View Full Version : Another stupid question
Well, since stupid questions seems to be my wheelhouse, here goes.
I've had an annoying chirping noise coming from the DS rear when the car is rolling down the road. It seems to somewhat dissipate when the brakes are applied, but even when coasting it is there. No noise when sitting still. I think it may be in the rear brake, something rubbing or whatever. Car doesn't have enough miles for it to be the pads being worn down, but who knows.
My question is, I am thinking about putting it up on jack stands, removing the rear wheels, starting the engine, and putting it in gear so that I can see if I can locate the chirping noise. Is this something that I shouldn't be doing for other reasons besides the one that has me a bit spooked, the car shaking itself off the jack stands and destroying who knows what? Do I have to worry about the rear suspension being at full droop and being rotated by the driveline? It's a T-Bird IRS. I've just never done this with any car, nor been around when someone else did it with their car. Any specific concerns, red flags etc.?
I defer to the people on the forum who have more knowledge than me. This would include, I believe, most all the members of the forum!
egchewy79
06-21-2023, 04:22 PM
Another user chased a sound down to the straps against his fuel tank. Resolved after putting a rubber isolator between the two. Try multiple things to pin down that sound
Dave 53
06-21-2023, 04:26 PM
Seems like a logical step in trying to find that noise. I would argue, if done in a safe manner, it's safer than someone running next to the car or riding in the trunk or getting close to a spinning dyno.
I will admit that after I got my new transmission installed a couple of weeks ago, I ran it through all the gears on jack stands before pulling it out of the garage for the first time.
As in all endeavors, mitigate risk, first personal safety, then material damage. I ain't crawling under the car when the wheels are in the air spinning. I wouldn't get out of the car with the wheels in the air spinning, ready to take action to minimize material damage (stop the car if it falls off). I wouldn't have the second person get unreasonably close to moving parts.
Basically, don't do it alone. I'm free tomorrow after 10:00.....
EG, I plan to check everything that I can think of that might be causing the noise.
Dave, as usual, that would be fantastic. I wish you had given me a call when you were doing your transmission. I'll make sure to have it all set up for when you get here.
Jeff Kleiner
06-21-2023, 05:23 PM
Don't do it at droop; put the stands under the control arms so that the suspension is loaded.
Jeff
Jeff, that was what I was thinking about. I thought that I had read somewhere that it might not be a good idea. Will the jack stands and the car be stable enough under the control arms with it in gear and running? Would it be a good idea to have jack stands under the frame rails as well?
weendoggy
06-21-2023, 05:37 PM
Wilwood brakes?
Glenn, no they're the T-Bird brakes that came with the IRS. I'm guessing that I assembled something wrong (??), and it is rubbing somewhere. The brakes work well from my estimation it's just annoying to have this constant "chirp-chirp-chirp" as you drive along the road.
OK, so today Dave came by to give me a hand trying to determine where the chirping noise was coming from. Got it up on jack stands per Jeff Kleiner's recommendation, thanks Jeff, started it up and put it in gear just letting it idle. As soon as the clutch was let out and the rotors started turning you could hear the chirping noise. I was in the car and Dave was trying to find where it was coming from. With all the aluminum panels back there, everything seems to echo so it's hard to pinpoint the noise. I had an automotive stethoscope from HF, and Dave was immediately able to find the culprit. It turns out that one of the rotors that I purchased brand new during the build is warped. Once we located the noise you could see the caliper moving side to side, and the pads deflecting of the warped section of the rotor. I'm glad that appears to be all that it was, so that's good. Unfortunately, Dave noticed a fuel leak from a fitting at a transition from flexible to hard line that will need to be addressed as well. It's not in the best of locations, so it's going to require disassembly of one of the fuel lines to be able to correct it. Just keeping my fingers crossed that I don't find any other items that require attention when I'm fixing these!
boat737
06-22-2023, 08:57 PM
After I completed the car, I too had a chirping. I finally found that the body (or the trim ring, or both) were slightly rubbing on the roll bar. I think it was just one of the three legs. Just the tiniest amount of silicone lube (and I mean hardly any at all) stopped the chirp. Hasn't come back in 5 years.
Its Bruce
06-22-2023, 09:55 PM
In the effort to be positive, the perspective should be that you were FORTUNATE enough to find the fuel leak before it became anything more serious!
Boat, I always felt that it was going to come down to something brake related. Just really disappointed that the rotor was apparently warped from when I purchased it.
Bruce, you are correct in your perspective. Even though it's a very small drip I am glad we found it, and it will be a very high item on my list.
CraigS
06-23-2023, 06:36 AM
Realizing it is more common on an older car w/ a bit of rust, it may be that the rotor isn't sitting perfectly on the end of the axle. Maybe a small piece of debris is between inside of rotor and axle. Once you have the caliper out of the way, remove the rotor and check it and the axle. Wire brush and clean off both surfaces. Reinstall the rotor w/ 3 lug nuts. Be sure you have the caliper tied out of the way and repeat your test. Or, it may be easier to have the caliper as a visual reference point so go ahead and reinstall it also. The good thing is that rotors are cheap in the overall scheme of things so not terrible if you need a new one.
Craig, didn't think about that possibility, so we didn't check for that issue. The rotor seemed to just have one spot that pushed on the caliper, but the rest of the rotation seemed to be straight, if that makes any sense. It's almost like the rotor took a hit to one spot that deformed it in just that area, but it was hard to specifically determine the extent. I'll definitely check that when it's time to tear it down.
weendoggy
06-23-2023, 03:55 PM
Use a dial indicator to make sure the rotor, and more important, the hub is true. If in doubt, pull the rotor off (after marking the hub and rotor that's "off") and rotate it to another lug hole, remount and test. If the area changed with the rotor, it's the rotor, if not...well, you get the idea.
Thanks Glenn. I'll make sure to check that out. Unfortunately I have to put everything back together, even if I'm not done, so that the Boss can still get her car in the garage. I may have to do a few of these tests this weekend, and if needed, order the new rotors on Monday.
Fixit
06-23-2023, 08:53 PM
Use a dial indicator to make sure the rotor, and more important, the hub is true.
If you don't have a dial indicator, any kind of stiff wire (coathanger, welding rod, etc.) rigged up as a squeaker/pointer will work. FYI, a Post-It note is about .003" thick.
John, that's good to know since I don't have one. I'm pretty sure the rotor is toast since you could actually see it deflect as it rotated. Unless it's something like what Craig mentioned about some debris or whatever being between the rotor and hub surfaces, it has to be the rotor. I should have taken a video of it rotating so you could see the caliper being moved side to side, and the pad rubbing causing the chirp.