spyfish007

I blew out a tire last night so I got two new rear tires today. I had purchased some reconditioned wheels with tires last spring. I really hadn't driven the car that much till this spring. Anyway, 205/50s were on the car and now 225/50s are on the car. I also got an alignment at the same time. There was an excess amount of toe in on both the front and rear and a slight imbalance of camber, mainly in the rear.

Since getting the new tires, I feel more body roll or should I say lift from the back end. It feels solid enough, just more lift ... kind of that feeling you get when driving a convertable. The tires do seem to hold better and don't break free as much. I just went with some Yoko A550s because they were available and cheap. I don't really drive the car in the rain either. Let me know what you think about what I am noticing and what is going on with the suspension. Also others input on the tires would be interesting as well.

DamonB

I'm not sure what you mean?

You mean the inside lifts more because the car rolls more? If so, that doesn't suprise me. The wider tires should have more grip which will make the car corner harder which will make the car lean more.

maxcooper

Different tire models feel different, sometimes very different. When I switched from Yoko AVS Sports to S-03s, the car felt very different and it took some getting used to. The AVS Sports had very stiff sidewalls and the S-03s have softer sidewalls, so the car felt different when I put side loads on the tires in a turn. You will get used to it, and your new tires will feel normal soon. Just be careful in the transition period.

-Max

spyfish007

Damon: Yeah you got the message correct.

Max: I wasn't sure if it was in my head or something real-and yeah I am not going crazy on corning till I get used to it.

So basically it is the tires and not really the alignment?

maxcooper

Well, it could be due to the alignment, too. But tires can feel very different, so it might just be the tires.

It might also be as simple as having more grip now, which will give you more roll before the tires slip.

-Max

spyfish007

Thanks Max

spyfish007

So I've been driving the car for a month now and it just feels plain scary. I need some help here.

My aligment settings are:
Front
Camber -1.1 -1.0
Caster 5.1 5.4
Toe 0.05 0.03

Rear
Camber -1.3 -1.3
Toe 0.04 0.09

Previously my toe in the rear was 0.34 and 0.29. My thrust angle is -.02 degrees. I really need some help and I am at a loss for what is going on with my car. I can't keep up with cars that I know I should at high speed. Low speed feels ok, but high speed is twitchy at best.

Mahjik

iTrader: (1)

I've been using the Pettit specs for a while which feel really good:

http://www.pettitracing.com/faq/index.html#handling

I'm currently using the "Short Track" setup.

DamonB

Are those toe settings inches or degrees? Are they positive (toe out) or negative (toe in)?

Describe scary. In what situations does it happen and what does it do?

spyfish007

All of those numbers are in degrees. The toe setting is positive on my sheet and if I remember correctly positive on the machine was toe in.

Under heavy acceleration the feeling of the car is amplified when compared to light acceleration or no acceleration. The car does squat pretty good under acceleration, but I don't think the shocks are fully worn out as I have pushed on the hatch and the car comes back up to ride hide without bouncing. The scary part is a couple of things. In a straight line at say 90 mph and up during acceleration the car seems to want to turn/float/(hard to describe here) and then I give a little correction input the other direction and this goes back and forth until it seems like I'm backing off the throttle because the car isn't that stable. In a corner the same thing... the car rotates more than I want/floats and then I get out of the gas and maybe break. Before I could feel the car step out from power on oversteer but that was very predictable and it felt solid. This mess now feels bad because the back end feels really unpredictable. I'm going to go for a realignment today.

adam c

iTrader: (2)

Sounds like a re-alignment is needed. One difference you may notice when cornering is tread flex. Worn out, bald tires have no tread, so tread flex is zero. New tires with full tread will feel much different. The tread will flex when cornering, giving a slightly "mushy" feeling in comparison.

spyfish007

Well I got another alignment and discovered something. My toe link on the driver's side is bad. I'm going to get another one and realign the car. I still wonder why my car feels like it is lifting at 100 mph.

Howard Coleman

iTrader: (6)

an interesting thread...

"wandering" problem at high speed.

insufficient toe in
bad shocks
incorrect longitudinal body angle.

toe in...
assuming the numbers you post are a percent of a degree of toe... you need more toe. your front toe is about .02, rear is .05 of an inch. run .1 of an inch total toe front and rear. i think that will make a huge difference. i run at a track where i hit 170 in a banked corner and i could be reading a newspaper in the turn. cars wander at high speed without the proper amount of toe. you will be shocked at the difference at .1 of an inch of total toe.

thrust angle.... get it properly set at zeeero. (0) you do that before you set anything else.

shocks
highly misunderstood. shocks have 3 sets of valves. highspeed for bumps, medium speed for undulations and low speed for corners and control of wandering at high speeds. pushing on the bumper doesn't do it for evaluating shocks... that said, i have a shock dyno and have not dynoed a bad or worn oem fd shock. i have seen one that was leaking fluid. check your shocks for any leaking fluid.

aero
don't laugh, above 90 areo is king. aftermarket wings, body kits, huge front splitters can hugely screw up vehicle balance. the factory worked at getting the balance right in a wind tunnel and bolting on different noses (w the aerodynamics of a hummer) all kinds of wings totally can mess up 4th and 5th gear handling. IF your problem is aero it would be from too much rear downforce which causes.... to much front LIFT. front lift equals wandering.

bushings
carefully check and replace if worn:
1.rear toe links
2. front & rear bushing in rear longitudinal link
(before alignment)

air pressure.... set yr tires at 30 fr and 27 cold

do all of the above and let us know the results

good luck,

howard coleman

Skeltah

Howard,

What is you body set up then? Stock? I was under the impression that the stock(93-95) Mazda rear wing was useless. I'd love to know your take on the "optimal" body set up for a RX.

Thanks,

Matthew Walsh

DamonB

If a worn toe link was discovered that's most likely it; especially if only one was worn. Under power the worn toe link will toe in too much and will steer the rear of the car away from the worn side. Under braking it will steer the rear of the car towards the worn side.

You're alignment guy should have noticed this.

I run 1/8" of total rear toe in and there is a big difference between running 0, 1/16" or 1/8" on the rear of this car. 0 is downright unruly when pushed hard, 1/16" is drivable but 1/8" really lets you get on the power earlier in the corner without the rear trying to pass the front.

Howard Coleman

iTrader: (6)

the handling difference that can be effected by changing toe just a small amount is shockingly great.

a 1/16th can change a car.

i use a laser/mirror setup from Advanced Racing Technologies. i think it was around $300 and worth ev penny as it is so accurate. i wish i would have had it during my 22 seasons of SCCA racing rather than the old tape measure...

Damon is right as to the toe link and toe settings.

howard coleman

spyfish007

Well I'm working on getting a toe link before the end of the week. Anyone have a good idea oh how to test a toe link out of the car? For the record I have from R1 lip and no R1 spoiler. There are no leaks in the shocks as I checked during the alignment. All of the factory underbody panels are still in place. Three years ago I had every bushing in the rear changed and added a RP drag launch kit. So the toe links are the last thing to get changed.

Howard: Thanks for the input. I was thinking of adding more air pressure. You think I should go lower, why?

Howard Coleman

iTrader: (6)

the toe links come out w a couple of wrenches... make certain you don't switch the right to left upon reinstallation. grasp one side of the bearing w your thumb and the other side w your index finger. any wiggle and replace.

while you have an 14 mm wrench in hand spend 5 minutes and remove the rear bolt from the lower longitudunal link and yank on it. even though yoursherical bearings were new 3 years ago they need to be constantly checked. sort of like your oil.

i run an r1 splitter in the front and no wing. the car balances nicely and has minimum drag.

as to tire pressure... i determined the proper psi using my pyrometer, measuring temperatures across the tire face. if you run more than 30 cold front and 27 cold rear your tire edges will run cold and the center will run hot. your car will feel like a buckboard and you will have less grip as your tire face will be rounded and not contacting the pavement properly. the equivalent of running ford escort tires on your fd... not a pretty sight

howard coleman

spyfish007

Thanks I know how to get them out. I usually don't do but one side at a time, but good tip none the less. So I shouldn't be able to move the bearing at all or just not within that rubber surround?

Still not sure what I am looking for here. Can you please add some more description of what is good/bad.

This is the first time I have ever heard anyone say to go lower. Most people who auto-x say go higher. Howerver I will try it out.

Thanks again

Howard Coleman

iTrader: (6)

i wasn't aware that you were looking for an auto-x setup.

my tire pressure & suspension settings comments are for aggressive street driving only. they are also a starting point for road course setup but the camber setting and final tire pressures are determined w a pyrometer only.

i raced SCCA nationals for 22 seasons but have zero experience w auto-x. i am sure others w experience can help you.

when checking the toe links.... they do rotate around their center as they are spherical in nature. they should not have any slop, as in clearance within their housing. if you can feel a click click as you move them they are loose and need to be replaced. no click click, they are good to go. generally, toe links last considerably longer than the lower pillowball/spherical bushings situated within the lower latitudinal link. the reason is that they carry no vehicle weight.

there are 3 other key bushings on each side of the rear of the car...

the (1) front bushing on the lower longitudinal link... i believe you have replaced the stock aluminum link w an aftermarket piece. this front bearing feeds most of the engine and braking torque into the car.

the other (2) bushings are located in the lower latitudinal link and carry the vehicle weight.

you previously stated that you had replaced all the bushings... however i don't completely trust the the (1) front spherical bearing so do check it...

howard coleman

DamonB

As howard says, check all the pillowballs. Granted my car sees daily driving along with lots of events and lots of time on race tires but I eat pillowballs about every two years. The one in the lower lateral link that takes the trailing arm and the one in the lower rear upright seem to go first, then the last one in the top of the rear upright.

I was still using stock bushings in the front of the trailing arm but recently switched to jimlab's there. Car is much easier to drive at the limit with solid bushings in the trailing arms; I was suprised at the difference. When the rear starts to get away you can drive the car much more easily with it out of shape rather than having to immediately gather it up before moving on like I had to with the old trailing arm bushings. If I want to drive sideways it's much easier with the nylon trailing arm bushings

FWIW my Geez! chassis software says I consistently pull 1.2+ g in near every corner with the car on 245/45/16 Victoracers.

spyfish007

Well I am not really looking for an auto-x setup. I was just making a comment about how they set their cars up. I think the lower tire pressure has helped. I was at 36 all around from the alignment gig.

Did mazdaspeed ever make bushings for our cars that were 40% stiffer? I think that might have been what I got for the rear control arms and such. The trailing arm is one from RP. If I understand you correctly you are saying the front bushing that mounts to the car is the problem? I believe that is a metal spherical bushing. And thanks for the explanation on the the toe links.

DamonB

The large bushing inside the front of the trailing arm. Stock it's a very large rubber bushing with lots of deflection. This is where the majority of the power is fed into the chassis and the biggest contributor to wheelhop along with the diff bushings. There is a Mazdaspeed version that is 40% stiffer available from Mazda Motorsports that fits the stock arms. Then there is the nylon jimlab version for the stock arms and finally aftermarket trailing arms that replace this bushing completely with a solid rod end.

spyfish007

Well I have a solid rod end ... is that going to go bad?

Howard Coleman

iTrader: (6)

solid is good. just check to see it hasn't worn to the point where it has slop in it. solid lessens axle bounce under acceleration and heavy braking.

howard coleman