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Shocks, Coilovers, and general suspenion knowledge links

Old 11-04-2010, 05:19 PM
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TX Shocks, Coilovers, and general suspenion knowledge links

Okay, let me start by saying that I don't know Jack **** about suspension for the most part. But, I am trying to educate myself. I know you have to consider the source and then form your own opinions just like everything else in life but I thought I would share some reasonable short but informative articles that I have read lately

Alignments:

http://farnorthracing.com/autocross_secrets22.html

Suspension:

http://farnorthracing.com/autocross_secrets5.html

http://www.screamingtyres.com/?p=4677

http://www.hotchkis.net/_uploaded_fi...ons162file.pdf

Shocks:

http://farnorthracing.com/autocross_secrets6.html

Buying Shocks:

http://farnorthracing.com/autocross_secrets18.html

Shock tuning:

http://www.ozebiz.com.au/racetech/th...hocktune1.html

I have not gotten to reading this yet but supposedly it is recommended if you really want to learn about adjustable shocks.

http://www.penskeshocks.co.uk/downlo...TechManual.pdf


Please feel free to question, argue, and share any useful sites or material you may have on the subject. Thanks!

Last edited by 9krpmrx8; 07-25-2012 at 04:40 PM.
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Old 11-04-2010, 09:36 PM
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i was looking for that link a while back and couldnt find it, read it a long time ago and ended up with fat cat revalves
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Old 11-04-2010, 11:03 PM
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This is good information. I have this bookmarked and refer to it frequently.
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Old 11-05-2010, 09:35 AM
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It's amazing how many different resources, opinions, etc. there are. Then you have to sort the marketing hype from the unbiased professional opinions. Some it seems are loyal to shock brands the same way they are to particular tire brands, parts brands, etc.
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Old 11-07-2010, 05:08 AM
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This may be old hat to you however this is a great resource at the track--especially when you have a handling problem that is perplexing you:

http://www.amazon.com/Carroll-Smiths.../dp/0965160017

I would contribute that the use of a good double adjustable coilover shock that accepts standard 2.0, 2.25 or 2.5" I.D. springs is required. Many a forum surfer is unaware of the huge, huge range of springs that are out there for coilover shocks. Here is a sampling. Look at page 11 for the near unlimited spring range options: http://www.hypercoils.com/PDF/Parts_List.pdf

We use a 2.25" I.D. as it fits underneath the front upper control arm (the aluminum triangle thingee) and around our Koni 2812 shock bodies. 9" front and a dual spring rear setup (a little more technical but plants the inside rear wheel during higher degree roll.

Most road racing teams will carry with them varied spring rates for tuning the car. Softer springs when grip is less (like when it's raining or if the track is really dirty). An example would be something we use to run (and this is dependant on tire---the more available grip you have, generally the higher spring you can run---generally). 300 rear and 350 front with swaybars detached with a Hoosier rain tire on a very wet and rainy surface or a wet surface that is not going to dry out. More below.
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Old 11-07-2010, 05:17 AM
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For a dry surface running an RA1 Toyo or 888 Toyo, we ran a 400rear, 450 front with the MazdaSpeed 3 piece front speedway style bar assembled and labeled by Speedsource. You'll need to purchase this through Mazdaspeed as Mazda has 3 front RX-8 swaybars available: stock, mazdaspeed via dealerships and the 3rd, and hard to find/purchase bar the one I talk about above. We have been running the rear mazdaspeed bar for several years.

Link to front bar: http://www.mazdaspeeddevelopment.com/news/?p=95

We carry an assortment of front and rear springs with us in our trailer: rears of 300 to 600 rates in 50 lb increments. Fronts from 350 to 750.

For a stickier tire (like the R80 or R100 Hoosier slick, we run a 600F, 500R rates.

Generally speaking the logic of tuning a car for a Club Racer or motivated amateur looks like this (IMHO). See below.
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Old 11-07-2010, 05:52 AM
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Pre-event setup:

Car is aligned with 1mm total toe out up front and 1mm total toe-in rear. This is pretty standard stuff used on most race cars. We've been running this for about forever. Camber is dependant on tire grip, strength of bars and springs. The more spring and bar (or spring or bar) you run, the less the car will roll.

Cross. Generally speaking you put anywhere from 50.0 to 50.7% cross in a car for a predominatly right hand turning course. Mid-Ohio, Lime Rock, Watkins Glen, VIR to name a few. For a majority of left handed turns (like Miller in Utah), you run less cross or 49.5% as an example. Camber is around 2.5 neg front and 1.5 rear to start (assuming your running an aggressive street tire with aftermarket coilovers with "street/track" rates.

So now your car is aligned and you arrive at the track. You'll need (and need to buy if you want to get anywhere in driving) a good tire pressure gauge, a tire pyrometer (longacre makes some good ones that are cost effective) and a buddy to help you.

Now here is where it gets tricky.

The better the driver that you are the better the quality of your tire feedback. For example, if you drive the car and turn and hold the wheel like a crazy wild man and hammer and hold the throttle the same, you would get massive understeer and your tires temps and pressures would reflect this. This is also true if you have small tendancies to drive this way. MANY new drivers do this unknowingly---thinking that they have to mash the throttle and hold it and that this is the fastest way to drive a car. If this is you, you are NORMAL. One of the reasons an HPDE beginner program will emphasize late apexing corners is to counter the natural tendancies of drivers to go to throttle early which brings out a much higher probability to understeer. Add to this a knucklehead who has added fancy XYZ upgraded mods to his car thinking that it's either cooler looking or faster and you may have a car that understeers EVEN MORE---making it harder to drive in, through and out of the corner. So for the purposes of this dialogue, let's pretend the car handles neutral.

So we are taking tire temps (with a decent tire) while driving the car spirited and without massive under or oversteer and we pull into the pits (not after a cool down lap EVER) and take tire data. We (you) want to do this all weekend. Pull in about 2/3'rds of the way through your session when the car is rockin and the tires have built heat and take temps and pressures. Do the temps first. Do them quickly. Write them down correctly. Then take pressures (or have a second person take pressures simultaneously while temps are being taken). Write these down. Move quickly. Write them down legibly. It is OK and preferred to bleed down tires to a target PSI. This is normal.

For example: In Grand-Am we found our tires like 39 psi. This is a very similar compound to the Hoosier R6. Our target was 39. 39 exactly. One of those larger tire pressure gauges that allows you to more easily see 1/2 lb increments (or less) is very helpful for this. I've never worked a digital gauge and never encountered any professional race team that uses one FWIW.

For the Toyo 888 we ran 32 hot. Street tires or performance street tires are alot different as there are so many brands. The maximum PSI a tire can handle is not your target. Your target is where YOU THINK the tires are best working for your car. A heavier car will build more heat and pressure then a lighter car which is why the corvette guys or the viper guys have different target psi on the same tire. Track conditions can be different also---a cold or wet surface is much harder to build pressure and heat which is why we tire test and practice down South in the cold season. A proper race tire NEEDS target heat numbers (around 190 to 210F for a DOT R compound on a 2,900 lb car like an RX-8). This would be Hoosier R6, Toyo RA1 and Toyo 888.

So we are taking these tire temps and bleeding the tires down to 37 let's say. After the session is over we analyze the data. Typically you will see higher pressures and temps in the front left for a street/track car like the ones probably owned by readers of this post. For THAT particular track on THAT day, you would want to add more neg camber to the front left if the outside temp is higher than the inside or middle temp----OH----forget to mention. You take tire temps on 3 areas of your tire: inside, middle and outside. Apologies for not mentioning this. A 15-20 degree F spread (the inside being hotter than the outside) is your target for a DOT tire. You DO NOT want the same temps across the board. A car with negative camber will ALWAYS have higher temps on the inside tire due to it's greater weight and contact patch when it's driven in a straight line/not in a corner. 15 degrees F for a street/track setup. 25F max.

Continued
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Old 11-07-2010, 06:04 AM
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Typicaly what a beginner tire temp and pressure driver will see using a performance dry street tire (not an R compound) on an aftermarket street/track alignment with similar mods is this:

Highest temps in Front Left (FL)
Higher pressures and pressure gain in the FL
Lowest temps and pressure gains in the Right Rear (RR) when there is no passenger. Adding a passenger will change your data just a bit.
Left sides will be somewhat close.
Fronts will be somewhat close.

This is a general rule of thumb

TYPICALLY, you'll see higher temps in the center of the tire because this is the nature of the tire construction. You can't do much about this other than lower your psi. INCREASED or too much tire pressure will balloon your tire and limit your actual contact patch to just the center of the tire. Think about this a second--the bigger the tire you have (a really wide 245 for example) and you take temps and find your 30 degrees hotter in the center equates to this: your only using the center of the tire. Again, the best way to learn this is to start taking data.

When your car has 15-20 degree spreads and your target tire pressures are less varied, you can start thinking about springs and bars. If your car has been modified and your using your fancy 82 F-ing way adjustable shocks (which 99% of people don't know how to use) your car may never get to these figures. Add to this a crappy driving style and you'll get frustrated taking data.

A note from a professional driver who has taken data religously for 6+ years and pretty much during every session on every track I've ever driven: Those who take data go faster than those that don't. Too often then not a buddy or friend will tell you that your efforts are worthless. Let me tell you something sports fans---those that have told me this are still finishing mid-pack in Club Racing at their home track. They have one year experience driving five times. They will always be slower than their potential. Always. Fast guys take data for a reason. Take data and go faster. Screw those who nay-say your efforts to learn. Screw em. You will learn more about your driving (especially as a beginner) and this will help you understand what YOU are doing.
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Old 11-07-2010, 06:10 AM
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Thanks Eric ..good info
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Old 11-07-2010, 06:28 AM
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Flashback to VIR full two weekends ago. Sky is sunny with no clouds. Outside temps in the 70's. Track is getting sun and therefore heat. We are testing a new tire for us, the R80 Hoosier Slick. Two weeks prior we scrubbed in a set of sticker tires (5 to 7 hot laps), pulled into the pits and yanked these tires. Put them away to use at VIR two weeks later. This is done (especially for this tire) to increase it's life. Fast forward back to VIR. Our first session we scrubbed in a second set of R80 sticker tires to be used the following day---always planning ahead to use the best rubber possible so we can get the most consistant tire feedback possible.

In preparation for this VIR event we set up the car with a 50.5% cross and added a bit more camber FOR THIS TIRE. A phone call to Hoosier tire revealed that this tire likes a bit more camber, a 20-25 degree F temp spread and a target of 30-32 psi (for a 2,900 lb car with driver and some fuel). These were our targets.

Eric goes and drives the heck out of VIR. Luckily I've had a zillion laps at VIR and enjoy this type of track. This gives us great lap times relative to our competitors and tells us we are in the hunt for the podium. Basically the driver is fast and the data should be accurate. Had we been too slow the tire data (and car feedback) would be different than if we were going faster. Generally this is slightly higher tire temps and pressures as well as more accurate car feedback (slight hints of under or oversteer).

Fortunately we had guessed very well back at the shop and our tire temps were within 20-25 degrees of each other. The data suggested we could stand up the right side of the car a bit----.2 to .3 less negative camber. This is because there are few left turns at VIR and the car is largely loaded on it's left side---rarely loaded on it's right side. Standing up the tire on it's right side allows a greater contact patch which puts more even heat in the tire. This allows the right side tires to arrive at a corner warmer (or hotter) than they would if the tire had lots of negative camber. I tell people that tire grip is like bubble gum---the colder a stick of gum is the harder it is to chew. The more you chew it the sticker it gets. Same with a tire. The more correct temp a tire is (around 200F for our Hoosier) the better grip potential it has. Think about this for a second. Have you ever seen someone spinout at your local track during the first session on track in the early morning? Happens all the tire: Not enough heat in the tires to make that bubble gum nice and chewy.

So we are running some amazing lap times on this new Hoosier, the car is handling very well and the tire temps suggest good things but need a little less camber on the right side (again, probably .2 to .3). Now we can go to driver feedback. The car is slightly pushing (understeering) mid corner out (apex to track out) DURING OFF THROTTLE ROLL. OFF THROTTLE ROLL with very little to no gas. Cars like to work off throttle. Add big throttle and weight transfer is to the rear, the front gets light and the car understeers. THE CAR ISN'T UNDERSTEERING, THE DRIVER IS PROVOKING UNDERSTEER. Many of you advanced drivers may fight this logic but that's how you drive a corner sports fans---off throttle. When set up properly a car will roll through a corner and work wonderfully. This is contrary to the vast majority of HPDE instruction and expert driver logic. Many of you will disagree with this. Put me in your car and I can prove it too you. Hard skill to learn. Faster way to drive.

So......when rolling through VIR T1, T4, 11 and 12 the car is telling me it oversteers just a smidge. Just a smidge. Add to the front bar to make it just a smidge stiffer for the next session. Car works better. Push the car more. Car tells us the same. Add a little more front bar stiffness. Car is perfect.

2.09.7 best lap with a 215 hp 2,900 lb car. Pretty good weekend. No dents. 20 hours on motor and $2K worth of Hoosiers used up.

More later. Sorry for the long winded keyboard vomit. A good nights sleep and strong coffee. Off to the shop to help a friend strip his interior and prepare for a full roll cage.

Eric
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Old 11-07-2010, 06:32 AM
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Good Sunday morning read Eric.................thanks as always..............and yeah, you might wanna back off on the coffee!
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Old 11-07-2010, 07:41 AM
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^ lol it's prop not so much the coffee , it's called excitment and focus

(this stuff is helpful if you want to setup your coilovers and alignment based on tire data)

A Eric describes, getting **** about the tire temp stuff is getting into some serious performance tuning and is lots of fun....I've settled on real-time tire temps readings as a more practical way of seeing temps during actual cornering while the tire is doing its work. Although not an internal temperature reading, it's by far a more immediate read of what's going on at the tire than running into the pits. Even forgetting the VAST increase in quantity of temp data recorded, tire temps change REALLY QUICK and even racing into the pits to get a more accurate internal temp reading is more than offset offset by the time taken/temp changes taking place before getting the in-pit reading. And how often can you go to the pits lol anyway!??

When I first saw the charts I produced I could hardly believe how rapidly temps decrease over time. Obviously some of this is due to the fact these are surface readings and not internal temps, but nonetheless, while the work is being done, the temps are real.

...here's vid showing the in-car monitor... (I don't think this is terribly useful as it's too fleeting and hard to watch while driving).... but it's cool to watch here!

http://www.youtube.com/watch?v=ktEdeUl8W70

...recording the tire temp data is more helpful. Here's a vid showing 4 sensors, 1/tire and how quickly temps change on track. Hint: Blow the vid up to full screen, it's too hard to see the graph otherwise.

http://vimeo.com/3160916

...as Eric mentions, and for the serious tire temp buff, get the full 12 sensors and record 3 reading/tire all the way round. I only use four, 1 each aimed at the outside half of each tire, and record them to the Traqmate's 4 analog inputs for later graphing and review. Deatails http://www.opti-grip.com/Opti-grip/Opti-Grip.html


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(I know scale is off the charts to big, and reading are low- I hadn't correctly calibrated them yet - and was just starting w/the temps graphing)

Last edited by Spin9k; 11-07-2010 at 10:19 AM.
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Old 11-07-2010, 07:51 AM
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^..........T'was merely the amount he chose to type early on a Sunday morning!
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Old 11-07-2010, 08:56 AM
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Thanks!!! It's always nice to hear from you Eric, thanks for taking the time to educate us.
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Old 03-30-2011, 09:38 AM
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Bump for noobs.
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Old 09-02-2011, 10:18 AM
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Bump for good info.
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Old 09-02-2011, 11:19 PM
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This should definitely be stickied in the racing section.
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Old 09-03-2011, 02:21 PM
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So much knowledge!!!
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Old 09-03-2011, 08:52 PM
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great read!
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Old 06-26-2012, 11:34 PM
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Bump
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Old 06-26-2012, 11:57 PM
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Originally Posted by 9krpmrx8 View Post
Bump
thankyou for bumping this 9k
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Old 07-22-2012, 06:39 AM
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great info
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Old 07-22-2012, 08:40 AM
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Thanks man, check out this article I just added to the first post.

Screamingtyres Talking to the experts / Q&A with Josh Coote of MCA Suspension
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Old 07-25-2012, 04:40 PM
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Updated first post with this from Hotchkis

http://www.hotchkis.net/_uploaded_fi...ons162file.pdf
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Old 08-07-2012, 08:45 AM
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Great thread, thanks for posting. This is pretty helpful. I was trying to find out about koni shocks and a spring set up and found my way to this thread.
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