yesterday, my mechanic and i took my truck out for a test drive. the trans works well but there is a vibration that i noticed almost immediately. we got out on the highway and took it up to about 70mph and the vibration was bad and got worse as soon as i put in the clutch. putting the trans in neutral made no difference. the vibration only subsides as the speed decreases. so we're thinking that the driveshaft needs to be balanced. i am going to suggest a test to unhook the driveshaft from the trans, start the truck and run through the gears. no vibration means that it's in the driveshaft, right? could this also be a trans alignment issue? any advice would be greatly appreciated. thanks!
Your test won't prove anything, but I would definitely lean towards balancing the driveshaft. One thing though, if your U-Joints are bad, they'll shake like a mother too.
You said your " mechanic " did the work,so why can"t he figure it out? and did he install a pilot bushing? and did he replace the u-joints in driveshaft?
A bad pilot bushing will cause clutch chatter when you leave from a dead stop, not driveline vibration. Get the driveshaft checked over and put in new u-joints if you didn't allready.
Remove the driveshaft and try "rotating it" 180 degrees and reinstalling it....see what happens. If the vibration changes noticeably for better or worse it helps narrow the problem down. But at this point it doesn't seem to me that you definitely have a driveshaft issue, unless you've done some elimination that you didn't mention.
Checkout the input shaft on the trans, T5 transmissions unless they were the world class models are 90% junk! The input shaft will probably have too much play in it and there is no way to fix them, they have no pilot bearing in the back of them. A really bad design! had many cause excessive vibrations from a bad input shaft!
That sounds like driveshaft problems to me. I've shortened and welded up a bunch of driveshafts over the past 30 years and finally did one that did the same thing and would shake pretty bad at speed. I'd check it over and see if it had a fresh weld on one end to show that it had been shortened and go from there. Also check for dents or crush marks from being squeezed in a vise, that's a common cause of vibrations. I'd also jack the rear wheels off the ground and run it and watch the drive shaft to if you can spot something amiss. Also make sure that enough of the yoke on the driveshaft is in the trans because if it isn't in far enough it may be causing a vibration. I wouldn't be driving it until it was fixed, at least at any speed as it may damage the tail shaft on the trans.
Rule out the 'shaft with my lo-tech test. Take a wheel weight, 1-1.5 oz is fine. Hose clamp it to the rear of the 'shaft. Go for a ride and see if it improves. If not rotate it 90 degrees and try it again, repeat as needed, but don't exceed 360 degrees or you're pissing in the wind. Bob
actually, you take out the play by re-shimming the front bearing. I've had several used units with play, and they never vibrated like this. Every used S10 T5 will have some play, yet you don't hear of people pulling them for vibration issues, do you?
no it was a 3sp manual. we have a pilot bearing in place. the mechanic shortened the shaft but did not balance it. he's getting that done today. i went out there this morning and the driveshaft is out and will be balanced. i used this opportunity to start the truck and run it through the gears. it does so perfectly and with no noise what so ever. when we took it for a test drive, i heard a "dragging" sound along with that nasty vibration. is the trans/clutch noise under load more noticeable ? i talked about that with the mechanic today and he thinks that the angle is fine. i do not know how much it changed though. how much angle is considered acceptable? i do not know about "phasing" of the u-joints. please explain what that means and i'll ask the mechanic. Mr48chev: thanks i'll look at the shaft when it comes back from being balanced. hopefully the shop that balances it will look for these problems. i asked about this yesterday and he said that the yoke was a snug fit into the tailshaft. snarl: if the balance job doesn't solve the entire problem, i'll have him install new u-joints. THANKS! well, he kinda pissed me off because he using the excuse of an non-stock. 5sp installation as a reason for not doing the job correctly. he's kinda moody though so i just humor him. i don't know if he replaced the u-joints or not. i'll ask him later today. yeah, i was worried about that. i hope that we didn't do any damage already. we didn't drive it very far though. Bob: the shaft is already being sent out for balancing. i'm pretty sure that this will do it because it's a long unsplit driveshaft. any imbalance will cause big problems. this was a concern of mine from the beginning. some 8' beds have a split driveshaft.
where transmission bolts to bellhousing two different size holes , the t5 has small one , bigger cars have large holes bolts line up but hise size difference want let it line up incorrectly, it will viberate , put three trans ,7 drive shafts , was bell housing
dragsta,it is time to find you a REAL mechanic,nobody cuts a driveshaft without balancing it.What kind of excuse is he going to make if you let him put brakes on your truck and you hit a tree? must have used the wrong brake fluid!
the center hole size on the bellhousing isn't the problem. They didn't start using the 5 1/8" center hole till much later, and never on a 235. Again, the driveshaft needs to be balanced...
yeah, i have to agree but the jet is at the end of the runway..... can't abort the takeoff now. i've known the guy for 20 years and he's a good guy so i cut him some slack. i sure hope he cuts me some after all of this... yeah, that's happening today. i think that the trans install is good because it runs through the gears very nicely with no problems what so ever with the driveshaft off. thanks for all the replies. i should be able to test drive it again tomorrow.
Had a buddy help me install a T5 in my C10 this past winter. He did the job as kind of a fill in between paying jobs. I played gopher and apprentice mechanic. Also downloaded a crap-load of HAMB info for him. We both learned along the way. But I did go for a new drive shaft from a local source (ACME in Decatur) because we both knew just enough to avoid that problem. Actually, I was just warned enough about drive shafts before we started the project. At any rate, the truck's running great, shifts nice and smooth. So far so good. Worth the headaches I guess.
DRAGSTA...check and see if the U joints are centered in the YOKE'S. also check and see if the tranny REAR MOUNT isn't split...POP.
If the flywheel was unbalanced to the engine it would vibrate as you rev the engine, not dependate on speed and it would do it all the time. Definataly a driveshaft or u joint problem. Also on a side not a good shop won't balance a driveshaft with bad u-joints as its a waste of time.
If the retaining clips are in place the u-joint WILL be centered. If the clips are not in place centrifugal force will spit the bearing cups out in short order. Frank
i just read a ton of info on phasing. however, i'm having trouble visualizing how the u-joints speed up and slow down . but they say that the driveshaft can't be more than 3º out of phase. i'm going to ask the mechanic about this. he does driveshafts all the time so i'm assuming he knows about correct phasing. this page is loaded with info: http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml#Phasing
See if this helps, I have a better video but its not on youtube. The U-Joint travels in an elliptical which causes it to speed up and slow down each revolution. If you look closely in the video you can see it happen. http://www.youtube.com/watch?v=D7VaRuoBO4I Hope this helps.
What Snarl said. The input shafts going bad are typically input bearings which manifest themselves as noise or high-frequency vibrations in all forward gears except 4th due to the side-loading of the input shaft. If, by no pilot bearing on the input shaft' you mean the mainshaft doesn't have anything on the input shaft, you're incorrect - there are roller bearings in there. I have to agree with this statement. While I have cobbled together driveshafts in a pinch, it's definitely something better left to folks who do this work. You can successfully shortened driveshafts with a hacksaw and mig-welder, but there's so much more to it than cutting and rewelding...
i checked the input bearing before i took the trans to be installed. i told the mechanic the torque values. i will have to ask him again to make sure he didn't over torque that retainer after he cut it down to fit. i'm hoping that the shop where this driveshaft has been taken for balancing will notice anything done wrong. they should check to make sure that it's in phase and straight before balancing right?
The Jalopy Journal
