911SC Alignment
 

I'm seeking advice from the forum about getting a proper alignment on my 1983 911SC.

I freshened the suspension, including TBs, shocks, Turbo tie rods, bump steer spacers, ER bearings, sway bar bushings, new tires and lowered to Euro specs.

I took the car to what I considered the premier Porsche alignment shop in my area. They have a current and very impressive Hunter alignment system. The technician understood the machine and procedures and I followed his progress as far as it went.

When he got to my front camber and castor, the Tech informed me that my car's castor couldn't be adjusted. I knew better and pointed out the axes of adjustment to the camber plate should include fore and aft movement. When he looked at my camber plates, he said they had never been adjusted after leaving the factory because the rubber cushoning had never been broken. In order to adjust the plate for camber or castor, he said he would have to chisel-out the rubber. I didn't like that. My right camber was -1.2 degrees, only slightly out of spec and told him not to proceed with the chiseling.

On the rear, this shop couldn't find the tools they needed to adjust the camber and toe cams on the spring plate. They had allen sockets which would fit, but couldn't get them in the nut firmly enough to turn the cam, while the car was resting on its suspension, . So we agreed to disconnect the machine and stop the procedure.

The service manager didn't charge me for any alignment and we agreed not to proceed until they received the correct tools.

I looked up the tools on this web site and they are simple cam tools which can be turned with a wrench or socket. I expect this shop just mis-placed their tools and will get them replaced.

I'm more troubled about the front camber and caster adjustments. Is it true that the original cushoning material under the camber plate has to be removed in order to adjust these values? Is it common for a car this old to have never had these values changed?

The only way to prevent your front end from going under the knife is to restore yor car to it's original factory height which will automatically bring your camber and caster values back to original factory spec.

Cheers,

Joe

Thanks, Joe. In that case, I'd rather put it under my own knife before going back for alignment.

Can anyone describe exactly what I need to do? Or will it be obvious to me when I remove the camber plate? Is there a good reason to consider the various after-market camber plates? This is a street driver with only occasional DE.

Fritz

I'm not favorably impressed by that shop's approach to Porsche 911 alignments. I've got the proper (12mm?) Allen tool and all the other tools that would be needed (except for the alignment rack of course), and my MINIMUM expectations would be that a proper alignment shop would have them as well.

The tops of the front struts, inside the trunk, are spooged with a black brittle substance. I suspect that substance is there for the purpose of waterproofing the trunk. At any rate, that stuff cracks over time anyway. I have seen no good reason to fret over whether it is replaced after an alignment or not. If my trunk gets wet, I'll seal it. The black stuff is not under the camber plate. It is on top of the camber plate, according to my recollection. At any rate, I would not hesitate to crack that stuff and remove it. It surprises me that an alignment shop would even hesitate to do that. It needs to be done in order to complete an alignment. Raising the car to US ride specs probably wouldn't result in "perfect" castor settings anyway. It would probably still need to be tweaked, requiring that the black stuff be removed. And besides.....who wants to drive a 911 that rides THAT high?

If it were me, I'd probably take it to another alignment shop that understands Porsches, if possible, and just tell them up front not to worry about the black stuff.

Superman, your point about the shop's reluctance to break the black stuff is important. Aparently no other shop has ever broken it to tweak the front camber or castor either. That makes me think that many shops set the toe, maybe tweak the rear settings a little (or not), and then tell the customer they just got a good 4-wheel alignment.

At least this shop is willing to let me stand by their tech when he's doing my alignment. To their credit, they didn't try to avoid breaking the black stuff; they pointed out that my camber was only out of spec by a little, and they asked me if I wanted them to chisel around the camber plate to free it up. I didn't like the idea of using a chisel to break this free until I asked this forum for advice. When the shop couldn't come up with the tools to turn the rear alignment cams, it became a moot point, and we agreed to stop the operation.

My rear adjusters have different size allen-head cams. The forward one is, I think, 12mm, and it's accessable with a standard socket. The rear one is very close to the banana arm and, I think, 17mm? A standard allen socket will not fit snugly enough to turn the cam when the suspension is under load. I can only turn it when my spring plate is unloaded.

Now I think I read enough to decide it's time for me to free-up the upper strut camber plates myself so I can get a proper alignment.

I happen to have the 17mm Allen tool also. That is the tool needed to deal with the tranny fluid plugs.

It sounds like you will not hesitate to chip away the brittle black stuff. It will remove easily. Not much chisel action will be needed. This is the right decision, I think. And I think you are on the right track in terms of overall approach. Even if the caster only needs a little tweaking, just tweak it. Many cars' alignment systems do not allow certain adjustments to be made. Also, many cars are not lightweight high performance vehicles. Your 911 is a precision-engineered lightweight high performance machine. 'nuff said.

I took my '83 911SC to the Porsche dealer for alignment, after lowering to "European" ride height per Jerry Woods, as no other shop would touch it. It spent 4 hours on the rack becuse the tech had to chip away the brittle black stuff. They charged me a flat rate of $250.00. What a difference, car handles so much better. The cost of doing it correctly was well worth it.

It MIGHT bring it back to factory specs but where's the fun in that?

If you do a search you will likely find ways to remove the black tar stuff. I would do it myself before having some flat-rate alignment guy work it off and maybe scratching the surface more than needs be. I've read that people here using a dull screwdriver tip or a blunt-tip hardwood tool..etc. Maybe even dry ice. Go slowly and you can get it off. Yes..it needs to come off to do caster and/or camber adjustment. Yes..it is also possible that this car never had ( or needed !) caster and/or camber adjustment.

Right camber at -1.2 degrees is *not* just a little off. It is quite a way off from factory spec. Are you seeing a lot of inside-edge wear maybe the inside one inch or so ? Good setting for track work but a bit extreme for straight-ahead normal road work. When I bought my 85 Carrera as a used car it too never had an alignment ( caster/camber) since the goo was still there. It also had the passenger side at more negative camber than spec...like yours.

You can't just keep the car weight on the wheels and start loosening the top shock plate bolts...the car at some point will "crash" down to max negative camber! Get the front of the car on jackstands and maybe even support the bottom of the wheels or suspension with bottle jacks if you loosen the top plate bolts.

I'll check my records and report back...but I think 1 mm lateral adjustment on the top plate will affect camber by 0.1 degree ( 60 minutes in a degree).

Once you get the goop off, yes, there is the possibility of water or humidity intrusion into the trunk area. While you're adjusting, there will be a moment when you can keep 2 bolts in place...or one bolt in place (depending if you're working on the front side or backside plates, the number is different)....which allows you to remove the *other* plate on that shock. Then you you can smooge some goop into the body recess and then re-attach the plates on top of the goop without disturbing the alignment settings you want to keep. While doing this , the car weight must still be off the wheels. When you snug all the bolts back up, then you can drop the car weight back onto the wheels.

- Wil

Thanks, Wil. That's the kind of detail I need to make sure I get it right. I appreciate all suggestions/tips anyone may have.

Fritz

Confirmed on camber change relative to top strut change-->

http://forums.pelicanparts.com/showthread.php?s=&threadid=140259&highlight=front+ strut+angle

- Wil

I chipped-out the black stuff from my strut tops exposing the camber plates. Photos I've seen before show a camber plate over the strut, covered by the adjusting plates. I only have the two plates. Am I missing something I should have? Photos attached.http://forums.pelicanparts.com/uploa...1185052985.jpg http://forums.pelicanparts.com/uploa...1185053042.jpg

You're perfectly fine.. remember what I said in my previous response ??---->

"....While you're adjusting, there will be a moment when you can keep 2 bolts in place...or one bolt in place (depending if you're working on the front side or backside plates, the number is different)....which allows you to remove the *other* plate on that shock....".

As confirmed by your picture....you have a "backside" plate with 2 bolts...and a front-side plate with one bolt. As long as you're careful and support the car in front ( including the tires)..you *should* be able to loosen the front ( keeping the rear tight)., or loosening the rear ( keeping the front tight)..so you don't disturb the settings you want. Still...when you're depending upon the "one bolt" tight...the shock may still "pivot"..so support those wheels!!!"

Ahhh...go a bit more slowly and easily on the tar removal...you can do a bit less paint damage than shown, if you use a dull instrument. Others on this board may have a better way to remove cleanly. Good paint color ( solid, not metallic) for an easy "match" in case you want to touch up later .

- Wil

Alignment Results
 

Wil,

Thanks for your suggestions. I took my Porsche in for re-alignment yesterday with the below results:
http://forums.pelicanparts.com/uploa...1186141491.jpg

The problem with front caster and camber was that the goop surrounding my upper struts probably restricted the available adjustment play. The only way I can see how to allow more movement would be to follow your advice above to free the upper struts, including the camber plate, clean everything and then re-align. If that didn't work, I guess I'd have to consider purchasing after-market camber plates to allow more movement.

Although my camber and caster settings are slightly out of spec, these settings don't look like they would be a problem for either street handling or tire wear. What do you think?

Fritz

It's not the goop but the ride height which is obviously below what would even be considered european height.

Bottom line...get the height right and everthing else falls right into place. Simple as that.

Get the shop to measure your height. They have all the specs and see what they say.

Cheers,

Joe

You have to understand that Stlrj has a rather unique view of alignment settings, postulating that the Porsche OEM is ideal for everyone under all street conditions. This is not to incite, it's simply his view vs. my own and is exhibited in previous threads on this toipic where we both chimed-in with this opposing viewpoint. Perhaps it was unfair for both of us, Stlrj and myself..to offer opinion without first saying where we're coming from.

So.... let's first say this. I'm from the camp that says the Porsche factory specs are OK for the 'normal' driver using compromises that Porsche *thinks* the average guy will see. If *you* , however, want a bit more aggressive settings and are willing to trade-off some tire wear for improved handling, the settings you have should work very well for a basically street car with a bent toward a more sporting setting. Porsche themselves issued a completely different alignment spec for "sporting purposes" ( read "racing") when the 911 first came out.

It all depends what *you* want out of the car.

EDIT.. even though we're on opposite sides of the fence on this issue, Stlrj ...where is the basis that says he's below Euro ride height? I don't tsee that mentioned in the discussions numerically.

I'll confirm that my ride height is lower than Euro. Like many (most?) others on this forum, I use the convenient "fender lip" method of measuring. I'm now riding at 14 1/2" rear, 15" front.

Wil,

Thanks to your calculator, I was able to get my ride height spot-on after refreshing my suspension, including 21/27 T-bars. I centered my spring arm adjustment, so tweaking my rear ride height is almost as easy as doing the front. I have bump-steer spacers in front and am very satisfied with the handling so far. I'm not concerned about my front camber/caster, but am interested in feedback about the consequences of being slightly out-of-spec.

Thanks to all for your feedback.

Fritz

If you're at 25.5" ( ground-to fender lip) front and about 25" for the same measurement in the rear, this is taken ---in general-- to be Euro height. Using a "normal" 24.8" to 25" rolling diameter tire.

As long a your front lower A-arms are parallel to the ground ( or angled "down" from inboard pivot relative to outboard or balljoint pivot), then you're OK. Don't get so low that they angle the other way around ( lower on the inboard pivot). A 12-13mm thick rack spacer is OK for "minor" lowering below Euro...say..about 1/2", but not more than 1". If in the 1" or more lowering range, you need the spendy Elephant Racing or other bump-steer kits, that allow lower settings and can be fine-tuned for bump steer.

"..where is the basis that says he's below Euro ride height? I don't see that mentioned in the discussions numerically."

I based my observations on the fact that his front camber settings were so far negative which could only have resulted from the front end below euro spec.

As a point of reference, front torsion bar height measurements between US and euro spec SC's are only 9mm apart which is less than half an inch difference in height. (page 73 Porsche Technical Specifications 911SC, Turbo 3.3)

So raising the front to euro spec at the minimum would be a benefit.


Joe

i'm no expert, but the tires are supposed to be "pushed" before setting toe.

I believe if not "pushed" then you make that up w/ -7.5deg or -1/8"