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Clark Griswald's Avatar
 
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Unhappy Alignment woes

Having just completed lowering and corner balancing my '86, I went in today for a 4 wheel alignment.

The car is 25 inches front fender, 24.5 inches rear fender. Agressive, but not an extreme lowering. The car has never been hit to my knowledge.

The guy could not get the rear into spec. Here is what I ended up with:

Rear Spec
measure min max actual

Camber L -1.16 -.84 -.69
Camber R -1.16 -.84 -1.11
Toe L 0.0 .31 .32
Toe R 0.0 .31 .46

Only 1 of 4 measures is in range! He claims the eccentric bolts that do the adjustment did not have enough to dial it in. I was standing there but did not turn the wrenches myself.

We got the front in range except for Camber.

Front Spec
measure min max actual

Camber L -.16 +.16 -1.30
Camber R -.16 +.16 -1.08

The left side was at the end of the adjustable range (the negative camber could not be reduced). This I did check myself, much to the iritation of the guy doing the work. The bolts are at the end of the slots.

The right side could adjust to a lower value, but I had him raise the camber to try and match the left side (he wasn't quit there).

Now a bit more negative camber than stock is a good thing. Idealy I probably would have asked for -1.0 camber front to try to keep tire wear down. So I don't think I am too bad with the front.

But the rear is just not right.

On to my questions -

Why does my car have insufficient adjustment range to bring it into spec?

How can I fix this?

Am I going to see poor handling or tire wear with these existing values?

Thanks



------------------
Chuck - '86 Cab, '77 Targa, Family Truckster
Old 05-29-2001, 04:16 PM
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Hi Clark,
I beleive that neutral camber is standard or reccomended up front (vertical) but up to 1.5 neg camber for the rears is the max reccomended unless you want to get serious tire wear!.
I run with 0 up front and neg. 1.0 on the rears(I beleive my heights are similar to yours as she is lowered to euro specs).
My car would not allow for any extra neg camber, which is was also confused about!.
So you are not alone, although I cannot shed any light as to why it is so!.
Rgds Ben
Old 05-29-2001, 05:46 PM
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Those aren't scary numbers but it would be preferred to have more negative camber in back than in front. i.e. if you have -1 deg in front, you want -1.5 in the rear. My guess is that the rear can be adjusted more but the eccentric can't do it all. You can cheat by putting a small prybar between the eccentric bolt head and the slot it runs in and prying it for more adjustment. If there is room between the eccentric head and the slot in the arm, then it can be adjusted more. I have seen this happen many times on 911s. The other possibility is that the rear control arm is bent. If the head of the eccentric bolt is at the far end of the slot and it still doesn't have enough negative camber, then it is likely bent. With the car lowered that much you should be able to get at *least* 1 deg. negative.

This is all assuming of course that the alignment tech had the heads properly mounted and compensated and actually knows what the hell he's doing.

------------------
Tyson Schmidt
72 911 Cabriolet
92 C-2 Cabriolet
Old 05-29-2001, 09:05 PM
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If you plan on doing any performance driving events with your car, then you want at least -1/1.5 camber in the front, and -1.5/2 in the rear. This is for minimal tire wear. If its a daily driver, then you can bring them out .5 or so. -.5 and -1.0 is a good setup for a daily driver. -2.0 and -3.5 is a good club racer spec. You get the picture. Now as far as your problem goes, its hard to tell what could be causing this without seeing it. To many variables, like machine setup/calibration, bushing wear tire width, bearings, etc. It is common for the adjusting plates/bolts to wollow out. The best thing you should do is adjust the other ones to match the worst one. In your situation, the only adjustment i would worry about was to bring the rear camber closer together. If you cant bring the left one in any more, bing the right one out to match. The rest are fine. Going in this direction will give you better tire wear, but you dont want to get into a 'pulling' situation by having them more than .5 apart. Dont sweat the small .2's etc. You'll never get them just right.
Old 05-29-2001, 09:11 PM
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Now I am not so sure the guy was adjusting the rear camber correctly. Here is a picture of my spring plates:



The toe is set by loosening the four bolts at the back of the plate - three slotted and one round. The round one has an eccentric bolt that when turned pulls the assembly through the slots for toe adjustment.

So how is the rear camber set?

Looking at this picture and working from memory how it all goes together, I don't know how the camber gets adjusted using these bolts. The guy doing the job only messed with these four bolts, nothing else.

Is it at the inner bushing on the banana arm?

Is my problem the mechanic?



------------------
Chuck - '86 Cab, '77 Targa, Family Truckster
Old 05-30-2001, 08:41 AM
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No, your guy was right, all the alignment adjustments are made with the two eccentrics in front of the two rear mounting bolts. The front rear eccentric does toe, the rear one - camber. The two hex heads up front near the pivot are only for adjusting ride hgt/corner balance. Be that as it may, changing things here will effect your camber setting somewhat.
Old 05-30-2001, 09:29 AM
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Whenever a 911 is lowered below specs it becomes impossible to align to factory settings since all adjusment parameters are affected by the lowered geometry.

So, what you need to do in order to compensate for this newly created problem is to modify your spring plates and front shock hats in order to get the needed additional adjustment.

The front shock hats are fairly simple; just remove them and grind the sides so as to allow extra clearance outwards for more positive camber.

In the rear you need to have it aligned with the lower spring plate bolt removed which allows you to adjust the rear camber to zero or whatever you want. Later you can file the spring plate hole so you can get the bolt back in and secure it.

The numbers on my car are now:

25 3/4 front w/ +.25 camber L/R

25.....rear w/ 0 degrees L/R

And she's never handled better!

Joe
86 Carrera
Old 05-30-2001, 12:41 PM
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Joe,

Is this the hole you are suggesting should be left without a bolt when setting the camber:



Your suggestion on the front is clear. I think I could get away with grinding 1/8 inch or so.

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Chuck - '86 Cab, '77 Targa, Family Truckster


[This message has been edited by Clark Griswald (edited 05-30-2001).]
Old 05-30-2001, 01:07 PM
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Maybe this is a better illustration:



Either the slotted hole that bolt #21 passes through does not have enough slop, or eccentric bolt #25 does not have enough range to make the adjustment on rear camber.

If it is a matter of elongate the slots, that I can manage. If the eccentric bolt is not eccentric enough, I am not sure what to do.

I still don't understand why my car is having a problem. I am only 1/2 inch under Euro height.

The spring plates are not bent. I suppose the banana arms could be, but both? I don't think so.

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Chuck - '86 Cab, '77 Targa, Family Truckster
Old 05-30-2001, 02:47 PM
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Chuck,

Your pointer is right on which makes it bolt #21 on the diagram.

Yes, even a half inch lower will throw you alignment beyond there design limits of adjustment.

Most of the grinding on you strut hat is in the area of the rubber bushing and you can knock off about a quarter of an inch out there easily.

Joe

[This message has been edited by stlrj (edited 05-30-2001).]
Old 05-30-2001, 06:10 PM
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I took the bolts off, one a time to have a look at where the adjustment lies without changing the alignment. Here they are:






This is the driver side, shots taken from the outside looking in.

It is hard to see in this picture, but the lower bolt is all the way at the back end of the slot.

The top bolt is in the mid range of the slot.

The front eccentric bolt is at the top of its range. This is not so clear from the picture, but the bolt portion of the eccentric bolt is up high, rotating the banana arm counter clockwise as we are looking at it.

I think I want the banana arm to rotate further counter clockwise to acheive added negative camber. To do so I would grind away some material from the back of the lower slot where the arrow is pointing in this following picture:



And potentialy removing some material at the bottom of the front slot where the arrow points in the following:



These two changes should allow some added counter clockwise rotation of the banana arm and more negative camber.

Is this correct?

------------------
Chuck - '86 Cab, '77 Targa, Family Truckster

[This message has been edited by Clark Griswald (edited 05-30-2001).]

[This message has been edited by Clark Griswald (edited 05-30-2001).]
Old 05-30-2001, 09:08 PM
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I would leave the camber adjuster alone and do the alignment without the lower bolt so you have an idea of how much to file off.

Besides, both the camber and toe eccenters can be removed or backed off and rotated 180 degrees to open up the slot in back for more rear adjustment on the camber and up and down for the toe.

Joe

[This message has been edited by stlrj (edited 05-31-2001).]

[This message has been edited by stlrj (edited 05-31-2001).]

[This message has been edited by stlrj (edited 05-31-2001).]
Old 05-31-2001, 09:52 AM
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Stlrj,

I'm not sure I follow your comment about rotating 180 degrees?

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Chuck - '86 Cab, '77 Targa, Family Truckster
Old 05-31-2001, 10:49 AM
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Chuck,

If you file where your arrow is pointing on the spring plate at the camber eccenter you will reduce camber adjustment potential...not a good thing.

The only filing that is necessary is the lower spring plate hole.

Sorry if my desciption regarding the 180 degee rotation of the eccenters is confusing, but I'm certain your alignment man could do a better job of explaining it to you.

Joe



[This message has been edited by stlrj (edited 06-01-2001).]
Old 06-01-2001, 09:05 AM
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Today I took it in to get it sorted out. Over the weekend I ground some extra adjustment into the driver side front mount.

This time it was a different mechanic and a different rack. He got the rear dialed in no problem, without grinding and without leaving a bolt out. So I now conclude either the other mechanic or the other rack was not working properly.

We ran out of time and didn't complete the front, that will be done tomorrow.

I set the rear up for -1.75 degrees of camber. This is -.75 degrees more that factory. I will have the front set for -.8 degrees camber, this is -.8 degrees more that factory.

My objective is a good compromise street / track setup.

I am asking for excessive tire wear with this?

------------------
Chuck Moreland - '86 Cab, '77 Targa, Family Truckster
Old 06-04-2001, 09:27 PM
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Of course he could not set it to factory specs.; thats why you ended up with all that negative camber which puts only 33 percent of your tire print on the road, twichy handling and a great way to eat up your tires inside.

If you all you do is run cones all day and don't mind the tire wear...great.

(If you thought 911's ate up rear tires at stock settings, you won't believe what that extra camber will do in a few thousand miles).

This might help:

http://www.europeanimport.com/tech.htm


Joe

[This message has been edited by stlrj (edited 06-04-2001).]

[This message has been edited by stlrj (edited 06-04-2001).]

[This message has been edited by stlrj (edited 06-04-2001).]
Old 06-04-2001, 09:54 PM
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Well Joe, you convinced me. Looking at the rear tires with that much camber, the inside was clearly carrying the load.

I had the rear camber brought in to -1.20 which is just a tad more than the specs call for. To bring this in on the driver side, we had to remove the bolt you suggested:



Instead of grinding, we put in a slightly smaller diameter bolt that fit okay.

The front camber didn't have enough adjustment to bring it in all the way. The driver side could only get in to -.31. This is the one that I ground to increase the adjustment range.

The passenger front wouldn't come in any more than -.80. So I will have to grind that one down too.

Except for the passenger front camber, everyting looks good now. I have just a tad more camber than stock which is fine. The car drives much better now, stable and solid.

I realize my starting rear camber must have been way off. I have much more clearance at the sidewall / fender than before. Maybe 3/4 inch.

Thanks for the tips.

------------------
Chuck Moreland - '86 Cab, '77 Targa, Family Truckster
Old 06-05-2001, 03:28 PM
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If you can get a little more aggressive with the grinding wheel you should be able to get both front struts within spec.

By the way, how much caster are you running?


Joe
Old 06-06-2001, 11:21 PM
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