FarmerBeau

iTrader: (2)

As some of you may know, my truck is giving me shitfits! I blew my driveshaft out a while back and had it replaced with a stock unit and limped around on that. It worked fine other than the small vibrations. I then had a unit built with 1350 u joints, spicer 1350 forged slip yoke for the tranny and my stock pinion yoke(soon to be changed with a forged/u-bolt style yoke). After installing the built driveshaft, it enhanced the vibration. I beleive this is because it has more rotating mass being a steel driveshaft than my stock aluminum peice. At 80mph my truck would vibrate like crazy. Upon closer inspection i find the trans mount to be bad. I changed it out today with a polyurethane mount and now it vibrates at 65mph the same as it had done at 80mph previously! WTF?!

The vibration is felt in the seat, rather than in the steering wheel so this leads me to beleive the cause is at the rear portion of the vehicle. I have put it in park and revved the motor to the same rpms as it is at those speeds and i feel nothing. I revved the motor up slowly in park to see if there is a vibration at any engine speed up to 6000rpm....nothing This leads me to beleive that the vibration is not coming from the engine, flywheel or torque converter as they spin as one unit. There is no leaking fluids out of the tranny or pinion seal to lead me to think that the output shaft or the pinion shaft is bent or tweaked in any way. Im at a loss here fellas. I dont know what it could be.

It just gets further enhanced everyday! Any ideas or tests that i havent thought of? I need to find this issue before school fires up again! Tomorrow im gonna put it up on jack stands and pull it up to those speeds and see if i can visually see where the vibration is comming from. SUGGESTIONS NEEDED PLEASE!!!

TurboGibbs

iTrader: (6)

I was going to suggest the jackstand run. Take the tires off while on the jackstand and see if there are any changes. Also rotate tires from back to front. Just to make sure you don't have a tire seperating internally. Sounds like a bent output shaft on the trans. maybe. You said stock yoke, as in the one that was on it when it broke? If so, that may be an easy fix with the new yoke.

Mr. Sandog

My take is the supposed 'problems' you have been having are only symptoms of a larger problem. Have you had your drive angles checked by a professional (tranny output shaft vs. driveshaft vs. pinion)? Bad angles will wear joints and blow out driveshafts. Ask me how I know.

moregrip

iTrader: (8)

2 roads I see

1st, process of elimination
2nd, pay a shop to find it and/or fix it

negativeswitches

iTrader: (15)

check your tailshaft bushing

when my driveshaft lost a weight and became unbalanced it wore that sucker out fast

easy fix all you do is pull the tailshaft and replace it

i suggest getting a new tailshaft seal too

i had a problem with my seal that i replaced it with

apparentally gm released 3 different tailshaft to yolk seals

1 long seal that is a main seal and a dust seal (thats what i had)

1 short flat seal

and 1 extended snout type seal (this is what i ended up using)

i may switch to the short all flat one cause it still leaks a little

-erik

oh yeah i had 2 bad front lower balljoints to that were doing the 65 mph trick and i couldent feel it in the steering wheel, i knew they were bad so i replaced one it got better i'm replacing the other one tomorrow hope it does the trick







damn longbeds

CHEVY6000VHO

iTrader: (2)

Ummm, have you measured your pinion angle lately? Changing out all those parts could have thrown off the pinion angle.
Measure the tranny output yoke angle at the (tranny yoke u-joint cap facing down), then measure the pinion yoke angle at the same place. Take your measurements with the dial facing the same side as your first measurement.
The angles should be close to the same but opposite. If they are more than 1/2 to 1* off, you will need to shim the axle. You really need the pinion angle a 1/2* lower than the tranny angle. This is due to acceleration twist of the axle.
Also measure your angles at each u-joint. You do not want anymore than 3* and no less than 1* of u-joint working angles.
Confusing a little, but you need to do this first before proceeding to the next possible issue. This would eliminate bad driveline angles.
If need any of this cleared up about this, just PM me.
Good luck with the fix.

Jim

1ImperialSS

iTrader: (5)

the poly-eurethane bushing will enhance vibrations no matter what FWIW. pretend you replaced your rubber motor mounts with extra hard plastic or something, you would feel the vibrations alot more. but for the initial vibrations i would also check your angles. then if that doesnt work, burn it.

95ImpSS

iTrader: (2)

Let us know what ya find... I have the same issue at 95+ mph. Not too bad on the street b/c I hardly go that speed on the street. But... trap speeds at the track are definite. I've broken a tailshaft housing (was suspicious about that since I got the trans), and bent a driveshaft at those speeds on the street. Lucky for me, that didn't send the truck catapulting... thanks to the trans mount that kept the housing bolted.

FarmerBeau

iTrader: (2)

I know i still need to check my angles but i cant find a ******* shop that will do it. I have been talking with the guy that installed my gears and we are trying to figure this out.

Mark- The tires are balanced. I just took them in but i will take the tires off and see what i can find. When i blew the driveshaft, the tranny slip yoke was still attatched when i stopped which meant that the tranny was spinning just a half of the driveshaft at 80+ mph. It isnt leaking fluid out the rear seal and the dshaft was aluminum and i think it would break or bend before that hardened steel output shaft bent.

The stock yoke accepts the stock ujoint. I converted to 1350 u joints and i am running conversion caps on the stock pinion yoke untill i have the time and money to buy the forged/ubolt peice. Yes the said "stock yoke" was on it when it broke and merely had the u joint still attatched. I beleive the ujoint failed and caused the entire failure. It seemed like the yoke is worn out because i had to hammer my straps to actually hold the ujoint to the yoke as they were loose within the straps. They are being held tight now and there is no fluid leaking from the front pinion seal either.


Erik- yea it sucks! I have an FLT tranny that came with the short flat seal. It is tight and doesnt leak fluid at all. I will check my ball joints for ***** and giggles though. Thanks


David- I know a poly mount will further enhance the vibration as it doesnt dampen it as well. When i say vibration, im talking "MY ******* TRUCK IS COMMING APART VIBRATION" Thanks for the suggestion though bud.

Grippy- You said the word "pay" of which takes money. I am in the hole because of all of the **** that has been breaking and money is really tight right here at christmas being a po assed college student. If all else fails, i will see if my parents can help me. Im sooooo tired of this truck. Thanks for the suggestion!

Jim/TBSS- I will get the angles checked asap. Thanks

1ImperialSS

iTrader: (5)

good luck dude...i know it sucks ALOT begging the parents for help money.