Popping sound when I start

[jackboeker83]

https://youtu.be/2uSAFFRSP2A

So after about 500 miles I am hearing a popping sound when I start to drive. I heard it before but not as bad. It happens when I shift and give it gas. I put it on stands and nothing is loose and all the bolts are tight. It doesn't do it when it's on stands but I have narrowed it down to the drivetrain. There is play between the driveshaft and transmission. I know there is supposed to some play but not sure how much is too much. Just wondering if anyone else has had this issue before or can give me some advice. This video wasn't meant to show u the sound so u only need to watch the first part to really hear it.

Coyote with tko 600 with IRS

[Bren]

Did you mean "popping"?

[jackboeker83]

Lol yeah

[jackboeker83]

Did you mean "popping"?

My cat as been pooping of the floor and been texting my wife that a lot lately... spell check or maybe just habit... who knows lol! Probably should of left it to get more people to be like wth is this guy talking about lol

[seagull81]

The pooping sound is you with all that torque! Sorry Jack I had to do it. I hope you find it.
Is it all the time on shifts or only when cold?

[jackboeker83]

I lifted it up off the ground today and had my wife put it in first and let go of the clutch to see if I can get it to do it... I get a lot of chatter in the drivetrain but I got yelled at my neighbor (live in an apartment) for starting my car at 0900 on a Saturday so I couldn't get it on tape. It still isn't doing the loud popping sound because I think it needs some actually resistance to the drivetrain. Anyway can anyone tell me if this is normal play for a drivetrain and maybe help me nail down what is making this noise that you hear in the first video above.
https://www.youtube.com/watch?v=plKtATk0Doc
https://www.youtube.com/watch?v=YzNmXGzETbw
https://www.youtube.com/watch?v=beQOOlpF3hQ

[jackboeker83]

It is all the time, it doesn't matter if it is cold or hot. I will get a better video of me driving today to let everyone see what I am talking about. Its when I start to drive as you can hear but also if I am going slow when no gas then give it gas as in there is too much play somewhere.

[GoDadGo]

I don't have the same transmission, but mine does clunk a little when it is in gear when you attempt to move the yoke, but not as much as yours and the movement is very, very minimal.

Since the drive shaft isn't in and everything is brand new I wanted to get a comparison as to how much movement you are showing versus how much my virgin gear box actually has.

With that being said, my recommendation is to contact one of the supporting Vendor/FFR Enthusiasts, the manufacturer of your transmission or maybe a shop that specializes in modified Mustangs.

The bottom line is I think something is wrong and would hate to see you make matters worse by driving it.

Good Luck!

[2bking]

I can't exactly hear the noise you are describing because of the exhaust. The sounds in the videos from under the car sound normal and the slack you are finding is normal also. The rear U joint can be seen and looks OK. Make sure the front one is tight and no evidence of grease escaping around the bearings. Check the seals at all the moving parts in the drive train. A leaking seal may indicate a worn bearing. Some limited-slip differentials are known to make a popping sound when the friction modifier is not installed or the fluid needs changing but that noise usually happens on slight turns or turning corners. It looks like you have the IRS so one the wheel bearings may have the axle nut loose. The noise can also come from a bad CV joint. Check the mounting of the pumpkin for lose or broken hardware as well as the heim joints in the suspension. When the noise is caused by hundreds of foot-pounds of torque, the source is hard to find with the drive train unloaded.

[DaleG]

Drive shaft hitting something in the tranny tunnel under load? Just a thought. Does the popponing increase with revs?

[AC Bill]

Gear lash play is apparently not uncommon with the Mustang IRS. Many of the Mustang forums have comments about the clunk or popping sounds, and they are determined to be normal for the most part.. My solid axle has some slack and is not dissimilar, as to when you turn the driveshaft back and forth.

What worries me, is in that last video of you moving it side to side..Might indicate the rear pinion bearing is hooped.

[jackboeker83]

Drive shaft hitting something in the tranny tunnel under load? Just a thought. Does the popponing increase with revs?

I don't think so because I have IRS and my driveshaft doesn't move up and down. It has plenty of clearance as well

[jackboeker83]

I can't exactly hear the noise you are describing because of the exhaust. The sounds in the videos from under the car sound normal and the slack you are finding is normal also. The rear U joint can be seen and looks OK. Make sure the front one is tight and no evidence of grease escaping around the bearings. Check the seals at all the moving parts in the drive train. A leaking seal may indicate a worn bearing. Some limited-slip differentials are known to make a popping sound when the friction modifier is not installed or the fluid needs changing but that noise usually happens on slight turns or turning corners. It looks like you have the IRS so one the wheel bearings may have the axle nut loose. The noise can also come from a bad CV joint. Check the mounting of the pumpkin for lose or broken hardware as well as the heim joints in the suspension. When the noise is caused by hundreds of foot-pounds of torque, the source is hard to find with the drive train unloaded.

You can really hear it at about the 10 second mark with the video of me driving.

[GoDadGo]

I listened to you video (Eye Shut) several times.
To me it sounds to me like the U-Joints may have given up the ghost.
I've got an old C-4 Vette and the half shafts eat up the U-Joints about every three for four years because I drive it like I stole it.
Those half shafts are short like the Factory Five drive shaft and take tons of abuse so it can't hurt to check the U-Joints and CV Joints.
It may not be the transmission or differential making the popping sound, but something simpler.

[jackboeker83]

Two new videos to help describe what is going on... I placed the phone on the trans tunnel as I drove. I also checked the CV joints and I have no leakage coming from them and the U-Joints look fine to me. I called a local shop and will be taking the car in Monday to them if I cant figure out. Good news tho... the owner has a factory five coupe!!!! lol small world. I just want to thank everyone who has helped me so far and continues to help me.

This video is 30 seconds and you can hear the pop over and over... what I am doing is giving it gas then letting it lose momentum and giving it gas again which causes the popping sound.
https://www.youtube.com/watch?v=rEew_KyjMLQ

This video I almost stall it so you can really hear it.
https://www.youtube.com/watch?v=zmpDv0zECPU

[2bking]

The sound seems to be from slack in the drive train and mine has a similar noise although not as pronounced as yours. I have a torsen differential which is known for more slack than the other types. This may be a little far out but could be the transmission is very low on fluid or is wrong type. A lose axle nut could still be a cause.

[GoDadGo]

That doesn't sound like bad U or CV Joints to me after listening to these new recordings.
Check to see if your pinion nut has backed off a bit.
If you pull the drive shaft and then try to turn the pinion back and forth you may find that it is moving in and out of the case if the nut has started to back off.
I've had that happen on a 3rd Gen Camaro that had the 7.5" Ring Gear and it created a "Clunk" on acceleration and deceleration.
I tightened the nut and the noise went away, but it eventually loosened causing me to replace the nut.
Basically, it clunked when you gave it gas or dragged the car down in gear, but it didn't clunk or click all the time, just in acceleration or deceleration as the pinion shifted.
If it is in the transmission, I am not able to assist.

[rich grsc]

The sound seems to be from slack in the drive train and mine has a similar noise although not as pronounced as yours. I have a torsen differential which is known for more slack than the other types. This may be a little far out but could be the transmission is very low on fluid or is wrong type. A lose axle nut could still be a cause.

Common issue.

[jackboeker83]

Common issue.

Not the axel nut. Checked both and still are torqued down.

[Railroad]

Probably not an issue, but check the pinion flange on the rear end for movement, in and out. You may need something to pry, for checking.
Any movement indicates the crush sleeve has developed loss of preload. You can tighten the pinion nut and correct this. Get informed before just tightening it up.

[WIS89]

Jack-

I hate to suggest something so simple, but since it appears to be happening when you give it some acceleration, is it possible that your engine mounts are loose? I could see how temporary misalignment as a result of the engine torque causing such a noise.

I know you said you checked U-joints for grease, but is everything snugged tight? It just seems like something is perhaps aligned correctly when static, but when the engine wants to go, something falls out of alignment.

I am not sure I helped, but I didn't want to miss something that may have been overlooked. Good luck getting it resolved!

Regards,

Steve

[jackboeker83]

Jack-

I hate to suggest something so simple, but since it appears to be happening when you give it some acceleration, is it possible that your engine mounts are loose? I could see how temporary misalignment as a result of the engine torque causing such a noise.

I know you said you checked U-joints for grease, but is everything snugged tight? It just seems like something is perhaps aligned correctly when static, but when the engine wants to go, something falls out of alignment.

I am not sure I helped, but I didn't want to miss something that may have been overlooked. Good luck getting it resolved!

Regards,

Steve

That was my first thought as well but they are still tight and it doesn't do it when I rev the engine only when it is in gear. I think it is coming from the trans or belhousing area. I am taking it to a local mechanic who has a ffr coupe and see what he says before I go that route.

[GoDadGo]

Good Luck & I Hope This Is Not A Costly Repair!

[CraigS]

If you apply the parking brake, can you let the clutch part way in 1st and then in reverse to load it to make the pop sound? If you can, and if you have access to either a 4 post lift or an alignment rack, maybe you can produce the pop while someone is under the car so they can locate it. The only other things I can think of that haven't been mentioned is all the nuts/bolts on the rear suspension control arms. It seems to take a fair amount of load to produce it so one of those being a little loose and allowing the bolt to move .030 inch could cause it and be hard to find.

[jackboeker83]

So last night I took it to a shop and we tried everything. Couldn't figure it out so I was like hey. Let's just check the driveshaft. Everything was already tight from befoee but let's take it off and see if everything is moving normal. We took it off and everything was working properly and put it back on then that fixed the issue. Not sure what we did to fix it but i don't care lol.

[CraigS]

Excellent, you got lucky. I used to be a Lexus tech and one of the worst problems to have is like you had. We even had a set of chassis ears where you clip a wire to multiple suspension parts and listen them one at a time while driving. Trouble is that noise telegraphs through from one part to the next real well.