should this spring be loose and the jam nut on the perch free to spin by hand?
10-17-2010, 07:04 PM
#1
Drifting
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should this spring be loose and the jam nut on the perch free to spin by hand?
Just trying to diagnose why my rear end was very loose in left hand turns yesterday.
Matt
10-17-2010, 07:32 PM
#2
Melting Slicks
Those look like pfadts right? I used to set them up so the springs were snug between the perches but would still turn by hand (ie. not pre-loaded too much). The jam nut should be tight to lock the perch nut in place. Make sure both sides are set the same and corner balance if possible.
While your back there check your sway bar endlinks and make sure everything is tight and no preload on the endlinks when the car is back on the ground. Also make sure the sway bar is free to turn in the bushings, which might require synthetic grease with poly bushings.
While your back there check your sway bar endlinks and make sure everything is tight and no preload on the endlinks when the car is back on the ground. Also make sure the sway bar is free to turn in the bushings, which might require synthetic grease with poly bushings.
Last edited by redtopz; 10-17-2010 at 07:34 PM.
10-17-2010, 08:19 PM
#3
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Those look like pfadts right? I used to set them up so the springs were snug between the perches but would still turn by hand (ie. not pre-loaded too much). The jam nut should be tight to lock the perch nut in place. Make sure both sides are set the same and corner balance if possible.
While your back there check your sway bar endlinks and make sure everything is tight and no preload on the endlinks when the car is back on the ground. Also make sure the sway bar is free to turn in the bushings, which might require synthetic grease with poly bushings.
While your back there check your sway bar endlinks and make sure everything is tight and no preload on the endlinks when the car is back on the ground. Also make sure the sway bar is free to turn in the bushings, which might require synthetic grease with poly bushings.
The jam nut and perch on this one were freely rotating. I could just reach in there and spin both of them and the spring was very, very loose.
On the other three shocks the jam nut is tight on the perch and can't move, although the spring can be moved with a good push indicating the pre-load is minimal.
Looks like it is time for a new alignment and corner balance. Should I replace the jam nuts and perches while I'm at or is it normal for them to work loose?
Matt
10-17-2010, 08:38 PM
#4
Race Director
just because something seems loose and turns when jacked and unloaded does not mean it is happening when loaded. While it MIGHT be moving, I'd load the sucked up on jack stands and see how loose it is. Also, paint marks on the joints to see if anything moves when you drive it. Depending on your particular car, it is possible that your car is perfectly corner balanced and one spring is looser than the others at a static, unloaded position.
10-17-2010, 09:01 PM
#5
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just because something seems loose and turns when jacked and unloaded does not mean it is happening when loaded. While it MIGHT be moving, I'd load the sucked up on jack stands and see how loose it is. Also, paint marks on the joints to see if anything moves when you drive it. Depending on your particular car, it is possible that your car is perfectly corner balanced and one spring is looser than the others at a static, unloaded position.
But I'm talking about the actual perch itself. I spun it a turn with just my hand, the jam nut is not binding the perch enough to stop it. Who knows how far it has moved since the original corner weighing.
10-17-2010, 09:41 PM
#6
Melting Slicks
Yes they are Pfadts, all I could afford at the time.
The jam nut and perch on this one were freely rotating. I could just reach in there and spin both of them and the spring was very, very loose.
On the other three shocks the jam nut is tight on the perch and can't move, although the spring can be moved with a good push indicating the pre-load is minimal.
Looks like it is time for a new alignment and corner balance. Should I replace the jam nuts and perches while I'm at or is it normal for them to work loose?
Matt
The jam nut and perch on this one were freely rotating. I could just reach in there and spin both of them and the spring was very, very loose.
On the other three shocks the jam nut is tight on the perch and can't move, although the spring can be moved with a good push indicating the pre-load is minimal.
Looks like it is time for a new alignment and corner balance. Should I replace the jam nuts and perches while I'm at or is it normal for them to work loose?
Matt
). I used to do 2 fingers in front and 3 in back with the Pfadts and my car handled great. IMO corner balancing is either overrated or as long as you set your ride heights evenly as I did, the car will be corner balanced close enough. I also installed my newer LG coilovers and set ride heights the same way, but lower and did my own alignment using David Farmer's guide. Again my car handles great. Out of curiosity I put my car on scales last month to check the corner balance and weight distribution. It was dead on and needed no adjustments. Maybe I was lucky or like I said, just get it close and you will be fine. 
10-17-2010, 10:18 PM
#7
Melting Slicks
As Dave said!! It is possible for both to be loose when the suspension is unloaded. When the jam nut is locked under load, it's possible for it to be loose when you take the load off of the perch. If you don't mess with them when the load is off, they will usually be tight when you reload them. You can prevent this by taking the load off after you get them where you want them and then tightening the jam nut. JD
10-17-2010, 10:25 PM
#8
Perch should not move on jam nut. They control spring position thus ride height. Loose spring is fine as long as everything is controled under action. Sometimes a zero preload helper spring is used to control a loose mainspring so they are not so noisy vs. a real dual progressive spring that results in a dual rate. Also check the rear tierod for play and the bearings. OEM bearings gain play, crack, then fail. There are many pictures of OLI blowing those things up until we all switched to the SKF bearing from Van Steel or hardbar. Oli has some video on youtube of bearing blowing up. Also, if a shock is dead you'll get weird symptoms like totally changing the spring rates if you are riding on the bump stops which would increase loosness.
10-18-2010, 01:10 AM
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As Dave said!! It is possible for both to be loose when the suspension is unloaded. When the jam nut is locked under load, it's possible for it to be loose when you take the load off of the perch. If you don't mess with them when the load is off, they will usually be tight when you reload them. You can prevent this by taking the load off after you get them where you want them and then tightening the jam nut. JD
10-18-2010, 05:30 PM
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Spring perch and jamb nut should not be loose at all. You don't need new ones, just tighten them.
On the Pfadt's you set the spring preload on each spring the exact same.
Then you corner balance by adusting the length of each shock. The shock body and spring are in the threaded bottom mount so you can do this without affecting preload.
On the Pfadt's you set the spring preload on each spring the exact same.
Then you corner balance by adusting the length of each shock. The shock body and spring are in the threaded bottom mount so you can do this without affecting preload.
10-18-2010, 07:42 PM
#11
Melting Slicks
Spring perch and jamb nut should not be loose at all. You don't need new ones, just tighten them.
On the Pfadt's you set the spring preload on each spring the exact same.
Then you corner balance by adusting the length of each shock. The shock body and spring are in the threaded bottom mount so you can do this without affecting preload.
On the Pfadt's you set the spring preload on each spring the exact same.
Then you corner balance by adusting the length of each shock. The shock body and spring are in the threaded bottom mount so you can do this without affecting preload.
