Wilwood brake upgrade unbalanced?
 

So I've had my wilwood brakes for a couple months now and I feel comfortable with them but lately I've noticed when I really stomp on them the passenger front always locks up before the drivers side even when I have a passenger. So is there anything I can do about this? I have the front to rear prop valve but side to side? Also, when I installed them I thoroughly bled all four corners so they should be good but I'm just not sure why that one side seems to be grabbing harder than the drivers side. Any ideas?

Only other thing I can think of is actual tire contact patch if the alignment is off or camber is greater on that side? opinions?

It might just be that it is a lot easier to lock the right front now that you have a nice flat spot on your tire.

Could also be a corner weight issue I guess.

Bob

IIRC, stock Miata brake systems tend to lock the front right tire first as well.

--Ian

I would imagine it has something to do with weight distribution. More weight over the driver's side than the passenger side

I used to have this problem with my stock brakes on my old suspension. Since I put in the new suspension and corner-weighted the car, the problem is gone.

My front right is always the first to lock up as well. Stock sport brakes here.

If you have coilovers, try "lowering" the right front or left rear by half a turn at a time, or "raising" the left front or right rear.

Looks like its time to 4 corner scale the car and even her out and re-bleed just to be safe.

Pre-load on the front sway maybe. Disconnect and endlink and see if the problem is better.

I'm just thinking out loud here, but could it be as simple as the driver's weight being on the driver's side? I have never had occasion to lock up a tire with a passenger, but their weight might balance things out. I should also specify that the corner-weighting that solved the problem on my car was ballasted to my weight.

Which can be fixed by adjusting the coilovers as I described above.

Which can be fixed by adjusting the coilovers as I described above.

Sounds like there is too much front bias too. Very common with Miatas.

No doubt about this....I have stock 1.6 rears. I'll be upgrading to sport rears soon.

True, but for a quick and dirty diagnosis removing one end of and endlink is easier to do and reverse.

In the end an adjustable endlink might be necessary.

How about some datalogs…from an iPod/iPhone, Blackberry, or racing logger? Then you can see where you are now, how much the sport rears help (they are +30% stronger than 1.8 brakes which are in turn stronger than 1.6 rears). Plus you can get the balance maxed and confirm stability via trail braking tests / G-G.

Prop valves only cut braking…if you go adjustable and cut less…you are still stuck with the inherent limitations of the basic F/R balance. It's not unusual to be able to set the prop valve to full rear (little or no reduction) and still front-lock…this is where actual braking hardware clearly needs changing out if you want optimized braking and handling.

Yup…you can test in a zero bar preload state by just pulling one bolt from one link at each axle.

No because adjusting a coilover perch does the same thing.

Except adjusting the end link has no effect on ride height.

Ok, so I was driving to work this morning and braked hard and the right locked (a lot easier on cold roads) and I almost rear ended someone. So on my way home this afternoon I thought I'd try to see if it was bad enough to pull the car to the right...and it does relativly bad. From like 60 mph it will pull into the other lane without my hands on the wheel. So when a friend get over I'm going to bleed the drivers side hoping I can find an air bubble....we'll see. You guys have any other ideas besides what you've already stated and the possibility of a bad caliper.

Largest issue is that you have two wheel braking for the most part. Get larger rears, something like NB Sport Rears at least. You have a big brake kit and stock 1.6 rears, is that correct? Get the car corner weighted, make sure calipers are good and well bled, basic stuff.

I know brake bias is your "topic of the week" but I'm having a pretty hard time seeing how a front/rear bias issue would cause the car to pull to the right. He should address bias, but it's not causing his particular issue.

spd, bleed the fronts, check tire pressures, and if you have coilovers at least make sure the ride heights left to right are close to the same. Chances are you have a low tire or a bubble in a caliper somewhere.

Topic of the week, huh? How about my first post on Miata.net over five years ago?

See post #18: http://forum.miata.net/vb/showthread.php?t=41805

Brake balance is basic Engineering and is far off on many, many Miatas. In fact my first posts on Miata.net years ago noted the issue. I always test that on any car when performance-driven. Excess front bias will accentuate any tendency towards pulling as there is insufficient stabilizing from out back / sharing the work at a given rate of deceleration. Miatas tend to front-lock the front right corner, just as this person has experienced. If you want your car to stop as fast as possible, in a controllable and consistent manner, you need all four tires helping out in a balanced manner.

I used to design braking systems, many are out on the market.

Following the principles I've explained here and elsewhere leads to better braking. I showed a now well-biased Miata braking system which can trail brake like crazy, unlike most Miatas. The car has been transformed, inexpensively. You can't fool the datalogger along with some basic tests Mr. S. Let's see your G-Gs and other data, if there are any issues I'd be happy to help you out.

From what I can gather in this thead, the OP needs some attention to braking fundamentals on his car. Such as those noted, and others. This seldom comes from vendors.

Yes, topic of the week. You have an exceptional ability to constantly talk about a very specific topic, regardless of whether the topic is relevant to a specific problem. I'm not sure why you think G-G plots of Miatas showing excellent trailbraking capabilities has even the slighest thing to do with a car that pulls right under hard braking. I have a car exactly like the OP's sitting out front of the shop right now (Wilwoods on 11" rotors in front, 1.6" rears, stock bias) and it will stop straight and true from triple digit speeds. I won't argue that the bias isn't absolutely awful on that car, and we'll be adding a bias valve and 1.8 rear rotors (just like my own turbo car which has excellent bias) but it doesn't cause undesired lane changes on street tires or r-compounds - this is a fairly concrete fact.

I'm not really sure what you're trying to insinuate with your vendor comment, either. It appears at first glance to be an exceptionally petty (and poorly veiled) shot at me and Trackspeed, but I'll give you the benefit of the doubt on that one. There are plenty of vendors that understand the bias issues these cars have. FM had their own fittings made to make the Wilwood prop valves install significantly easier than they normally would. M-Tuned offers a bracket that allows 1.8 owners to install sport rotors without changing the caliper over, which makes it easier and cheaper to address bias issues. V8Roadsters offers different piston areas front and rear on their mondo 4-wheel 11.75" BBK to ensure proper bias. Trackspeed recommends the use of a Wilwood prop valve with our 11" BBK, and that recommendation comes from our own experience comparing stock bias vs. modified bias on Wilwood 11" fronts and stock 1.8 rears.

When the OP is ready to address his bias issues, there are a variety of vendors in the community that will be more than willing to assist him with a solution that matches his needs and usages, and Trackspeed is one of those vendors - but I won't attempt to delude the OP into believing that a rear brake upgrade will somehow solve a problem that isn't caused by inadequate rear brakes.

Are you a vendor? If so, of what?

I know a lot about brakes, and share what I know. I'm helping 4-5 Miata owners get their brakes optimized right now. They'll all speed up and their Miatas will be easier to drive fast.

I'd be happy to help you out, just let me know.

I'd love to hear what you can do to improve the brakes on one of the top 3 fastest Miatas in the country, I genuinely mean it. I'm not sure which caliper he and I have up front in respect to bore size. I don't seem to have a problem trail-braking into the apex with my car even without aero.

That's a very generous offer.

What kind of help could you supply?

I am thinking of going to 1.8 front brakes.

But I will probably be stuck with 1.6 rear brakes.

Upsizing my brakes is an issue because of RPF1 clearance.

Going to much larger rear brakes would likely require new wheels.

I have no idea when my budget would support both new wheels and brakes.

So probably I will just try it and see if I can correct bias with different brake pads.

:facepalm:

You can trail brake about any car, but are you doing so using all of the available traction or not, and how stable is the car at that time, etc?

Cars that are running well tend to have things ignored on them, just the way it goes. Since they are fast enough to beat those they presently run against, effort eases off. Some of the earlier Miatas I measured with significant brake bias woes left their brakes alone at the time, noting that they were beating others. There are always things to improve on any car. Whether it be brakes or other stuff.

Let's see some performance data on the cars you noted to start out with, along with the brake specs, car setup, lap times, driver comments, etc.

Thanks.

If one has no adjustable end links, adjusting one corner up and the opposite wheel down will also not affect height.

Not my car. I just wrapped up my 4th win in a row at Buttonwillow in the Miata Challenge Unlimited class, edging my main rival by about a tenth and a half (1:55.804 to his 1:55.930). Second time this season we've been split by less than two tenths of a second. In addition to tires (NT-01s to C71s and back again) and power development (up to 350whp and 290wtq, peak torque available from 4200rpm to 6200rpm, ABSURDflow owns your soul), I've had three different pad compounds in the front this year, two different compounds in the back, with constant tweaks to the bias knob to ensure the car is to my liking. Not to toot my own horn, but I cut my teeth 7 years ago on 125cc single-speed karts with rear brakes only so I like to think I know a thing or two about the benefits and nuances of trailbraking. One of my pet peeves is a car/kart that doesn't rotate on the brakes.

Congrats!!! Would love to see an in car of you hustling the car around the track!!

Wilwood front calipers (not sure on piston size) on Corrado rotors
1.8 rear brakes
Wilwood prop valve
DTC-60 all the way around
AST 5100 shocks with 700/400 springs
2.7*f/2.5*r camber, 3.5*caster, 1/16 tow-in rear
4.0"f/4.25"r ride height
No aero

4.1 seconds under the SM record at Hallett, my buddy who knows how to drive went even faster. I should have added rear sway bar because it still under-steers a little but the car is incredibly easy to drive in all situations (my "real-driver" buddy agrees and got out of the car commenting about how much he liked the car).

Do you have data besides motor output?

Rear braked karts don't really trail brake.

Car details besides power and that you've used a few brake pad compounds?

Need aero and downforce figures, etc.

Datalogs for a few sessions at a few tracks, and other details?

Check out BOTH build threads - information you seek is there. In the real world - faster is faster. I have watched both of these cars morph into what they are now. There is a method to their madness, and depending solely on datalogs and dyno plots is for bench racing. Lap times speak for themselves, period.

Do you want "shock-pot" data too? I don't have a data-logger that logs YAW so i guess we'll have to assume that everything is wrong. I'm certain that no matter what anyone posts here, you'll deem it "wrong." Its easy to go through your posts here and on miata.net and see you demonstrate that no one has ever done anything to your liking. Obviously your service of arbitrary criticism is a labor of love. I'm also fairly certain that you'll never find the CFD, wind tunnel, YAW logs, or any other data you dream up that no low-budget, weekend warrior owns. Now is that part where you'll tell us that we cannot pick the "appropriate brake equipment" without $20,000 in data logging equipment so we should all leave our brake stuffs stock.

Perhaps a new thread could be opened as this one is getting off topic for the OP. If one wants some help from the experienced, a decent attitude might help.

So far the only data I see here is a few chassis dyno plot peak readings. On yaw FWIW you can get decent information from the GPS alone if so desired…if more detail proves necessary then you can add a sensor. I've set up many, many very fast cars behind the scenes, and helped them go even faster. A key requirement in such an endeavor is a good attitude, this appears to be hidden or in short supply here. Perhaps I am mistaken, I have limited time, so I choose.

"Insufficient data" on a handful of the fastest Miatas in the country [not mine] doesn't bode well for you assertion of abject failure, nor does it suggest that your attitude is "good" either.

Please guys, let's not get in a big fight over track data, upgraded brake bias, and trail braking.

Can't we all agree that without very careful g-force tests, this is mostly bench-racing?

And of course there are so many variables including tires, aero, and car weight.

It's hard to see someone assimilating all that info just from description.

Is sjmarcy's point about the Miata's poor natural brake bias true?

I couldn't say. My street car rarely sees full braking force.

But the number of good track cars says otherwise.

Not to mention Savington's vast experience.

I think I'll stick with my own brakes.

Mostly because I'm cheap.

Well, poor, not cheap.

Not the same.

Just poor.

/\ + 993

SOooooooooooooooooooooooooooo OP update here.

I bled the brakes yesterday afternoon only to find it did nothing. Still pulls to the right and locks on the right in hard braking. I have the wilwood compound E pad which are pretty agressive for street use and I can see a small nitch in the rotor where it is wearing more on the passenger side FYI. It almost feels like that side is doing 75% of the work. Possibilites I can come up with that could be the problem(please assist me in guessing the problem):

1) Bad caliper
2) Something wrong internally in the brake lines/system (I have no idea how to source the problem there)
3) Mild possibility of installing the prop valve wrong?? (really doubt it bc it seemed real straight forward)
4) NO effing clue??

I'm positve sport rears would def lessen the problem but it just irks the hell out of me to drive a car I dont feel confident in. Both my cars have BBKs and I upgraded for a reason. Just really frustrated this isnt cut and dry like most of the problems I had with this car since I've had it. Thanks for the help guys and I'll forgive the off-topic convo on the other page....lol
3)

Just caught something......

http://www.flyinmiata.com/support/in...ning_valve.pdf

In this link of instructions on the FM prop valve installation on the bottom of page 1 and top of page 2. Does it not look like they have 2 different lines ran to the top of the valve in these pics?

I hope this is the problem (I installed this wrong) as it would be an easy fix....I'm headed home now to see if it makes a diference when I tun the valve.

Wish me luck.....

I'm back...I reversed the prop valve and it only made things worse since all the bias was at the front and all the front is on the right.

FAIL.

Back to the drawing board......I think I'm going to try and switch the calipers this weekend??

Could there be a dent or something in the hard line to slow flow going to the driver's side? Possible?

Another thought....if I switch and realize there's nothing wrong with either caliper(which is most likely true) would it be possible to run another prop valve to adjust the side to side bias?????????

Just a thought??? Possible?

This may or not be relevant so bear with me ;)

I had the same issue with my stock setup, it locked the passenger wheel first without fail. I tried bleeds pads swooping calipers left/right etc etc.

The problem ended up being one of the rear calipers sliders were seized, freed that of and bingo, car pulled up straight as a die again.

I realise our setups differ greatly, but it's worth a look.

No, don't do that. Please.

See folks, rear brake issue…changes bias if you think about it.

The OP's car needs a thorough look over it appears, given the prop valve reinstall.

Once the fundamentals are addressed, voila, it will stop much, much better.

One of the local Miata guys I helped out is still thanking me RE his now excellent braking.

He's still thanking you?!?!?! Wow!!!!

Yeah after a long time getting nowhere listening to the forums, local shops, and guys in his car club…we fixed his car so that it finally stops very well. I just used the car for tire break-in recently and it now does excellent G-Gs, trail brakes well, and is very stable. Mission accomplished on that Miata.

So what'd you do? What's the big secret?

Read his post, he stayed away from the troglodyte forums which lack intellectual fortitude.

What is your secret for proper tire break-in? I never broke-in my tires so I'm probably leaving time on the table.

Ohhhhhhh! Well then, :bowdown:

Anyone else have an opinion on this? :sadwavey:

Pad wear can tell you if you have a stuck or sticking caliper. Look and see if you have even wear on each pad and between the two pads on each caliper.

In my case I didn't put up with the issue long enough for pad wear differences to make a difference, YMMV and all that tho.

You're a master, dude. It's absolutely incredible how you can read a post, warp it in your head, and make the same rhetoric you've been babbling about recently seem relevant to it.

He said that a rear brake caliper sticking caused the front right to lock. All he did was bring his STOCK system back into working order, and it was an excellent system again - and you've masterfully twisted his analysis of his problem and solution into a bias problem that he somehow solved by dicking with the rear brakes, and then furthered your attempt to mislead the OP into thinking that poorly biased brakes is somehow causing his issue, when it is not.

You want shitty attitude? Why are you trying to consistently mislead the guy? I understand that brake bias is your talking point this week, and you've got to put all that data you've got to good use, but brake bias is not the OP's issue.

All of the data you're posting to "prove" your point, attacks on other people's character, sly comments about attitude, and self-aggrandizing "well i helped this person whose driving abilities I've conveniently neglected to mention and THEY ARE STILL SWOONING OVER MY INNATE ABILITIES" - it just furthers your talking point, regardless of whether it's relevant or not.

Stop trying to mislead people on this forum. You talk a lot of shit about how forums don't give good answers, and then you provide shitty, shitty answers in the same thread. Just stop posting and let those of us who have a reasonable view of the OP's issues help him solve his problem.





OP, find another Miata or a factory service manual and set the bias EXACTLY AS STOCK. Then go through all 4 corners of the brakes, make sure the slider pins are greased, make sure everything is bled, nothing leaks. Check your wheel bearings, check your tire pressures, ensure that there is no significant cause of drag that would cause the car to pull to one side or the other. There is nothing inherently wrong with your braking system, it's just not functioning properly - and that's the problem you need to solve.

self-aggrandizing
self-ag·gran·dize·ment (slf-grndz-mnt)
n.
The act or practice of enhancing or exaggerating one's own importance, power, or reputation.