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Old 10-26-2005, 01:36 PM   #21
vaio76109
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GC street/track kit, 525(f)/550(r), with camber plates...
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Old 10-26-2005, 02:09 PM   #22
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Stiffer rear springs huh...do you have more under or over-steer now?

I take it that you want to adjust your camber at the tracks. Take into consideration that changing camber means changing toe but not vice versa. So when you align the car, make sure the tech jots down the toe change along with camber change. 1/8" toe can make a lot of differences.
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Old 10-26-2005, 02:23 PM   #23
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I talked to Jay at GC and he was actually familiar with the track i frequent the most and that setup is what he recommended, and close to what i was thinking. It will also work well with other tracks in my area.

Right now my car tends to understeer into a turn, but pretty neutral(maybe a tad bit of oversteer) through the turn. Remeber im just running sways now.

This alignment sounds like it gonna be fun. Is there a printout or something I can hand them with all the "right" settings?
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Old 10-26-2005, 02:34 PM   #24
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Quote:
Originally Posted by Mr Paddle.Shift
So when you align the car, make sure the tech jots down the toe change along with camber change. 1/8" toe can make a lot of differences.
I saw something on TV the other night - the Dream Car Garage guys and a 68/69 vette they built for vintage racing - this was a special 1 hour show that was very good by the way. In any case, they were talking about toe in on the rear to help control the rear end under hard braking - and my car can really get a bit squirrly under hard braking into 10a at Road Atlanta - you go from 130ish down to about 50 going generally downhill. I turned the front Konis to full stiff that helped, but it still can be unsettled to some degree when I really push it.

I thought playing with the toe in would interesting.......... as I was explaining all this to my wife during the show, she simply repsonded - "how much wear is that going to put on the rear tires every day just so you can brake 20 feet later or go 5 mph faster when you really don't need to do either"? She's getting this car stuff too well these days.
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Old 10-26-2005, 02:39 PM   #25
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Old 10-26-2005, 02:45 PM   #26
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Quote:
Originally Posted by TwoE46s
as I was explaining all this to my wife during the show, she simply repsonded - "how much wear is that going to put on the rear tires every day just so you can brake 20 feet later or go 5 mph faster when you really don't need to do either"? She's getting this car stuff too well these days.
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Old 10-26-2005, 02:51 PM   #27
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I am under the impression that toe adjustment affects directional stability, ie turning into corners. Same for both fronts and rears. You always want toe-in for the rears.

What you have experienced under heavy braking could be due to lack of corner weighting or incompatible spring/damper rates. Do you feel a "rise" from the rear and a "dive" in the front? What are your suspension specs? Did you corner weight your car? Brake mods?

The other thing you might want to look into is roll center.

Quote:
Originally Posted by TwoE46s
I saw something on TV the other night - the Dream Car Garage guys and a 68/69 vette they built for vintage racing - this was a special 1 hour show that was very good by the way. In any case, they were talking about toe in on the rear to help control the rear end under hard braking - and my car can really get a bit squirrly under hard braking into 10a at Road Atlanta - you go from 130ish down to about 50 going generally downhill. I turned the front Konis to full stiff that helped, but it still can be unsettled to some degree when I really push it.

I thought playing with the toe in would interesting.......... as I was explaining all this to my wife during the show, she simply repsonded - "how much wear is that going to put on the rear tires every day just so you can brake 20 feet later or go 5 mph faster when you really don't need to do either"? She's getting this car stuff too well these days.
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Old 10-26-2005, 03:05 PM   #28
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Quote:
Originally Posted by Mr Paddle.Shift
I am under the impression that toe adjustment affects directional stability, ie turning into corners. Same for both fronts and rears. You always want toe-in for the rears.

What you have experienced under heavy braking could be due to lack of corner weighting or incompatible spring/damper rates. Do you feel a "rise" from the rear and a "dive" in the front? What are your suspension specs? Did you corner weight your car? Brake mods?

The other thing you might want to look into is roll center.
Oh, I get huge nose dive / rear rise going into 10a - it's really not that noticable anywhere else on the track. I've got the Dinan Stage 2 suspension (Konis, springs and bars) that is more street oriented than track, so given Dinan's reputation, I will assume the car is generally well balanced, but not necessarily set up with spring / shock rates that are optimal for the track, nor is it that low to effect roll center. As I noted, I did go full firm on the front Konis and it did help the dive somewhat - I'd adjust the rears as well, but they are a real pain to do.

It would sure be nice to have 2-ways on the rear - from what I think I am getting to understand on this, the optimal adjustment would be to firm up rebound on the rear to control the nose dive / rear lift - please correct me if I am wrong - every time I think I get something down on suspension set up, I find something else that seems to contradict it.

Going with the R compounds with 235s all the way around (up from 225 in the front and down from 245 in the rears, obviously didn't help this senario either, and I would assume a more aggressive brake set up would also make this senario worse.........

So given that I need to keep the car very streetable for everyday use, I'm limiting myself at this time on any modifications that will lead me down more of a upgrade this - now upgrade that senario. My expectation is that in a couple more years this will become a more track oriented car, retired from day to day use, and then we'll go to a more track oriented set up without as much consideration for daily use.

Your input is / will be greatly appreciated!!! Thanks!
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Old 10-26-2005, 03:13 PM   #29
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Quote:
Originally Posted by vaio76109
This alignment sounds like it gonna be fun. Is there a printout or something I can hand them with all the "right" settings?
What you can do is tell them what spec you need. Btw, my rear OE control arms can go up to -2.75deg. Aligned it for -2 for now.

Usually corner weighting precedes alignment.

Corner weighting procedures are pretty standard. They put the car on the scale and if needed adjust the height of the car. It's the 50:50 cross weight that's important. This time, we have a good 50:50 on my car. Actually, it's 50.0724:49.9276. My F:R ratio is 51.8:48.2. Slight oversteer. Fender measurement is carried out too. Also, corner weight + alignment are best performed with you in the driver's seat.

I also showed up with 1/2 tank gas and empty trunk.
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Old 10-26-2005, 03:37 PM   #30
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Hey we are all learning from each other.

I am not very familiar with Dinan's setup. Seems like they have linear springs but are the shocks adjustable? What about spring rates?

Your intuition about rebound is correct. But you can think about firming up the front too. Or using a higher spring rate for the fronts. Maybe lower the car further. At the end of the day, each corner of the suspension setup is a mass/spring/dashpot system we learnt back in physics. Actually the tire and wheel combo is a mass/spring/dashpot system as well but for the sake of a simple illustration we close an eye to that. I have a simple 1-dof (degree of freedom) model, 2-dof and working on 4-dof. PITA for the last one. But the 1-dof model give you a basic idea of how that corner of the car responses by changing rebound, compression rate and spring rate. Ideally, you want to achieve a critically damped response. Meaning should there be a bump (or disturbance as they call it in controls), the system should response with the minimum time. There are some systems where oscillations are desired. But not here. Then again the real world has imposed other challenges to this simple task.

It's nice to have DA setup. I toyed with the idea. But decided to try a more aggressive SA setup first. Maybe next step I will move up to DA.

What R-comps are you using? If you fit 245/40/17 in the rears, take note that with Kosei K1, tires will rub. Have to roll the fenders and adjust the alignment a little.

Quote:
Originally Posted by TwoE46s
Oh, I get huge nose dive / rear rise going into 10a - it's really not that noticable anywhere else on the track. I've got the Dinan Stage 2 suspension (Konis, springs and bars) that is more street oriented than track, so given Dinan's reputation, I will assume the car is generally well balanced, but not necessarily set up with spring / shock rates that are optimal for the track, nor is it that low to effect roll center. As I noted, I did go full firm on the front Konis and it did help the dive somewhat - I'd adjust the rears as well, but they are a real pain to do.

It would sure be nice to have 2-ways on the rear - from what I think I am getting to understand on this, the optimal adjustment would be to firm up rebound on the rear to control the nose dive / rear lift - please correct me if I am wrong - every time I think I get something down on suspension set up, I find something else that seems to contradict it.

Going with the R compounds with 235s all the way around (up from 225 in the front and down from 245 in the rears, obviously didn't help this senario either, and I would assume a more aggressive brake set up would also make this senario worse.........

So given that I need to keep the car very streetable for everyday use, I'm limiting myself at this time on any modifications that will lead me down more of a upgrade this - now upgrade that senario. My expectation is that in a couple more years this will become a more track oriented car, retired from day to day use, and then we'll go to a more track oriented set up without as much consideration for daily use.

Your input is / will be greatly appreciated!!! Thanks!
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Old 10-26-2005, 03:59 PM   #31
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Quote:
Originally Posted by Mr Paddle.Shift
Hey we are all learning from each other.

I am not very familiar with Dinan's setup. Seems like they have linear springs but are the shocks adjustable? What about spring rates?

Your intuition about rebound is correct. But you can think about firming up the front too. Or using a higher spring rate for the fronts. Maybe lower the car further. At the end of the day, each corner of the suspension setup is a mass/spring/dashpot system we learnt back in physics. Actually the tire and wheel combo is a mass/spring/dashpot system as well but for the sake of a simple illustration we close an eye to that. I have a simple 1-dof (degree of freedom) model, 2-dof and working on 4-dof. PITA for the last one. But the 1-dof model give you a basic idea of how that corner of the car responses by changing rebound, compression rate and spring rate. Ideally, you want to achieve a critically damped response. Meaning should there be a bump (or disturbance as they call it in controls), the system should response with the minimum time. There are some systems where oscillations are desired. But not here. Then again the real world has imposed other challenges to this simple task.

It's nice to have DA setup. I toyed with the idea. But decided to try a more aggressive SA setup first. Maybe next step I will move up to DA.

What R-comps are you using? If you fit 245/40/17 in the rears, take note that with Kosei K1, tires will rub. Have to roll the fenders and adjust the alignment a little.

The Dinan shocks are adjustable Konis - the front has the easy to do knob to adjust them, but the rears you have to undo to adjust - I haven't even looked into how to do it.

I'm running Toyo RA1s - 235/40 -17 all around (full tread, now with 4 days of track time on them) on 17-8 OZs, which is a really nicely balanced set up. Playing with tire pressures is probably my next viable set up option, but again, every time I think I'm getting good information, I seem to hear something else 180 degrees off. My hot temps are about 40-41 front and 44-45 rear, starting at 33/37. I was told to try 32/38 and no higher hot temp than 47 by a reputable ex racer that knows the Toyos very well, albier on an E46 track car that probaly weighs 500+# less than mine. So I decided to pick pressures right in the middle and see how to adjust from there. Any tire pressure theory would be greatly appreciated!

Since I'm not going to toss the springs / shocks yet......... the rear bar is full stiff, the front bar is either mid or full soft (I need to re-check it come to think of it), and I've gone full stiff on the front shocks - it seems I'm a bit limited at this time to tire pressures and maybe the rear shocks to full stiff.....

So, given all that, how do you model your set up, and what are you looking for, control points, etc?
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01-Dinan3/330ci (sold); 03-325it; 07-E92/328; 06-Cayman S
Wagon:
17X8 BBS RXs & 225/45 Toyo Proxes 4s
Coupe:(sold)
Dinan "S" plus Throttle Body & Stg 3 Software
Dinan Stage 2 Suspension
UUC Shifter
UUC Underdrive Pulleys
Goodridge Braided Brake Lines
Michelin Pilot Sport PS2s on factory M Double Spoke 68s
Track Stuff - 17X8 OZ SuperLeggeras & 235/40 Toyo RA1s; Shroth Harnesses
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Old 10-27-2005, 02:16 PM   #32
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Quote:
Originally Posted by TwoE46s
I'm running Toyo RA1s - 235/40 -17 all around (full tread, now with 4 days of track time on them) on 17-8 OZs, which is a really nicely balanced set up. Playing with tire pressures is probably my next viable set up option, but again, every time I think I'm getting good information, I seem to hear something else 180 degrees off.
I know how it is like. I can recommend a few books that you can read:

Chassis Tuning by Herb Adams
Race Car Vehicle Dynamics by Milliken and Milliken
Chassis Design: Principles and Analysis by Milliken and Milliken

I have the second and third books by my desk. Interesting stuff to read during breaks.

Quote:
Originally Posted by TwoE46s
My hot temps are about 40-41 front and 44-45 rear, starting at 33/37. I was told to try 32/38 and no higher hot temp than 47 by a reputable ex racer that knows the Toyos very well, albier on an E46 track car that probaly weighs 500+# less than mine. So I decided to pick pressures right in the middle and see how to adjust from there. Any tire pressure theory would be greatly appreciated!
I am running Cups and like yourself, I am playing around with tire pressures. Next thing I need work on is the tire temp. Get a pyrometer with a probe, not IR. And measure the outer, mid and inner section of the tires, immediately after you pull into the garage.

Quote:
Originally Posted by TwoE46s
Since I'm not going to toss the springs / shocks yet......... the rear bar is full stiff, the front bar is either mid or full soft (I need to re-check it come to think of it), and I've gone full stiff on the front shocks - it seems I'm a bit limited at this time to tire pressures and maybe the rear shocks to full stiff.....
Hey, no need to toss anything. Upgrade only if you think you have outgrown them. Treat it as a way of learning something different. I never rush to jump a few steps to upgrade anything (except for the SC mod argh!). I know the PSS9 is way too soft for the track. But I used it to the fullest extent on the tracks. I played with the adjustability and tire pressures. Only recently, I decided to upgrade to a different set of coils with stiffer springs. My next event will tell me if I like the new coils!

Quote:
Originally Posted by TwoE46s
So, given all that, how do you model your set up, and what are you looking for, control points, etc?
The simple way is of course to treat each corner of the car as a two-mass/two-spring/two-damper system. You can build a matrix system include 4 corners. I use Matlab/Simulink to run some simulation to see how's the response like. The trick of course is to guess what's the external force, be it a bump from the berm or a weight transfer from braking/accelerating. You can also feed in external force as a function of, say, the roughless of the road. Everything is a rough estimate. No model is accurate to the dotted i's and crossed t's. But least it give you an idea of how the shocks and springs response due to an external force.

There are no control points really...except you adjust the different spring/damper rates. BUT...TEIN and AC Schnitzer has a feedback control system where they can adjust the damping rates according to vehicle speed. That's an interesting system.
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Old 10-28-2005, 08:49 AM   #33
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I just read Carrol Smiths' Drive to Win, and it had a bit of tuning info in it, including a small piece on sway bars that cleared up how the front affects the rear and vice versa, but really didn't go into overall balance very well. I think his Tune to Win will be my next read. I'll check out your other recommendations too.

As far as your modeling, what kind of engineer are you?! I have an engineering degree (mining) but even given that it applies more to playing in dirt with big trucks, I do a good job of grasping most technical things, but you lost me.....................big time.

SME (Society for Mechanical Engieers) has had a couple of semiars here in the Atlanta area in conjuction with Panoz on race car set up, but it's $2500 if I remember right. It's definitely aimed at real race engineers, but I'm sure it would be informative and I could pick some valuable knowlege - maybe not in the details but in general, and maybe even save me more that $2500 in the long run. But, $2500 is $2500, so I've passed.

I know we've highjacked this thread, but this is all good stuff. Let's keep things going. So where can I get the cheapest clears anyway??!!
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01-Dinan3/330ci (sold); 03-325it; 07-E92/328; 06-Cayman S
Wagon:
17X8 BBS RXs & 225/45 Toyo Proxes 4s
Coupe:(sold)
Dinan "S" plus Throttle Body & Stg 3 Software
Dinan Stage 2 Suspension
UUC Shifter
UUC Underdrive Pulleys
Goodridge Braided Brake Lines
Michelin Pilot Sport PS2s on factory M Double Spoke 68s
Track Stuff - 17X8 OZ SuperLeggeras & 235/40 Toyo RA1s; Shroth Harnesses
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Old 10-28-2005, 01:45 PM   #34
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So where can I get the cheapest clears anyway??!!
HAHA, turner motorsports . Front and rears for $230....well I did atleast.
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Old 10-28-2005, 01:52 PM   #35
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HAHA, turner motorsports . Front and rears for $230....well I did atleast.
So what happened to the "I like ambers"??????????!!!!!!!!!!

I just couldn't bring myself to do it if they were $50, just because I'm so sick of "clears, DDES" "my car is burning up", etc. etc.!!!
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01-Dinan3/330ci (sold); 03-325it; 07-E92/328; 06-Cayman S
Wagon:
17X8 BBS RXs & 225/45 Toyo Proxes 4s
Coupe:(sold)
Dinan "S" plus Throttle Body & Stg 3 Software
Dinan Stage 2 Suspension
UUC Shifter
UUC Underdrive Pulleys
Goodridge Braided Brake Lines
Michelin Pilot Sport PS2s on factory M Double Spoke 68s
Track Stuff - 17X8 OZ SuperLeggeras & 235/40 Toyo RA1s; Shroth Harnesses
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Old 10-28-2005, 01:53 PM   #36
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An oppurtunity of a lifetime came by, thats what happened. I was going to get them sooner or later, I was just waiting for a deal to come along.
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