Can coil springs be over compressed?

[Dave Affleck]

I have occasionally "heard" that coil springs can and should not be "over compressed". That it will cause them to sag (reduce the effective rate).

In the near by "sitting level" thread, AEVJim mentions a "bulldozing" procedure during spring manufacture that sounds to me like perhaps we really can't over compress our springs with anything like a normal setup.

Reason I'm asking... I'll be installing some Nth 3" springs within the next month or so. Along with some Bilstein 5100's. After a couple of quick and dirty measurements, along with looking at the published specs for the shocks, I think I will probably only need about 1.5" of bump stop extension to prevent the shocks from bottoming out, and I think my tires should still have fender clearance too. All that will get sorted out by actual testing when I install the lift parts.

So, if I only need 1.5" of bumpstop for the health of my shocks and my tires are clearing the fenders, then I don't want to use any more BS and give away free up travel if I don't have to (I do a lot of fairly high speed desert running and my bump stops see frequent use). But... If over compressing the springs is actually anything to be concerned about, then I'll have to rethink things a bit. If I need more bump stop anyway, just for the health of the springs, then I may as well run longer shocks.

Anyway... Over compressing coil springs - fact or fiction?

Thanks in advance for your thoughts!

- Dave Affleck

[djb_rh]

In theory, no, you can't over-compress them. In practice it depends on the quality of the spring. I'd think based on what you've said you've got nothing to worry about, though.


--Donnie

[AEV Jim]

In theory, no, you can't over-compress them. In practice it depends on the quality of the spring. I'd think based on what you've said you've got nothing to worry about, though.


--Donnie

Ditto
-Jim

[Dave Affleck]

Cool, thanks for the input.

I did some test fitting and measuring yesterday and it looks like I really do only need 1.5" of BSS on the front and 1" on the rear to keep the Bilsteins from bottoming.

- DAA

[AEV Jim]

Curious about your 'recipe' - could you tell us what your overall setup is (the vertically-oriented components):

Springs
Bumpstop spacers (and what bumpstops - real OEM ones or urethanes)
shock p/n's
Any other relevant items like coil spacers, shock shifters, etc.

Thanks! Jim

[Dave Affleck]

Sure, no problem.

I test fitted the shocks and checked for required BSS with the springs out - I just wanted to see how much bump stop was going to be required to prevent the shocks from having to act as bump stops and that's easier to do with the springs removed. But, the springs I'll be using are AEV/Nth 3".

The shocks are Bilstein 5100's:

Front - BE5-2731-H5
Rear - BE5-2732-H5

These are OEM mounting type, with the bar pins nicely vulcanized. The collapsed lengths are about 1-1.5" longer than stock (Rubicon), with 2" more travel, so about 3-3.5" longer extended. I'm using all factory mounting for them (including loseing th BPE's I've been using w/the OEM shocks).

I'm keeping the OEM bumpstops as is and plan on using the RE poly extensions (trimmed to fit) bolted to the perches.

Don't know for sure yet, but think I'll likely end up using one or two OME trim packers to space the rear springs. Just depends on what kind of rake I end up with. The Jeep goes from topless and empty, to hard top and full compliment of long range camping gear complete with jerry cans etc., so I like to have a bit of rake when it is empty. Would prefer to leave the trim packers out, but have a feeling I'll be using them.

- Dave

[AEV Jim]

Sounds pretty good Dave. Let us know how it turns out. Thanks for the info...

Jim