Driveshaft alignement and vibrations

VladasapSVT · Mar 13, 2012

Hey guys,

recently installed an frpp alu d/s however there were no factory markings on the pinion nor the rear of the trans when I pulled the stock d/s out.

To the best of my ability, i tried putting the new ds in but no matter what it didnt line up the way the old one did.

It went in just fine but ended up having to turn the trans with the ds to line up the holes on the pinion side.

Is there a way to align the trans and the rear end and then the the driveshaft?

I am asking because i am getting a slight shifter vibrations every once in a while. at high speeds + high rpms and that goes away the moment im out of gear so I am sure that its the ds. Mind you, i still have the stock 3.08s....so i can imagine whats gonna happen when i install 3.73s as i am planning...

Ill pop the diff cover if need be too. Maybe theres a marking on the gear that can be lined up with the rear of the trans somehow.....anyone know???

Thanks in advance!

CC'S95GT · Mar 13, 2012

No need to remove the diff cover. Being that it's a new DS, if you get vibs your just going to have to unbolt the DS from the pinion and clock the DS 90* then drive it and ck for vibs. Repeat if necessary.

Gtnut1996 · Mar 13, 2012

If it goes away after you take it out of gear it could be the transmission. If its a new driveshaft I would think different. My car has a vibration at about 85 but I got 3.73s. It was around 120 with the 3.08s. I have a new driveshaft going in this week hopefully. It is sitting in my extra room now.

VladasapSVT · Mar 13, 2012

CC'S95GT said:
No need to remove the diff cover. Being that it's a new DS, if you get vibs your just going to have to unbolt the DS from the pinion and clock the DS 90* then drive it and ck for vibs. Repeat if necessary.

I remember the output shaft on tranny has one grooved position but the d/s doesnt. Does it not matter how the ds goes into the tranny?

vermilion · Mar 13, 2012

even though its new have you had it spun check for balance? i agree with CC on the 90* clocking method.

CC'S95GT · Mar 13, 2012

no.there is a slot on the input but not on the tranny output splines.

VladasapSVT · Mar 13, 2012

CC'S95GT said:
no.there is a slot on the input but not on the tranny output splines.

Are you 100%? i could swear that it did.

Maybe im thinking of the d/s. Does the d/s yoke have one specific grove on the splines?

One of them does, that I know for a fact... Maybe im wrong with being the tranny

And also, the vibration ONLY happens once in a while. Lets say 1 out of 25 times i punch it, so thats why i figured that it may be just a hair bit off and was asking if it matters how the d/s goes into the tranny, cause i know that the pinion + d/s alignment is important.

Musturd · Mar 13, 2012

Make sure it hasn't backed off the bolt that Is

CC'S95GT · Mar 13, 2012

The splines on the DS has what looks like a keyed spline, but the splines inside the tranny do not. (they are all equally spaced)
You can try to fine tune the vibration by changing it 1 tooth at a time. But I would rotate the rear end first..

gopher_6_9 · Mar 14, 2012

This is really an old wives tell. Do you think ford spends the money to have a driveshaft perfectly balanced with rear end? They don't. if you think you have a vibration turn the driveshaft 90* and try again.

CC'S95GT · Mar 14, 2012

Whether you think it's a wives tail or not it's the truth.I replaced my trans and after the DS was reinstalled I had horrible drivetrain vibs. I rotated the DS 90* on the pinion and the vibe got better. I rotated it another 90* and it got better still.