Hey all,

Ive had this issue a while (going on a year thats its done this)but I've been kinda ignoring it when really i shouldnt be. Anyways at about 45-55 mph for some reason the truck will intermittantly vibrate. I notice that its mainly when the truck settles in 4th gear and is about to go into overdrive is when it happens. If it give it a little gas and it stays in 4th but the OD turns off then its fine, but as soon as it settles back in OD it will vibrate the whole truck for about 5 seconds, then quit for about 30 - 60 seconds then start doing it again. At lower speeds and higher speeds its just fine but right at about 45-55 it does this. Something tells me its probably the transmission going belly up (dear god i hope not, i already rebuilt it once and i dont want to have to pay for that again) but maybe its something else. Kyle, Bill, or anybody got any ideas? Im all ears.


Edit: Addmittedly its been about 2 years since the trans has been flushed, could this contribute to that? Reguardless I'm gonna flush it next week.

 

It could be a rear ujoint going bad, this was happening for me when my rear ujoint happened.

 

Not having the tranny serviced could contribute to it, but in 2 years? It depends on how far it has been driven and how hard its been driven. If the filter has any trash in it, it'll shake when it shifts and will slip occasionally.

 

I would check your U joints. My 98 Suburban was doin the same thing... i felt the u joint and it had very little play so i replaced all bearings in the rear end and tranny work done and ended up being the u joints.... Leason learned i guess. Even if you dont think it is bad i would replace them... Cheap fix compaired to blowing one at 55-60 and havign that drive shaft slap around... $$$$$

 

i had the exact same problem but mine did it at like 70mph. i replaced my u joints and it didnt help. maybe this might help....i dont know what did it, cept that it hasnt done it ever since i lowered the truck

 

Thanks for advise but infortunately i dont think ill be lowering my truck any time soon. I still havent looked at the u-joints yet but i get paid friday so ill run on down to autozone and get some parts and see if that helps. If nothing else its good maintenance as there is already 140k miles on that driveshaft.

 

yea thats true..
do you think maybe it has to do with the tires maybe? maybe one is outa round or somethin?
i wish i had the cure but like i said....i never figured out what it was.

 

For me its not tires, cuz ive had 2 other sets with this same vibration. As for yours being that its 70MPH i would think its tire balance (been through that on my last set of tires, ug was that anoying, NEVER GET TIRES AT WAL-MART).

 

Ditto that, never get your tires at Wal-Mart.
Get them from a shop that has a Road Force Balancer.
As for the vibration, look for the vibration thread in teh Help-Section. It covers 90% of all vibrations.

If your getting vibration during torque converter lock up, it could be your torque converter going out. Did you replace it when you rebuilt the tranny, and if you did, did you pop for a decent unit. If it is your torque converter flaking apart your nect thread will be my tranny wont shift gears. That would be due to pieces of clutch material getting stuck in a vavle or governor.

By the way, your transmission only has 4 gears. 4th gear is Overdrive. Its a common misconception that torque converter lock up is overdrive. its not. If the torque converter doesn't lock up at highway speeds you will fry your tranny due to excesive heat. If your TC is locking unlocking continuously you need to down shift, or you need to get your engine tuned up. Your puter controls the tranny shifting, if your engine is not performing properly the puter will make adjustments to teh tranny and to the engine to optimize perofrmance.

Be happy if its u-joints. they are eiaser then just about everything else.

 

Ok thanks Tim, that makes more sense now. It wouldnt surprise me if its the torque converter. I had a new one put in when i had the trans shop rebuild it and it went out about 3 months later so they put in a new one. The ones they have been putting in have all been borg warner which from what i hear are pretty ok. Also the TCU went about a week or 2 after the trans was rebuilt (because they reused the stocker) so they put a new one in so its possible thats to blame too.

At any rate, at freeway speeds its perfectly fine but it seems like the lockup isnt sticking between 45-55 or the driveshaft is to blame. I'll try the driveshaft u-joints and if thats not it then i'll have my uncle take a look at it.