Front U-Joint possibly making contact with body?
Forum: C3 Engines, Driveline and Handling
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r
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Send PMWarrenton, MO - USA
Joined: 1/3/2004
Posts: 144
Vette(s): 1971; Numbers Match; Convertible; Red Ext.; Red vinyl Int; Black Conv Top; Red Hrdtop; 327-270HP; 4-speed; Factory Air Cond; Pwr Steer
I have a 1971 Convertible with a 4-Speed and the 270 HP engine. There are no driveling modifications that I am aware of. (Eng, Trans, Diff all numbers matching. My Problem: When driving the car it occasionally makes a sound directly under the transmission tunnel that sounds like the driveshaft or fron u-joint may be making slight contact with the body. This is intermittent and occurs during regular driving (at legal speed, in-town tppe driving) I have had the body mount doughnuts replaced by a reputable body shop.
Does anybody have any ideas what could be causing this? Anyone who has had this problem? Could it be worn motor mounts (they do not appear to be bad) or possibly the transmission mount? I would appreciate any input or help you may have for this problem. Thanks in advance.
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[QUOTE=red70-oneconv]
Could it be worn motor mounts (they do not appear to be bad) or possibly the transmission mount?
[/QUOTE] Yes, the engine mounts or transmission mount can be broken. Also make sure that the transmission crossmember is secure at both sides.
corvette440hp
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Send PMCOPPERAS COVE, TX - USA
Joined: 7/6/2002
Posts: 475
Vette(s): 1972 corvette stingray convertible
2007 coupe
MOUNTS MAY BE WEAK AND ALLOWING THE ENGINE TO TORQUE OVER TO MUCH. I WOULD LOOK UNDER CAR FOR ANY SIGNS OF IT HITTING (MARKS). SOMETIMES YOU CANT TELL IF MOUNTS ARE BAD JUST BY LOOKING.
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Duncanville, TX - USA
Joined: 11/8/2003
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Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
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#2-1985 Bright Red/Carmine Cp.L-98/auto
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Check your park brake cable...if it's loose, it can contact the driveline while your driving...just an added idea.
Also, check the foil-type insulation that fits over the top of the trans. It can become loose over time, and slide back, contacting the front u-joint.
Normally, if the mounts, engine or trans, are bad, it will create a vibration issue. For sure, check to see if anything is hitting the body...don't need no driveshaft sticking up thru the floor...
Also, check the foil-type insulation that fits over the top of the trans. It can become loose over time, and slide back, contacting the front u-joint.
Normally, if the mounts, engine or trans, are bad, it will create a vibration issue. For sure, check to see if anything is hitting the body...don't need no driveshaft sticking up thru the floor...
Joel Adams
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more than likely a tranny mount,if'n the motor mount was that bad fan blade would hit the rad shroud or hood,dats bad
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Duncanville, TX - USA
Joined: 11/8/2003
Posts: 22742
Vette(s): #1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/
Am-Fm/map light National/Regional/Chapter NCRS "Top Flight"
#2-1985 Bright Red/Carmine Cp.L-98/auto
Member: NCRS, NCRS Texas, Corvette Legends of Texas
[QUOTE=red70-oneconv]I have had the body mount doughnuts replaced by a reputable body shop.[/QUOTE]
Did you have this issue before the mounts were done?
Did you have this issue before the mounts were done?
Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
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r
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Send PMWarrenton, MO - USA
Joined: 1/3/2004
Posts: 144
Vette(s): 1971; Numbers Match; Convertible; Red Ext.; Red vinyl Int; Black Conv Top; Red Hrdtop; 327-270HP; 4-speed; Factory Air Cond; Pwr Steer
Yes. I had the problem before the body mounts were replaced. I had them replaced due to advice from a body shop that some mounts could be missing or broken and this could be causing the problem. Thanks
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Another thought. If anyone has ever jacked up the car from the center of the crossmember, it could have bent it up. Not the correct place to raise the car but it has been done. Solution-put it on a frame rack and bring the crossmember back to the place where it should be. A clue. Put a straight edge on the crossmember with equal blocks on each side about 1" thick so the straight edge clears the exhaust holes. If you don't need the 1" blocks, the crossmember is bent up in the center. A very common problem. The crossmember should be straight with the exhaust holes slightly below the straight edge. You will not find this measurement in the frame books but the problem described happens more often than it should. The crossmember is not strong enough to lift the car without bending it up. Good luck.
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