Setting the Preload on your BC Coilovers (or other brands)
03-10-2011, 05:42 PM
#1
Senior Member
Thread Starter
Join Date: Mar 2009
Location: STATEN ISLAND NY
Posts: 546
Setting the Preload on your BC Coilovers (or other brands)
THIS WRITE-UP HAS BEEN BROUGHT TO YOU BY YOUR FRIENDS AT WWW.INFINITISCENE.COM
ADJUSTING BC COILOVERS (PRELOAD)
TOOLS:
SUPPLIED SPANNER WRENCH’S
SAFETY:
ALWAYS USE QUALITY JACKSTANDS WHEN WORKING UNDER YOUR VEHICLE.
NEVER WEAR LOOSE FITTED CLOTHING AROUND A RUNNING MOTOR.
ALWAYS WEAR SAFETY GLASSES.
PLEASE STAY SAFE.
-------------------------------------------------------------------------------------------------------------------------------------------
1. RAISE YOUR CAR ON JACKSTANDS AND REMOVE THE WHEELS.
2. CLEAN THE COILOVER THREADS WITH COMPRESSED AIR AND A RAG BEFORE MOVING THE LOCK RINGS.
3. LOOSEN LOCK RING (B)
4. LOWER SEAT (A) SO THAT THERE IS NO TENSION ON THE SPRING.
5. NOW RAISE (A) BY HAND UNTIL IT TOUCHES AND HOLDS THE SPRING FIRMLY IN PLACE WITHOUT PUTTING TENSION ON THE SPRING. (THIS IS KNOWN AS A 0 PRELOAD).
6. RAISE (B) UNTIL IT TOUCHES (A).
7. TAKE YOUR SPANNER WRENCH AND RAISE (A)(WHICH IS NOW PUTTING TENSION ON THE SPRING) UP 5MM (TOP OF (B) TO THE BOTTOM OF (A)). THIS IS KNOWN AS A 5MM PRELOAD (WHICH IS WHAT BC RECOMMENDS FROM THE FACTORY).
8. AFTER YOU GET YOUR 5MM PRELOAD RAISE LOCK RING (B) BACK TO (A) AND TIGHTEN THE TWO TOGETHER.
9. YOU ARE FINISHED.
ADJUSTING BC COILOVERS (PRELOAD)
TOOLS:
SUPPLIED SPANNER WRENCH’S
SAFETY:
ALWAYS USE QUALITY JACKSTANDS WHEN WORKING UNDER YOUR VEHICLE.
NEVER WEAR LOOSE FITTED CLOTHING AROUND A RUNNING MOTOR.
ALWAYS WEAR SAFETY GLASSES.
PLEASE STAY SAFE.
-------------------------------------------------------------------------------------------------------------------------------------------
1. RAISE YOUR CAR ON JACKSTANDS AND REMOVE THE WHEELS.
2. CLEAN THE COILOVER THREADS WITH COMPRESSED AIR AND A RAG BEFORE MOVING THE LOCK RINGS.
3. LOOSEN LOCK RING (B)
4. LOWER SEAT (A) SO THAT THERE IS NO TENSION ON THE SPRING.
5. NOW RAISE (A) BY HAND UNTIL IT TOUCHES AND HOLDS THE SPRING FIRMLY IN PLACE WITHOUT PUTTING TENSION ON THE SPRING. (THIS IS KNOWN AS A 0 PRELOAD).
6. RAISE (B) UNTIL IT TOUCHES (A).
7. TAKE YOUR SPANNER WRENCH AND RAISE (A)(WHICH IS NOW PUTTING TENSION ON THE SPRING) UP 5MM (TOP OF (B) TO THE BOTTOM OF (A)). THIS IS KNOWN AS A 5MM PRELOAD (WHICH IS WHAT BC RECOMMENDS FROM THE FACTORY).
8. AFTER YOU GET YOUR 5MM PRELOAD RAISE LOCK RING (B) BACK TO (A) AND TIGHTEN THE TWO TOGETHER.
9. YOU ARE FINISHED.
03-10-2011, 09:34 PM
#4
Senior Member
Thread Starter
Join Date: Mar 2009
Location: STATEN ISLAND NY
Posts: 546
5mm was recomended from the factory...i guess for the street use.... and you use "A" to adjust the preload on the spring..."B" keeps "A" nice and tight..."C" you loosen and then use "A" to lower or raise your car and tighten "C" again to keep it their lol
03-11-2011, 12:22 PM
#8
Are your springs linear or progressive? A truly linear spring will not see a spring rate increase from adding preload. I'm pretty sure those collars on the coil overs should be used to adjust ride height, and then corner weights. If your springs are too soft, buy stiffer springs.
03-11-2011, 01:53 PM
#9
Linear if im not mistaken. My rears have no preload on em what so ever. There was a ton of slack on it. A ton of play. Fronts seem fine; its the rears that need to be addresses so im thinking setting preload to zero at least would cure the soft ride.
03-12-2011, 04:36 AM
#11
This thread from another forum explains it pretty well. Look at the post that starts "Preload is one of the tougher spring concepts to visualize"
In summation, when adding preload, you add ride height until your springs no longer sag when your car is lowered off the jacks. If you have a 500 lb/in spring and preload it 2.5 inches on the front of a Maxima, you have a force of 1250 lbs in the spring. Because the Max weights approximately 1000 lbs on each front corner, there would be no sag. Not only that, but the spring would not start to compress until an additional 250 lbs acted on it. This is bad. But most times it never gets to this.
To learn more about linear springs, check out Hooke's Law.
The bottom line, the spring rate of a linear spring will never increase by adding preload.
If you think your rear is too soft (bottoming out/too much body roll), get some new rear springs. Hyperco makes good springs. There are other manufacturers as well. Search around.
In summation, when adding preload, you add ride height until your springs no longer sag when your car is lowered off the jacks. If you have a 500 lb/in spring and preload it 2.5 inches on the front of a Maxima, you have a force of 1250 lbs in the spring. Because the Max weights approximately 1000 lbs on each front corner, there would be no sag. Not only that, but the spring would not start to compress until an additional 250 lbs acted on it. This is bad. But most times it never gets to this.
To learn more about linear springs, check out Hooke's Law.
The bottom line, the spring rate of a linear spring will never increase by adding preload.
If you think your rear is too soft (bottoming out/too much body roll), get some new rear springs. Hyperco makes good springs. There are other manufacturers as well. Search around.
03-17-2011, 11:53 PM
#13
I sprayed 1 can of PB blaster and half can of wd40 and 3 guys with gehtto ehomemade extension spanner wrench...
04-28-2011, 11:40 AM
#17
Yes. You could do it before, but you'll end up re-doing it once installed on the car as you cant replicate suspension droop w/o the coilovers installed.
05-18-2011, 09:11 AM
#18
Member
Join Date: Dec 2008
Location: Memphis,tn
Posts: 221
Anybody know how to do pre-load in the rears n changed height? I'm confused since rears is independent suspension setup. I know I need 9pm of preload to the spring but I just don't know how to do the rears one.
05-24-2011, 10:41 PM
#20
Member
Join Date: Dec 2008
Location: Memphis,tn
Posts: 221
My rear making squeaking sound when hitting bump is that me my rears are blown n also I'm using the digit scale when I set 5mm on them do we used outier measure or interiors measure on the scale?
05-24-2011, 10:46 PM
#21
Wait a minute so u don't add pre-load to ur jic? Like mine when I reset it to 0 then I add 5mm of pre-load to the springs.
My rear making squeaking sound when hitting bump is that me my rears are blown n also I'm using the digit scale when I set 5mm on them do we used outier measure or interiors measure on the scale?
My rear making squeaking sound when hitting bump is that me my rears are blown n also I'm using the digit scale when I set 5mm on them do we used outier measure or interiors measure on the scale?
05-28-2011, 11:37 PM
#24
Member
Join Date: Dec 2008
Location: Memphis,tn
Posts: 221
Today I went through problem will I was trying to lower the car in the FRONT, but I did loosen up C collar the put spanner on the A collar n put right to left but after that is didn't lower the car at all. Am I suppose to loosen the strut bolt that hold the strut in place?
05-29-2011, 11:09 AM
#25
Today I went through problem will I was trying to lower the car in the FRONT, but I did loosen up C collar the put spanner on the A collar n put right to left but after that is didn't lower the car at all. Am I suppose to loosen the strut bolt that hold the strut in place?
05-30-2011, 12:22 PM
#27
No. Loosen the C collar, and spin the whole threaded assembly so that both the A and B collar are closer to the C collar. No need to undo the whole assembly. This is why these struts have threaded bodies.
Were I you, I would find a local race shop and let them handle it.
Were I you, I would find a local race shop and let them handle it.
05-30-2011, 04:05 PM
#28
Member
Join Date: Dec 2008
Location: Memphis,tn
Posts: 221
I can't let my shop do it bec there cross-threaded my coil. So I'm trying to do it myself.
So lossen up C collar then move the thread by hand or spanner? If I put spanner on the thread won't I strip it?
My question is how the strut gonna move if A n B collar are tight each other unless I loosen up the bolts behind the brake?
So lossen up C collar then move the thread by hand or spanner? If I put spanner on the thread won't I strip it?
My question is how the strut gonna move if A n B collar are tight each other unless I loosen up the bolts behind the brake?
05-30-2011, 04:12 PM
#29
I can't let my shop do it bec there cross-threaded my coil. So I'm trying to do it myself.
So lossen up C collar then move the thread by hand or spanner? If I put spanner on the thread won't I strip it?
My question is how the strut gonna move if A n B collar are tight each other unless I loosen up the bolts behind the brake?
So lossen up C collar then move the thread by hand or spanner? If I put spanner on the thread won't I strip it?
My question is how the strut gonna move if A n B collar are tight each other unless I loosen up the bolts behind the brake?
I actually discovered this by accident.
Last edited by essential1; 05-30-2011 at 04:15 PM.
08-31-2011, 05:12 PM
#33
09-01-2011, 02:11 PM
#36
Most progressive rate coilovers have tapered springs, at least that I've seen Matt. The only ones I know of with varied spacing is the PSS9/10 from Bilstein.
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