driveshaft out of balance?

[GIXER7502006]

I had a vibration for a few years, new tires and they would all balance with no problems, then I took the 10 hole rims off and put a differnt set of rims and wala the vibration was gone, best drive of the cars life. I was doing the happy dance, it is just a thought

[grabbergreen84]

Man, that car looks immaculate, under there!

[slimj]

Thanks grabber green ! I had these ten holes on with the 7.5 rear and it was smooth . But you never know could be a bad belt in a tire. I am getting new rims over the winter and tires just to switch out every now and then. Thinking weld rod lites , But not sure still looking lol.

[burntorange84]

Yeah I put all new rubber bushings in the control arms top and bottom. And put new rubber bushings in the rear also. Everything is new , Everything but a new universal joint but it was greased and it is tight. Maybe that will be a winter project new universals front and back. And I wanted to put new lower control arm,s on over winter, I am going with MM adjustable lower control arms. Yes I had the rear on jack stands then I tightened all the control arms

Technically the whole car should be level and tightened with the real ride height so you have the real weight on the rear; meaning the front is not nose dived which adds more weight to it and less on the rear. I drive the front on ramps and adjust the rear stands to be as normal height as possible. Unfortunately that doesn't leave a whole lot of wiggle room under there to tighten things...it would be nice to have a drive on lift for stuff like this but it gets it done

That vibe is going to be tough to diagnose over the board. You can spin it in the air and see if that goes away...then a tire is probably at fault.

-j

[slimj]

Burntorange I didn't know the car had to be level to do this. It is something to think about, Well like I said I am going to put new MM adjustable lower control arms on over winter, And a set of new welds and tires, To change it up a bit, had the ten holes on for awhile now, Need something a little different for next year. I will level the car after I put the lower control arms on, Then tighten everything down.

[Jerry peachuer]

In my opinion You can try to rotate the drive shaft 90 degrees to see if that helps
Most driveshafts are pretty old and the stick on weights fall off possibly

If you get it balanced then get new u joints really check the car over
Clutch? To flywheel I wouldn't just assume it's ring and pinion
How is your front bearings and are they set properly to loose and could be a slight wobble
Alum drive shaft is nice but factory will get the job done try to duplicate the shake and push clutch in to see if it goes away or stays shaking jack up the front check out your suspension and ball joints
Good luck with your project

[slimj]

Thanks jerry, Yeah I need to do some checking, I seem to be the only one that feels it lol, Everybody that rides with me says what vibration lol. Like I said the 7.5 with 273,s were super smooth didn't feel anything, But the new 8.8 and 373,s I feel something, Maybe its just me ha ha.

[Jerry peachuer]

Once you upgrade a part your more In tune with before and after
You probably do have a vibration and you passengers can't feel it cause you know your car so well
Mark your drive shaft with a colored marker or something visible and keep un bolting it and rotate it and boot it back up until you think there's no fix then I would un bolt it take it to a shop that can balance it and have the. Put new u joints on it if there isn't new ones on it already then bolt it back up and you may have to still rotate it like before then if that doesn't cure it I would try to really determine what gear or what rpm or what is it that starts the concern and be open minded it may be the rolling chasis itself or it may be the trans Id then wait for it to shake and push the clutch in to see if it's better or still present if it's still driving you crazy take it to a alignment shop to see if something is off
Good luck and keep updating

[slimj]

Thanks for the help everyone. It will be awhile till I drive it again as they started to salt the roads ha ha !! But I will be doing some work to it over winter, If I figure it out I will let you know.

[cb84capri]

i never did a follow up on this way back when.... but i had fleet pride in toledo, oh balance mine after my last post. the problem went away completely after that. the tech said it was pretty out of balance. back then it had 3.55s and now the car has 4.10s. the vibration came back after the gear swap between 70-75mph. slower or faster than that it's perfectly smooth, same feel as before. result of the gear swap. i'm sure it was probably there before at a much higher speed, but i never spend any appreciable amount of time cruising at over 80mph.

i have a better yoke and non grease-able spicer u joints i plan to install for extra strength, since grease-able u joints are weaker due to being hollow. i'll be installing this stuff before the car comes out this spring and going back to fleet pride for another balancing. i won't be bothering with grease-able u joints on anything i drive anymore. take my old truck for instance... you can't get to the body mounted zerks when it's mounted in the shaft and yoke. the capri has precision hd (moog?) grease-ables now. as far as accessibility and strength are concerned vs the ones on my truck, the design is better as the zerks mount in the caps. the problem with these u joint is that they use some funky zerk with an uncommon thread that you have to use a needle tip with, and i have never really been able to get grease to go into them... i also tend to believe that a grease-able u joint is going to be more likely to create a balance issue - probably more-so the further away from center the grease zerk is.

drive shafts are balanced as a unit. the whole rotating it 90 degrees song and dance i have seen posted on here so many times over the years is just a waste of time. i have had the driveshaft out of mine numerous times over the years and can assure you it didn't bolt back up to the flange the same way every time, and never caused any issues.

cale

[ZephyrEFI]

Interesting, thanks for the update! How much did the balancing cost you?

[cb84capri]

i think it ended up being like $70 the first time 6 years ago. i imagine it will be more expensive now.

cale

[83gtstang]

I have an aluminium drive shaft, mine vibrates like he'll when I punch it. Cruising at 70 or so, it's bad as well. Mine has to be very off balanced as well.

[burntorange84]

Thanks for the update Cale. I have old threads I need to snitch up....

-j

[cb84capri]

I have an aluminium drive shaft, mine vibrates like he'll when I punch it. Cruising at 70 or so, it's bad as well. Mine has to be very off balanced as well.

what you describe sounds like play or movement somewhere in the drivetrain. you should inspect the condition of your u joints and yoke, as well as the condition of your engine mounts, transmission mount, and cross member bushings. if that all looks good, start looking over the rear suspension and torque boxes.

cale

[PaceFever79]

Also check the transmission tail shaft yoke bearing. To check the bearing put the rear end up on jack stands, with the trans in neutral, grab hold of the yoke at the trans and push it up and down. If the yoke has any up down movement (slop) inside of the tail shaft then the bearing needs replaced.

[Jack Hidley]

Cale,

The driveshaft can be perfectly balanced, but still cause vibration in the car for several reasons. When the driveshaft is balanced it is gripped on each end in the balancing machine and then spun. Which feature the machine uses to grab the driveshaft at each end will affect the balancing results. The differential end of the driveshaft has a counterbore in the end of it to center it on the pinion flange of the differential which has a matching raised pilot section.

Both of these features are not perfectly concentric with their respective parts. This is just due to machining tolerances. As part of Ford's supplier requirement, both of these parts are marked by the vendor with dots to indicate their points of maximum runout. When these two parts are assembled in the car, the dots are to be phased at 180 degrees to each other. This minimizes the total system runout, which minimizes vibration.

Turning the driveshaft 90 degrees at a time to find the case with minimum vibration is a good technique to do the same thing. Just by trial and error. Auto manufacturers mark lots of rotational parts with maximum runout dots for assembly on the production line. You just don't read about it because most people don't have access to OEM drawings. Runout dots on wheels and tires is probably the most common example of this in the parts business that regular consumers would see.