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Discussion Starter #1
I bought a set of what I think were rear sport springs off of a member here a good 5 years ago and would like to cut them to accommodate the existing lowered kit on my mark viii.

My questions are-

Does it matter which end I cut? Both look identical, bottom/top "flattened" at the end of each side. If they are that would be great as it seems the bottom(?) half coil on both springs is pretty rusty which means that would be the side I'd cut off.

Any visual differences in a jjjj spring vs a regular one? No visible marking from what I can see.
 

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sbcaprice305 said:
My questions are-

Does it matter which end I cut? Both look identical, bottom/top "flattened" at the end of each side. If they are that would be great as it seems the bottom(?) half coil on both springs is pretty rusty which means that would be the side I'd cut off.
Yes..This picture was taken from this Sticky:Correct Way To Install Coil Springs
Thunderbird Cougar Rear Spring Orientation.jpg

This is the proper rear coil spring orientation..Notice how the coils are slightly closer together on the top of the coil spring..

You should cut from the top of the "rear" coil spring..So you don't increase the spring rate anymore than it already is..

Depending on which side of the coil spring that is rusted..

If you have to cut off the rusty end, and it ends up being the lower portion of the spring..Then you will increase the spring rate..

Which will necessitate the use of Bilstein or Koni rear shocks..
If you try to use stock shocks on springs with such a high spring rate your rear end is going to bounce around like a pogo stick..



sbcaprice305 said:
Any visual differences in a jjjj spring vs a regular one? No visible marking from what I can see.
Yes..If your coil springs still have the tags on them..Sport or SC coil springs have a green coil tag on them..

Real Sport/SC coil springs should have a "JVC" tag on the front springs..The rears should have a "NUD" tag on the springs..

The 96-97 MN12's with the Sport package a lot of times had the "JVC" code springs up front, and the "GER" code springs out back..

The "GER" code rear springs are just regular V8 coil springs..

Earlier 91-92 Sport/89-95 SC Thunderbirds always had the "JVC"+ "NUD" combo AFAIK..

One other way to check whether or not you have regular coil springs vs Sport/SC coil springs is to measure the thickness of the coils..

Rear Sport/SC coil springs should be roughly .70" inches thick..You'll have to use a digital caliper to measure the center portion of the spring..

If you can..Take a measurement of your rear coil springs, and report back..





Rayo..
 

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Discussion Starter #3 (Edited)
Rayo, thank you for the detailed post.

The thing is both ends of the spring look like the "top" in the provided picture.


They are tag-less so it looks like I''lll have to measure them. All I know is that they are a lot thinner than the rear springs on my lowered AAS kit. I assumed the bottom was the side with rust, just seems like the lower portion would be impacted more by winters fury and due to the dead coils rubbing on each other.
 

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Rayo, thank you for the detailed post.

The thing is both ends of the spring look like the "top" in the provided picture.


They are tag-less so it looks like I''lll have to measure them. All I know is that they are a lot thinner than the rear springs on my lowered AAS kit. I assumed the bottom was the side with rust, just seems like the lower portion would be impacted more by winters fury.
That picture shows progressive rate springs, which LX springs and most aftermarket springs are. SC/sport springs are linear rate springs, so they are the same top and bottom.
 

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All MN12's use progressive rate coil springs..

You may have trouble noticing it at a glance..

If you take the time to measure the space in between the coils you'll see there is a difference in the space between the coils from the top, and the bottom..






Rayo..
 

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Rayo, thank you for the detailed post.

The thing is both ends of the spring look like the "top" in the provided picture.


They are tag-less so it looks like I''lll have to measure them. All I know is that they are a lot thinner than the rear springs on my lowered AAS kit. I assumed the bottom was the side with rust, just seems like the lower portion would be impacted more by winters fury.
NP..

Take some measurements of the coil thickness..As well as the space in between the coils..Like I said it may be hard to notice at a glance, but there is a difference..

One other thing..It's not unheard of that the rear coil spring was installed upside down on the factory assembly line..

So if this was the case with your springs you may have lucked out, and the rusted part might be the side with the coils spaced closer together..






Rayo..
 

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1997 Thunderbird 4.6, 1998 Mark VIII LSC
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I can understand why cutting one side's coils off rather than the other's due to one side having a different rate.... but how can it matter what orientation the spring is installed in, aside from potential mounting differences? There are only two points on the spring where it exerts pressure, and the amount it exerts on both surfaces will always be identical, whether it's a linear rate spring or progressive rate spring, whether it's at rest, expanding, or being compressed.
 

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Discussion Starter #8
After further inspection the rust isn't as bad as I remembered, so orientation isn't an issue if I have to cut the non rusty side. Here are the pictures. If I have to keep the rusty ends in place I plan on fixing the issue.

The rusty end as seen on the right has the coils ever so slightly spaced closer together, that's the only difference I noticed.







I don't own a caliper so this is the best I could do.



Standing as how I think they were originally installed with the rusty end/tighter spaced coils on the bottom.




So what do you think?
 

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Judging by your pictures..The rusty side is the end you want to cut since the coils are more closely spaced on that end..

It's hard to say without actual measurements from a caliper, but those don't really look like SC/Sport springs..

If they're not SC/Sport springs I wouldn't even mess around them..

See if you can find a caliper to use to measure those springs you got to confirm the coil wire diameter..






Rayo..
 

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Discussion Starter #10 (Edited)
Judging by your pictures..The rusty side is the end you want to cut since the coils are more closely spaced on that end..

It's hard to say without actual measurements from a caliper, but those don't really look like SC/Sport springs..

If they're not SC/Sport springs I wouldn't even mess around them..

See if you can find a caliper to use to measure those springs you got to confirm the coil wire diameter..






Rayo..
I don't care much if they're sc/sport springs. I just thought that's I bought many years ago, guess they must be regular v8 springs.

The issue with mine currently on the car is a busted bottom coil, if these are usable with a coil or 2 cut off then I'd like to try it. That's if I won't have any adverse handling issues doing so.

The lowered m8 springs are cut standard height m8 conversion springs, which are essentially thunderbird springs so I can't image there being much of an issue. :)

.
 

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Discussion Starter #11
So let me get this right..

Cut from the rusty/tighter coiled side and use that side up? Or down?


That's my last question, I swear. :)
 

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Q: How are you going to cut the springs?
I cut my front sport springs years ago and minimized the heat transfer by marking my cutting point with some tape, wrapping a wet towel around the segments after the cutting point, and then using an angle grinder (vs. a plasma cutter or torch) to cut the coil section I wanted to remove.
 

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Discussion Starter #13
Q: How are you going to cut the springs?
I cut my front sport springs years ago and minimized the heat transfer by marking my cutting point with some tape, wrapping a wet towel around the segments after the cutting point, and then using an angle grinder (vs. a plasma cutter or torch) to cut the coil section I wanted to remove.
I will be using an angle grinder. This will be my first time cutting springs (Obviously :tongue: ) I just want to make sure I cut and mount them correctly. Thank you for the tips!
 

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No problem. the key is you don't want to mess with the tempering so you want to minimize the heat transfer into the spring.
-g
 

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So let me get this right..

Cut from the rusty/tighter coiled side and use that side up? Or down?


That's my last question, I swear. :)
Cut on the rusty side of your spring since those coils are more closely spaced together..

Then when you install the springs make sure the rusty part of the spring is facing up..

Don't cut more than 1 coil..

Here's a picture to give you an idea how you measure your cuts when you're cutting 1/2 or 1 coil..

Cutting Coil Springs.JPG






Rayo..
 

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Discussion Starter #17 (Edited)
Springs are cut and installed.

I took a coil off and they were 1" taller then what the previous springs were, uninstalled...Yet I gained maybe 1/4" in ride height. Am I missing something?

I'm racking my brain as to why I gained so little height. When I first cut them I was almost certain that they would end up being too tall, but I was ok with that as I could take them out and take a bit more off if necessary. Now I'm trying to understand where it went wrong.

If I remove my speaker box it does increase in height the same as the old springs. I just can't help but think something is binding back there preventing it from going higher..

On the bright side I no longer have a broken spring back there. :)
 

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Are these new springs or just the ones you took off your car?
Springs can take time to settle. A few weeks to a month of daily driving OR 30 min on a road course.
If you took a full coil off, I would NOT mess with it for a few weeks and then come back and see if its down to your desired ride height.

-g
 

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Discussion Starter #19
Are these new springs or just the ones you took off your car?
Springs can take time to settle. A few weeks to a month of daily driving OR 30 min on a road course.
If you took a full coil off, I would NOT mess with it for a few weeks and then come back and see if its down to your desired ride height.

-g
They were previously installed springs and the ride height is LOWER than I wanted. I was hoping they were going to settle if they were too high, now I hope they don't settle or I'll be right back to where I was. :(

Stock bird spring = 13 1/2

1 cut coil = 12 1/2

Lowered Mark viii spring = 11 1/2

Measurements taken out of the car.

With the original kit I could leave the upper control arm bolt in while I installed them. With the cut bird spring I had to remove it and damn near fully extend the bottom in order to get the spring in...Yet it's pretty much identical in ride height. :confused:
 

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I didn't realize you were intalling these springs in a MarkVIII. Do you have a spring perch in there? If not, that will take up another half-inch or so and raise the ride height back up a bit.
 
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