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Good morning! I’ve got a lingering clunking sound when I either accelerate or slow down rapidly in one of my ‘63’s. I’ve changed the snubber rubber, and the main drive shaft u joints. I still hear it but only when it’s an abrupt hitting of the brakes or accelerator.
I have owned this car for several years and not yet changed the rear diff fluid. Thinking it couldn’t hurt. I see a square bolt up top, which I assume is the fill plug, but where is the drain plug? Do you drain it by removing one of the snubber bushing bracket bolts?
Check your half shaft u-joints...you said you checked the main (drive) shaft u-joints. Also, be sure all your shims are still in place in your trailing arms.
The motor mounts look ok, but maybe? I’ll look again after lunch.
I’ve got her up on the lift and did a quick visual inspection. Nothing obvious at the moment. What’s the easiest way to check the u joints on those two drive axles: put the car in neutral, tires off the floor, and try moving the wheel, wiggling the axles, listening for the sound?
Michael
If the original front differential mount is still on your 63 there is a good chance that the side mounting holes toward the front of the car have become slotted which causes it to move when accelerating or decelerating causing the clunk you hear. Most of my friends, me included, had that problem with our 63's caused by constant abuse in drag racing. I still have marks on the underside of the tunnel where the rear driveshaft U-joints would hit. One of my friends actually wore a hole in his tunnel.
Later models were thicker where the side bolt goes through.
Gary
Michael
If the original front differential mount is still on your 63 there is a good chance that the side mounting holes toward the front of the car have become slotted which causes it to move when accelerating or decelerating causing the clunk you hear. Most of my friends, me included, had that problem with our 63's caused by constant abuse in drag racing. I still have marks on the underside of the tunnel where the rear driveshaft U-joints would hit. One of my friends actually wore a hole in his tunnel.
Later models were thicker where the side bolt goes through.
Gary
Hmmm, good to know. If this is the case, I could probably tell by simply removing the bolt and looking at the holes that it passes through, correct? Or if it moves forward or backwards with a little force?
Michael
My holes were pretty slotted and easy to see but from my earlier post when I showed picture of my tunnel you can imagine how slotted mine were. I'm not sure what degree of slotting would allow the clunk and still not be very visible. Sure worth a try to do some prying to see if there is movement and/or take a bolt out and do a visual.
Gary
The motor mounts look ok, but maybe? I’ll look again after lunch.
I’ve got her up on the lift and did a quick visual inspection. Nothing obvious at the moment. What’s the easiest way to check the u joints on those two drive axles: put the car in neutral, tires off the floor, and try moving the wheel, wiggling the axles, listening for the sound?
And, also, having someone looking at the half shaft u-joints while rotating the tires forward and back. Rotate a rear wheel a quarter of a turn clockwise and then jerk the wheel back a quarter of a turn counter clockwise. The snapping of the wheel back and forth should reveal if one (or more) of the joints is bad.
If the suspension is at full travel like when the wheels are off the ground it’s not a good idea to try and turn the half shafts as your putting the u joints in a bind
The motor mounts look ok, but maybe? I’ll look again after lunch.
I’ve got her up on the lift and did a quick visual inspection. Nothing obvious at the moment. What’s the easiest way to check the u joints on those two drive axles: put the car in neutral, tires off the floor, and try moving the wheel, wiggling the axles, listening for the sound?
Often, when U-joints are failing, you will see a fine, rust colored powder on and around the trunnions. Start by looking for that. That said, I suspect the snubber bracket is shifting on the differential, as suggested by Gary (Ol Blue). It's a common '63 problem.
Michael
If the original front differential mount is still on your 63 there is a good chance that the side mounting holes toward the front of the car have become slotted which causes it to move when accelerating or decelerating causing the clunk you hear. Most of my friends, me included, had that problem with our 63's caused by constant abuse in drag racing. I still have marks on the underside of the tunnel where the rear driveshaft U-joints would hit. One of my friends actually wore a hole in his tunnel.
Later models were thicker where the side bolt goes through.
Gary
I agree this is where I would be looking as well as the other items. The 63-4 brackets were too thin, many times they cracked and ripped. The revision of welding in washers helped but the best ones are the 69-79's as Chris shows. The front hole in the 63-4 diff is a tapped 7/16-14 hole that a 1.250 bolt was used with, it was a bad idea and changed in 65 to a through hole and long bolt. I have drilled out those front holes and converted to the long bolts and 69 brackets, never had a comeback on one.
On my 63 the holes in that bracket were oblong causing the movement. I simply removed the bracket and welded thick washers (same size as the bolts) over each hole.......easy fix and problem solved.
If the suspension is at full travel like when the wheels are off the ground it’s not a good idea to try and turn the half shafts as your putting the u joints in a bind
Keith,
Doing what I have suggested will do absolutely no harm whatsoever. Now, if you were to start the car and run the drivetrain with the suspension in full travel you would most likely have issues...but, that's not was suggested...read my post again.
Good morning! I’ve got a lingering clunking sound when I either accelerate or slow down rapidly in one of my ‘63’s. I’ve changed the snubber rubber, and the main drive shaft u joints. I still hear it but only when it’s an abrupt hitting of the brakes or accelerator.
might check the rear wheel bearings while you are under there. My understanding is that these will “ clunk” upon acceleration/deceleration …
Keith,
Doing what I have suggested will do absolutely no harm whatsoever. Now, if you were to start the car and run the drivetrain with the suspension in full travel you would most likely have issues...but, that's not was suggested...read my post again.
what you wrote is true, but I have seen people try and run their engine though the gears
might check the rear wheel bearings while you are under there. My understanding is that these will “ clunk” upon acceleration/deceleration …
back wheels are elevated off the floor, and when I rotate back and forth the sound actually comes from the passenger side middle of the wheel, as if in the bearing. I could have sworn that the sound was from drivers side, but it’s pretty quiet. Are the rear wheel bearings on the C2’s a pain to swap out?
Wheel bearing that would be clunking would have a lot of play in them. Rock the wheel at 3&9 and at 6 &12 , if you find play, remove the wheel grab a wheel stud and see if you can push and pull on it and feel the axle move.
All 63-82 wheel bearings are the same. The early 63's were slip fit and a bad idea that failed, the mid 63-82 are press fit. They are tapered roller bearings but the correct method to dial them in can be argued forever. I set them up for -0- lateral play, regardless if they are drum or disc brake cars. The Vides on YT are terrible, following some will lead you right back to where you are now if you have bad bearings.
I would do a very detailed inspection looking at the bearings, joints, bushings, axle play in the diff, and the front bracket as discussed. When correct there is no clunking, there is no inner axle endplay more than 007, no outer axle endplay more than 002- although the spec goes up to 008", strut rods should be straight. Maybe post some pictures of the back of the car for us to look over.
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Clunking sound
