Pull to the left under hard braking - Miata Turbo Forum - Boost cars, acquire cats.

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Old 05-04-2010, 07:53 PM   #1
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Default Pull to the left under hard braking

I can't figure this **** out.

I just put on new rotors and pads on the front. I bed them in etc. etc.
Under hard braking I get a pull to the left. After some inspection, its fairly obvious that the LF is working harder than the RF. The wear pattern on the LF rotor is pretty well established, the RF rotor still has some machining marks on it. I change the caliper on the RF with one I had laying around. Same ****.
I bleed the system. 3 times.

I'm about to swap the rotors and pads from side to side and see what happens.

Could this have anything to do with the MC?
Any ideas? ***** bugging the hell out of me.
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Old 05-04-2010, 07:55 PM   #2
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The only thing i can think that would do that is siezed slider bolts...did you clean and lube them?
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Old 05-04-2010, 08:01 PM   #3
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Yep, multiple times.
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Old 05-04-2010, 08:09 PM   #4
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Hmmm, im thinking a bad caliper. The one you threw in was it new? Cause if your bleeding them and your getting fluid through the caliper its not the master, if it was the master your pedal would go to the floor.
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Old 05-04-2010, 08:12 PM   #5
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I suspect cheesy master. On Miatas, proportioning valve only deals with rear lines (if my memory is good for anything).
You're getting different flow (volume) to LF than RF. Change master, and tell us.
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Old 05-04-2010, 08:15 PM   #6
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Thats what I was thinking, is the split a diagonal split? As in if my RF isn't getting sufficient pressure, my LR probably isn't either?
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Old 05-04-2010, 08:20 PM   #7
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And it was working perfectly before? How are the brake lines, check them then look at the calipers.
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Old 05-04-2010, 08:22 PM   #8
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It seems to have slowly gotten worse, replaced the front lines with steel lines, no leaks.
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Old 05-04-2010, 08:25 PM   #9
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Don't think so.
I've been playing so much with my Galant VR-4, that my memory is fuzzy.
Besides, with Miata in the garage, there's nothing to look at.

But, going by manual, the master supplies fluid to LF, RF, and rear. Rear is fed through prop valve. I think the pressure is split only front/rear.

Check your rotors in the rear.
And, swap the master.
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Old 05-04-2010, 08:28 PM   #10
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Isn't the Miatas system wayyy biased towards the front anyway? My rears took forever to get a wear pattern on them last time I changed the rotors.
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Old 05-04-2010, 08:32 PM   #11
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Yep.
But, your problem isn't that the rear isn't locking. If that, then I'd look at prop valve.

The problem is uneven pressure distribution. Faulty master (I'm guessing).

Start by replacing it, and not spending time on Internet forums.
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Old 05-04-2010, 08:49 PM   #12
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Have you checked your tires? I had a newer tire on the front right of my integra and it would pull slightly to the right while driving.
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Old 05-04-2010, 08:53 PM   #13
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He says it's only under hard braking.
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Old 05-04-2010, 08:56 PM   #14
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are the bleeders tight? I chased this issue on my wilwoods, only 10-failure points between the pair!!!
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Old 05-04-2010, 09:37 PM   #15
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Yep, bleeders are tight. Just swapped back to the old caliper that isn't painted VTEC Red. Swapped pads and rotors side to side. Gonna see what happens. MC is on order.
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Old 05-04-2010, 09:56 PM   #16
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I had the same problem. It was the OE bushings coming apart on the bottom front control arms at the camber bolts. It was pulling right and about half of one the bushings had come out, so I was get some big toe out under heavy front load. No fun on a roval.
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Old 05-04-2010, 10:09 PM   #17
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does it have brakes like this?


...


sorry. i had to.
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Old 05-04-2010, 11:26 PM   #18
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Those are top quality race brakes right there.

So I switched pads/rotors from side to side. Now I have a pull to the right. The rotor with not much of a wear pattern on it has a strange yellow hue towards the center.

Wtf?
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Old 05-05-2010, 12:10 AM   #19
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It's your tire pressures.
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Old 05-05-2010, 12:13 AM   #20
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I would machine the rotors and try some dofferent pads. Also check measure the rotor thickness to confirm that onw rotor is not way thicker than the otheri

What is the wear on the left side like now? Is it starting to wear a little better? One might be beded a little better than the other. Drive it for a but to see if the left will come in. What kind of pads are you running? Report back after a little more driving.

Have a great day,
Jared
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