U-joints? Mounts?

A_+

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95 mustang. I've been hearing a fast knock, a rattle if you will, from inside the car. Kinda sound like its coming from the drive shaft but I can't hear it when I'm underneath. Motor mounts look good, as well as the trans mount. Nothing is loose, I don't think. The u-joints don't look too bad either....but what the hell do I know. Has anyone else experienced a similar problem and solved it?!
 

94mustangsvt

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Are you sure it isn't an engine noise?

Is the air injection system still installed on your car? Did you check to see if the metal tube that runs back to the cats is whacking into anything? That can actually make quite a bit of noise.
 

A_+

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Aftermarket CAI. Cat's deleted. I'm being told,strut mount?
 

kaveman

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I just fixed a thudding under my 98 with a Stiffler's crossmember and urethane trans mount. I didn't think anything was wrong with the stock parts but the new parts were cheaper than the driveshaft work I was going to do and when I got everthing bolted in the noise was completely gone.

I don't know how similar your knocking is to how mine sounded but if the knocking is definitely coming from under the car particularly from under the driver/passenger floorboards, then a new crossmember might do the trick.

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A_+

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Thanks for the advice. I'm going to replace the wheel hub assembly and if that doesn't fix it, I'll definitely look into that. Thanks,chief.
 

kaveman

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No problem bud! Good luck and feel free to ask if you have anymore questions

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A_+

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Of course. It didn't fix it. When I get time I need to put it on a lift
 

A_+

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Damn....still chasing that knock [emoji3525]
 

dcm0123

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Might help if you were more specific about when you hear the knock-
While accelerating?
When you go over a bump?
When braking?
 

A_+

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I’ve done a lot to this car to rule out some issues, since I first made this post. Trans has about 35k, clutch was replaced 3 months ago and the drive shaft was balanced a few years ago when I began the journey to find this gremlin. Stifflers crossmember was installed with a stock mount and bent the exhaust that was touching the car. That being said....
The car seems to rattle when it begins to warm up and the rpm is under 2.5k so pretty much when I’m on the street and I’m slowing down on the highway. I have no problems when I hit a bump or breaking or turning.I feel like the stock mount rubber is too soft. Is that a thing?
 

dcm0123

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A soft mount will not cause the problem unless the motor is moving and allowing something else to contact the frame or another part.
Had a similar problem in the past on deceleration. It was a loose brick inside the catalytic converter. Did you say you removed the converters?

Are there any other loose parts on the exhaust like heat shields or baffles in the muffler? hit it with a rubber mallet and see if it rattles.

How is the oil pressure? Bad rod bearings may also cause a rap on deceleration.

You may want to take out the drive shaft and check the bearings by rotating the joints. If you feel any binding or looseness, replace the joints.

Are you sure the drive shaft to differential bolts are tight? Had them loosen up in the past.
 

A_+

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Yes, I’m running an O/R H and both sides were coming into contact with the car so I just banged them in with a hammer. The motor mounts are new but they sit at the very bottom of the hole they bolt into. Idk if that’s a problem. The trans shop I took it to said that the trans was good but the mount looked a little tall. They’re all that size though? I’ll double check the DS
 

dcm0123

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If it is a rapid noise like a rattle, I doubt if it is related to anything hitting.
Tall should not matter as long as nothing is hitting.
 

A_+

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Yeah, when I took it to a muffler shop, they put it on their lift and we didn’t see it touching anywhere. Its more of a rapid thud that sounds and feels like its coming from the shifter but also sounds like it may be coming from the bell. I’m thinking I might have to take it back to a trans shop so they can take it apart [emoji29]
 

dcm0123

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If it was making the noise before they put in the clutch, probably has nothing to do with the clutch.

I have had the best luck finding noises by supporting the car on heavy wooden blocks then putting it in gear and seeing if it will make the noise. If it makes the noise then you have someone help you trace the noise down.

Make sure both rear wheels are off the ground. Put the supports under the each end of the rear axle so the road height is correct. Pile up 6 by 6 wooden blocks about 2-3 feet long each (cut from 6x6 pressure treated timbers). Never use concrete blocks to support a car. is very dangerous because they can crack and you end up with car on top of you.
 
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A_+

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That’s just it, a buddy of mine picked the car up with a forklift and I was in it keeping it at 2k rpm and he didn’t see anything and I couldn’t hear anything either. Could suspension have anything to do with it? It sits very low and idk if that screws with pinion angle.
 

dcm0123

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Did you support it under the axle to keep it at the right ride height? This would put the pinion angle at the same position as when you drive.
I would have accelerated and decelerated as well to see if it caused noise. Apply the brake to put a load on the drive train while accelerating.

Do you have another set of tires to put on? If not, switch them front to back and see if the noise changes. Check the tires to see if they are out of round or have a shifted belt by spinning them while in the air and you look at them from the front or back of the car.

Check the front and rear control arms to make sure the rubber is not worn allowing the metal parts to contact. I would pull the driveshaft and inspect the bearings. When you do this make sure the flange on the rear axle is not loose.

I would not expect suspension to cause a constant thud. If the road shifted or you hit a pothole it may cause a thud.
 

Paladin1001

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Was the flywheel checked for cracks when the clutch job was done? I know i'm in the middle of a clutch job due to a bad clutch fork and pilot bearing and I thought my flywheel was ok until I inspected it carefully and it has cracking occurring so I had to order a new one.
 

A_+

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Did you support it under the axle to keep it at the right ride height? This would put the pinion angle at the same position as when you drive.
I would have accelerated and decelerated as well to see if it caused noise. Apply the brake to put a load on the drive train while accelerating.

Do you have another set of tires to put on? If not, switch them front to back and see if the noise changes. Check the tires to see if they are out of round or have a shifted belt by spinning them while in the air and you look at them from the front or back of the car.

Check the front and rear control arms to make sure the rubber is not worn allowing the metal parts to contact. I would pull the driveshaft and inspect the bearings. When you do this make sure the flange on the rear axle is not loose.

I would not expect suspension to cause a constant thud. If the road shifted or you hit a pothole it may cause a thud.
i guess it wouldnt be suspension since it only makes the sounds while under load. No, we didnt maintain pinion angle but he was only looking the exhaust touching. Honestly, i didnt get on it very much, this dude had me in the car while i was about 6 ft in the air. it was kinda scary especially when this dude keeps telling me to trust him :D
But that is sound advice. i will get on that tomorrow. Could it be sway bar? I just thought of that on my drive home....
Was the flywheel checked for cracks when the clutch job was done? I know i'm in the middle of a clutch job due to a bad clutch fork and pilot bearing and I thought my flywheel was ok until I inspected it carefully and it has cracking occurring so I had to order a new one.
I hope it was. the place i had the clutch done said the part i gave them couldnt be installed then somehow damaged my rear main seal when they installed the new clutch. i didnt know till i got home and i was leaking oil. they charged me to resurface the fly wheel so im assuming that they inspected it. then again, they forgot to install a bolt that connects to the bell.
 

Paladin1001

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i guess it wouldnt be suspension since it only makes the sounds while under load. No, we didnt maintain pinion angle but he was only looking the exhaust touching. Honestly, i didnt get on it very much, this dude had me in the car while i was about 6 ft in the air. it was kinda scary especially when this dude keeps telling me to trust him :D
But that is sound advice. i will get on that tomorrow. Could it be sway bar? I just thought of that on my drive home....
I hope it was. the place i had the clutch done said the part i gave them couldnt be installed then somehow damaged my rear main seal when they installed the new clutch. i didnt know till i got home and i was leaking oil. they charged me to resurface the fly wheel so im assuming that they inspected it. then again, they forgot to install a bolt that connects to the bell.

If I had to lay odds on which bolt they forgot I would bet it was the drivers side upper one. That one is a bugger to get at.
 

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