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Cutting Rear springs...to level the car...(not a newb at cutting) but...

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Old 10-21-2012, 07:40 PM   #21
baddog671
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I'm not an expert on suspension by far, but I'd say the intelligent way to get your desired height is mark the springs out in 1" increments and start low. If it doesn't look enough, go to the next mark. And do so with a full tank so you're at full weight.

But then again, you've done this before. You should know that....
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Old 10-21-2012, 08:02 PM   #22
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Learning now why cutting coils doesn't work with progressive springs...
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Old 10-22-2012, 06:59 AM   #23
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If the length of the cut spring end up being shorter more than one inch over the OEM, it could get crooked into its seat. Not good.
If it's much shorter, it will eventually fall out... how sweet!

It wouldn't be a problem up front where the spring has nowhere to go on a Mac Person design but in the back, it's totally independent from the shock.
So you guys with the "It's been done since springs were invented" comment, please don't quit your day job!
The cutting doesn't work in all applications...
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Old 10-22-2012, 12:42 PM   #24
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Originally Posted by pascal View Post
It wouldn't be a problem up front where the spring has nowhere to go on a Mac Person design but in the back, it's totally independent from the shock. So you guys with the "It's been done since springs were invented" comment, please don't quit your day job!
The cutting doesn't work in all applications...
Not questioning your almighty car knowlegde, Pascal, but since the weight of the car rides on the springs and not the shocks, the springs should stay in place unless you completely unload the suspension, regardless if its a independent spring/shock or a coil-over design, as in the macpherson.

Please let me know if Im mistaken so I can add to my knowledge base.
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Old 10-22-2012, 01:10 PM   #25
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Originally Posted by Barrybobvt View Post
Learning now why cutting coils doesn't work with progressive springs...
Doesn't the S197 have linear rate springs? I believe I read somewhere that even if you got some aftermarket "progressive" springs, the weight of the car would pretty much compress the springs to the point that they become linear...

I still wouldn't suggest cutting them though, especially if you don't even have the means to measure equal cuts! That will cause you to have different spring rates on either side of the car (not sure what this could damage, but will probably create problems when cornering/braking).
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Old 10-22-2012, 01:14 PM   #26
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Not questioning your almighty car knowlegde, Pascal, but since the weight of the car rides on the springs and not the shocks, the springs should stay in place unless you completely unload the suspension, regardless if its a independent spring/shock or a coil-over design, as in the macpherson.

Please let me know if Im mistaken so I can add to my knowledge base.
I'm not sure about having to completely unload the suspension, but I've heard of people with cut springs (imports, but that shouldn't really change anything) that took a pothole, or bumpy roads and that caused their springs to fall out of position.
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Old 10-22-2012, 02:17 PM   #27
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Quote:
Originally Posted by PNYXPRESS View Post
Not questioning your almighty car knowlegde, Pascal, but since the weight of the car rides on the springs and not the shocks, the springs should stay in place unless you completely unload the suspension, regardless if its a independent spring/shock or a coil-over design, as in the macpherson.

Please let me know if Im mistaken so I can add to my knowledge base.
I would imagine if the car bounced hard enough and extended the length of the strut farther than the uncompressed length of the spring, you could risk it falling out.
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Old 10-22-2012, 05:42 PM   #28
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Cut a rear spring on these cars too short and it can easily fall out if the suspension ever goes to "full droop".

Cut it badly enough so that it's trying to bow out sideways and it will always trying to pop out. Might not have to completely unload the suspension to full droop for that to happen in this situation.

Cut them with poor enough technique and you can make the spring metal brittle and it can and will break. Then you have a too-short spring with an end that's pretty much guaranteed to be the wrong shape (plus a loose piece of spring that's either going to get in the way or fall off the car).


All that said, cutting springs is in fact successfully "do-able" - even if the springs are progressive - if you understand spring design and what to avoid doing. But if you don't even know what the questions you need to ask are, don't try it.


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Old 10-22-2012, 07:53 PM   #29
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Quote:
Originally Posted by PNYXPRESS View Post
Not questioning your almighty car knowlegde, Pascal, but since the weight of the car rides on the springs and not the shocks, the springs should stay in place unless you completely unload the suspension, regardless if its a independent spring/shock or a coil-over design, as in the macpherson.

Please let me know if Im mistaken so I can add to my knowledge base.
Thanks for the compliment but I think that between Norm, Sam and other folks here, they have the almighty knowledge in check...

It is not that uncommon to unload the suspension on normal driving.
So like Norms says, cut them too short and they will bail.
Don't know if you dropped your car or not but if you did and did it yourself, did you notice how easily that shorter spring goes back into place? And the OEM one isn't that hard to remove BTW...
So you don't have to cut them a lot before you get in trouble.
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Old 10-27-2012, 01:32 PM   #30
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Cut springs compromise the ride integrity.
Sure it looks cool, but take a corner to fast and
the weirdness of the rear suspension could just
catapult you right into the ditch.
I personally like looks and function hence the
Roush rear springs and shocks only.

I have heard that heating them while under pressure
is the way to go to shorten an OEM spring.
It can be done using the vehicle as the pressure part.
Just heat the coils until the rear end drops to the desired
height. Done deal and you didnt even have to remove
the springs. Dont worry about the gas tank under there
as it is made of Asbestos and it fireproof.
A strap to limit the suspension travel will help
keep those now shorter than OEM springs in the seats.

Or just buy a set of $100 Roush rear springs...
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File Type: jpg SpringsShocks.jpg (20.8 KB, 14 views)
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Old 10-27-2012, 06:32 PM   #31
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Quote:
Originally Posted by 157dB View Post
Cut springs compromise the ride integrity.
Sure it looks cool, but take a corner to fast and
the weirdness of the rear suspension could just
catapult you right into the ditch.

I have heard that heating them while under pressure
is the way to go to shorten an OEM spring.
I dont believe any part of this is true. And Im pretty sure the second part cant get any more wrong if it tried.
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Old 10-28-2012, 06:57 PM   #32
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Get your parents to buy you some springs. Seriously, who can afford a 2010 mustang, but can't buy some rear springs?
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Old 10-28-2012, 08:13 PM   #33
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What, you guys don't occasionaly Hazard it up over some train tracks or something? Pretty sure I unload my suspension over some dips and such on a monthly basis.

Also, who am I to question the Gods of the MFers in this thread, but if I have read the previuos posts correctly, heating the springs changes the carbon levels in the metal which makes them more brittle. Heating them while on the car and just letting the car settle lower seems like it would just leave you with some brittle rear springs. Think I'll stick with my Steeda/Tokico plans.
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Old 11-03-2012, 07:28 AM   #34
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Get your parents to buy you some springs. Seriously, who can afford a 2010 mustang, but can't buy some rear springs?
+1 - I cut springs on my 99, but it was a 5k car. Hard to justify on a 20-30K car.

FYI: Rear roush springs lowered my 12 GT TOO MUCH. I have brembo as well, but the rear sat .25" lower than the front.
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Old 11-03-2012, 08:41 AM   #35
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The heating idea was a joke. So wrong in so many ways it
was designed to seem pretty silly.
The idea to be conveyed was to just buy proper lowering springs...
But if you must, 1 coil equals roughly 2" of drop.
So chopping 1/2 of a coil should be safe from drop-out at full
suspension extention.
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Old 10-09-2013, 09:30 PM   #36
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The heating idea was a joke. So wrong in so many ways it
was designed to seem pretty silly.
That's how they used to do it in the '50s and early '60s .... and even later in some areas.

Personally, I've never considered heat for lowering as it ruins the temper in the spring .... but I have cut springs.

Of my current fleet, my '92 T-bird Sport rides a bit lower and does so very comfortably and stable like with 1 coil cut in front and 5/8 coil cut in rear "Sport" (JJJJ) springs with Tokico Blues. Yes, spring rate was increased some, but the shocks handle rebound well and car hasn't bottomed out, ride is stiff enough, corners flat too. I also only cut from the open end when I did it.

We just bought our 2008 GT in June, I like it ..... but I am a bit annoyed with the excessive rear gap over the tire at top ..... "fender gap". I have no desire to drop the whole car as I drive in the real world, just want to bring the back down about 3/4". I also notice in driving that the car has a feel of understeer to it, the front feels heavy, it seems to like straight better than hard right or left. To me this says it would respond favorably to a slight increase in rear roll resistance .... either through slightly larger rear sway bar .... or slightly stiffer rear spring rates. A slight trimming of rear springs will increase rear spring rate slightly, maybe not noticeably, but still it is a step in the right direction.


http://www.eatondetroitspring.com/cutting-coil-springs/



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Old 10-18-2013, 08:36 PM   #37
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OK ....... so last night I bid on some Roush rear springs, I wasn't willing to go but so high ..... but I did drive a bidder up. I wasn't willing to spend $123.99 on rear springs for an inch just yet so I didn't.

Today I did all that one must do to safely remove and cut and reinstall our 2008 Mustang GT's rear springs. This morning before I started I again measured the distance at each fender opening from carport to top of fender arch at maximum, fronts were 28-1/4" and rears were 29-3/8".

My goal was to eliminate at least 3/4" in the rear and not need a panhard bar change.

I cut using a Dremel tool with a fibreglass HD cutoff wheel. I read of people worried about heat .... and often resist the urge to respond. The spring end last half inch got a little bit warm, but not even uncomfortably so, the cut is so small and narrow and weighed against the mass of the spring, does not get the steel hot. I cut one full coil off the top end of the coils plus an inch which was where I marked using a 1" wide rule against the spring end. The Dremel HD cutoff wheels last and even after cutting two springs the wheel shows minimal wear, just take it easy.

Click the image to open in full size.

After I was finished, I took a short drive and then I measured again in the same spot on the carport, and I am glad I did not cut more! Imagine my surprise to find that now all four fender tops, front and rear, are each 28-1/4" from the floor. All 4 the same, and just a hint of rake along the lower edge of the rocker panels.

Click the image to open in full size.

Click the image to open in full size.

(I only posted left side pics, I have all 4 though.)

I checked to see if I needed to work any on the panhard bar, had decided if within 1/4" I'ld leave it alone .... with a straight edge from fender down to tire sidewall bulge (rear tires at 33 psi) the gap to upper sidewall is "near the same".

Before:

Click the image to open in full size.

After:

Click the image to open in full size.

I think it looks great, certainly worth the time spent and $$$ saved which is like "earnings" as opposed to what I would have done had I won that bid last night ....



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Old 10-19-2013, 08:38 AM   #38
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Have you considered fabbing up a spacer of 1/4" or maybe 3/8" thickness? I'd use steel.

You should put such spacers or shims at the ends of the spring where you made your cuts, and incorporate some means of positively locating the spring such as welded-on locating lugs, tabs, or a ring sliced from a piece of exhaust tubing. Don't forget that without the small diameter end coils the spring is no longer as positively located at the cut end as it was in the all-OE configuration.

I've done this sort of thing before.


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Old 10-19-2013, 10:11 AM   #39
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On 10-19-13 I decided to double check my side to side centering with a level and plumb. I was pretty sure it was OK but I had already (before even yesterday) decided if I found it off much, instead of an adjustable PHB, I'd just move the stock hole a little bit on one end (example being that if one side had been 1/4" more or less than the other, 1/8" movement would correct it).

I placed a level across the spoiler top and found it level, checked carport floor and it was level under rear bumper, so I hung a short string with weight from each fender top at center and measured from string to tire sidewall .... driver's side just a hair under 3/8" but over 5/16" (about 11/32"), passenger side right on 3/8" mark (12/32") and that's "pretty darn close" to being the same.


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Originally Posted by Norm Peterson View Post
Have you considered fabbing up a spacer of 1/4" or maybe 3/8" thickness? I'd use steel.

You should put such spacers or shims at the ends of the spring where you made your cuts, and incorporate some means of positively locating the spring such as welded-on locating lugs, tabs, or a ring sliced from a piece of exhaust tubing. Don't forget that without the small diameter end coils the spring is no longer as positively located at the cut end as it was in the all-OE configuration.

I've done this sort of thing before.

Norm
Funny you should mention ` .... I came really close to taking a (say two) piece of 1/8" sheet cut into a circle to fit inside the stock perch up in the frame, as you know it's in a deep upside down well. I was thinking maybe putting a sheet of inner tube rubber between it and the car frame metal. The stock upper spring isolator just snaps out (almost falls out) and I was going to maybe use a plastic snap in retainer (like used in so many places on cars now) to hold it in place in same hole while spring is inserted.

Then on the spring side of the sheet, was thinking maybe build up a half circle gradual ramp maybe rising 3/4" total in 180 degrees with a 3" center pretty much as you describe. It would be really easy to make. Not so needed for keeping spring in but more for a better seating.

I may still do it one slack day.

I looked at the stock spring isolator, it's pretty thick, and so I gave it a try as is, there is no way it can jump out as the spring is still snug when shocks are fully extended and that's a deep well and the lower end of the spring sitting on the axle is un changed. I did look at the angles between the axle perches and the floor of that upside down well and after thought, decided best to put long side of spring towards rear of car.


See below for more:

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Old 10-22-2013, 07:34 PM   #40
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Today (10-22-13) while delivering parts I had some time to think (some parts runs are out into the county and last an hour or more) and suddenly I recalled a bunch of 89-97 Thunderbird rear spring rubbers I had in a box, and they have a built in ramp and step to seat a coil with open ends.

I got home after work, pulled the Mustang around onto ramps, jacked and set frame on padded stands, and removed ramps and undid lower shock bolts and eased axle down with jack and removed the coils I had cut a few days ago. No permanent bends yet and we drove them over 250 miles Sunday alone on a not smooth roadway.

Mustang springs are about 3.5" ID, the T-Bird springs in a 89-97 Thunderbird rear are about 4" ID, the rubber snap into the coils. I modified them a bit .... cut a section out where the two tie wraps are closest. I then reinstalled the springs with the pigtail part of top towards rear of car, centered in spring seat with new T-Bird rubber between spring and Mustang Rubber with center bumper.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Where immediately before todays "spring seat rubber" mod the top of the rear fender arches were 28.25" from floor, afterwards they were nearer 28.5" .... a gain of just under 1/4". That's still a good full inch below where they were and that's OK. I was looking through pictures from Sunday, with camera gear and tripod and tool kit and stuff in trunk, the rear was maybe 1/4" low anyway?

Click the image to open in full size.

See what I mean .... a good 1/4" low in back loaded then, so the added 1/4" won't hurt.


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Old 10-22-2013, 07:34 PM
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