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Lowering front end after tire change

 
Old 07-05-2010, 11:39 PM
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Ed MD
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Default Lowering front end after tire change

I'm doing an autocross and want to swap out tires to try a different set and see how the two compare in times and handling. The question is: How can you lower the front end quickly after changing tires? Ed M
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Old 07-05-2010, 11:45 PM
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Pretty sure the quickest way is to just drive it. If you can find a bumpy road that would probably shorten the time to settle the front end. The other option would be to find a jack that is low enough to get under the lower arm so the suspension doesn't decompress when you lift the car. Good luck.
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Old 07-06-2010, 12:25 AM
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Originally Posted by G Man View Post
The other option would be to find a jack that is low enough to get under the lower arm so the suspension doesn't decompress when you lift the car. Good luck.
Nifty!. I would bet driving up on a couple of 2x6s would give the jack a little more space to pull this little feat off.

Years ago I heard of someone recommending straps. Maybe tie-down straps to recompress the suspension? Not sure exactly about the where and how. Never tried this myself. Just passing the info along.
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Old 07-06-2010, 02:38 AM
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Ed

A quick spirited drive with tight turns and some hard braking will settle the front about 90%. The rest will happen during the AX course.
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Old 07-06-2010, 11:08 AM
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You could also loosen the LCA bolts to finger tight along with the sway bar mounts. Drive up and down the street and that'll settle it too. Retorque to 88 ft/lbs on the LCA and 33ft/lbs on the sway bar. Sway bar drop links if loosened go to 62 ft/lbs. The apex of a driveway or a few 2x6's as said before are high enough to get a wrench on the LCA and swaybar.

But driving is a lot better Rx
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Old 07-06-2010, 11:28 AM
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no, none of that stuff will do it. most of ALL the issue is in the ARMs bushings, upper and lower. nothing you can do but drive it. certainly the A-Arm technique will not work, as the lever moment is way too far inward, and the tire will droop. thats why this technique doesnt work for the alignment folks.
as was said, a couple of stops and hard turns and you are 90% there. during the autox, it will be fine after the 2-3 turn.
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Old 07-06-2010, 11:53 AM
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Default ride height

A quick look here: https://rennlist.com/forums/928-foru...ol-thread.html

did not turn it up, but a search for "ride height" should. There is a tool for bringing it down. Another thread suggests that 928 Specialists has such a tool, I would call them 828-766-9280

Back to the tool list: That is a pretty comprehensive list and thanks should go to Rob Edwards for putting it together.
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Old 07-06-2010, 12:07 PM
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dr bob
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The ride height tool expects the car to be on the alignmnet rack, where there's a crossmember in the rack to attach the tool for the pull-down. Most folks don't have that at the AX course.

If you decide to loosen the LCA bushing clamps to let it settle a little more quickly, the torque requirements for the front and rear clamps are different IIRC. Also, there is zero benefit to loosening the clamps on the anti-roll bar.
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Old 07-06-2010, 12:16 PM
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+1

this technique rarely works and only compresses the suspension so that a proper alignment can be done and doesnt work for that purpose in most cases anyway. after the weight is removed, the chassis raises its self back up.

the you can remove the lower control arm brackets and the car still wont move much. . you are fighting a losing battle here. just drive the car, its the only way, OR, get a different suspension set up, as the stock shock/spring set up is most of the problem.

Originally Posted by dr bob View Post
The ride height tool expects the car to be on the alignmnet rack, where there's a crossmember in the rack to attach the tool for the pull-down. Most folks don't have that at the AX course.

If you decide to loosen the LCA bushing clamps to let it settle a little more quickly, the torque requirements for the front and rear clamps are different IIRC. Also, there is zero benefit to loosening the clamps on the anti-roll bar.
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Old 07-06-2010, 12:29 PM
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Originally Posted by mark kibort View Post
<<....>> OR, get a different suspension set up, as the stock shock/spring set up is most of the problem.
[scratches head...]

Mark, can you expand on this a bit? My shocks seemed to work smoothly with no stiction when I did the push-pull on them a few times to purge the gas from the oil inside prior to installation. The coil springs are, well, they are springs, and have nothing to stick. I don't think the bolt through the bottom bushing and eye has enough friction to make a difference at all.

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Old 07-06-2010, 12:32 PM
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BTW, specs for the front LCA bolts is 63 ftlbs, and the rear LCA bolts are 88 ftlbs. Just got done doing it.
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Old 07-06-2010, 02:11 PM
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I dont know what the reason, but with the oil shocks like the konis, when I changed over, the setting issue seemed to be a heck of a lot less. Part of which might be because of the lower droop, or because the shock has a lot of "bump" pressure and takes a while to bleed off, or actually needs action for it to settle to its final and equilibrium point. I dont know. But, what I do know, is that the system, has the car at about 1" too high upon lifting the chassis, until driven pretty hard for a few miles. (both braking and cornering)

Originally Posted by dr bob View Post
[scratches head...]

Mark, can you expand on this a bit? My shocks seemed to work smoothly with no stiction when I did the push-pull on them a few times to purge the gas from the oil inside prior to installation. The coil springs are, well, they are springs, and have nothing to stick. I don't think the bolt through the bottom bushing and eye has enough friction to make a difference at all.

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Old 07-06-2010, 02:32 PM
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I devised a solution to this problem in my garage that does not require driving the car to settle. Since I did an entire front end refresh recently, I did not want to settle the car with my brand new tires. Reading the manual, it stated to use a special tool to pull the car down and hold it there for two minutes. Well we thought why can't you push the front end down? After some brainstorming we created a device out of wood to push the front of the car down to settle the suspension. It involved creating a double sided T end and using a pump jack. Then you just put the device in between the roof and the car, pump the jack and hold it there for two minutes.
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Old 07-06-2010, 02:43 PM
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It will be fine until you punch a hole in your roof.
Originally Posted by 928 obsession View Post
I devised a solution to this problem in my garage that does not require driving the car to settle. Since I did an entire front end refresh recently, I did not want to settle the car with my brand new tires. Reading the manual, it stated to use a special tool to pull the car down and hold it there for two minutes. Well we thought why can't you push the front end down? After some brainstorming we created a device out of wood to push the front of the car down to settle the suspension. It involved creating a double sided T end and using a pump jack. Then you just put the device in between the roof and the car, pump the jack and hold it there for two minutes.
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Old 07-06-2010, 02:51 PM
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Originally Posted by mark kibort View Post
It will be fine until you punch a hole in your roof.
Yes but thats where the T shape design comes in, it spreads the force enough so that you do not blow a hole in your ceiling.
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