[65gto69]

Hi Guys, I developed a rattle under the car somewhere that I can't seem to figure out what it could be. It doesn't do it while sitting still and idling, only does it while moving. Rattle does seem to pick up speed as the car picks up speed but not like it is a rolling wheel or something, it seems to level out at a point even though the car is still picking up speed. I can feel it in the floor board or in the gas pedal and sounds like it is coming from the passenger side.

Ant suggestions at what to look at would be very helpful.

I have already checked exhaust and rear tailpipe was loose so I fixed that but sound didn't go away.

What would rattle in a way that I can feel it in the floor board?

Thanks for your help,

Mark

[Dick Boneske]

Drive shaft hitting tunnel at the rear of the trans? Exhaust hitting somewhere--sometimes torque to move the car twists the exhaust to rub. That's all I have.

[jspeed]

Could be loose converter bolts... at the flex plate..

[65gto69]

Thank you,

I will check those areas.

[chrisp]

Lost 10 mm socket.

[LATECH]

Transmission cross member maybe.

[OG68]

Cracked flex plate

[Johnny99]

Parking brake cable?


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[Johnny99]

Transmission cooler lines are a thought as well



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[65gto69]

Thanks for more suggestions. I have not looked at the car yet due to being too busy right now.

I know it is not tranny lines as mine are rubber from trans to cooler.

I will definitely check t.c. bolts, just put the motor in about 60 miles ago so i hope they didn't come loose yet. Used thread lock on the flexplate bolts so they should be good. Flexplate is a TCI one from about 15 years ago (it is the solid plate not like the current TCI with holes in it), so I hope that didn't crack or I would have other issues I would think.

I will check exhaust, trans cross member, drive shaft as suggested.

I will let you know what I find.

Thanks,
Mark

[footjoy]

Sway bar links
Door or window mechanism?

Greg

[64-3Deuces]

My 64 had a similar noise and symptons after taking it out of storage after a number of years. Traced it to the front universal joint which I guess dried out and developed a lot of play causing noise.

[65gto69]

I really haven't had any time this past week but I did have the car out and seems the rattle is getting worse. I checked the exhaust pipes again by grabbing the pipe and really trying to shake it. They didn't make a sound let alone move very much.

I will try to get under the car this week to check engine and tranny mounts. I also have a tranny mount bolt in driveshaft loop I want to check. I know that the loop is very close to the floor board, but the metal on it is so thick I can't imagine that moving or vibrating, but will check it.

Thanks for the other suggestions. My car does sit a lot more than it is driven. Last year I put the new motor in it and only put 60 miles on it. This year I tacked on another 40 miles maybe so only 100 miles in 1 year. Probably only have maybe 2000 to 3000 miles on the car total since I purchased it in 92.

At this point I wish what ever it is would just let go so I know what the problem is.

Thanks again,
Mark

[rohrt]

If you think the rattle is caused by the car moving down the road. Get a friend to help you bounce it and up and down sitting in the driveway.

[65gto69]

I think I found my rattle. I believe it is my driveshaft loop. It is a tranny mount bolt on type and with having a th400 trans in my 65 GTO the driveshaft loop is in the driveshaft tunnel and there is very little room for it to fit properly. It seems to be 1/16" away from the floor board and the slightest push from hand makes it hit the floor board and pretty much sounds like the sound I am hearing in the car and would also be why I feel the rattle in the floor.

I am going to wedge something in between the loop and the floor and take the car for a drive to see if that solved the issue.

Will post results.

Thanks,
Mark

[65gto69]

Worked on the rattle last night.

It was the driveshaft loop. It was just barely off the floor board so the vibration of the engine caused the loop to move just enough to tap against the floor board making the sound worse than what it the problem was.

Wedged a piece of wood shim between loop and floor board and took for a drive and no more rattle. So just have to bend the loop down a bit so it does not hit the floor board while the car is running.

Thanks for all the suggestions,
Mark