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View Full Version : Foxbody Drivetrain Vibration??


blown96cobra
09-29-2010, 06:28 PM
changed the ujoints in my lx today and it has a nasty vibration at higher speeds 60+ and lower speeds at 3k+ if i get on it at all. On the freeway at 60 if i put it in neutral or push in the clutch it doesnt go away so i dont think its the tranny. Do i need to have the driveshaft balanced?
Stangman
09-29-2010, 07:33 PM
Try taking out your driveshaft and turning it 90 degrees and putting it back in, that usually gets it sometimes. Might take a time or two. If all you did is put U joints in it and it's vibrating... then that's gotta be it. I always mark the driveshaft to the yolk, and the yolk to the trans/rearend when doing U joints.

Also, maybe it's a bum U joint? maybe got a bad one right off the shelf.
blown96cobra
09-29-2010, 08:20 PM
i just read on corral that there are white marks from the factory that need to be lined up. I thought it was a bolt in and go type deal. ive tried moving the driveshaft 180 and checked the ujoints when i had it out no luck. ill check to see if the marks are lined up in the am.
draggin50
09-29-2010, 10:15 PM
Clocking the driveshaft seems to be an ongoing problem with foxes. I have done it several times and fixed the problem. I know insaneba had the same problem but not sure if he got it fixed or just sold the whole car.
blown96cobra
09-30-2010, 10:04 AM
well i just lined up the marks and its still shakin like hell at about 2800+ is it time for an alum driveshaft? The bitch of it is it was fine before the ujoints went. Ive had 20+foxbodys and never had this issue. Im wishing id kept my new edge now.
blown96cobra
09-30-2010, 10:59 PM
Picked up an aluminum driveshaft. Hopefully this fixes it!
facemelter71
10-01-2010, 09:45 AM
I swapped mine out for an aluminum DS years ago.have not looked back.
blown96cobra
10-01-2010, 01:51 PM
:Dswapped out the ds for an frpp aluminum one and no vibrations! wooooohoooo!
blown96cobra
10-02-2010, 09:39 AM
well im sad to say the vibration is back its no where near as severe and it completely stop when you push in the clutch. Its mainly under load, could this be the tailshaft bushing and trans mount or is it something in the front of the trans? any help would be greatly appreciated fellas.
denial
10-02-2010, 10:22 AM
The input shaft bent on the tranny maybe?
blown96cobra
10-02-2010, 11:50 AM
i hope thats not it ive had two different people tell me that it may be the pinion bearing?
347sc
10-02-2010, 11:52 AM
Does the car have stock suspension in the rear or after market?Transmission mount in good shape or changed? It could be the pinion angle.
blown96cobra
10-02-2010, 01:26 PM
stock upper and lower control arms just replaced the bushings in the uppers, rear springs are stock front are aftermarket and pretty low. everyone is telling me now it could be a bent input shaft or a bad pinion bearing(dont know how theres no noise from the rear), the vibration is only under load, when i let off the gas it stops and when i push in the clutch you cant even tell the car is running.
chris91
10-02-2010, 01:39 PM
Just for shits and giggles check your balancer. I know you said it goes away when you push your clutch in so it shouldnt be that but itll only take you two seconds to feel the back of it to make sure the rubber hasnt worked its way outta it. I had a nice vibration coming from mine one time.
blown96cobra
10-03-2010, 12:10 AM
gonna change that tommorrow. damn this is gettin expensive lol. gotta pay to play i guess. ill post findings. hopefully this will save someone a headache later. any of you drivetrain experts feel free to chime in any advice is good advice.
draggin50
10-03-2010, 12:21 AM
Im gonna say pinion bearing... I had a 88 GT that had a vibration like you mentioned and had the rear end gone through and it went away. I think it had something to do with the pinion again also. Hope you get it figured out soon!
blown96cobra
10-03-2010, 03:09 AM
wouldn't the rearend make some sort of noise if the pinion bearing was bad?
cobra429boss
10-03-2010, 03:18 AM
Does the car have a gear? Maybe its not set roght
draggin50
10-03-2010, 10:16 AM
wouldn't the rearend make some sort of noise if the pinion bearing was bad?

Mine didnt whine a bit... It just had a vibration to it under certain speeds and when Id push in the clutch it would go away.
blown96cobra
10-03-2010, 05:16 PM
Sounds familiar. Changed the balancer and bolted on some bbk udps that I had. Still there. Rearend is next.
chris91
10-03-2010, 06:10 PM
I wouldnt have messed with the balancer if the rubber was in tact. If you had one layin around then I guess it doesnt hurt though. Kinda weird that the vibration didnt start until you replaced the U-Joints though. Or were the old ones so bad it was just hiding it?
blown96cobra
10-03-2010, 08:10 PM
I wouldnt have messed with the balancer if the rubber was in tact. If you had one layin around then I guess it doesnt hurt though. Kinda weird that the vibration didnt start until you replaced the U-Joints though. Or were the old ones so bad it was just hiding it?

The back one was shot. i speed shifted it and popped it, the rubber was deteriorating so it wasnt a bad idea to swap it. Id say its either a bad trans mount, or motor mount throwing the pinion angle off or the pinion bearing is ate up. well find out tomorrow when i have it ripped open.
blown96cobra
10-04-2010, 11:15 AM
Does the car have a gear? Maybe its not set roght

Yes it has a 410
blown96cobra
10-19-2010, 01:36 AM
well the whole rearend has been gone thru and its fine, there wasnt anything wrong other than the pinion seal was bad and leaking gearset is a 373 not 410, vibration was still there but minimal, i also had one of those cheap flexalite fans that i drop kicked in favor of an electric fan and i think that cleared it up alot. Now that ive ripped the topend off and done started a h/c/i swap i found all kinds o shit wrong, every header bolt was barely tight, intake bolts were not tight at all hell one i took out with no socket, the #1 sparkplug was only hanging on by about 3 threads, the back intake gasket was blown completely out. whoever has this engine apart last was an asshat! Im thowing in a b cam, lightly ported gt40p heads,cobra upper and lower. The one thing that did look great was the shortblock, i think it has a stock replacement shortblock, pistons are stock bore and look new. Its goin on the dyno friday if i get it back together in time ill post results.
INSANEBA
11-16-2010, 02:34 PM
Draggins right, I had a driveline vibration after about 60mph. Mine came after I put in an 8.8 with 4:10's I got from him. I could feel it through the shifter really bad. It didnt go away when the clutch was pushed, but it sped up and slowed down with the speed of the car. Mine ended up being a clocking problem, but it also coulda used a set of u joints too, and yes Draggin, I sold the car lol. Hopefully I can keep this one around alot longer though....