock 87-93 rates aren't shown in that chart. They are in other charts I've seen, and they're listed as something like 165-265, which jives with the appearance of every single rear spring I've seen on a stock foxbody 5.0.

 

So to be 100% happy I have to go coilovers?

 

Coilovers solve a LOT of problems!

(To be fair, you could also solve this by buying factory-type springs with the rate you want and going to a LCA in the back with an adjustable perch, which is what I did in the back.)

 

Well guys, I ended up cutting 2 full coils out. At full droop with the shocks completely extended on themselves the springs still remain in the perches but they are definitely loose enough for comfort. Here's the kicker though...the car is still just as high as it was with the Steeda's. Now I haven't had a chance to drive it yet (waiting on a new fuel line for the carb) to see if the suspension is somehow bound on itself or if the springs need to hit a bump and settle, but I am baffled. The springs are physically 1" shorter than the Steeda's when they are put side to side, so I don't get it. I may be in for a bad surprise when I do get it out on the street but I am excited to find out.
What's it going to take to drop this thing? :shakehead

John

 

What's it going to take to drop this thing? :shakehead

Let's try this again. Describe, in detail, your read end setup. What control arms? What bushings? What shocks? What sway bar?

 

Mustang GT's and LX 5.0L from 1985 thru 1993 used variable rate rear springs. The rate were 200-300#/in.

This page lists most of the spring and sway bar options:

http://1985mustanggt.com/index_files/page0003.html

Also, the FMS B & C springs use the stock rear spring rate.

If your car sits "too high" have you tried removing the top or bottom isolator? If you added a new urethane isolator that may be most of your problem.

--Vince

 

When you alter your spring length (as when cutting springs) you really need to loosen up all your upper and lower control arm bolts and drive the car a short distance. Once you've done this your bushings SHOULD have readjusted themselves to the new spring lengths and altered ride height. Then torque your control arm bolts to the proper tension with the wheels on the ground (or drive-on lift) and full weight on the suspension.

If your bushing sleeves have rusted to the control arm bolts your car may not change ride height and you have a more serious issue than just ride height problems.

 

Based on the following:

1) observed difference in visual appearance of the springs

2) observed difference in ride behavior even while holding the dampers constant

3) other listings I've seen posted going back years that list stock rear spring rates

I respectfully refuse to believe the B and C spring sets are the same as stock. There is simply no way.

 

DITTO!

We (the few of us) recommend NOT cutting springs. If you still wish to do that... then go ahead. You can use the calculations and make it work, I just wouldnt.
For the price of springs and not %$#@ing it up, I would (and have several times) bought springs. My route: stock, Eibach 450-530, BBK 650linear, [edit] then SSS coilovers at 400#(front), 275# coilovers (rear).

 

Here is the link directly to the FRRP Catalog:

http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=272

--Vince

 

I'm not disputing the B/C rates, I'm saying there's no freakin' way they're the same as the stock rear rates, which are more on the order of 165-265 vs the B/C 200-300.

 

spring rates



The stock '85-'93 Mustang GT and LX 5.0L rear spring rates are 200-300#/in. Which is the same as the FRRP "B" and "C" springs.

Check page 161 of the 2008 FRRP catalog (it is page 163 of the PDF file), it lists the stock spring rates. They are 200-300#/in.

http://www.fordracingparts.com/download/catalogs/2008-pp.pdf

--Vince

 

OK, I see it now, but I still don't believe it :rofl:

What's printed just does not jive with what I've seen in the field. Granted I've never put any of them on a spring checker, but they're visually different. Which may have more to do with the fact that the B/C rears are longer than to any difference in rates. They sure feel different too.

 

OK, I see it now, but I still don't believe it :rofl:/QUOTE]

MFE,
No big deal. You help a lot of guys on this board and it is much appreciated. This is just one of those Melvin facts that I was extremely sure about. I guess it is from reading my early to mid 90's Ford Motorsport catalogs so many times that the pages fell out! It is interesting that the SN95 cars got softer springs. Also, I never thought that my "C" springs were too long.

[/hijack]

My81Capri,
What stock springs do you have in there now? Are they the '81 Capri springs? If so they were 160#/in linear. If you have '87-'93 V8 springs then you started with the 200-300#/in variable rate springs. Are you running isolators on the top and/or bottom? If you have isolators in place remove the bottom ones and see if you like the change. If you want it lower still then remove the upper isolators also.

FWIW, I ran the FMS "C" springs for a long time with no isolators in the rear and only an upper isolator in the front and I liked the stance on my car very much.

Good luck,
Vince