"I have to pretty much set the tire pressure every time i go to the track right?"

you set tire pressure every time you go (on) the track. i can't say enough about tire pressure. NASCAR competitors trim their chassis to a QUARTER OF A POUND OF AIR PRESSURE. think it isn't important?


and what are the chances that your are running correct pressure? without a pyrometer, not great. That’s because the temps across a tire will reveal optimum pressure.

You go to the track and air your tires to 30 27. You go out and run 3 to 4 laps as hard as you can. Re-measure tire pressure. It will have grown differently on all 4 corners. Compare the pressures to optimal pressure.

if, for example, the all important LF tire has grown from 30 to 40, and the optimum is 35, you start it at 25 and it will grow to 35. You will have diff growth numbers at each corner. every time you change something growth will change a bit.

You will, no doubt, eventually end up w different starting pressures at all 4 corners.

Ideally you do not set overall handling w tire pressure. You set it w swaybar etc. all four tires should end up at their best pressure. You can, as mentioned above re NASCAR, do final TRIM w pressure.

David posts some items that are really on the money. for instance, if your car is in the paddock and one side is exposed to the sun it is going to totally screw up pressures to the tune of easily a couple of pounds. bring a couple of covers (old bedsheet squares work well) to the track. also... use a high quality tire pressure gauge w a bleeder. i bought a Laboratory Quality pressure gauge, 5 inch face, accurate over the entire scale to 1%. i use it to check all my pressure gauges.

"keep a good record of pressures"

like anything in life if you want to excel you need to be organized and have data. get a clipboard. put together a setup sheet. springs, shock settings, swaybar, tire pressures, ambient temp, track, setup alignment, tire temps (3 on each tire), pressures before and after each session. if you are organized you will soon be able to use all 4 tires to the max. plus, being organized allows you to win without being a genius.

as to whether my Durometer is on the Shore scale, i don't know. it is a Longacre which most use.

tire stick, according to John Rastetter, is a combo of many factors.... tread design,
rubber compound, carcass architecture, in addition to durometer. of course other things being equal i will opt for low (soft) durometer numbers. that's why i preliminarily am happy w the 62 i recorded on my HTR Z IIIs.



hc

 

Wow, soooo much great info here!!


I dont have time to read through everything right now. But this thread is exactly what i was looking for, i am contemplating coilovers for a street use FD.


Thanks to OP Howard for starting this wealth of knowledge and thanks to everybody else for contributing.


Once i read through the entire thread ill try and come to a decision .



=Ben

 

Damn Howard, I might have to try those Sumitomos. The price is a fraction of the Yoko AD07s I've been considering......

 

Awesome info.


How do we find out what the section width to tread ratio is on a particular tire?

Also, I'm interested in bleeder valves but reluctant to drill holes in brand new RPF1s. I'm going to go search for pics to see how bad the damage is, hehe..

 

"How do we find out what the section width to tread ratio is on a particular tire?"

i have found the greatest overall accumulation of tire info on TireRack's site. if i find the tread width is not specified, i go to the mfr's site.

as to bleeder valves... i don't suggest they be used on the street. if i was track only i would be grabbing the drill. Longacre sells them.

hc

 

Howard, speaking of Tire Rack data, I'm curious as to what your take on this is:

Sumitomo HTR Z3 section 11 inch, tread 10.2 inch
Potenza RE 050A PP section 11.4 inch, tread 11.3 inch

All other parameters are pretty much the same. A difference in tread width of over 1 inch would seem to be quite a big difference, no?

 

I'm running nitrogen now, seems like a significant advantage

 

Howard I trust your input and am very interested to see how you review the Sumi's, but I have heard poor things about them in the past couple years. Problems with graining and uneven wear, especially when pushed on the track... I was very surprised to see you chose them over some of the more expensive and well-known options. Look forward to reading your review...

 

you pays your money and takes your choice....

i am not in any way claiming that the HTR Z III is the be all and end all tire. there were some things i really liked about them.

i wanted a 255 and a 295 18 and that excludes a number of brands.

i wanted DRY TRACTION. the HTR Z IIIs recently won a test over a number of excellent tires (Potenzas included) both overall and in dry traction/laptimes.

best lap time, highest lateral Gs. i talked at length w John Rastetter so i am comfortable the test was a test rather than a marketing push.

here's part of what Tire rack said:

"The track is where Max Performance Summer tires really show their stuff, both for their fun factor as well as their absolute capability and overall traction. In the dry, the Sumitomo HTR Z III proved quickest overall, aided by its total package of responsive handling, stable cornering traction and confident braking grip. Continental's ContiSportContact 3 lapped our course less than 2/10ths of a second behind the Sumitomo, but required more concentration to produce the fast laps. The Conti displayed significant levels of lateral and braking grip, but its overall handling was not as crisp or precise as the others in this test, requiring smooth inputs and a delicate touch to turn a fast lap. The Bridgestone Potenza RE050A Pole Position was found to be the most responsive of the group, feeling almost edgy in its steering response. Unfortunately the overall grip level was not high enough to take full advantage of its quick steering. Yokohama's ADVAN Sport seemed to lack some overall grip, displaying noticeable understeer when pressed hard. The lively handling we felt on the road disappeared when pressed to the limit on the track, with the steering feel becoming somewhat vague."

the HTR Z III is a completely new tire V the HTR Z II. i actually have heard some nice things about the II, but it is a different tire. the II has the Vs treadwise which i don't prefer.

then there is price:

according to Tire Rack:

295/30/18 HTR Z III is $185

295/30/18 Potenza 050 PP is, cough, cough uh... $325.

finally, now that i have them i am very surprised at the 62 (soft) durometer. with a nice tread pattern and the 62 they should fly.

i am looking forward to showing my rear tread pattern to the higher dollar guys w my HEATERS... (HTR, get it).

i will spend the $140 saved per (rear) tires on methanol.

as i said you pays your money and takes your choice.

hc

 

I may have missed it but what kind of car(s) did they use for this test?

 

While I was shopping at http://www.longacreracing.com for the bleeder valves I found that you can purchase something called "quick change adaptor" which replaces the stock valve stems and allows you to swap out the bleeders for another adaptor you can use to air up the tires.

That way you can use bleeders and don't have to drill holes in your nice rims Also, you can take the bleeders off for street driving.

I also ordered a nice digital pressure gauge (0.1 psi readings) and a $100 pyrometer.

 

Just wanted to give an update.

Apparently since January 08' Tein no longer does any custom spring rates on any coilovers. So it is 12/10kg and **** you charlie. Prostreet just called me and informed me that all they can do is sell me the springs seperate but that these are 190$!!!, previously it would have been just 150$ to upgrade the springs.

So I don't really know if I am going to wait for something else now or just go ahead and buy these, again Howard it would be terrible to have the 12kg/10kg rates because it would give less overall grip and be much harder to drive on the limit?

alex

P.S Also they bumped up their price from 800$ to 835$ while I wasn't looking, sneaky bas****

 

Most likely a BMW 3 series.

 

Yes, a 2006 BMW 325i Sedan. Here's the link to the relavent
Tire Rack test from July '07:

http://www.tirerack.com/tires/tests/...ay.jsp?ttid=93


David

 

i am planning on releasing some of my shock dyno data which is quite supportive towards the Tein SS and Flex. i do think, however, if they aren't going to offer the right springs for the street/track (dual purpose) i would have to look elsewhere.

i will give Tein a call tomorrow and see what we can accomplish.

i received my 6/32 shaved HTR Z IIIs from Tire Rack today so things are getting headed towards being on the road after the snow melts.

dyno first, Blackhawk second.

hc

 

Me? haha

 

I wasn't trying to be abrasive in my comments, I was just surprised at your choice... But I did not recognize later that you had bought the III, the newer version of the tire. Hopefully you find your new "heaters" toast the competition (heater, toast, get it? ) and all for a great price. If you give them a positive review, I'm sure the TireRack will be flooded with orders from all the rx7 guys reading this thread, probably even myself

 

Thanks howard, you sir are baller!

Charlie it is an expression not directed towards you or else it would be Tein said: "F*** you Alex"

 

haha thats what I thought you meant, I'm a bit sleepy

 

Howard thank you...I ordered my TEINs along with the 8 and 6kg springs. ProStreet seemed very attentive, I guess the real key is their follow through on the order. SwapBars and mounts are next

 

I guess I am gonna have to call Ryan back and see what's up after howard gives us the feedback from Tein.

 

i prefer not to get into too technical a discussion of shocks on this thread but since i owned a shock dyno i would like to share some info and dispel some confusion.

while shocks look pretty similar the only way to evaluate their characteristics is on a dyno. the dyno strokes the shock w adjustable force and measures the the resultant speed of the shock. using force and speed the resistance of the shock can be calculated.

since shocks turn linear resistance into heat, and therefore get hot (duh) the dyno tests should be done at a consistant shock temperature. i use 135 degrees.

shocks offer varying resistance based on force and resultant shock shaft speed.

shocks generally have 3 sets of valves. low speed for the center half of a turn- around 5 inches per second, medium speed for corner entry and exit and braking 5 to 9 inches per second, and high speed for potholes. note speed in inches per second is plotted on the vertical axis.

shocks and shock settings do not effect total lateral weight transfer... there's that all important factor resurfacing. they also do not effect total roll. they do effect the SPEED of the transfer and they can apportion the LWT longitudinally during transitions. if too stiff they can cause tire chatter and loss of contact w the track, read SLOW. if too loose the car will wallow as the springs take too much of an undampened role. the shock's primary funtion is to dampen the spring oscillations.

i have plotted a stock FD shock, a Tein SS-FLEX-HA set at mid (8 clicks) range and a GAB at mid range.

since vertical is speed and horizontal force the farther the plot is from the zero X axis the softer the shock resistance. for example if we zero in on the all important 5 inches per second (corner control) note the GAB is the softest as it's shaft speed raises above 5 inches per second just past the 124 pounds force while both the stock shock and the Tein at 8 clicks maintain 5 or less at higher force levels.

don't hyperventilate over the stock shock high readings as the bread and butter is in the 5 area and it does fairly well. i like the way it works w Eibach springs. BTW, i run my Teins at 6 clicks a softer setting than the 8 posted.

i also noted a significant difference between the resistance offered by the GAB between right and left front as well as rear. a no no.

i have dynoed 31 FD shocks and found all but one almost exactly similar regardless of miles. i found the Teins to also be exactly similar.




generally when you read an article on shocks they mention that there are 3 types of resistance curves. progressive, linear and digressive. progressive applies more resistance with increased shaft speed. while that might initially sound good it isn't as you don't want a lockup when you hit a curb or pothole or you will have a blown shock. progressives are ancient.

linear increases resistance w force. still overkill against a pothole.

digressive is the hot setup and most modern. more resistance against a lesser force and less against a greater force. i bring this up because there lots of shock vendors saying their high dollar shocks are, digressive. if you note the following chart you will see the OEM FD shocks as well as the Tein and to a lessor degree the GABs are digressive.



no doubt the charts will raise various questions and i will be happy to address them if they relate to the general drift of this post. i have no interest in debating mono tube versus twin tube and getting in to race shocks that need to be rebuilt often.

not that these aren't interesting and valuable topics but they are for another thread. i do not want to miss the forest for the trees.

i may post one other chart which shows the vast range of adjustability of the Tein's 16 clicks making the point that the Tein SS or Flex do NOT need to be revalved as per tein when switching to 8/6 or 10/8.

BTW, i will be contacting Tein this aft re spring rate options.

howard coleman

 

here's a Private message i received this morning.

i have continuously suggested that one of the most cost effective ways to TRANSFORM the FD is with just the addition of Eibach Pro Kit springs and proper suspension settings.

Marco apparently agrees. i publish this with his authorization:

" Originally Posted by FuturePerfect
Hey Howard,

It's been almost two years, but I finally got the Eibach Prokits and went ahead with the Tokico Illuminas. The difference is amazing. I followed your recommendations to a "T," and am blown away at the significant increase in handling. Friggin' sweet!

Happy rotoring, and many thanks!

Later,
Marco

Re: Suspension Upgrade to Eibach Pro Kit

--------------------------------------------------------------------------------

Hey Howard,

Please feel free to use whatever you'd like of our conversation regarding this suspension set-up. Might I add that on my work commute, I took a corner yesterday between 5-7 miles per hour faster than usual, without really noticing it. I only noticed by glancing at my speedometer on my way out of the corner, just before I hit the gas. I cannot wait to hit some twisty roads!

Thanks,"



still running stock springs? spend a couple of hundred bucks, an afternoon installing them and a trip to a good alignment shop and you will be smiling all summer.

howard

 

Howard, I think several people on this thread are on the fence WRT purchasing Tein shocks, only if they can get them with 8/6 springs at a decent price. If Tein is made aware of the potential (non)purchases maybe they will be more ameniable to offering a better price for the 8/6 setup.

 

Tein-Tech-"Ryan" 562-861-9161

Tein offers alt springs for the SS.

part #

front

6 KG ST060-01175
8 KG ST080-01175
10KG ST100-01175

rears use prefix "SJ" rather than ST according to Tein

they carry small inventory. if Ryan received some calls maybe they would either stock more or change the rate. i have made my call.

hc