diff probs
Thread Starter
4th Gear
Joined: May 2013
Posts: 4
Likes: 0
diff probs
Hey everyone new here. I have a 71 w/four speed. Was letting the wife drive it, she had it tached up in 2nd, shifted into 1st instead of 3rd and dumped the clutch. 
. now it clatters everytime you lift off. jacked it up today, could hardly roll the wheels (yes E-brake off N). started & ran on stands, had a little thumping noise, tires stop spinning as soon as you apply clutch. what broke & do I try to fix myself? I'm a decent wrench. thanks
. now it clatters everytime you lift off. jacked it up today, could hardly roll the wheels (yes E-brake off N). started & ran on stands, had a little thumping noise, tires stop spinning as soon as you apply clutch. what broke & do I try to fix myself? I'm a decent wrench. thanks
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Melting Slicks
Joined: Oct 2002
Posts: 2,314
Likes: 111
From: St Louis MO
If the clatter is coming from the engine, do a leak down check to see if any valves are bent.
And, never spin the wheels when the car is on jack stands - the u-joints will bind with wheels fully extended.
And, never spin the wheels when the car is on jack stands - the u-joints will bind with wheels fully extended.
Le Mans Master
Joined: Apr 1999
Posts: 6,134
Likes: 46
From: Raleigh North Carolina
Edit: I remember a vague "caution" in the service manuals referring to this... but I can't find it in a 66 or 70 manual. When rotating by hand, the "thump" is not noticeable. When rotating by the engine, it was.
Last edited by Tom454; May 7, 2013 at 08:22 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Burning Brakes
Joined: Sep 2006
Posts: 851
Likes: 10
From: Palm City, FL
Hey everyone new here. I have a 71 w/four speed. Was letting the wife drive it, she had it tached up in 2nd, shifted into 1st instead of 3rd and dumped the clutch. . now it clatters everytime you lift off. jacked it up today, could hardly roll the wheels (yes E-brake off N). started & ran on stands, had a little thumping noise, tires stop spinning as soon as you apply clutch. what broke & do I try to fix myself? I'm a decent wrench. thanks
. now it clatters everytime you lift off. jacked it up today, could hardly roll the wheels (yes E-brake off N). started & ran on stands, had a little thumping noise, tires stop spinning as soon as you apply clutch. what broke & do I try to fix myself? I'm a decent wrench. thanksThe first thing I would check in the process of elimination if your hearing a thump, is make sure it is coming from the rear and not the engine, then check the u-joints. Your car has 6 or them. 2 on the drive shaft, and 2 on each half shaft. If they are Ok, raise the rear wheels off the ground, disconnect the driveshaft, load the suspension (so the half shafts have no angle), and see how hard it is to turn the wheels, and if you hear clunking when you do. If it is hard to turn, and/or hear too much clunking (some noise is normal), your problem is in the rear, and you have a lot of work to do to get the pumpkin down. If not, then start looking at the trans, doubt it is there. Maybe you are hearing clutch chatter?
Burning Brakes
Joined: Sep 2006
Posts: 851
Likes: 10
From: Palm City, FL
Another thing to check:
If not the u-joints check to see if the front mounting bolt for the diff is tight and that the front mounting bushings for the diff are not worn out.
I had a similar thumping, and after replacing 2 bad u-joints on the driveshaft, I had less thumping but still some thumping... found the the diff mounting bushings were completly worn out. Replaced them and its all good.
If not the u-joints check to see if the front mounting bolt for the diff is tight and that the front mounting bushings for the diff are not worn out.
I had a similar thumping, and after replacing 2 bad u-joints on the driveshaft, I had less thumping but still some thumping... found the the diff mounting bushings were completly worn out. Replaced them and its all good.