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Im having a heavy Vibration Problem, but just at around 3200-3400RPMs??

6

69vettester

Guest
Ever since Ive had the car,(25000 miles worth). Ive noticed a "HEAVY" vibration at around 3200-3400 RPMs,no matter what gear Im in.The shifter buzzes like crazy and the car sounds like something is "grinding"(that may not be the right word). The vibration smooths out when I power through to higher RPm's or decel to lower Rpm's). Im not sure whats causing this?? Possibly.. Flywheel?.. Something with the Muncie?..Drive shaft or halfshaft?..Rear diff?? wheel bearing??..Yikes..:s .Ive recreated the vibration to try and pinpoint the cause, but I have no idea whats making it?? Anybody have any thoughts about where to begin getting this diagnosed and fixed??
Thanks
Tom
 
C

c4ever

Guest
Tom,
Taking your previous post into consideration, I would start with the driveshaft,half shafts,u-joints. Usually it's not that hard to spot when you can get under her and get a good look. And as Chris mentioned, I would go for a diff. fluid change regardless.
Good Luck;) and keep us posted.
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
Tom,

I am more convinced now that you have at least one bad U-joint. This is exactly what they do. The nose comes from the fact that they are not rolling easy anymore and making a griding/binding noise as speed, and a clunk at take off.

When you replace them, I suggest the kind without the grease fitting as they are stronger that way (IMHO).

Man I wish we all lived closer, because I got the U-joint swap down to a science using my press and some specific sockets and chunks of metal from around the shop.
 
L

lytemup

Guest
damper

i'm not sure if an older engine had this in the way new ones do, but you might want to check the harmonic balancer (torsional damper, pulley, whatever you want to call it), maybe someone changed it out with the wrong one, it's loose, or the rubber is worn or missing. just a thought.
 

Shawn's 78

Well-known member
Joined
Oct 22, 2002
Messages
91
Location
Bellevue, WA
Corvette
1978 Beige L48 4sp
I'm having the exact same problem as Tom (Tom i sent you an email). I have a 78 L48 4spd. 3200 rpms and i think someone put $10 in quarters in the vibrating bed! Any solutions to this problem?
Shawn
 

Mako

Well-known member
Joined
Oct 31, 2002
Messages
171
Location
Bay Area, CA
Corvette
1969 Hotrod
Shawn's 78 said:
I'm having the exact same problem as Tom (Tom i sent you an email). I have a 78 L48 4spd. 3200 rpms and i think someone put $10 in quarters in the vibrating bed! Any solutions to this problem?
Shawn

In a very rough order of cost to repair, assuming you pay to have the work done and have an engine in good working order:

- Tires: have them spun balanced.

Note: I've seen water and mud get into tires from track events, if you race and have gone off track into the dirt, be aware you could have crud in there. Dittos for Fix-A-Flat, that goo has to be removed from the wheel as it messes up the balance.

- Engine and tranny mounts

- Externally balanced engine: Harmonic dampener counterweight problem.

- Engine accy AC, Pumps (PS, AIR and water), ALT bearings failing

- U-joints (inspect yokes too)

- Suspension failure (inspect all 4 corners carefully)

- Diff C clips worn out

- Twisted half shafts or drive shaft (HiPo racers only)

- Clutch improperly installed, have the clutch and flywheel balanced as a pair.

- Wheel bearings and spindles

- Tranny internals

- Internal engine problems - so much for in good working order...

Good luck!
Mako
 

Jack

Well-known member
Joined
Dec 27, 2000
Messages
1,825
Location
Florence, SC (Timmonsville SC)
Corvette
71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
69vettester said:
Ever since Ive had the car,(25000 miles worth). Ive noticed a "HEAVY" vibration at around 3200-3400 RPMs,no matter what gear Im in.Tom

Tom:
Can you reproduce the vibration when car is parked? If so, it's likely the harmonic balancer/damper has slipped its outer inertia ring. Slipped ring is sometimes obvious to naked eye ... sometimes not. Run it up to 3500 rpm & hold rpm ... If you have trouble maintaining a stable timing mark under a timing light ... that's a dead giveaway the balancer's bad.

After 25K miles it would pay you to check the u-joints ... regardless. However, seems to me that if this vibration were a u-joint problem ... and it's existed for 25K miles ... it seems likely the u-joints would have already failed in a big way.
JACK:gap
 

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