RebekahsZ Posted September 6, 2016 Share Posted September 6, 2016 (edited) Anybody ever use a gauge like this to try to sort out a brake-induced pull to one side? Edited September 6, 2016 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
JMortensen Posted September 6, 2016 Share Posted September 6, 2016 What is that gauge going to show you? I think it's pretty unlikely that you would have a pressure differential from one side of the caliper to the other. If you had one on the left and the right wheel, or front and back, then you could look for some obstruction in the hard lines. Outside of that I think the pressure to the pistons is going to be the same even if the pistons themselves are frozen. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 6, 2016 Author Share Posted September 6, 2016 I'm just trying to think thru it instead of "parts swapping." The brakes are getting hot on both sides, although I didn't put a pyrometer on the rotors like I should have. Quote Link to comment Share on other sites More sharing options...
Miles Posted September 6, 2016 Share Posted September 6, 2016 (edited) I'm just trying to think thru it instead of "parts swapping." The brakes are getting hot on both sides, although I didn't put a pyrometer on the rotors like I should have. Front or back brakes getting hot or both getting hot? 1. Pulling to one side suggests a stuck/leaking caliper. 2. Hot front brakes on both sides suggests: Brakes dragging due to improperly adjusted master cylinder push rod. Are the rear brakes hot too? If yes check the push rod. Unbalanced or undersized brakes: Rear brakes undersized. Improper rear brake PV adjustment (to much front bias). Brake pad selection. Drive the car around 4 - 5 miles in a safe area staying off the brakes as much as possible and pull off road and check front and rear temperature of the calipers/wheels. If both front and rear brakes are hot then they are dragging possibly due to the push rod issue. If the front brakes are hotter relative to the rear brakes then there may be a front bias issue due to undersized rear brakes, PV adjustment or brake pad selection. If the fronts are pulling then inspect them. A weak/sticking caliper will cause the opposite caliper to grab and pull. If you find a bad caliper replace both sides. Let us know what the road test shows. Edited September 6, 2016 by Miles Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 7, 2016 Author Share Posted September 7, 2016 You won't believe this: The throttle cable on my LS-swapped S10 daily driver/tow vehicle failed today. So I swapped on my street tires and will daily the Z this week while figuring out what to replace my throttle cable with. The Z continues to be the most reliable car in the stable. Using theocracy car to get parts for the shop truck.....10 days 'til race day. Quote Link to comment Share on other sites More sharing options...
Miles Posted September 7, 2016 Share Posted September 7, 2016 So did you solve the brake problem? Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 7, 2016 Author Share Posted September 7, 2016 No. Throttle cable broke in my truck, so I'm driving the Z to work while awaiting parts for truck. One broken vehicle at a time. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 9, 2016 Author Share Posted September 9, 2016 Burned the midnight oil to make some progress. As I drove the car around town for the past 2 day, I noticed that there was a noise coming from my right wheel on slow right and left turns. The sound was similar to the noise that Chewbaka makes when trying to get Han Solo's attention. Well, I've decided that the left rotor is warped. How is it warped-I dunno. But-I have a set of street rotors and pads, so I swapped those on all 4 corners. Prior to that, I though perhaps that left caliper was not releasing, so I cracked a bleeder and the noise didn't change or go away, so I don't think that is it... There was no visible runout on the rotor, so I'm not counting my chickens until I drive the car tomorrow and do some high-speed stops. I wanted to put a dial indicator on the system to check for runout, but I couldnt figure out where to mount the magnetic base, so I said F-it and changed all the wear items over to my street stuff. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 9, 2016 Author Share Posted September 9, 2016 (edited) Feedback from commute to work. Pull to the left is less noticeable, but likely only due to less aggressive pad compound. However, the pull is still present in spite of replacing the rotor. I plan to try the gauges as originally discussed. I have a tracking number for a new caliper that should arrive next week. Car has to be on a trailer Thursday night ready to race....midnight oil.....argh...I guess "that's racin'." I am taking advantage of the delays to ready other aspects of the car. Checked temperature of rotors. Drove down long straight road, stopped using parking brake and checked rotor temp: cool to touch (cooler than my seat covers!). Did done hard(er) braking on way home and checked rotor tenp with I/R thermometer: 132 degrees both front rotors. Wish I had tried this before changing rotors. I'm just looking for something definitive. Edited September 9, 2016 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 10, 2016 Author Share Posted September 10, 2016 Trouble shooting delayed by truck with a broken throttle cable forcing me to use Z as primary transportation. I did check temps on the rotors yesterday. Does anybody have a good rule of thumb for how many degrees (temperature) similar or different the temp of left and right rotors should be to be acceptable? Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted September 10, 2016 Share Posted September 10, 2016 I'm guessing that your caster is not equal left to right. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 11, 2016 Author Share Posted September 11, 2016 (edited) I'm now certain that you are correct. Read to end to find a question. Soooo, I mounted the gauges on both front calipers and used my line lock to set pressure to get measurement to eliminate some human element. Left side showed 100psi higher pressure. Swapped gauges-now right side says 100psi higher. Therefore, psi is same left to right; my gauges are 100psi out of calibration from each other-ha! We were very methodical about this so I have total confidence in our test. So, I'm saying brake hydraulics are good. Then, we swapped calipers left for right and kept the pads with their associated rotor to keep them bedded. Bled system carefully. And went on test drive. Car still pulls left on braking. Very subtle drift left with hands off wheel while cruising. I will be starting tomorrow after church with caster adjustment. My caster gauge says that both sides are at 6.0 degrees caster. Here's my question: do I ignore the gauge and set the length of each TC rod to equal measured length, from center to center on the TC rod clevises? And if I measure and find both TC rods to be equal length now, with the car pulling left (and the left wheel locking first), would you go longer on the left TC rod, or shorter? I'm freakin' exhausted. My plan is to change the TC rod, adjust toe, then test drive-over and over until done. I so, appreciate all the help from everybody! At least I'm done with brake fluid... Edited September 11, 2016 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
Leon Posted September 11, 2016 Share Posted September 11, 2016 Any race-alignment shops around you? Are your tire pressures even L/R? You can eliminate any tire/wheel issues pretty quickly by swapping left-to-right and going on a test drive. I've had unevenly worn tires do this, although it seems like you have the same issues with both sets of tires you've tried... Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 11, 2016 Author Share Posted September 11, 2016 (edited) Same issue with multiple tire combinations. Sitting under car I look up and say: "damn, all this caster changing probably affects corner weights..." Of course I don't know anybody with scales... Having a ball and learning lots. Just a little on the tired side. Edited September 11, 2016 by RebekahsZ Quote Link to comment Share on other sites More sharing options...
Leon Posted September 11, 2016 Share Posted September 11, 2016 I don't think caster settings will inherently throw off static corner weights by much. It's more the jacking effect from camber changes that causes that. Time to put some corner scales on the to-buy list! Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted September 12, 2016 Author Share Posted September 12, 2016 A touch more caster Left side fixed it!!!!! Tomorrow we see if airdam needs trimming. Thanks every body! Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted September 12, 2016 Share Posted September 12, 2016 Here is a little light reading regarding caster, its measurement, and its effects. http://www.disco3.co.uk/gallery/albums/userpics/24543/steering-geometry-and-caster-measurement%5B1%5D.pdf Quote Link to comment Share on other sites More sharing options...
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