Hello everyone, I have a 65 Cutlass 442 with a 400 CID. This car originally was an auto that has been converted to a 4 speed. Problem is that at aprox. 70 - 75 MPH or about 3100 RPM the car has a vibration problem coming from the drive train, rear end. Originally re-balanced all wheels, replaced u joints, trans. yoke. When the trans. was removed found transmission welded input shaft to conversion pilot bearing due to improper clearance. Replaced clutch, clutch pressure plate, Hurst competition shifter and rod kit, clutch fork spring,and clutch pedal return spring, clutch disk, throw-out bearing and conversion pilot bearing and had the clutch plate zero balanced. Input shaft of the trans. was modified to install proper clearance to stop any further damage from input shaft being pre-loaded against the crank shaft. Most of the items that were replaced were done as they needed it. After all of this the vibration issue has some what decreased, but it is still there. Thanks everyone, Jerry.

 

Had this vibration in my '65 four speed years ago, added a couple thick washers between trans and trans mount. Fixed problem on mine, read somewhere about the drive line being too straight.

 

Hi,

You didn't mention if you swapped put the driveshaft as automation ones are 2 piece (tube in a tube) with a rubber pieces between them, after 50 years it can wear out. Manual transmissions had a single tube. Either way maybe have it checked at a shop.

Regards,

 

Yes, check the driveline angles.
Have the shaft dynamically balanced with good spicer ujoints.
Not sure if the 65 Automatics had the two-piece shaft? All Olds Stick cars had a monotube shaft.
If it has the two tube check it for ujoint alignment... end to end (phasing) They will twist and out-of-phase the yokes from parallel. If true its junk. Call Dennys Drive Shafts for a new one.
But first, have the tires and rims checked for balance, run-out and tire hop etc...A good tire tech will know what all of this is.
Is the chassis and suspension tight? Loose steering linkage or rotted bushings etc can contribute to vibrations.

 

Hello everyone, thanks for all of the great feedback. I have checked the front end and have replaced some bushings and had the tires balanced. I didn't do anything with the trans washers, drive shaft or check the angles. The car is in storage, (in Michigan), but spring is starting to come around, I will get at it in the next few weeks. Do you have a contact number for Denny's drive shaft, thanks again for all of the great help, Jerry.

 

One other thing you should check, the condition of the bushings in the rear control arms. I too had a vibration around 70-75 and after replacing the control arms the nose of the rear end came up and my vibration disappeared. The bushings were perished enough that the pinion angle changed by approx. 2 deg.

 

I'll add that one to the list, thanks Jerry.

 

I found Denny's on line, thanks Jerry.

 

I had the same problem back in the early 70s with my 65 442 4 speed car. The vibration would start at around 75-80 but then it would go away if I went faster. Have you ever tried going faster to see if it goes away?
Had the driveshaft balanced, even took the tranny to a mechanic who inspected it and couldn’t find anything wrong. I never did find out the cause but I would like to see what you find on yours.
best regards
greg

 

Have you checked your tires? Back when I was a young Lad I had a 900 Kawa. motor cycle, rode as smooth as glass until about 90 then it started to develop a high speed wobble in the front end. I would fight it to a 100 and it would smooth right back out and same thing on the way back down. I had the problem till I changed the front tire. My point is your tires my have a flaw in them that only shows up at a certain speed. Have your tires rebalanced and checked at high speed. It will eliminate one variable

 

Hi Greg, that's exactly what happens, and then it disappears when you go over aprox. 80 or so. As soon as I get the car out of storage I'm going to start work and I'll get back to you.

 

Hello Guy, thanks for the great info. The tires were high speed balanced, this was the 1st thing I checked, Now about checking the tires out for any issues, that I didn't do. I'm starting to put together a check list, hopefully I will be able to start soon, Thanks again, Jerry.

 

The vibration is definitely drive train related. The car originally came with an automatic and the last owner converted it to a 4 speed. I'm a little confused about which type of shaft that I will need and the correct angle that is needed for installation, I have never had any experience in drive shaft issues before

 

With a stick car use a one-piece shaft. The two-piece or tube in a tube shaft is for automatic cars. It was designed to provide a smoother ride feel on the driveline.
It will work in your car but the shock a stick trans delivers under aggressive shifting will eventually twist the tube in tube...if its not already twisted
This twisting or slippage of the two-piece shaft will out of phase the Ujoint yokes. The yoks have to be parallel to each other viewed by eyeballing a straight line down the shaft from one end.

Heres some links.

https://www.google.com/search?q=driv...hrome&ie=UTF-8

 

Thank you for the great info, sorry for the delay in getting back with you, I hope to start checking this out in the next week, thanks again, Jerry.