Rubbing noise after car is driven for a few minutes

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Rmach1

Well-known member
Joined
Apr 7, 2019
Messages
98
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Location
Ky
My Car
1971 Mach 1 351c H code
[url=https://ibb.co/xFgFn66][img]https://i.ibb.co/PDWD2gg/BB339-FB4-2-E55-42-B6-A6-AB-490-B03-BEDC84.jpg[/img][/url]
Hi, this is a strange one. I’ve been test driving my 1971 Mach 1 for the first time as I’m getting close to finishing the build.

I noticed a scrubbing noise under the car when on basic terrains and basic movement  and when I stop and bounce it up and down, it makes the same noise when sitting.

Then after it cools down after a while, the noise goes away when bounced...

I’m thinking exhaust? I can’t see anything underneath and don’t have access to a lift... so just wondering if anyone else  has had this happen

Thanks all!!

 
As for the noise you are describing - is it constant when you are driving or only occasionally. Can you give a rough idea what area of the car does it sound like it is coming from - front, back, side?

Since it seems to be a heat related issue and can be heard when bouncing the car it would seem to be a part that moves. If your exhaust is mounted properly it should remain stationary to the car frame and not caused any noise when bouncing the car unless hitting the rear axle.

Besides your exhaust it could also be a shock or the leaf springs. The shocks oil or gas is heated as the shock absorbs road bumps. After sitting for awhile it cools back down.

Try some wd40 and spray your leaf spring and take around the block. If that doesn't seem to make any difference than I would lean toward a bad shock.

 
Last edited by a moderator:
As for the noise you are describing - is it constant when you are driving or only occasionally.  Can you give a rough idea what area of the car does it sound like it is coming from - front, back, side? 

Since it seems to be a heat related issue and can be heard when bouncing the car it would seem to be a part that moves.  If your exhaust is mounted properly it should remain stationary to the car frame and not caused any noise when bouncing the car unless hitting the rear axle.

Besides your exhaust it could also be a shock or the leaf springs.  The shocks oil or gas is heated as the shock absorbs road bumps.  After sitting for awhile it cools back down. 

Try some wd40 and spray your leaf spring and take around the block.  If that doesn't seem to make any difference than I would lean toward a bad shock.
Ok all sounds about right. I’ll do some lubrication on those areas.

thanks for the info!!!

 
Oh I left out an answer... the noise comes front right over the differential so I’m thinking shock or shock mount maybe so I’ll check all those
See image for what was causing the noise

always make sure your exhaust vendor lets the car sit and settle on the ground before you drive away

niw I have to take it back and have them adjust the exhaust



 
I think the junction block on the brake lines is out of place should be more over the axle. The repo are made wrong also. I found that out when working on my 73 they used different size fitting from factory. There was a bracket there also. Can't show you a pic.
I certainly would rather move that block than the exhaust cross over pipe!!

thanks for the input and I’ll check for a correct part.

 
I did find one pic that you can see the junction block but not very good. 
Interesting... mine looks the same so I’m thinking the worse and I’ll have to move the exhaust toward the front... I may just make a bracket to move it toward the wheel instead of messing with the exhaust... it was very hard to make it fit. Bends were off and ends flared ends were too short etc. thanks for the pic post!!

 
I did find one pic that you can see the junction block but not very good. 
Interesting... mine looks the same so I’m thinking the worse and I’ll have to move the exhaust toward the front... I may just make a bracket to move it toward the wheel instead of messing with the exhaust... it was very hard to make it fit. Bends were off and ends flared ends were too short etc. thanks for the pic post!!
The new pic shows the bracket and how it appears to be made incorrectly as it sits too close to the exhaust. The pipe is in the richer place. So I will have to either extend the bracket to its side and drill another hole or I’ll have to cut the top and move it to the left and re-weld it give the. 1/2” clearance needed.

 
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