Vibration, no really!

JimsGems · #1 (**permalink**) 05-06-2004, 01:37 PM

Hey guys & gals;

I know this isn't specifically a Cobra Question but, I know the brain trust we have here on CC, I need you help and assistance anyway.

The suspension in my Jensen Healey Mk I was designed by Mr. Healey and his engineers, here's my situation.

When I drive it, the car feels like it has front "wheel hop" very much what feels like a vibration in the front end, but I'm not 100% sure about the location. This just started last weekend.

The wheels were balanced yesterday and the problem is still there. I looked under the JH and could see nothing missing or bent on the front suspension parts. The ball joints looked tight and I'm going to have the front end looked at today.

The most unusual and tell tale thing about this is when I am at speed, anywhere from 5 MPH to 65 MPH I have the vibration, when I depress the clutch at speed, the vibration stops! Should I also check the U-Joints and drive shaft. I had the transmission rebuilt less than a year ago and it seems very tight.

I'm not sure what "unloads" when the clutch is depressed, but there is a cause and effect for sure. The clutch seem quite locked when shifings with no apparent slip.

I'd appreciate your help and assistance on this. Thanks.

Jim

Curt C. · #2 (**permalink**) 05-06-2004, 02:35 PM

Sounds like a clutch and or flywheel issue. Even when you depress the clutch, the drive shaft, etc. is still turning.

flipper35 · #3 (**permalink**) 05-06-2004, 02:49 PM

Pilot bearing/bushing maybe?

NeedAntiVenom · #4 (**permalink**) 05-06-2004, 02:59 PM

Jim,

To help narrow it - do you feel it more in the steering wheel (tires, wheel bearings, etc.) or shifter (drivetrain).

Some things to look at (some obscure):

Out of round tire - it may be balanced but is it round.
Separated tread tire ply.
Bent rim.
Loose wheel bearing.
Bent axle.
Alignment (tie rod end).
Damaged steering gear.
Motor mount.
Pilot bearing.
Bent transmission input shaft.

mr0077 · #5 (**permalink**) 05-06-2004, 03:34 PM

Jim, Hi, I'm a former JH owner, number 14710...absolutely GREAT car, wish I still had it (except when I got caught in a sudden downpour...took ten minutes to put up the top in a nine minute deluge...2 inches of water in the floorboards)!
Anyway, if the vibration stops when you depress the clutch, it seems like it has to be in the parts that rotate with the motor. If so, you could go make the "hop" occur, depress the clutch to make it stop, then repeatedly rev the motor to see if it followed the motor RPM rather than the "driveline/road speed" RPM. If it doesn't follow the motor RPM, then I'd have to believe it is either something in the bell housing (bent input shaft, but how the heck or, like the last post, the motor mounts, particularly the left one. If the left mount is separated, it could allow the motor to go through a series of lift/fall cycles during acceleration...that motion would stop during deceleration or when the clutch is pushed in, FWIW.
Let us know what you find.

flipper35 · #6 (**permalink**) 05-06-2004, 04:47 PM

To add to that, does it stop in neutral? Coasting or sitting still? If not in neutral, it probably isn't between the engin and tranny.

JimsGems · #7 (**permalink**) 05-08-2004, 06:27 PM

Well I guess it could be worse... seems the FOD I hit on the freeway damaged the drive shaft, putting a rather large dent in the tube, and bending the rear transmission (mount) cross member. The U-Joints were not tight either, so the repair will include repairing the cross member and having the drive shaft trued and replacing the U Joints. I’ll order the repair parts and I’ll see if we discover anything further when we get the work started in about two weeks.

Thanks all for your ideas, thoughts, and suggestions.

Steve R · #8 (**permalink**) 05-09-2004, 07:08 AM

Jim,
Let's hope that's it. Those vibration problems can be enough to drive a man to quit drinking.

Steve

JimsGems · #9 (**permalink**) 05-09-2004, 01:28 PM

Steve;

Too late to stop drinking, but... your point is very well made.

I had the tires, looked at, balanced and aligned in phase I of this little project. The underside is anything but "slick" and I guess I did hit something very heavy on the freeway (FOD), I didn't see anything coming, but I heard and felt a metallic clang when I must have hit it.

Next is the short in the horn circuit. While Lord Lucas reigns supreme, in this case the electric’s on the J-H are at least 100% improvement over my ’56 Bentley S1, which were simply awful.

I’m prayin’ this is it on the vibration thing too. After all, I’m all shook up over it. LOL. Thanks.