North American Turbocoupe Organization



Vibration problem (solved again)
Ryan H Offline
Posting Freak
#1
Well guys, my vibration problem is still present. At 70 MPH or more, my entire car is vibrating/shaking. It all started when the vibration dampener broke off of my drive shaft. The local drive shaft shop said they can't get a new one and told me to grind the rubber off. I did and had them install new u-joints and re-balance the shaft.

They did install the new u-joints and it appears they at least attempted(?) to balance it because an old weight was knocked off of the shaft, but they didn't install any new ones.. is that normal?

I called them and asked if they could redo it and he said sure, so I'm thinking I might just go one step ahead of him and knock all the weights off, and replace the u-joints again myself and he'll be forced to re-balance the damn thing. I don't think he used high strength joints to be honest and I've seen them break at work before, and I have a 1,200 mile trip coming up next month.

The tail shaft seems to have a little bit of play in it so it looks like I'll be pulling my tranny again tomorrow and ripping it apart for a new tail shaft bushing and oil seal. UGH! I freakin HATE installing those! A local shop offered to do it for $70 and some change, but for another $45 I could just buy the damn tool and the parts and do it myself without pulling the tranny, so it looks like I'm doing it the hard (cheap) way. HOPEFULLY my vibration problems will be gone after I fix that.

On to the pinion. The pinion seems to be slowly leaking gear oil out of it. Is my differential near the end of it's life? There doesn't seem to be any play in the flange when I grab the drive shaft firmly and pull from side to side / up and down (that I can tell anyway).
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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Ryan H Offline
Posting Freak
#2
Further adding to this topic, I just went through the entire driveshaft indexing procedure Don H gave to me in my previous vibration post. It didn't help at all, so either the driveshaft is not balanced or I'm thinking the tranny, rear end, or both are the culprit.
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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Pete D Offline
Administrator
#3
Ryan, when you say the tailshft has play, do you mean the tailshaft in the tail housing, when the driveshaft is removed. I ask because I talked to the Ford mechanic that does the trans work at the local dealer. He said that shaft can be moved all over the place, it's normal.
Pete Dunham


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trashline Offline
Posting Freak
#4
check the pinion yoke when the driveshaft is removed. You might not always get side play put in and out play. It is a shaft that the pinion gear is attached to. Theres a big nut make sure that is tight. If you have alot of play in the pinion then I could see wear effecting things, but I think either the seal is bad or the pinion nut is loose. I used to get nasty vibrations in my mustang from the back yoke being loose. I had to use lock tite to keep it on there.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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Ryan H Offline
Posting Freak
#5
Pete,
The guy at the transmission shop I went to told me it should be nice and tight, and it really does make sense to me.. are you sure that guy knew what he was talking about? The reason I have doubts is when I did my last output shaft bushing, the yoke had zero play in it after I went back together with everything. If you ever get your hands on one of those bushings and a spare yoke, slip the bushing over the yoke and see for yourself. They are machined to extremely tight tolerances!

Brian,
eek! I hope that bolt isn't loose because that bolt requires a certain amount of preload on it or it will smoke the entire differential! I'll check it for sure.. but I hope that isn't the case!
'88 TC Smile Walbro 255HP, Stinger FMIC, PIT BOV, Pro 5.0, Kirban, RR cam, FRPP strut tower brace, T3
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trashline Offline
Posting Freak
#6
well if it is leaking then either the seal is bad or it is loose. Or both. A little leak isnt bad and all ford rears have play in them. But just make sure it is tight b/c it can cause a vibration.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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Jeff K Offline
Administrator
#7
Leaking pinion seal doesnt always mean bad pinion bearings. Seal replacement is relatively easy. You need a holder for the companion flange. I have one I made yeas back out of a 3 foot long piece of 2" angle iron. Drilled 2 holes in one end and gorund some material out so it could be attached to the flange with the 12 pt bolts. then you index the nut so you know its exact position relative to the threaded shaft. Remove nut and flange. Nut will be tight.... clode to 250+ ftlb. With flange off, replace seal. Reinstall flange and nut, and tighten it just a little tighter than it was (about 1/16" farther than the original index mark). that will put the correct preload on the ponion bearings. Dont replace the crush coller, or you will have to pull the axles and diff, and reset bearing preload via measuring the torque needed to rotate the pinion gear.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Keman Offline
Member
#8
Quote:Originally posted by Jeff K:
Leaking pinion seal doesnt always mean bad pinion bearings. Seal replacement is relatively easy. You need a holder for the companion flange. I have one I made yeas back out of a 3 foot long piece of 2" angle iron. Drilled 2 holes in one end and gorund some material out so it could be attached to the flange with the 12 pt bolts. then you index the nut so you know its exact position relative to the threaded shaft. Remove nut and flange. Nut will be tight.... clode to 250+ ftlb. With flange off, replace seal. Reinstall flange and nut, and tighten it just a little tighter than it was (about 1/16" farther than the original index mark). that will put the correct preload on the ponion bearings. Dont replace the crush coller, or you will have to pull the axles and diff, and reset bearing preload via measuring the torque needed to rotate the pinion gear.
If you retorque the nut to 250+ ft/lbs, it's going to re-crush the collar. The methods I've read from someone who knew the black art of dialing in the backlash and wear patterns explained that if you HAD to do this, retorquing the nut to 15 /inch pounds/ was appropriate... as in, not much torque at all. All of this was always followed with "You shouldn't be doing it this way though" and how long the rear is going to last afterwards is kinda up in the air.

That being said, mine is leaking from the front too and one of these days I plan to get around to pulling the flange and seal using this method.
Eric "Keman" Uratchko
1990 Mustang 5.8 GR-40
1988 Thunderbird Turbocoupe 5sp
2005 Audi S4 Avant MT6
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Jeff K Offline
Administrator
#9
Note that I didnt say to retorque the nut to 250 ftlb!! I said to tighten it down until it is just a hair past the original indexed position, and that the torque needed to do this will probably be around 250.

I have used this method several times before, and never had a problem. I learned about this method from a professional mechanic.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Pete D Offline
Administrator
#10
Ryan, no I don't know if he knew what he was talking about or not.
Pete Dunham


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