I just put my 944 Turbo on an alignment rack, Hunter DSP 4000 and the following happened.

Loosened spring plate bolts to set rear camber and toe, and low and behold the rear sagged wayyyy out of alignment. -3.5+ camber.

Now, I can't seem to get less than -2.3 camber with .03 toe in at the rear. It takes a great deal of force to turn the camber ecentric, too much force I think.

What happened? How come I can't do better than -2.3 camber? I'd like -1.8 in the rear.

Suggestions?

 

Hey Bill;

First off, I must say that this is the absolute worst part of our beloved 944s. The only part I truly hate. It may be the stupidest bit of design I have ever seen. Simply begging to become a problem, and after 20-some-years many of them are.

You loosened the bolts too much. You only want them loose enough to turn them. There needs to be enough friction present to hold them in any position on the eccentric, and to keep the eccentric well engaged in the hole. God forbid you lube them!!!

I am seeing more cars over the years that "cannot be brought into spec." There can be a number of reasons for this.

To start, if the car was in spec before, then it can be brought back. Do you know where it was before? If it was -2.3 or greater, now you know why.

Sometimes bringing them back must be done by mechanical means other than the eccentrics. I've used 5-6' pry bars, and even a come-along. This may sound a tad savage, but it takes what it takes. Obviously something is amiss if these tactics are necessary, but it is not always at all clear what that is.

Sometimes the eccentrics or the holes in the blades themselves are worn and will not work properly. This usually stems from lots of alignments, and/or people loosening the bolts too much and wearing out the eccentrics. You can weld up and re-contour the eccentric shoulder on the bolt. I've done this many times. I've also refurbished the holes in the blades.

I've done cars that had no visible signs of anything being amiss, and yet they would not come into spec. I could get the camber right, but I could not even get near 0 toe, let alone toe in. I have re-positioned the holes - in this case forward - so that I could get the proper toe settings with reasonable camber.

You can see sets of parallel lines scribed in the blade for all 4 holes. These represent current position, and then a 1/4" movement forward for each. The bottom rear hole has already been radiused forward using a die grinder. all 4 holes were done likewise, and then welded up and re-contoured at the rear.



All tolled this took 4.5 hours, not incluing all the failed alignment time, and the successful one subsequent to the mods.

Good Luck!

 

Can I just replace the Camber eccentric? Everything else looks like it's in good shape.

To answer your question, I don't know if I could ever get less than -2.5 camber. I wasn't happy with the amount of push I was getting, and the guy who did my alingment last put -2.5 on the rear because he said this is what he put on other 944's. Everyone I talk with says -1.5 to -1.8. So, I thought I'd do the alignment myself.

THe new shop I'm working with is trying to get more experience with 944's that are set up for the track.

Do I need to take the rear suspension apart to replace the camber eccentric?

Thanks for the help.

 

Yes, if it is worn. If you can find them. You can re-contour them if you can weld and grind.

I'm not sure what the rear camber will do for push. Too much negative in the rear should give you OVERSTEER in the extreme.

The amount of camber you need is governed by your tire wear. If you are wearing the inside, you need to drive harder, or set less camber. If you are blistering the outsides, you need more negative. This will also vary according to the track you're driving. -1.5-to-1.8 is a good place to start for your tires, but don't expect it to help the understeer.

No.

 

First of all - I don't see any indication that you have the car in the air when you're trying to adjust the camber? Since you are effectively trying to lift the car with that wrench - you might want to lift it up.

If you do have it in the air, I'd disassemble, clean, and reassemble. If you go too far, the eccentric should just cam-over and start increasing camber again.

Not that I'd be that upset with 2.3 deg... I'm surprised that you want so little camber... I'm at 2.75 and going for 3, it's what my tire temps say they want... and I believe it, everyone else running Hoosiers is there. Not sure what you're running for tires, but would be surprised that any other tires would want much less!

Another note on camber adjustement as relates to ride height. As you lower the rear, you will have more camber, and your upper and lower achievable camber points will increase. My car is at 5.25" at the rocker panels (without seams), just above the min for the class, and I doubt I'd ever be able to get much below 2 degrees of camber. But like I said, at that point it just cams-over and starts increasing again. I could probably get mine pretty close to 4 degrees, if I wanted and could use that much...

 

Another note on setup, since I see you were complaining about push. Your camber settings should be determined by tire temps, and only by tire temps. Get a probe pyrometer and start tracking them. You should have about a 15-20 degree split inside to outside after coming off the track hot, inside hotter naturally. Your handling balance is something that should be adjusted using your springs, bars, and dampers. How much front camber are you running? I'd highly recommend the same as the rear; if not, that would explain the push.

I wouldn't expect to see the car get loose until you get to 3.5 deg or more camber in the rear - you're looking for that optimal working point in camber, and it should somewhere around 2.5-3 degrees, like the shop said (depending on your tires). If it's pushing, you need less front stiffness - start by softening the front bar, if your camber's right. You don't mention what front springs you're running, or t-bars, so hard to define the balance there...

 

OhhhhhhHHHH.....

You racers. You guys never remember that most people don't drive hard enough to use 3 degrees. Many people will be just fine at -1.5-1.8.

Point well taken on the pyrometer. It's the best way. Tire wear is not quite as immediate.

 

He's the one who's calling it a racecar!!!