DS balanced on vehicle?

[gt90stang]

Hi all,

Ok, since I had my gears changed to 373s I've had a vibration. I had my stock DS balanced and it was better but not perfect (had a shop do this). So I decided to get an FMS aluminum DS and it too was even better but not perfect. So I hooked up with this website.....good info.

http://home.hiwaay.net/~ctfrench/procedure.htm

Well I ended up measuring the runout on my pinion flange and it is 0.002". I played around trying to get the balance better by indexing front and rear and putting washers and finally a hose clamp on the pinion to counter act the runout. The balance is really pretty good with slight vibrations at 52 and 57 MPH so it seems that there are two modes going on. I can live with it the way its because it is barely noticeable with our bad roads.

I'd like to find some place that can balance the assembly on the vehicle. I called around and nobody has a clue. Any ideas would be appreciated.

BTW, its not the tires or anything else but the pinion and DS...I'm pretty sure.

I even made a poor man's vibration analyzer using a KK Music Big Shot transducer stuck on my console inside the car and a real time 1/3 Octave audio analyzer. This way I could get repeatable data instead of SOTP which works for gross improvements but not fine tuning.

Thanks for reading, Don

 

[HISSIN50]

Don, im pretty sure you can do it. my neighbor in Seattle used to have it done often. i had thought it was called dymanic balancing - the driveline shop would balance it using computer stuff with everything in place and the car on a lift. so, like balancing a tire, the puter told them where to add weight (but for that analogy to be correct, it would be like balancing a tire/wheel with it on the car).

so im of no help to you, but thought i would toss that out (dont lose hope) and see if this rings a bell with anyone else.

the vibration analyzer sounds neat (i have no idea what you are talkin about, but it sounds neat. ).

with all the stuff you have done, that is weird that you still feel anything.
good luck, Don.

 

[giddyup306]

Sounds like it's out of phase. Try rotating it 90* or 180*.

 

[gt90stang]

giddyup306,

Yeah, I've totally indexed both front and rear every 45* and it can't get better, but like I said it is pretty darn good but not perfect.

HISSIN50,

Yeah, I just have to find someone near Sacramento, CA. I called both DS shops and they only do it off the vehicle which won't do me any good.

Thanks, Don

 

[gt90stang]

TTT

Thanks for the input so far, more please.

Don