How is your 911 Track Car Setup??

[Devil Dog Mosport]

Originally Posted by Dan J

Stock 3.0 SC with headers It's all suspension

Agreed.. all the HP in the world is useless, if you can't keep the rubber on the road!

[Matt Monson]

Devil Dog,

Just a heads up if you haven't already figured this out, but the Dan J posting here is the same Dan Jacobs I suggest you contact in the PCA header thread a week or two back.

Regards,

Matt

[Devil Dog Mosport]

Originally Posted by Matt Monson

Devil Dog,

Just a heads up if you haven't already figured this out, but the Dan J posting here is the same Dan Jacobs I suggest you contact in the PCA header thread a week or two back.

Regards,

Matt

Matt, yes sir I did and have contacted him via email. Thanks.

[Matt Monson]

Just making sure. He flies a little under the radar here and on RL. You're welcome. Keep updating us on the progress of your car.

[KTL]

The soft rear t-bars allow for way too much squat and roll. The 911 being so rear weight biased wants a considerable amount of rear spring rate back there. A 28mm rear torsion bar is not nearly enough in my experience, even on the lightest of 911s.

LRP requires some cajones, especially that last turn coming onto the main straight. Had to use all the track there to get that fast lap! All suspension and the dood behind the wheel were key!

That video is a good example of a guy being on it the whole lap. Either on the gas or on the brake, virtually no time wasted there. A lot of people starting out in racing don't realize how critical that is. I fell into that category and often still have to remind myself to be "on" & not become too comfortable. Point being is, car setup is only part of the equation. Driver has to have his personal setup right and drive the wheels off.

[Dan J]

Fred is an alien

[michael lang]

Originally Posted by Devil Dog Mosport

have a proper and proven shop do the corner balance and ride adjustments

Happy New Year and God Bless the Corps!

I have been following this thread pretty closely since I'm a big proponent of being able to drive a slow car fast. I think you should start there and then move on to your other items once you get a good known neutral setting. My point is, without starting there and jumping in to have all those other things done you will never know what single item actually fixed the problem that you were originally having of the car swinging around on you. I am by no means saying to not have any of those other things listed done to your car. Truth be told, I would love to have a Guard LSD put in my car. I think what I'm getting at is that in order to truly understand the benefits of one mod and how it compliments another or to reap the whole benefit of the modifications the car must remain neutral in its set up.

Years ago, my car had this problem of the right front wheel locking up under aggressive braking especially at the end of a long straight like T1 at Summit Main or really hard braking like just before turn in at T5. I messed with my car and messed with my car. I tried rebuilding the calipers, I tried diffent pads, I thought the problem was in the tire, I spent so much time and money messing around with that stupid car on that problem. On a whim, I decided to have an alignment completed because I noticed that the rear tires wearing unevenly. I got a phone cal from the alignment shop asking me how bad the car was pulling, I told them there was no pulling at all and that I had dropped it off for an alignment as a preventative maintenance reason. This is when I learned the problem, the alignment was way out of adjustment but more importantly, the right front was sitting on about 330 lbs. and the left front was reading 680 something while the rear was coming in at just over 1100lbs on the left and 800 on the right. Ironically enough there was zero pulling and because I rotated back and forth between street/track tires they never were on long enough to wear out. I never knew the magic these cars have until after I had my car properly balanced and aligned.

This is why I originally posted that with your car's current set up, you should absolutely be handing other drivers their asses on the track. Best of luck in getting your original problem figured out and I wish you much speed in '14. Please keep everyone updated on your progress.

[Devil Dog Mosport]

Hi Mike,
Yes agreed. I've done the change of brake pads per your stated method.. Much learned. Per my next steps the "major" change will be the LSD. Regardless of another shot at having a better corner balance and alignment done over the last attempt.. the LSD I feel is a given at this point.

Logically, when only one wheel is driving and the other does nothing but go along for the ride, trying to hold fast corners when either wheel might be off the pavement, does not make a stable situation. There's just not enough "meat" keeping the car mated to the surface.. This is where the LSD makes the difference.

Additionally, the corner balancing should only enhance the LSD experience by optimizing the "road contact", at differing forces. With all this, brake pad change impact should be lessened as they now become just another enhancement of the former changes to ensure proper corner setup and keeping the car in check.

I should know pretty quickly what these changed will bring.. but of course in this part of the country that won't be until late April early May.. !!

[Jedi]

As said before the first place I would look at is initial setup. Incorrect toe in the front will make the car unstable under braking and this can throw the back around, espacially if you dont have toe in at the back.

[JohnJL]

This is what I measured tonight after a day at the track. The settings moved around a bit from where I set them but that's to be expected as I just about rebuilt the suspension a few times.




Up front, I have never been happy with the amount to camber. I have elephant front monoballs and a triangulated brace. The brace is turned all the way in so that I am out of threads on the heim joints and the D washer in the monoballs is tight against the inside of the tower. I have not modified the towers. I have never been able to get and keep 1.8-2.0 degrees of camber. I am considering taking the sander to the D washer and see if I can get the struts leaning in to 3.0 degrees.

In back I have 1/4" toe in on each side, which I thing might be too much? It feels OK under braking, I have a GT LSD in a G50.

Right rear camber needs to get cranked up a bit.

I will check cornerweights tomorrow.

Any other observations?

[KTL]

Do whatever you need to do for more neg. camber in front. These cars are notorious for not affording you much ability to get neg. camber. Opening up the holes in the strut tower and offset camber plates are the typical approach.

I think that's a lot of toe in the rear. Typical performance setup for rear toe is 1/8" total toe in. You've got 1/4" per side?

You definitely need more negative rear camber IMO. Typical rear camber settings for a streetable track car is -2 to -3

[Devil Dog Mosport]

As the one who started this post, and now that season 2014 in over, at least almost. Here is what I did and results:

Up Front,
Stayed with the 23mm TBs - stiffened up the Sway just a bit. Put in quick adjust ER Camber plates. Reset alignment - Toe at 1/4' per side, -2.0 camber each side - Raybestos ST43 pads

In Back,
Stayed with 33mm TBs - softened up Sway bar quite a bit, Lowered to 24.0 inches, Reset alignment -2.5 camber each side, slight toe in, Raybestos ST43 pads.

Biggest Change - Guard LSD in my 915 trans, new synchros, replaced 2nd gear.

Results: A "Totally" different car and feel. Faster times, better handling, better feel, control of oversteer when and if it happens... not ONE spin or even close at every track this year! In sum, I think the LSD was the single biggest factor and MORE track time for sure. Now, I have more confidence in the grip and feel, pushing the car much faster than before.. Job Done!

[JohnJL]

Thanks. Sorry to hijack your thread.

Kevin,
I have 1/4" difference in the front of the rim to the vehicle line and the rear of the rim to the vehicle centerline. So the rim is 1/8" closer to the centerline from parallel and the rear of the rim is 1/8" further from the vehicle centerline than parallel. Measured across the front of the rims, I have a combined 1/4" toe in, if I am using the terms and understand them correctly.

[Devil Dog Mosport]

No Hijack, open to all! Just wanted to share my results after all the good feedback!

Good luck.

[KTL]

1/8 of total toe is plenty so I really don't think you need that much toe. You can measure it easily on one side by setting the other side to zero toe by turning the steering wheel to get your measurements to be the same at front & rear of the wheel rim edge. The other side's measurements will tell you the total toe. The steering rack "automatically" halves the toe for you when the steering self-centers itself upon driving the car.



Good discussion here http://forums.pelicanparts.com/porsche-911-technical-forum/297155-how-measure-toe-out.html regarding toe measurements and I should correct myself by saying that your wheel diameter is important when measuring toe

[cstreit]

Originally Posted by Devil Dog Mosport

Up Front,
Stayed with the 23mm TBs - stiffened up the Sway just a bit. Put in quick adjust ER Camber plates. Reset alignment - Toe at 1/4' per side, -2.0 camber each side - Raybestos ST43 pads

In Back,
Stayed with 33mm TBs - softened up Sway bar quite a bit, Lowered to 24.0 inches, Reset alignment -2.5 camber each side, slight toe in, Raybestos ST43 pads.

1/4 toe IN? or OUT? Either way that's a LOT... Not to say I haven't done it before, but 3/16" was usually the max I would go. What would you estimate at the rear?

[Jedi]

Originally Posted by winders

Well, if the car gets real loose under hard braking in a straight line, it could be any of a number of issues. The toe could be off...too much toe out front or not enough toe in at the rear. The alignment could be way off. The corner balance could be way off. You could have too much brake bias to the rear.

Something has to be off for the car to want to go sideways when braking in a straight line. After all, inertia dictates that at object will continue to travel straight unless acted upon by some other force.

I raced a 911 RS with a very similar set up to yours and had a very stable car. The rear TB was 31mm so that might be part of the issue but I don't think so. Winders is on the money with his advice above. I used to have 2mm total toe in rear and 4mm total toe out in front (most guys use toe in but I found toe out eliminates understeer completely). You can even go to more toe in at the rear, depending how you like the car to behave.

[Devil Dog Mosport]

I will continue to tweak it again this winter.. But, can tell you it's a totally different car than before , so much more stable under heavy straight line braking or trail braking. There is very little oversteer unless I turn in real late and if it does break I can easily catch it.

Tire temps are constant and even, tire wear is normal , so I am at least close. At smaller quicker tracks without high top end speed, it "feels" like a good setup.