Engine Vibration

Mike Goble

Mike Goble

Well-Known Member
Messages
1,627
Reaction score
1,250
Location
Fairfield, CA
I seem to have developed a moderate engine vibration in my 72 Bavaria after a spirited drive through the local countryside. It is keyed to engine rpms, and I've checked the compression, plugs, valve lash, timing, run it without the belts, etc, and I'm still baffled. Any ideas on what to inspect?
 
Imbalance running

Assuming carbs- check the plug condition to better isolate one bank of cylinders from the other. At 2000 rpm, you're off idle circuit and transitioning. This uses the needle like air jet of which one could be plugged. The fuel level in one carb- is it dripping slightly- will do the same since fuel pools in the manifold and gets used randomly as in slugs. Mid throttle balance- rig up a homemade manometer and check at the rpm the imbalance starts.

Ignition- check your advance. Simple- just temporarily reroute the vac to full manifold. Should speed up.

Timing steady?
 
x_atlas0 said:
How is your operational voltage and how are your engine mounts?
Click to expand...

I have a GM CS130 alternator on the car, and the voltage is 14.5 at all rpm. I also use an MSD 6T ignition fired by a new 231 184 008 distributor with the VA connected to full manifold vacuum.

I've got Weber DGV's.

I'll check the engine mounts today if it isn't too wet out.

I have a real u-tube manometer left over from my process control days that I'll rig up. I'm also thinking about putting a vacuum gauge on each manifold for general instrumentation.
 
Vibration when parked and idling, when driving, foot on the gas or coasting or both? Try to identify whether it is driveline or engine related. If engine, the others have you started on the road to recovery - if driveline then check engine mounts, tranny mounts (bolts all tight and rubber solid) the guibo and centre bearing to start with.

Doug
 
decoupe said:
Vibration when parked and idling, when driving, foot on the gas or coasting or both. Try to identify whether it is driveline or engine related. If engine the others have you started on the road to recovery - if driveline then check the guibo and centre bearing to start with.

Doug
Click to expand...

I've got a Getrag 265 and the giubo, centering sleeve and mid-mount bearing are all brand new. I recently took a trip to Phoenix and on the way back destroyed the giubo et.al, it came out in six pieces. I got the new parts from rmeuropean.com for about $65 total and they shipped them overnight for free ( surprised the hell out of me ).
 
I think he was asking if there was a vibration when parked and reving or whether it only occurred while driving.
The fact that your driveline is all new is actually bad news- most of the center bearings out there are cheap trash and many shops are reporting vibrations with new centerbearings.
 
Mike Goble said:
I've got a Getrag 265 and the giubo, centering sleeve and mid-mount bearing are all brand new. I recently took a trip to Phoenix and on the way back destroyed the giubo et.al, it came out in six pieces. I got the new parts from rmeuropean.com for about $65 total and they shipped them overnight for free ( surprised the hell out of me ).
Click to expand...

Did your vibrations start before or after the guibo cratered and was replaced? Did the vibrations start suddenly and consistently or sporadically and increasing over time? What does the engine sound like at idle and when slowly rev'd up to 4000 when out of gear? Still a vibration? Same question with the clutch depressed?

Doug
 
Last edited:
If the Guibo fell apart it must have been fitted the wrong way, the solid sections of the Guibo should push the propshaft, not pull it as most people think. But your vibrations soulds like the clutch has broken, usually only happens if you have over-revved the engine ? Spirited drive......?
Alex
 
Could be the clutch - you mentioned "spirited driving." My '74 once had a bad vibration after my son took the car for a drive and missed a shift. One of the centering tabs on the clutch body broke, so the clutch mass was off-center. This can happen.

Charlie Peavey
 
Since you have renewed the drive-line stuff you now feel a vibration...

You did not renew motor or tranny mounts...they could exhibit their age through vibration, check tranny mounts 1st. You will want to make sure these elements are solid. If they are weak they could cause the new, yet lower quality drive line parts (CB & GC) to fail sooner than latter.

Jon
 
You must log in or register to reply here.
Back
Top