Is it possible to adjust front camber and caster independently?
 

I'm thinking about doing my first home front end alignment. I believe I can get the measurements, but is it possible to adjust just caster without changing the camber? Are both changes made by loosening all three screws on top of the shock tower or can the forward and sideways movements of the strut be done independently? I don't have a good drawing of the adjustment slots and mechanism up there on top of wheel well.

Both are adjustable independently and very limited at best.

Couple of hints/tips (BTDT)
 

Remember to start with an inspection (A-arm bushings, tie rod ends, ball joints, strut mount, strut bushings, wheel bearings) first.

Double-check level (L-R and F-R) of your garage floor.

Make sure you measure/adjust/re-measure w/car properly weighted (full tank, weight in driver seat, etc.).

Also make sure your tire pressures are correct, too.

If hasn't already been done, remove all of the tar-like sealer around the top of the strut mounts (mine came off pretty easily w/metal paint scraper -- I rounded off the 'chisel' edge to not scratch the paint). Or you could use the 'freeze and shatter' method.

I used blue painter's tape at the leading edge and inward (toward the center of the trunk) edge of the strut mounts to mark my initial settings -- this helps you visualize how much movement you've made, and reduces the chance that you're changing camber while you're trying to re-set caster.

Get yourself a couple of those large tyvek envelopes from the post office or FedEx (they're free :)) and put them udner your front tires before you start adjusting. Because they're very thin they won't change level and because they have very low friction your tires will rotate in place very easily if you need to turn the steering wheel (e.g., re-setting toe).

And remember that changing caster will also change toe.

Much has been posted here on alignment & corner balancing; I've received incredibly helpful advice from Wil, Harvey, Steve, John, Max and many others.

Hope this helps.

D

Flat Six, thanks for the great info. But do I unscrew all three screws at once, or is one for caster, two for camber, etc.? If I just want to do front / back movement (and not sideways) do all three come loose and if so then how do I keep it from moving sideways?

All 3 at once to move the upper strut mount. That's why -- if you're trying to adjust just camber or just caster -- you want to mark your starting positions (in my case w/blue painter tape).

The tape that you run along the inside (toward middle of trunk) of the strut mount reminds you where your camber is currently set. As you loosen the three bolts, you can move the strut mount back toward the windshield (increase caster) or forward toward the bumper (decrease caster); keep the edge of the strut mount along your tape line. That way you can change caster w/little to no change in camber.

Do one side at a time and make sure you change caster equal amount on both sides (assuming roughly equal now, of course). That's why it's also important to mark the starting fore/aft position of upper strut mounts.

HTH

Get the Ray Scruggs book. a search here will turn up the necessary links.

Alignment of Porsche 911

D

The 3 bolts have nothing to do with adjustment. They are simply clamping the plate. If you want to do some camber adjustment, just move the top of the shock shaft straight in and out along an axis drawn between the 2 shock nuts. This will change the toe significantly.

For all intents and purposes, the caster will not change. However, there are some dynamics involved that might be felt by an expert. In which case the expert might choose to change the caster a small amount.

Unless Scruggs updated his book, he does not address adjusting or measuring caster.

Sherwood

Yeah, he does punt on the topic of caster.

It is more important that caster is even on both sides rather than the amount. The more caster you can dial in, the more beneficial camber change that you achieve during cornering in at the expense of increased steering effort vs low camber.

One trick to making sure that caster is even is after making sure your front camber and toe are even and centered, turn your steering wheel exactly one full turn left of center and record the camber of the each front wheel. Then turn the steering wheel exactly one full turn to the right of center and repeat. If the measurements don't match, caster is not equal.

when you get ready to adjust, make your marks, then just loosen the 3 hex bolts a little, and bump it with your mallet and drift to where you want it, is a little easier than just loosening all the bolts and having it flop around

The tar should comes off with a heat gun and paint mixer stick. Less damage to the paint underneath.

If you remove the strut top retainers it should be easier than scraping around them. Just remove the three bolts with car on the ground and take them off.

Ditto what Milt said. Don't forget that moving the top of the strut around will alter your toe settings. A lot with camber changes, a little with caster changes.

Another thought or two.

If interested in a sport setting, you want to start with the strut tops pulled all the way back (caster) and all the way in (camber should then be about -1.5 to -1.7 deg if the front is lowered to 25.5" fender height with stock diameter wheels ).

I think with a short digital level from Sears you can easily check these two for balance.

For neg camber put car on level ground. Remove wheel center caps, hold or bungee level against the caps surface.

For caster, put level on forward most surface of the strut. Measure and use the hold function to capture the reading. The goal is just to be equal on each side.

Then set toe.

I like Steve's double check method when done.

This is a good time to add turbo tie rods & if you are going to lower the front to install steering rack spacers to reduce bump steer.

Thanks for all the great info. What's the best way of moving the strut top once you have the mount bolts loose. Can you do it by hand or do I use the the mallet method of don gilbert. Would I need to jack up the car or can it be done on the ground. Obviously the measurements have to be done on the ground.

That's a good question since there can be quite a load on the strut shaft. I've tapped it with a plastic mallet but it depends on where you are trying to go. If you need to tap it inward, there's precious little room to swing a hammer due to the fender and trunk weather seal. I think I used a wood block to hit on and maybe as a lever.

Maybe a couple of wood blocks. I'm always improvising.

...If you are doing this on a concrete floor the friction of the tires will make a difference when making adjustments. In other words, make an adjustment, then roll the car forward and back a foot or so to settle the suspension before making a measurement.

More than a foot. I used to roll mine at least a complete tire rotation in each direction and bounce the front end before rolling back. But then, I was jacking the car up between adjustments.

Here's a poor man's alignment pivot: Take a pair of old hard VAT (tiles) and grease between them. Roll the tires onto the stacked tiles.

Shoot some spray lube inside two gallon freezer ziplock bags then run the air out and seal the bags up. Instant mess free slip plates. Put one under each front wheel. Don't put one under all for wheels or the car will sluff off to one side when you lean on it.