RX7 FC Track Car Tips and Tricks
 

As a bunch of you guys are now starting Lapping your car and actually competing in Time Attacks, I thought that I could start giving you guys tips on real world ways of making your cars faster, more reliable and more consistent track day cars. I will start with a few pointers and then as I get a chance, more information on setup, chassis details, fuel systems, etc.... All of these points have been gathered from racing the pig every year since 1998 and making every possible mistake.

Please feel free to add your own tips and information or ask questions in areas that require further help. Some of the points may make aftermarket parts guys nuts, but a lot of stuff that people bolt on their car, in the hope of going faster, really isn't needed. It looks cool, it can sound great and even make your car feel better, but they really don't help enough to justify your spend.

The first area I will cover is the most important and the over riding concern that you need to keep in your head anytime you modify your car.

Eric

Weight Is Your Enemy
 

First lets assume that you have your car is in very good working condition. If you have a bad tie rod or your exhaust is leaking and about to fall off, get that fixed first. The car has to be in very good operating condition first before you look at other things.

How can you make your FC, either NA or Turbo go faster for the least amount of money. Reduce the weight of the car!!!!!!! I have done a bunch of Bosch LapSim car simulations on my FC and 2 things make a huge difference in the car at Mosport on the GP Track and they make a bigger difference on tighter tracks. For every 10 rwhp I add to my car, I can reduce the lap times by almost 1 second. Keep in mind that this is with the aero and tires I have on the car right now. For every 20 kgs, I can reduce my lap times by .5 of a second. Part of the reason is that FC's have no torque. If the car is lighter your existing equipment has an easier time to move it around and slow it down.

In racing 1 second is golden. To add 10 hp to your car is going to cost a fair bit, but to achieve that same savings in weight means that you have to get 20 kgs out of the car somewhere. Take a look at your car. Before you go out on track, pull everything that isn't needed out of the car. Some class rules restrict what you can pull out, but if you are just lapping or if your rules allow yank everything out. This means seats, spare tires, maps, disco balls, monster stereo setups, sound insulation panels, headliners, etc... Hey, stop eating at McDonalds, loosing 10 lbs is a qurter of a second and you get healthier as well. Only you can know what you need to have in the car to keep it liveable and what you can get away with. Lightening your car is the cheapest way to go faster and the thing that makes your car more hardcore to drive.

As a secondary benefit, the reduced weight makes your car better on gas, The brakes work better and last longer, your tires work better as they have less mass to haul around and all the parts work less to move the car and have a bit more excess to move the car along quicker. Everything just works more efficiently. As a side benefit, if you reduce the weight of your car by 45 kgs or 100 lbs, your existing springs, shocks and swaybars effectively become stiffer improving the responsiveness of the car. Also, before going out to run hard laps, make sure that you only have the minimum amount of fuel in the car that you need. A full tank adds almost 100 lbs to the car. I tend to go faster and faster in my 1 Hour races and my fastest laps are at the end of the race. Why? Its not because I am superhuman or a mental midget that takes almost 1 hour to figure out how to drive my car, no its because the fuel load has burned off and the car just runs better lighter.

If you really go hardcore, there is no reason why you couldn't take 200 lbs out of your car. Bingo, without any changes at all you should be able to go 2 seconds a lap faster at Mosport and it really didn't cost you much at all just some time and comfort.

Discuss and complain about how you need that monster sub-woofer.......... You can't have a car that does everything. Decide what you want to do with it then start. Weight is the enemy of speed. Sometimes we all forget that, me too. I understand the need to keep the car street legal and also relatively comfortable. Well look for lighter cloth seats, no rear seats at all, strip out the interior and pull up all the sound deadening sealers under the carpets. Run a decent but smaller stereo setup with only 2 speakers. You really don't need A/C in a track car. Look for roll up windows instead of power. You guys know the drill.

Next time, the most important part of the car. Almost everything needs to be set so that these work in their best possible sweet zone........

Eric

<3

Subscribed. Cause I am trying to be faster in time attack:)

I would say essentials for the track would be:

Good condition pads and rotors
Fresh brake Fluid
Fresh coolant
Fresh oil change
Solid brake lines
Good tires

and Bring:
Oil
coolant
water
brake fluid
tool kit
jack
Rags
Flashlight
Tire pressure gauge

and mods for a 20 year car
good shocks/struts (can be stock)
Most definitely a Rad aluminum or a Newish rad dont rely on that 20 yr piece
Alignment
Bushing kit
Oil temp gauge is nice

then once you get more comfortable
Camber plates/rod
stiffer springs/coilover

then power mods



I wouldn't go to crazy with go fast mods I would always do the reliability mods first

Im trying to figure out what alignment i should run on the track with my car still

I run 3 degrees front and rear, The rear end steps out to easily on initial turn in or under braking but once settled in feels ok I am will be running less in the rear in hopes of getting more rear traction to around 1.5 as someone has suggested to me

I love this guy!..haha..Good info!
(but My car does go faster To MacDonalds than on the track!.gotta cut that Out!!)

Bwek, that is exactly the list that a decent track day car should have. Just a few points more directly stated than I wanted to at this point. On alignment I have found that there is no one alignment and suspension setup. They are in a range depending on the track.

For example, at Mosport Big Track you have to take a lot of things into consideration. I am getting some downforce from the aero stuff on my car and I like to have a very stable platform of a car so that I can attack the corners hard and still have a stable car. I run 600 lb front springs, 400 lb rear springs. With my Koni setup I run the adjusters full stiff to control the spring rate. I take off the rear bar and run the bigger Suspension Techniques front bar. I have removed all of the rubber from the front end, so I can control my front wheel movement under braking and side loading. I run as much negative camber as I can get, 4 degrees, but it still isn't enough because I still am getting the dreaded Toyo outside half tread wear lip. I run the front alignment straight ahead or 0 toe. I lower the front suspension until I only halve just over 2" of clearance to my front splitter. For the rear, I run the car as low as I can until the u-bolt holding one of the 90 degree 3" exhaust pipe bends starts scrapping the pavement in Turn 4 with a full fuel load. I run about 1/8" toe in and 1.5 degrees negative camber. I have also removed all the rubber from the rear suspension including the rear subframe bushings.

Is the car fun to drive like this? Nope, the front end jiggles up and down over every bump and the steering wheel is constantly fighting my hands. Is it fast? For me, yes it is. I can get the car moving very quickly like this and it gives me the flexibility to pass cars off line when I have to and minimizes tire spin coming out of 5b and Turn 10. I also get decent braking effect going into turn 5a and 9. I have generated 1.5 g's sustained in Turns 2, 3, 4 and 8 on my data logging system. For example, Al sets his car up very differently than I do. It really is driver specific and Al likes a softer more stable platform than I do. Must be my karting background still having an effect.

For Shannonville and Mosport DDT I run a completely different set up. I run 400 front and 275 rear springs. I raise the car until the front splitter is 3.5" off the ground and the rear tires are 1" out of the wheel well. I run a stock front sway bar (if I am being serious) or the Suspension Techniques bar in the softest setting and the stock rear bar. I run 1/8" toe out in the front and straight up in the rear. I adjust my rear shocks to mid soft to allow for squat and rearwards weight transfer coming out of the corners. I leave the front and rear cambers alone. I also change the brake bads to a softer rear and harder front to help the rear brakes stabilize the car going into the corners. I also crank up my rear wing a fair bit. It adds drag, but you are really only getting just above 100 mph on either track and the extra high speed grip can help out. It works great at Shannonville where the car has done very well in most of the races I have done there in about 4 of the tracks configurations, but I have never driven at Mosport DDT. It is really not my type of track.

One last point about Bweks list, make sure your wheel bearings are in very good condition and properly greased with high temp grease in the front. The extra heat from the brakes working hard and the side loadings from the corners really works the wheel bearings severely. Make sure that they are in gioood condition. Also, before you go out lapping, change your diff and gearbox oils. They will get a lot of hard work and you should treat them gently.

Eric

One last thing, Bwek the dartiness and snap oversteer you are feeling in the corners can be a number of things, but I expect it is the Dynamic Rear Steer bushings doing their jobs. These bushing deflect under street use and amake the FC feel very stable and pointy on the street at slower speeds. On the track they constantly are shifting around and makes the back end of the car feel unstable. It could also be your car hitting the bump stops in the rear or a bad shock or your rear sway bar hitting the chassis somewhere. Put a couple of tie wraps on the shaft of the rear shocks. That will quickly tell you if you are using up all the range of rear shock travel and bouncing off the stops if they are crammed all the way to the top. Check the end links or the end of the bar to see if they have witness marks from hitting the floor. I had to make 2 large dents to allow my rear bar to clear in its full range of motion when the car is fully lowered.

Eric

Eric

subscribed

good info for us newbies

Ya I've got dtss elimlinators sitting here in my tools box and just ordered fresh bearings this morning lol

I think it was my alignment causing the oversteer 1.6 degrees does that lol, I've fixed now and disconnected the rear sway feel much faster around a corner now

Excellent post Eric. I'll be following this to try to gather a bit more of your expensively won wisdom.

Out of interest, dare I ask what the race-weight of your car is?

Mine came in at just about 2350 with 3/4 of a cell of fuel.

Mine weighs in at 2425 with a full tank of fuel. Keep in mind that my car has a cage that a NASCAR Stockcar builder put in. I think it could stop a train, LOL. Also, from what I remember about AMP, the Shannonville setup (softer) would be the better route. Add a ton of wing and front splitter, higher ride height, Mosport alignment and Bobs your uncle. At least thats where I would start.

We are going to be putting the 3 ways on the car this fall and the new bump steered spindles to try to make my piggy handle the bumps a bit better. My lower front control arms are angled upwards by about 30 degrees, YIKES!!!!!!!

Eric

Great thread to start Eric. I'm primarily an autocrosser and the odd lapping day (thus far, one of these days time attack/solosprint), so my car retains it's interior, but I ditch any removable item I can, have an aluminum hood, and much smaller battery, and as light a wheels as I could find to save what weight I can within the compromise of staying in class rules, and keeping the car somewhat comfortable for some street use. I run softer springs than even your Shannonville/Mosport setup (350/275), and a lot less static front camber than you, but as much castor as I can, so my camber gain on turn in gives me very even tire wear.

Bwek - I completely agree with Eric, ditch the DTSS bushings, the car is so much easier to drive at the limit without the rear suspension changing the toe settings as the rears transition from grip-to-slip and back. I also added rear camber links to dial out rear camber gained from lowering, and found at -1.5 and 1/8 toe in I had way more rear grip than the -2.1 I had previously - more rear cornering and more brake grip, helping fight the early rear lockup that seems common to these cars, even though I run more aggressive front pads than rears. It even seems to help with getting power down at the rear without lighting up the inside tire on tight autocross corners.

I think that the big differences (tire wear and spring weights) is that I am getting some aero downforce out of the car and it tends to generate higher g-loadings than you would traditionally see in a street bodied car. As well, I may push the pig a bit harder than you as I don't have to drive it home. Regarding the rear, thats exactly what I am running. I made the front rear subframe adjuster out of rod ends and threaded hexagonal aluminum bar and it does the job. We have been playing with rear cambers as low as 1 degree and have found even more grip at a cost of outside tire edge wear. I am also running 15x7 wheels and 225x50x15 tires. My whole goal with this car is to keep rotational mass down so that what little torque it has can actually make itself felt.

What is funny, is that I can pull an awesome lap out of the car at Mosport, then get slightly balked on the next lap, loose 2 seconds, then it takes me 2 laps to get back up to speed again. I wouldn't have thought that the car is a momentum car, but they are. You have to be tidy and precise with the car to go fast. Any sliding around is fun and looks cool, but is really really slow.

Wait till I blow everyones mind when I talk about brakes.

Eric

Any chance you have some Old R-comps lol!

Im running Hawk hp+ on all 4 corners with my car (GXL) the Hauls down real fast and I get no Fade

Our set up is very simple lol. we run eiher 500lb front and 400lb rear or 400/300 depending on the track and solid Delrin bushings. My ride height is almost stock, when you start to lower your car all the geomtry goes for a crap and unless you start to remount control arms etc your car will drive better at stock height with stiffer springs. We have no rear sway bar either. Aligment is simple and proven for us, 3 Neg on the front, 6deg pos caster and at Mosport 1/16 toe in at Shannonville 1/16 toe out. Rear has toe eliminators, adjustable camber sleeves from Mazdatrix. Rear Alignment is 1-1.5 deg neg camber, 0 toe. We have played with tons of settings and this seems to be the best overall combination, we have run a 1:15 on Pro track at Shannonville and 1:36 on the big track at Mosport. With the stock Turbo gear box back in it those times will not be achieved lol.

what do you guys do with your oil system to deal with hard right hand turns?

is a baffle plate and a oil catch can good enough to keep the oil out of thee filler neck

In my case no. I have a Racing Beat Baffle plate and a funky oil diverter plate in the oil filler neck. I have also built a modified TII filler neck with 2 drain back tubes to control oil surge. Even with all that, I am still draining a quart a day out of my catch can at Mosport. At Shannonville, its a couple of teaspoons.

Al is absolutely correct. When you drop the RX7 the alignment all goes to crap and the car handles horribly. This is why I get all kinds of twitching and kickbacks from the steering wheel. The car handles like crap, but at Mosport, I have found that they reduced frontal area and better front splitter function, offsets the horrible bumpsteer effects. You should watch Al's car, smooth as silk and I bet the steering wheel is nice and well behaved, LOL. I would strongly suggest that you don't lower your car too much from stock. I run substantially higher rates than Al to control wheel movement and therebye bumpsteer. Al's way is better.

In my case, I don't have the HP that Al has and as Mosport is mostly monster straights, I need every trick I can think of to make the car go as fast as I can. As an example, in the 3 hour Race last Fall, I left the car at the stock ride height, but put the stiff springs back in. The handling was sooo smooth and silky over the bumps, but the car was sliding and washing out a ton and about 1 second slower than where it should have been. Granted my tires were old, but even in the past when my tires were very new, the car has always run quicker at Mosport with the lower ride height. I did the 1:38.0 at Mosport with a stock S5 Reman, 4 year old take offs from somebody else and the car scrapping the ground with the steering wheel twitching like a living thing. I just remember what my old team owner said to me once when I was complaining about the Suzuki Swift I used to race, bunny hopping all the way through Turn 2 at Mosport when I was flat out in 4th, he said that when the car handles great anybody can drive it, but when it is necessary to make it evil to go fast, then it takes talent to keep it on the track.

Like I said before, there is no magic bullet when it comes to setting up your car, just general guidelines. It really depends on what the car wants in setup to go fast and then what the driver needs to be able to control it, in that order.

Eric

Thanks for the tips Eric. For a lower-speed (relatively) track like AMP, I've got sufficient cage, but I probably wouldn't mind another 75lbs or so of DOM put in there in a few spots.
My car has been parked the last season and a half due to various circumstances, but I'm getting the itch to drag her back out.

Right now, from memory, I think my front springs are 375 and rears are 275. No front splitter currently (my Flatout motorsports splitter is currently a lot of expensive fiberglass shards) and I've just got the RX7 sport-package duck-bill lip on the back. I honestly never figured AMP was a fast enough track to get useable downforce, but that's not my area of expertise. But, I do need to tackle a front splitter project, if only for cooling. Can I ask what you are running?

Overall, my suspension is an updated version of what was on the car when I got it, within the means of my modest budget. The car ran some very fast times with it's original owner all those years ago, running the Mazdaspeed GAB kit from back in the day, Suspension Techniques front and rear sways, Racing Beat rear camber adjuster and DTSS elminators. I'm now running KYB AGXs (which are the old GABs from what I can tell) with fresh Eibach's of the same rates on Ground Control sleeves, left the sway bars on, new DTSS bushings went in when I did the 4-lug to 5-lug swap and put a fresh rear camber adjuster in (the old one was seized.)
I don't remember my specific height, but I tried to adjust it so that my front control arms were level to slightly down.

It might be because I'm NA, or I just don't drive hard enough, but it's never been a problem for me. I haven't had to do much. (Other than the usual pressure regulators, bypass pellets, oil jets etc.)
I have a Pineapple Racing oil pan with their windage tray. For a catch can, I needed one in a hurry on a budget in a panic one night before a race, so I just grabbed a water bottle for a bicyle and put it up in the fender well. A seasons worth of running the car, and there was about a teaspoon of oil in the bottom of the bottle.
3 years later it's still there, because, well, it works.

my car is alot faster than a N/A lol.
I went to cayuga last year and didnt know the importance of a catch can. I just did the rats nest removal before getting ready to race, had the lines just venting.
I did a couple warm up laps, went to do a hot lap took the hard right after the straight at 120ish oil dumped out all over my rear tires, spun the car out but i caught it, and was goin 60-70 in reverse looking in the windshield of a bmw lol so i signalled and pulled off the track still goin in reverse but it ended up seizing the front stationary gear bearing needed to be rebuilt......that was an expensive lesson lol

I want to make sure that issue is resolved completely before i go back. I got the catch can. im thinking about getting the Pineapple oil pan over the baffle plate. the baffle plate says it slows the oils return to the pan to remove air bubbles but nothing about keeping the oil from sloshing so i dont know if would help or make the problem worse since it would return slower.
i just dont want to starve my new engine of oil :)
I want to go back really badly, ive got a set of new r comps waiting to go on. but I want to make sure I everything is good to go

i was just looking ,the PR oil pan is on sale right now too it should work pretty good

A bit of advice for when you get your car out, as long as you are exceeding 100 mph, aero has an effect. Look at all those unlimited Solo 1 guys in the US. It just means that the slower you go, the larger the wing required to have an effect. As well the front splitter will have to extend out further, but if I recall correctly, a report from Simon McBeath in Racecar Engineering stated that splitter effect dropped off substantially after it reaches 3" from the forwardmost point of the front fascia. I am running an AWR GT3 1 piece nose that Al got with nhis car when he bought it. It isnt the best fitting thing in the world, but it really does the job. Its very light, about 5 lbs for the whole nose and spoiler and setup.

The rest of your suspension setup sounds very good and I do have experience with the old GAB,s and AGX's from my Suzuki days. The shocks should be capable of controlling those spring rates when you are close to the firmer settings. Honestly, the only thing I would try is removing the rear bar for a test to see if it allows you to reduce wheelspin and increase your acceleration out of some of your tighter corners. A good bushing kit would be good as well as it controls the arms better and minimizes deflection and that vague feeling.

As a side tip, I used to have the straight ahead position of my steering wheel change during and after the race. For the longest time I thought something was slipping in the suspension setup like a control arm or tie rod or camber plate. What I found, during an engine pull, was that the rack was slipping back and forth in the rubber mounts. I shimmed the bottom up with shim steel until it was solidly mounted and I have never had that issue again. I think this also shows effects of bumpsteer and the use of bionics in the drivers forearms.

Something cheap and easy to do to the car to make the steering more precise.

Eric

Just wondering about something. In an old engine I picked up from some guy in Brampton, was supposed to be a fresh S5, but turned out to be a beat S4, the oil control rings were very bad. It didn't smoke at all at idle or low rpm running. When the pressures built up from rpm or cold oil, it would smoke like a muther and fill the oil overflow can in one 10 lap session. As well, the baffle plate slows oil flow both ways, but the Pineapple race pan does look good. I am just trying to enjoy my car now and have stopped developing it for a while with lots of new parts.

Just an idea.

Eric

Ive taken that corner at the end of the straight at 120+ in my N/a how much hp has nothing to do with it, and ive never had my crankcase vent like your car did


The tip about shimming the steering rack is awesoem never thought about doing that!, i know what you mean about the steering wheel Eric when im driving mine on the street its all over the place, I personally dont mind it, reminds me of a go cart! hah

Alfred

i dont know how fast i was goin 120 is an estimate , it was fast I did a full pull down the straight.
so i was goin over 200

Excellent feedback Eric, thanks. Really good tip on the steering rack. Mine seems to be fairly solid, but will certainly look into that.

The car has mostly upgraded bushings in it, but some of them are probably getting tired all the same. Probably a project for this winter.

I've actually been wanting to try unhooking the rear bar just for a test, but I've never made it far enough down my testing list without something more important happening to get me started from the top again. (i.e. transmission failure, engine problems etc.) But, after you and Al both commenting on lack of rear bar (I've seen a lot of the ITS guys mention it as well) I'll make it a priority.

Now, for the Aero. I have no speedo in my car, but judging from my lap times (I reverse engineered it based on gearing and RPM once, but I can't remember now) and the speeds I've hit on the same parts of the track with my RX8, I probably close in on 180-200km/h for a few seconds at the fastest part of the track, and probably close in on the 100mph mark at one other point. So, knocking on the door of aero being useful. Would probably be a bit more useful if I could get over a few mental blocks and get my foot in it. The car is capable of running about 6 seconds per lap faster than I'm capable of pushing it. (Car has run 1.17s at AMP in it's past.)
So, sounds like Aero is going on the list for this winter.

Any more information on what you are running for a wing?

As for the splitter, the AWR stuff is nice, but may be a touch out of my budget. I may have to dig up some of the home-brew threads.

You FC guys are lucky you have Eric and Al sharing all the r&d they have painfully gathered over the years....i wish they had FD's
Great thread Eric....good luck with you testing on Monday.

Shims do help the natural bumpsteer issue when the car is lowered...

lol anyone going to shannonville on this long weekend? i think theres an event on monday. i would LOVEEE to sit passenger in one of your cars just to see how a fc performs on the track. all this talking about setups is making me want to get my rx7!!!! as soon as i get the right deal and enough money, ill finally get to join you guys!

never thought of it that way... I could raise the rack to help get rid of the bumpsteer?.. Off to metal supermarket I go lol

You can raise the rack to return the tierod angle back to stock and that will reduce bumpsteer some. I built some spindles with dropped rod end mounts that would allow the outer tie rod mounting point to return to stock angles. I haven't used them yet as I need to lengthen the threaded shaft coming out of the steering rack about 2" and I just haven't had time yet.

To eliminate it completely, you need to raise the height of the inner control arm mounts, which is darn near impossible with the way they mount. If you lower your FC you will always have some bumpsteer unless the complete front end is fabricated from tubes, lol. You should see what they did to my Cougar to eliminate bumpsteer. Whooooo baby, they spent a ton of money and time changing the car.

Eric

Al and I will be there on Monday to do some testing. You will be able to watch, but no ride alongs as I know I can't put a passenger seat in my car and I am pretty sure Al can't put one in his. Come on out anyways as you will get to see Al and I goof around some while I have some testing chores, then we can play some as well. Playing in the cars is the funnest part. Tire lock ups, smoke billowing, big slides and maybe some off roading, LOL.

Eric

http://mazdatrix.com/SteeringAngle.htm

these are what i plan on using eventually for my bumpsteer i'll just deal with it for now, i notice its alot worse with my 16 on compared to my 17's ,I use to bomb around in 6 wheel tanks that were older than me and many other canadian military gems lol my ride quality standards are alot lower than the average person :), but i do need to raise my car a bit

Exactly what I made for myself. Heck, it cost me more for the reamer than the $165 Mazdatrix wants for the kit. All in, I am over $250 CDN. Man, I wish they had them 2 years ago. Great find....

Eric

Just buy mine its ready to go!

You have never posted a sale price:)

You'd have to sell all your 7's and all the parts then start looking at the family heirloom china...

I an I dont post a price because most people have to make the mistake of building one to realize what a good price is lol. Jason if I sold my 7 the next one would be North American powered and drivelined so I could afford parts lol.

NICEEEEEEEEE cant wait to see u guys there. Im gonna be doing some shots, so watch out for some asian kid with a camera taking shots!!! lol and o1, never seen a post that you were selling an fc =T if its a turbo2.... lol ill come take a look at it

Canjams old FC race car use to run 1:29's at Mosport GP. NA.

I'm sorry to bring this thread from the dead, but it has great info in it! Are there any new tricks you guys have learned over the years for setting up our FC's for the track?

~Anthony

hey buddy, whats up :)

Andoru should chime in...his FC is stupid quick

What are your opinions on bushing replacement? Use the soft OE ones or replace with harder aftermarket bushings?

No reason to go with the soft OE ones, I re-bushed with Energy Suspension pieces a couple seasons back, I didn't find it really made the ride harsher, although in some fairness, I'm running coilovers that are much stiffer than stock, although short of true race-car firmness, so my ride was already a bit harsh.

Honestly, I really like the Energy Suspension pieces as the compliant bushings in FC's. If you go to solid bushings you can get binding and false stops when the bushings reach their limit of distortion. You either have to go from a relatively compliant bushing like the Energy Suspension type, all the way to rod ends to allow for the twisting. The Mazda FC rear suspension is a maze of different rotational arc's and all of them don't line up for smooth rotational over the travel of the bushing. They want to twist a bit. Mazda built this compliance in for the passive rear steer on the stock suspension.

You can replace them all with iron like firmer bushings, but you can end up with a darty unstable car under suspension loadings. Just go with the firmer street style kits unless you are going full race and re-engineer the car.

Eric

Thank you guys for the info! What methods do you use to counteract the fact that we're limited to our Macpherson style struts instead of the more modern double wishbone suspension? Would it be wise to run stiffer springs and lower ride height to help mitigate the camber changes or is that just something we have to live with in our chassis design?

Lowering is good, but excessive lowering can hurt your handling a couple of ways - and I'm not a suspension engineer, so if I misstate anything, people can correct me (like that's ever a problem on web forums!). Because the lower control arm mounting points can't be moved, lowering the car tends to lower the roll centre faster than the centre of gravity is lowered, which increases the roll couple - the effective lever length created by the difference between CG height and RC height. Although lowering the centre of gravity is good, increasing the roll couple isn't, since it increases the leverage of the weight transfer in cornering, and makes the car less responsive to steering inputs - meaning harder to drive at the edge. As has been mentioned earlier, bumpsteer also tends to increase with lowering, although there are tie rod ends that can be bought to deal with that.

Here's a couple of discussions relating to the effect of over-lowering stock suspensions - it's not a just Mac strut issue, Mac struts just suffer for the fact they tend to have little-to-no negative camber gain in under compression (so at-the-wheel camber quickly becomes positive at the outside tire due to body roll). Stiffer springs resist roll and help to fight the geometry change that results from the body roll changing the tire's camber - as will a stiffer front bar in particular on these cars, which also helps fight the inside rear tire lift that tends to go with a front roll centre that drops faster than the rear roll centre, which leads to changing the stock roll axis (already biased in most cars towards understeer), and increases weight transfer under cornering to the front outside tire.

A couple good articles on suspension geometry, specifically changing roll centre:
It's all in the geometry - roll-centre
Pro-touring.com - Negative Rollcenter Height

23Racer.

I recently collected some swaybars myself. Got the smallest OEM rear swaybar since everyone seems to remove theirs, so i figured it wouldnt hurt to grab it, just in case. I also finally added the adjustable front Suspension Techniques sway bar to my collection but haven't had a chance to use it.
My question is , are you use the OEM front swaybar on slower/shorter/tighter tracks?

I just realized that I haven't added anything to this in years...

Lets see what I can add to this that can help and blow peoples minds. Also, its important to realize that Anduro's car is stupid fast and he has gone totally crazy by basically building a tube frame car inside the stockish shell. I think of it like building a ship in a bottle. His car is about the ultimate fabbed RX7 around here. The other thing is that my RX7 is a race car and not a time attack car. To an average outsider, they look sorta the same, but mine was built to handle racing speeds for hours and Andrew's is designed to go freakin' monster fast for 15 minutes at a time. Big difference.

Anyways, new learnings from the start of this thread. First and incredibly obvious, tires make a huge difference to how you set up and use your car. Last year, we were fortunate to receive new set of ToyoR888's and a set of Toyo RR's. Both are considered to be state of the art R Compound Streetish tires. Both sets in the same size of 225x45x15. They were as different as chalk and cheese. We put the RR's on for the 2014 3 Hour Indian Summer Enduro and with 2 new drivers, the car ran consistent quick laps in the 1:40.xx range and there was no drop off in performance no matter how hard they were abused on track. The car finished the race and the tires looked like new. They are an awesome tire, durable and fast. These are my new go to R Compound tire. We ran our standard Mosport setup of Stock rear bar set up full soft, Suspension Techniques front bar full firm, 650 lb front springs, 400 lb rear springs 0/0 front and rear toe and 4 degrees front camber and 2 degrees rear. The car ran well and won its class! Excellent day.

Now lets talk about the Toyo R888's. I expect that the guys at Toyo know their stuff, but good lord they are an odd tire to try to get your head around. Super greasy, over heats way to easily, you have to minimize steering inputs and they are slower than the 10 year old Toyo RA1's I have. No bueno. Save your money for the RR's. I expect someone in North America has made them work for them, but I don't even want to try. They have a great tread design, so I am keeping them for rains.

Lets talk about 2015 and the complete change in the RX7 from before. God, have I mentioned how much I love this car? It is like a bull terrier and goes through design changes and different drivers and just keeps on motoring and getting faster. In 2015, we were fortunate to receive support from the good people at NA Carrera Tires. These are a purpose built slick and a bias ply tire. These would require big changes to the car to make them work and man do they ever work! First a little design knowledge between a radial and bias ply tire. The terms refer to the way the internal belts are constructed and how they lay over one another. A radial has 1 to 2 belt layers where the belts are laid at 90 degrees to the direction of rotation. They then have a few layers of belts that are run at a bias of 45 degrees. These 2 90 degree belt layers supposedly allow the tread to shift laterally under load and keep the contact surface flat to the direction of travel. This is great as long as you don't slide the car and it is at these limits and feeling for the limits, where the average driver feels the car is nervous or a bit vague feeling. If you are skilled enough to keep the car just inside the slide point, they provide strong grip and wear well. The Bias ply tire lays all the belts at a bias across the carcass. What does this mean to the driver? In this case under straight for and aft loads, the tire is more compliant to the road surface and the contact patch goes up a bit. In the corners, the inside edge will progressively lift as the loads increase. This gives the driver a huge window of "Feel" and 90% of racers will go faster. The other cool things is that the cambers go back to as close to 0 as you can get them. Caster goes to stock, toe goes to stock. Basically these work great on dual duty cars and extend the lifespan of suspension parts as they are not being forced to operate at extreme angles.

So, with this in mind we returned every suspension adjustment on the pig back to stock. Left the springs and bars where they were, swapped on a set of the slicks and went out and raced it in the 2015 3 Hour without any testing and with 2 drivers who had really never driven the car at Mosport before. Oh yeah, to add another little wrinkle, it was damp and spitting for most of the race. We were in second place overall for most of the first half of the race and ended up winning the GT class. Takeaway, these tires are awesome. They transformed the car and it should be monster fast in 2016 and I can hardly wait to race it again. I am hoping to pull a 1:36 out of it.

Anyways, back to the thing that is going to blow your mind. In the whole time I have raced this car, at TMP, at Shannonville, at CTMP GP Track and at the Toronto Indy, I have always used the stock 4 bolt single piston front and unvented rear brakes. I have always played with the pads a ton, added a lot of functional ducting, changed the brake fluids often and yes even once melted the front seals out of the calipers, but this car works so well with these brakes that I am loath to upgrade them. My basic philosophy is that if the brakes can slow you down as fast as you want to, don't fade or fail, still lock up if you push too hard and are durable, then why change? They are the lightest setup you can run on the car. They reduce unsprung weight which is crucial to keeping the tires on the ground and they are cheap. Only issue right now is getting good race pads for the fronts. At the present time I am using a carbon ceramic pad made by a company in Ohio, KFP and its awesome. Durable, heat resistant and doesn't seem to hurt the rotors.

There you go, the latest and far overdue technical update on the pig. Still out there racing, still belching flame and still winning races for 17 years.

Eric

If I can answer with, it depends? I run my Suspension Techniques bar all the time and play with spring rates. At Mosport the track is pretty smooth and I am more concerned about lateral weigh transfer. If I was going to go full gonzo on our local Shannonville or TMP tracks, I am more concerned about diagonal compliance due to bumps and I would run a stock bar, with hard bushings and softer springs in the 350 to 400 range. I would need to raise the ride height some to stop it from bottoming out, but I expect the car would be quicker this way. I think your local tracks like Palm Beach and Sebring would need the softer set up and Daytona and Homestead the firmer one.

Eric