thumping in left rear
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 19
Likes: 0
From: Largo Fl
thumping in left rear
before I get my 91 up on a lift I need opinions on this . Right after I changed my mufflers I started getting Thumping noise that does increase with speed but only when putting a little throttle in the first three gears and it backs of higher in the gear. Half shaft appears tight..so what should I check...
Safety Car
Joined: Nov 2008
Posts: 4,328
Likes: 15
From: Jacksonville FL
Look for any shiny spots along the exhaust system and thats where your issue is. Make sure all the exhaust hangers are tight.Good luck!
Instructor
Joined: Jan 2013
Posts: 163
Likes: 4
From: Perth WA
Check where the muffler mounting brackets sit in the rubber mounting blocks. I recently fitted a Borla cat back system and found the brackets were hitting the chassis on one muffler due to a weld on top. I had to put packers under the mounts to drop them down a bit. Made a terrible noise in the back that was initially very hard to see & detect.
Last edited by Cruizin; Apr 23, 2014 at 01:35 AM.
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 19
Likes: 0
From: Largo Fl
Thanks Guys. I have to wait for the lift to be free . Then I can check from front to back. I only changed the mufflers but it took some effort to break them free from the pipes. Maybe i have a rub near the main shaft as I don't see any way for it to be near the wheel.
Safety Car
Joined: Aug 2013
Posts: 4,429
Likes: 605
From: Minneapolis Mn
Thumping
Start with what you moved, uninstalled or changed while doing the mufflers. If it wasn't there before the muffler change then something that was touched was. I would start with the wheel or half shaft if they were moved as it sounds symptomatic of those areas, assuming one of them was removed. The obvious areas center around the exhaust if that was the only things touched.
Thread Starter
Heel & Toe
Joined: Mar 2014
Posts: 19
Likes: 0
From: Largo Fl
Put the back up on race ramps and checked all the exhaust. No rub marks anywhere and nothing near the half shafts.
Now I do notice it only happens when the car is cold and not up to temp. The car does a have an issue with it cutting in and out and jerk if given to much gas untill the temp comes up then she will take all you give, and again no thumping after she warms up.
So could the cold ignition problem cause enough sudden torque to cause the noise ..
Ok I'm fishing here.......anyhow I can get the lift for a day in about a week so I think we'll just do a complete check of the left rear...
Now I do notice it only happens when the car is cold and not up to temp. The car does a have an issue with it cutting in and out and jerk if given to much gas untill the temp comes up then she will take all you give, and again no thumping after she warms up.
So could the cold ignition problem cause enough sudden torque to cause the noise ..
Ok I'm fishing here.......anyhow I can get the lift for a day in about a week so I think we'll just do a complete check of the left rear...
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Instructor
Joined: Jan 2013
Posts: 163
Likes: 4
From: Perth WA
Put the back up on race ramps and checked all the exhaust. No rub marks anywhere and nothing near the half shafts.
Now I do notice it only happens when the car is cold and not up to temp. The car does a have an issue with it cutting in and out and jerk if given to much gas untill the temp comes up then she will take all you give, and again no thumping after she warms up.
So could the cold ignition problem cause enough sudden torque to cause the noise ..
Ok I'm fishing here.......anyhow I can get the lift for a day in about a week so I think we'll just do a complete check of the left rear...
Now I do notice it only happens when the car is cold and not up to temp. The car does a have an issue with it cutting in and out and jerk if given to much gas untill the temp comes up then she will take all you give, and again no thumping after she warms up.
So could the cold ignition problem cause enough sudden torque to cause the noise ..
Ok I'm fishing here.......anyhow I can get the lift for a day in about a week so I think we'll just do a complete check of the left rear...