BB767

Hi everyone, I was talking with a friend of mine about a problem he has started to experience with his 1960.



He has owned the car, pictured above, for more than 30 years, it's mostly original (engine, paint, interior etc.) and stock with no modifications anywhere. It has a 4 speed, 283 with stock dual carbs. The engine has developed a vibration starting around 1,800 to 2,000 RPM and the vibration continues as high as you care to rev it, 4,000+. The vibration doesn't seem to get any better or worse with changes in RPM once above 2,000 or so. The vibration can be felt, (there is no noise associated with it) sitting in the car, with the car driving or sitting still, parking brake set and revving it.

After this problem started about 1,000 miles ago he has replaced the clutch and pressure plate, pilot bushing etc., rebuilt the harmonic balancer, temporarily removed the fan belt to isolate the water pump/generator from operation. None of these steps did anything to change the vibration. Since it happens whether the car moves or not rules out any drivetrain/drive shaft problems.

I don't know if an ignition problem could be causing this as it does not appear to be be misfiring, but without diagnostic confirmation we don't know that.

The engine was rebuilt 25 years and 10,000 miles ago with no issues until now.

Can anyone suggest how to proceed with diagnosing the problem? Thank you in advance for any and all help with this.

Thomas

Bluestripe67

Thomas, I'm scratching my head, but here are some thoughts. Did the owner have oilite bushing installed or a bearing type? What about all the C-1 specific engine mounting. How about the collar that connects the oil pump to the intermediate shaft? What about the timing chain cam sprocket? Dennis

Harold Davis

I think you could have a pressure plate problem. If you lost a weight used to balance the plate it will shake.
I had the same problem with a 62.
Harold

Geralds57

Have him check the rubber engine mounts also.

GTs 58

..............?..................

Pilot Dan

The first thing I would do is hook up some test equipment like vacuum gage, timing light and dwell meter and see what the results are. It can help you to rule out a high speed engine miss (electrical issue) vs a true mechanical problem. With the timing light hooked up, observe the timing marks and see if possibly the balancer may have separated and the outer ring is moving . I am not leaning towards a mechanical problem based on the lack of noise and the fact that this engine has some miles on it. Pilot Dan

domenic tallarita

Don't rule out a compression check and valve adjustment.

Dom

427390HP

I am going to follow this thread very closely as I have a nearly identical problem with my '60 as Thomas' friend is having.

My problem started with converting the car back to a 4 speed. My vibration starts around 1500 RPM and, just like the OP problem, stays as high as you want to rev it. The only difference is that my vibration has a cyclical rhythm to it, i.e., rrrrrr, rrrrrr, rrrrrr, rrrrr, if that makes sense. The vibration is there whether driving, sitting in neutral with the clutch out, or any gear with the clutch in.

We (my brother and I) have done everything to figure this out and we have yet to solve this issue. We have checked fuel delivery, electrical, timing, balancer, no fan belt, 3 different fan blades, etc. All of the following is new: motor mounts, water pump, fan blade, fan belt, carb, intake, clutch, pressure plate, and flywheel (resurfaced), trans completely rebuilt.

I am so frustrated but when I get back to Utah (still in Iowa) I was going to get a new flywheel, clutch disc, and pressure plate and have them balanced together and see if that solves the problem.

I know this post doesn't help the OP, but I had to get it on this one.

Terry

rtruman

Look at the Harmonic balancer it broke loose or is moving when you rev it up.

hedgehead

Plug wire may be breaking down.

GCD1962

Did you change points, condensor, rotor and cap ?

BB767

To all, here's some follow up material to your replies.

-Dennis, I'll find out what type of pilot bearing/bushing was used as well as answers to your other questions. You might get to see the car in my shop during your Power Tour visit in a couple of weeks.

-Harold, the problem still existed unchanged after he replaced the clutch, pressure plate, pilot bushing/bearing and had the flywheel resurfaced.

-Gerald I'll check on the engine mounts.

-Pilot Dan, I personally think you're on to something with your suggestions. I'm leaning toward an electrical ignition issue rather than a mechanical one, especially due to the lack of any noise associated with the vibration.



I have an old school Sun Performance Analyzer in my shop that I'll use to help out along with the basics, a timing light and vacuum gauge.

I spoke with Kevin, the car's owner, and the ignition area is what we'll first explore. He has replaced the plugs and wires all with no change. I don't know what other ignition parts were checked or replaced but will find out. The distributor is a dual points unit and he's never run the engine with the shielding off so we'll do that as well. The problem remained unchanged after he had the harmonic balancer rebuilt.

-domenic I agree a compression check should be done as well.

-Terry, I hope we can help you out with your car's vibration problem as we run through different check's on this one.

-rtruman, the balancer was rebuilt with no change.

-hedgehead, the plug wires were replaced with no change but I want to remove the ignition shielding and see if that has any effect.

-GCD1962, I'll find out what parts have been checked.

Thank you everyone for taking the time to respond and offer your help. I'm just now getting involved in this problem so I don't know all the background work done up to now. Kevin and I are talking and developing a strategy to tackle the problem and I'll keep everyone informed as we proceed and our results.

Thomas

Harold Davis

At this point I have one other test. This is a pain but support the engine and remove the transmission. Start the engine and test.
If the front transmissions bearing will do the same things you describe.

Harold

Harold Davis

BB767. You said it started when you installed at new 4speed. I wonder if it could be the balance on the flywheel.

I personally chased the same problem for a year and a half. Went thru everything that has been described. What a pain

Harold

rtruman

Ok give me a shot at this I fixed a fellows 67 corvette that had a vibration like you have for 27 years .He took his corvette to many specials thru the years to no avail.

I bet him a 30 pack of beer if what I said was the problem he would gladly buy the 30 pack .
The next show he got my 30 pack .

He had a vibration after 55 mph I told him smoothing is touching on exhaust. When doing his body off years ago . The Exhaust bracket was for 2 inch instead 2.5 it touched the frame after a certain speed and caused the vibration.

The reason I know this my 63 exhaust was touching just barely I took a ball peen hammer and put a dent in the pipe the size of a dime till it wasn't touching .
When it touched it when thru the whole car you could fell it was ugly.
Hard to find but at different speeds and RMP and conditions it could be your problem sure could use another 30 pack . One was touching on frame the other time touching the under body on fiberglass. Exhaust cant touch anywhere at all .

I am not a good Mechanic but put 3 midyears together and road tested them till all the bugs were gone.

BB767

-Harold, the vibration started out of the blue. Nothing had been done to the car for years besides normal servicing when it started all of a sudden. The 4 speed is not new to the car.

-rtruman, that's an interesting possibility. I have a drive-on lift so we can put the car in the air with the suspension normally loaded and take a look see. Easy enough to do.

Nothing will be done this week on the car. I've got the Home Coming @ the NCM to attend later this week so we'll start running the problem down after the next week or so. I've gotten some good suggestions here to get us started so we'll methodically work through everything and I'll keep you posted with the results.

Thank you once again everyone.

Thomas

GTOguy

Check the fan, also.

BB767

As I stated in the 1st post, we ran the engine with the fan belt off to isolate out the water pump, fan and generator as a problem source. No change but thank you for the suggestion. I appreciate your help.

Thomas

GTs 58

Would a vacuum leak cause the type of vibration your dealing with?

TCracingCA

Engaging the clutch should change the vibration!