Not sure where this vibration is coming from. .....

[Canadian1968]

The car seems to have developed an odd vibration / drone this year. It's not matched to tire rotatio or engine rpm. Its an odd, dull oscillation sound, with slight vibration. It's not aggressive at all but i can notice it ..it's honestly hard to describe in text. I would
Describe it as once a second as apposed to an engine tick or something at road speed


Its most noticeable at around 60 - 75 mph . Doesn't really get much worse over that , and under that speed it not there . I changed the rear transmission mount recently thinking that could be it, but no difference. I pulled the drive shaft checked U-joints , and greased them. Checked my drive line angles even though nothing has changed and the car driveline is 100% stock location.

Tire pressure is good. I have green wheel bearings installed , but it doesn't really sound like a wheel bearing either .

Underload I don't seem to feel it , it's more on decell or cruise..... which kind of points to drive line angle ? But my transmission is 2* down and diff is 1.7* up . I don't think that should cause a problem?

Maybe a tire ?

 

[RemCharger]

What kind of tires and how old.
Should say on last part of dot stamps

 

[Canadian1968]

BFG g-force sport comp 2 tire
Date code is 2015.... getting up there but not crazy

 

[WileE]

Have you checked your pinion bearing preload ?

 

[Fran Blacker]

An easy no cost check rear trans bushing check if yoke moves more than ..003/.004. Had mine rattle 3000rpm, .014 clearance.

 

[Canadian1968]

An easy no cost check rear trans bushing check if yoke moves more than ..003/.004. Had mine rattle 3000rpm, .014 clearance.

I'm guessing you mean the transmission mount? I know there are two style, I think your talking about the style that a bolt threw it . Mine is the style that's just a large vulcanized rubber mount with single stud out the bottom. Which Is brand new. I changed it with no difference ?

 

[Canadian1968]

I

Have you checked your pinion bearing preload ?

I have not .... and honestly don't know how to do that! My differential experience is minimal

 

[Darter6]

I'm guessing you mean the transmission mount?

No he means the out put shaft bushing in the housing. Where the slip yoke goes in.

 

[Demonic]

I had a odd vibration years ago on the start of 2nd just after the shift. A rebuild on my 727 with all new bushings cured that.

 

[Canadian1968]

No he means the out put shaft bushing in the housing. Where the slip yoke goes in.

Ahhhh ok.... hmm never done that before either! The transmission was just rebuilt maybe 3000km ago . I know that means nothing

I can just check for movement of the slip yoke ? Leave driveshaft in place?

 

[440Coronet500]

You could try installing your driveshaft 180 degrees from its current location. 440'

 

[Fran Blacker]

I'm guessing you mean the transmission mount? I know there are two style, I think your talking about the style that a bolt threw it . Mine is the style that's just a large vulcanized rubber mount with single stud out the bottom. Which Is brand new. I changed it with no difference ?

There's bushing at end of tailshaft your yoke rides on if you grab onto yoke near tailshaft and it moves .01o or more it probably needs to be replaced. Picture of bushing and tool to change it. Probably not your problem doesn't cost anything to check.

 

[Dave6T4]

My '67 R/T developed a vibration tied to engine rpm. It turned out to be a bad water pump bearing.If you grab your fan blade, and can move it side to side, it is time to replace it, even if it is it not leaking. This test works best if your engine is not running. LOL

 

[Darter6]

Strange things cause vibrations that are hard to diagnose .
Engine and tranny mounts,wheel bearings, U joints. Even ride height can throw off the pinion angle.

I have green wheel bearings installed

When I first put my 63 together I was fighting vibrations . I had a used rear housing with green bearings and one was failing. Also I installed polyurethane engine mounts and transmission mount. I ended up replacing the trans mount with a rubber one. It helped allot.Plans are replacing the engine mounts with rubber too.
I'm putting this stuff out here, all is just a guess.

 

[Canadian1968]

I just read over another post by @HawkRod ... explaining a very similar issue. His turned out to be driveline angle problem.

He explained how he had similar driveline angles as me ... but was able fix his vibration with getting the angle of the diff DOWN so that under load it comes up to parallel . I'm starting at paralle, then under load it will naturally rotate up...putting. me out of spec?

 

[HawkRod]

I just read over another post by @HawkRod ... explaining a very similar issue. His turned out to be driveline angle problem.

He explained how he had similar driveline angles as me ... but was able fix his vibration with getting the angle of the diff DOWN so that under load it comes up to parallel . I'm starting at paralle, then under load it will naturally rotate up...putting. me out of spec?

My understanding is with a leaf spring rear, your engine and transmission combo should be 4* down, and your pinion angle should also be 4* down as well (for a total of 8* between the two). So if your pinion is parallel, I'd say that is too far up.

If you can, I'd try to get some shims and shim your rear down and see how the car behaves.

Good luck!

 

[WileE]

Could be Good Vibrations ?