Ford Mustang Forums banner

481 - 500 of 859 Posts

·
Premium Member
Joined
·
651 Posts
Discussion Starter #481
I took the car out again didn't solve it with redoing the brakes which I kind of figured wouldn't solve the problem but it was worth a shot. This time I used my gopro to film my feet as I drove the car.


Here's the times you can hear the knocking sound. You can see its when ever I use the brakes hard.
:59, 1:14, 1:32, 1:51, 2:09, 2:22, 3:09, 3:23, 3:38, 3:50, 4:39, 5:00, 5:16 5:35, 6:35, 7:26

When you hear the noise at the 5:00 minute mark you can hear how the knocking slows as the car slows down. I sent the first video to Todd TCE but he said he never heard it before.
 

·
Registered
Joined
·
736 Posts
I think you have probably found the source, it surely looks like something is off with the brakes. Any chance of video on the brakes during use?

Jay
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #483
I think you have probably found the source, it surely looks like something is off with the brakes. Any chance of video on the brakes during use?

Jay
The hard part is I can't see what's wrong with the brakes. I don't see any marks on the calipers like something is hitting nothing seems to move around. I kind of feel it in the chassis when the knock happens. I thought about checking the control arms and applying new grease to the bushings and check the ball joints.

I'm also going to run the noise by Wilwood to see if they might have an idea of what's going on.

Jack what grease would you recommend for your Delrin bushings.
 

·
Premium Member
Joined
·
3,184 Posts
Does the brake pedal pulse at all when you press firmly on it?

I suspect that there are two unrelated issues going on here.

I think that the clunk-clunk noise is the differential or trans gears. Because the TA is mounted very stiffly to the chassis and there is no compliance in its mounting, it conducts gear noise into the chassis of the car quite well. With no interior in your car, this is quite audible.

I suspect the one or more of your brake rotors has a thickness variation in it. This will cause the brake pedal to pulse and the brake torque to vary at a constant brake pedal force. This variation in brake torque is going to make the driveline rock back and forth against itself. I would take a caliper or micrometer and measure the thickness of all four rotors maybe 10 times around each one. You might be able to find this by having someone very lightly press on the brake pedal while you spin each wheel with the tires off of the ground.

For Delrin bushings, you can use virtually any grease. Delrin is a self lubricating plastic and doesn't need any grease. Adding grease will keep water out and stop any possible squeaking.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #485
The brake pedal doesn't pulse. Its pretty easy to check the brake rotors so I will try that tonight.

I honestly haven't put the torque in yet its something I'm planning on doing when I'm ready to have a professional shop do the exhaust. My main focus right now is get it ready to smog. But the four link with your road race lower control arms and the solid uppers does transmit allot of noise. I also have a Torsen T2R in the car. Plus the trans has close to 90k miles on it and I kick myself for not rebuilding it while it was out of the car it seems to me it makes more noise now.

I've also wondered if the solid motor mounts with the poly trans mount is also causing more noise in the car. I was running solid motor mounts before but with a stock trans mount.

Thanks again for your help Jack.
 

·
Premium Member
Joined
·
3,184 Posts
Peter,

If the brakes don't pulse at all when you apply them, then the rotors don't have a thickness variation.

I would check on the OD of the front rotors. Make sure that the OD of the rotor doesn't have a high spot, which is hitting the ID of the caliper body. This will leave marks on both parts.

Solid engine mounts will cause more noise from the transmission.
 

·
Registered
Joined
·
471 Posts
Just some quick troubleshooting thoughts: If you put the car in reverse and back up and apply the brakes do you hear the clunking? What are you running for back brakes? Have you checked them as it does sound brake related? With the rear suspension you have now you are going to be hearing a lot more noises from the back. It makes me wonder if the rear brakes aren't the source of the noise.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #488
Just some quick troubleshooting thoughts: If you put the car in reverse and back up and apply the brakes do you hear the clunking? What are you running for back brakes? Have you checked them as it does sound brake related? With the rear suspension you have now you are going to be hearing a lot more noises from the back. It makes me wonder if the rear brakes aren't the source of the noise.
I'm starting to go over the whole car now. I'm going to check the rear brakes also just in case. The hard part with the rear brakes is some stupid person namely me thought hey why don't you run the hard lines on the rear axle directly into the brake caliper instead of using braided lines between the caliper and the axle. So I'm going to redo the brake lines on the rear axle to add flex lines so I don't have to open the brake system every time I want to remove the rear calipers.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #489
I was thinking about it this morning and one thing I could do to figure out if its the rear brakes or the front making the noise is use the prop valve to disable the rear brakes or at least make it so they hardly function to see if the noise goes away.
 

·
Registered
Joined
·
1,982 Posts
That’s a good idea ^

What is the condition of your upper arms? I had a set of factory ones in there once upon a time that made a very similar noise, I assumed it was the driveline angle getting out of whack. Ended up pulling them and installing TQ arm (enabled me to set the angle) and no more noise.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #491
That’s a good idea ^

What is the condition of your upper arms? I had a set of factory ones in there once upon a time that made a very similar noise, I assumed it was the driveline angle getting out of whack. Ended up pulling them and installing TQ arm (enabled me to set the angle) and no more noise.
The upper arms are in good shape the spherical rod ends are still tight so not to worried about them. I also double checked the pinion angle and everything looks good. I'm wondering if something was going on with the rear brakes like the rotor being warped might cause the T2R to make a noise since one side might tighten up the loosen when on the brakes. Maybe that could cause the torsen to make a knocking sound.

I think the best bet is to disable the rear brakes take for a short drive and see if the noise goes away.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #492
Disabling the rear brakes didn't solve the problem. I also tried driving the car putting it in neutral and yanking the steering wheel back and forth and didn't hear any noises coming from the front. I also did the same thing while applying the brakes and still got the but it didn't change with the steering wheel movement.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #494
How did you disable the rear brakes?
I shouldn't say disabled but I used the prop valve in the car and made the rear brakes basically not function.

I had the car on jack stands I thought what if I start the car put it in gear let it run apply the brakes see if I hear a noise. If used the brakes too hard it would stall the car so I would apply a little gas to load everything up to see if I would hear any noise. I didn't hear anything so I went to the prop valve turned it all the way out to decease the rear as much as possible. Then started the car and put it in gear pushed on the brakes. No matter how hard I pushed on the brakes I couldn't get the car to stall. I could see there would be some load meaning the were still kind of working but not enough to stall the engine with it just idling. I figured that was the closest I would come to taking the rear brakes out of the equation.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #496
Well it looks like I finally fixed the knocking sound. I did a few things to the car over the past couple weeks I took the struts out of the car since it seemed like the spring perch was kind of close to the strut tower. Changed the spacers at the top and torqued everything down.

The other thing I did was replace the brake pads on the car. When I was at the last autocross I talked to a few people that I know about the issue. I was told the noise could be any where from the way the rotor was cut when it was made or it could be the pads by a guy that is a Wilwood dealer. I did allot of research on pads and decided to use a Porterfield pad. I went with there R41 compound on the car and what a difference pads make. The car stops so much better and far more consistent then the BP-10 pad. I'm not to surprised considering how much higher CF the R41 pad has over the BP-10.

Unfortunately I didn't follow my normal rule which is only make one change at a time. I should have just worked on the struts and tested the car before doing the pads but I did it all at once. The one thing I did do when I torqued calipers down that I haven't done before was torque the nuts a second time. I have a digital torque wrench when I torqued everything it showed I went to the 30 ft pounds I did both sides of the car then went through them again. Then I went through the second time the top nut didn't move went right to 30 ft pounds the lower nut was at 28 ft pound and turned a bit to get to 30 ft pounds it did this on both sides of the car.

I took the car out for a 30 mile drive today that went very good no problems and no knocking from the brakes which made me happy. I do have a few interior rattles I need to track down and a couple noises but all in all it was a good drive.
 

·
Registered
Joined
·
197 Posts
Yah know. I just got my car up and running and I am getting this same exact knocking sound but I get it while I'm coasting at 25 mph down to about 5.

Sent from my SM-G965U using Tapatalk
 

·
Registered
Joined
·
736 Posts
A bit anti-climatic, I was looking forward to that breakthrough problem, found and solved due to (insert cause), but I'm very happy for you. It's those nagging, hard to pinpoint issues that drive one bonkers. Care to hazard an educated guess on what was happening?

Jay
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #499
A bit anti-climatic, I was looking forward to that breakthrough problem, found and solved due to (insert cause), but I'm very happy for you. It's those nagging, hard to pinpoint issues that drive one bonkers. Care to hazard an educated guess on what was happening?

Jay
If I had to take a guess at it I think the problem was in the rotors or the pads. It was one of those or a combination of them both that caused the problem. I don't think pulling out the struts and torquing it all back down did anything. Everyone I asked at the autocross about the problem said either look at the rotor or the pads.

I'm just happy I'm past it now so I can move on to putting miles on the car. I'm hoping to get it out again next weekend for another drive. The plan is to adventure further away from home this time. I would like to get a couple hundred miles on the car before then end of the month. But that might be a tall order. There is also a autocross at the end of June that I wouldn't mind maybe making the practice event.
 

·
Premium Member
Joined
·
651 Posts
Discussion Starter #500
A bit anti-climatic, I was looking forward to that breakthrough problem, found and solved due to (insert cause), but I'm very happy for you. It's those nagging, hard to pinpoint issues that drive one bonkers. Care to hazard an educated guess on what was happening?

Jay
If I had to take a guess at it I think the problem was in the rotors or the pads. It was one of those or a combination of them both that caused the problem. I don't think pulling out the struts and torquing it all back down did anything. Everyone I asked at the autocross about the problem said either look at the rotor or the pads.

I'm just happy I'm past it now so I can move on to putting miles on the car. I'm hoping to get it out again next weekend for another drive. The plan is to adventure further away from home this time. I would like to get a couple hundred miles on the car before then end of the month. But that might be a tall order. There is also a autocross at the end of June that I wouldn't mind maybe making the practice event.
 
481 - 500 of 859 Posts
Top