Valkyrie

So I finally got to give my FD a proper shakedown, and while it's vastly faster and easier to drive in the corners than my MR2 (partially 'cause it weighs 350 pounds less) , I can tell there's room for improvement.

First, the steering is a little too light for my tastes. The front end kind of dances around on the highway while I'm driving to the track or back home. I'm running soft R-comps with very little tread left. I think I've got about two degrees of camber. I forgot how much caster I have. My alignment was put out of whack by an off-course excursion, so the wheel doesn't point straight). There's an ever-so-slight bit of freeplay in the front wheel hub. It might actually just be the aftermarket pillowball arm bushings wearing out? Would this make the front tramline?

On a side note, when I turn the steering all the way to lock, it doesn't come back. This makes steering in parking lots easier, but it's a little weird. What can cause this? Toe out? Ackerman steering? I also have adjustable tie rod ends with bump steer spacers that are slightly longer than stock. Would this cause it?


I would also like a sharper feeling to the steering. I was running 32 PSI hot. Is this too low? The front tires were about 20-30 degrees (F) cooler than the rears. Is this about right?

I love how well the car stops with race pads, but I don't have a rear wing and it's a little float when I really try to stop in a hurry (still much, much better than my MR2, which tries to turn around when you brake hard).

Springs are 10kg fore and aft. Dampers are pretty soft, to be honest.

Smokey The Talon

iTrader: (33)

there's a lot going on there man.

First things first, get the alignment corrected and make sure all of the components are in good working order. If any joints/pillowballs are loose they need to be replaced. You're going to just keep chasing your tail if you can't get the equipment reliable with a good solid baseline to start. Run more castor if you want a heavier wheel without much other negative effect. What ride heights do you have front/rear?

As for the tire questions, what tires are you running? How did you take temps? With a laser thermometer or an actual pyrometer with a probe? If not the pyrometer, then you can't use that to make tire temp decisions. You can play around with pressures to see where the car feels better, but you'll never know for sure until you can take proper temps.

For the "floaty" under braking, are you saying it's the rear? You can tune that out a bit with suspension changes, but be aware of the effect it'll have on other handling.

j9fd3s

iTrader: (3)

32 psi hot is on the low side, but still ok.

for everything else you need to check for worn/damaged stuff, get it aligned and then nut and bolt everything.

if it still feels floaty under braking, you might try more rear toe in, usually rear toe is pretty sensitive, so just a little

Valkyrie

Yeah, I know. I don't have any detectable looseness besides a tiny bit of free play in the front hubs. I did replace one rear pillowballs and all the aftermarket rod ends (rear toe links and outer tie rods). I have some noise coming from the rear suspension in fast corners but I suspect it's backlash in the diff or stabilizer links.
I will try to max out both next time.

Low but not stupidly low. I don't want to mess up the geometry or break something every time I go off the track. Front and rear are roughly even. The car was corner weighted and has a respectable left-right balance with me in the car (not perfect though, didn't want to have the ride heights too uneven).


Used A050s with very little tread left. 255s and 225s, but the fronts are a softer compound, which I don't imagine was really helpful. Gonna use new street tires next time.

Yeah, I used a real pyrometer.

Taking consistent readings is much harder than it looks, though, so even then...

Yeah, I'd be able to brake harder and probably turn in with more trail braking (that's about the only thing besides going too fast that would make the rear come out) if the rear felt a bit more planted under braking. A 2-way diff would probably help, too.

Valkyrie

I tend to use the stock pressure as the baseline hot pressure even though I should really have it a few psi higher for more response from the sidewall. In my experience I like the progressive grip of a slightly under-inflated tire.

I think the shop gave me about the same rear toe as the front even though I asked more a little more. I suspect a wing and fresh tires would also help greatly.

j9fd3s

iTrader: (3)

with a Mazda that actually does give you a good starting point, you might try a couple PSI higher, on old tires i wouldn't expect anything though.



or you could brake a little earlier, and harder.

we've run races with multiple drivers, and we'll look at data for everyone. everyone starts braking at about the same spot*, but the fast guy brakes harder, its upside down, but instead of a sine wave his brake pressure is i_i, square. his corner entry is actually slowest of the 5 drivers, but he is WOT sooner than everyone (again, its i_i). add that up 11 to 14 times, and he's a couple seconds faster.

i guess point being, he isn't trying to turn and brake as much, as it sounds like you might be.

second, he likes a car that understeers a little, if he's got a downside, he can be a little rough with the car.

*it turns out that since the track has width, the length of a lap varies, and you can't just lay everyones data on top of each other, as they won't line up. if you look into it, the textbooks get really big

j9fd3s

iTrader: (3)

oh another thing to try is to lower the rear. every car so far has been really sensitive to this, so go one turn, and be prepared to go back up.

the sweet spot on out miata is 1/4 turn, 1/2 turn was too much, thats like 1.5mm...

Smokey The Talon

iTrader: (33)

what rear toe are you running now? Is the "floating" happening in a straight line or only during turn-in? what suspension adjustments do you have available to you? You could always try running more compression in the front to fight dive under braking, but be aware that it'll obviously affect cornering in other situations.

Taking tire temps always requires a buddy system as you'll want to pull into the pits as hot as possible and have someone take them for you. If you can do that, then you'll get a better idea of if you're pressures and camber are appropriate or not. Of course with the different compounds you're running there's also the chance that the front is diving even more causing the rear to get light.

BLUE TII

iTrader: (9)

If you have any play in the suspension or steering that you can feel by hand it is WAY BIGGER DEAL than you are making it out to be.

Your vehicle is using its entire mass to push on that same joint - not some scrawny people arms.

Floaty feeling under braking? Sounds like loose front end parts for sure!

Fix your car before you try to set it up.

Valkyrie

Straight line. It only happens when I try to brake as hard as I can. I actually forgot to get the data after my alignment, but I don't think there was very much rear toe. It may have been the same as the front.

I can adjust alignment, preload, ride height, bump steer (not roll steer), and damping (but they're fairly cheap, albeit basically new coilovers and they seem too soft). I could adjust spring rate, but I'd have to buy springs... I know where I can buy an used adjustable (blade type) front anti-roll bar.

I really need to bring some note cards to actually write the temperatures and pressures down on.

Yeah, I plan on buying a set of new tires in the stock 99 FD size (235, 255). I would buy 255s all around, but I don't have 9s for the front. Also, the front tires are 225s, but I guess that doesn't make as much difference as the compound.

I also have front splitter that probably presses the nose down at high speed, and no rear wing, so that probably doesn't help my balance much.

Valkyrie

FWIW, it's not floaty in the front during braking. And it's still miles better than my MR2 ever was on its best day. It's almost nitpicking. I just suspect it could be improved.

I'm still not sure what's causing the free play. I don't notice any freeplay in the hub with the brake rotors off. Only when the wheels are on.

I suppose it could be one of the ball joints or the lower arms' bushings, which have been replaced with aftermarket pillowballs. I doubt it's the inner tie rods, since I'm only checking the play at the top and bottom of the wheel. Well, my alignment has already been ruined, so I guess now's the time to pull the suspension apart again and find out what's loose.


On another note, how much ride height (or rather, shock body length) disparity is acceptable? I wonder if I could get my cornerweight even closer to perfect (with me in the car) if I did a few more turns, but I don't want the car to end up cockeyed.

Smokey The Talon

iTrader: (33)

You have more leverage and can exert more force when the wheels are on. That might be why you only notice it then.

BLUE TII

iTrader: (9)

I suppose it could be one of the ball joints or the lower arms' bushings, which have been replaced with aftermarket pillowballs. I doubt it's the inner tie rods, since I'm only checking the play at the top and bottom of the wheel. Well, my alignment has already been ruined, so I guess now's the time to pull the suspension apart again and find out what's loose.


I had an instance where I was chasing this really weird handling on my FC where the rear end would slowly steer to one side going over a series of bumps. One or two bumps wouldn't do it, but go over a series of bumps and the rear was trying to crab walk to the passenger side.

Turned out one of the bolts to the rear tri-axial hub had worked loose. It had barely a hair of movement rocking the wheel side to side, not even a clunk. I had to watch the hub to see it move in the trailing arm while wrestling the rear wheel.

Tightened that bolt the 1/2 turn it needed and instantly the crab walking over series of bumps was gone.

ptrhahn

iTrader: (9)

Tons going on. Of course get everything checked, but just be aware that fat r-compound tires without much tread left and lots of camber are going to be a little darty on the street.

32 psi hot is a little low, I shoot for 34.

If it feels "floaty" under braking, that can be a lot of things, including the brakes themselves (bad calipers, poorly matched pad compound), soft front springs, or your technique if you're standing the car up on the nose under braking. It's probably pillow ***** though.

Valkyrie

Ah. I kind of suspected that was part of the issue.

Will do.


As well as the car actually stopped, I don't think it's the brakes. It only started to get floaty when I tried to max them out.

Springs are relatively soft. I'd like them to be about 60% stiffer (10 > 16 kg).

Rear pillowballs, I take it. I replaced one and couldn't find any other that were obviously loose. Will try to take another look.

Honestly it would probably be faster through this particular corner if I braked a little less and tried to increase my corner speed, but I want a little more stability for when I race wheel-to-wheel.

ptrhahn

iTrader: (9)

You may need to brake a little less hard, or less abruptly. It sounds like the car is standing up on the nose, and at the limit that means there's very little weight on the rear wheels and they will move around a little.

If you have adjustable shocks you might try cranking in more rebound at the rear.

Valkyrie

I wasn't braking abruptly, but I've got fairly aggressive race pads.

Honestly I think I just don't have enough rear toe and downforce.

Valkyrie

On another note, do I need a pickle fork to take the front suspension apart?

BLUE TII

iTrader: (9)

It will make it much easier.

I used one of these wonderful ball joint tools.

Valkyrie

Guess I'll have to get one.

On another note, I can hear some sort of light squirming/squeaking noises coming from the rear in very fast corners. I don't have any slop I can feel by hand in the rear. Could it just be the arm bushings, the anti roll bar links/bushings, or maybe just the shocks?

BLUE TII

iTrader: (9)

For my FD that has always been exhaust rubbing on something under the influence of its own mass and Gs or a broken power plant frame rubbing on the crossmember from the mass of the engine/transmission shifting around. Metal on metal contact noise.

Kind of a cricket-y noise?

Valkyrie

No, but I'd have to hear it again to properly describe it. My best guess would just the stabilizer bushings or links squeaking, assuming another pillowball doesn't have free play.(one that doesn't cause the suspension to have any free play, like the shock to the upper arm.)

It could be one of the muffler's donuts squeaking, I suppose.

For the record, I don't feel any play at all on the front with the brake rotor off, but I can detect play with the rotor bolted on.

Is it possible that my front hubs simply have a tiny amount of free play that is undetectable without the rotor or wheel attached? I don't think there's anything wrong with the mating surface or something...

I think I might want to replace the rack bushings to make sure that's not contributing to the mediocre feel in the steering. I wonder if it would be worth replacing the column bushing?

BLUE TII

iTrader: (9)

When my steering rack bushings went out on the FD I did not feel anything.

I just knew because when I was done turning the steering wheel would still be cocked a bit off center and when I was done turning the other direction it was cocked at an angle that direction.

The rack starts sliding back and forth a bit.

Valkyrie

I guess using a dial indicator would be a good way to see if they need to be replaced/upgraded.

LargeOrangeFont

iTrader: (7)

You don't need a dial indicator. Just yank and pry on it a bit. It it moves, replace bushings.