I have two questions that I could use some input on. First, I put my Bucamino on the lift today to try to tighten the pinion nut under the rear u-joint in an attempt to stop a shake at 50 mph +. (I have posted about this problem previously) When I looked at the front of the drive shaft I noticed that it only has about a half an inch of travel possible before the front slip joint will hit the rear of the tranny. This is with the car in the air on the lift. Seems like it will come close to hitting the tranny when the wheels are on the ground. Does that seem too close??? BTW, this Elky sits on a 65 Skylark GS four speed frame and suspension. So the engine and all driveline components are Gran Sport, including the rear-end and tranny. Second question is; is the pinion nut 1 1/4 or 1 5/16? I am going to buy a socket to tighten it and I don't want to buy the wrong one! All help appreciated.
Kurt, does it have a one-piece driveshaft? The 'two-piece' is made from two tubes with a rubber sleeve between them. You can see the gap for the rubber near the back on the shaft. Stick cars should have a one-piece. Stick cars shaft was a little shorter, maybe 59-1/2" Autos were 60" >>>EDIT: 66 GS 4 speed driveshaft is 59" Did you say there was play in the rear pinion? That could be a bad bearing. Sometimes the pinion nut can loosen, if someone had taken it off before. There is a correct procedure to tightening the pinion nut. But unfortunately, the center section section must be taken out. If you just want to check to nut to see if it's loose, you might be okay. Overtightening it can mess up the bearing preload, and lead to failure, so keep that in mind. Pinion nut takes a 1-1/4" socket.
Hi Walt, The pinion nut was loose so I torqued it to 150# while holding the u-joint part with a pipe wrench. I hope this didn't do any damage, but that was the way the local repair shop recommended I tighten it. The vibration is better, but not gone by any means. The driveshaft is one piece. Do you know what part I should measure to see if it is too long? BTW, I am beginning to think the brake drums are out of balance. They were put on the the PO and new at that time. I have an old balancer that was loaned to me that spins the tire on the car. That is my next thing to do to try to get rid of the vibration. Please let me post about measuring the driveshaft if you know the correct way to do that. Thanks, Kurt
Kurt, just measured the driveshaft from my 66 GS 4 speed. It's 59". I have a 66 V6/manual driveshaft and GTO one that are both 60" Measure from the center of the u-joint bearing cap that's pressed in the driveshaft, to the same point on the other end. I wonder if any damage was done by driving with a loose pinion? You could have a bad bearing, or damaged gear teeth. Turn the pinion by hand to feel if it turns smoothly without any rough spots. That would be easier to do without tires on it. The pinion nut could loosen again. Normally, they are not re-used. The crush collar should be replaced at the same time. Full procedure is in the Buick Service manual. BTW, 65 Service manual in online in the 'Electronic Garage' section of www.65GS.com. Vistit the forum while you're there!:beers2:
Walt/Kurt, My 65 4 speed had a driveline vibration when I bought it. One of the reasons it was sold to me was because the vibration couldn't be fixed. It vibrated strongly between 55-65 mph. I suspect the flywheel may have been on wrong, but I never checked that when I took it all apart. The damper may have been bad as well. I drove it to Bonneville for Speed Week in 1991, vibrating all the way and back. You could find speeds where it was minimized. It got much worse in the several months after I got back. The bearings in the rear were loud. After tearing the rear apart, the carrier bearings were toast. I replaced all the bearings in the rearend, but the vibration was still there when the restoration started. I still don't know if it will be fixed when it runs again, but the engine is rebuilt and balanced, the damper is new, it has a different driveshaft, and both the trans and rear axle have been gone through. Please let us know what you find out. Mark
PINION NUT: torque. There is no real torque spec to the pinion nut per say. It takes 120-175 foot lbs. to CRUSH the pinion sleeve to seat the bearings properly. The 15-20 ich pounds rating it the constant spin drag in the bearing to race mating seat that is required. Over tightening will crush the pinion sleeve to far causeing the bearings to be seated TOO tight into the races and then you will have your premature failure. Usually you can get away with tightening the pinion nut by hand as tight as you can with a 1/2 inch hand ractchet while holding the yoke in place. Then after you have it as humanly tight as you can take a punch pointed drift and stake the nut to the thread in 2-3 spots. guarentee that will not back off again for you and you will not over tighten the pinion bearings....IF the crush sleeve has not been over crushed aready... Vibrations... I tell you...Those trouble are almost as bad as electrical. I have had driveshafts out of balance bearings bad, u-joint cup bearing bad, tranny ooutput shaft bushing bad, flywheel clutch springs, tires, drums, axle bearings, shocks, pinion angle....all cause vibration trouble....!!!! :spank: :spank: :spank: :blast: :blast: :blast: o No: o No: o No: It is a crap shoot sometimes. Jim
:gp: Good info Jim. The guys @ NAPA just about refused to sell me a torque wrench for the inch lbs, they were telling me its got to be tighter than that! I had a vibration in my 70 GS that turned out to be a bent driveshaft- took ou the pilot bearing and was working on taking out the front trannie bearing!
Yah that is a part guy for you .... Does your car have A/C? What the heck does that have to do with the pinion nut? Jim
OH just remember the inch pound thing is totally usless unless the carrier is out of the housing. Trust me guys if the crush sleeve is still good enough to keep the bearings seated properly just tighten it as hard as you can WITH OUT bracing yourself to the car...lol. Some of you guy are pretty big I am sure. Now I am confident with a 12 bolt crush sleeve your biggest guy will not budge it with a 1/2" rachet...lol. Jim 8.5 and 8.2 you could crush sleeves are much smaller. Take care
I hope to get the car up on the lift tonight and spin the tires with the balancer, that should tell me if the drums are to blame. Considering the drums are new, I am suspicious of them and their balancing. I could just convert to disc brakes if the drums are defective....:Brow:
We have a good drive shaft man here in my town.... He told me and then demonstrated to me that there is no need to balance a drive shaft if it is straight.... He has built several fro me and when he finishes the construction he straightens them.... none that he has built has viberated...... Check the straightness of the drive shaft....
As a former driveshaft repairman thats just "BS!" A shaft should always be checked for balance no matter how close to "0" run out it is. Welding it and then letting it cool and getting it absolutly perfectly straight with no run out is just about impossible. Sure the straighter it is the less it will normally take as far as weights are concerned but the actual casting of the welded in "tube yokes" is not perfect nor is the casting on the trans yoke. Casting of the parts attached to a driveshaft such as flanges, CV yokes, tube yokes, trans yokes etc. aren't balanced. Therefore you need to have it balanced. :Smarty:
Well, i have no intention of argueing with you here on the board about it, even though you insult me.... I still know that the man built several driveshafts for me over the years and they all worked without being ''balanced'' and did not viberate nor tear up....That fact will not change..... nor will my mind.:laugh:
Doc, as usual my reply wasn't meant to start an argument nor insult you personally, as you (i don't believe) are the driveshaft builder just his buyer. It was meant to be correct information. I built QUITE a few driveshafts in my 13 yr. career and the truth is the truth. Most drive line components are cast with the exception of some CNC billet parts and are not balanced. Therefore when welded into a shaft and the shaft assembled they should be checked. I had to re-do other local to our "drive line repair shops" work that wasn't done right in the first place. Their customers that came in with complaints of still having vibrations were told the same thing by their shops "well its perfectly straight" and i guess others were just lucky going from a wicked vibration to a lesser more liveable one? uzzled: In your defense i suppose i could have left out the "thats BS" comment but thats what i was thinking at the time so for that i apologize sir. :laugh: I also rebuild differentials and this particular reply is why i normally don't bother to offer useful information. It just irritates me when someone gives what in my opinion is false information. MONZAZ (JIM) is doing a great job :TU: and he doesn't get jumped on when he tells someone that their way of doing something is not particulary correct. Maybe thats why OPH (ROGER) stopped offering advise as well? o No: KCOMBS, since its your question and post i'll give it one last try. I've read your other post awhile back and also this one. So first have that shaft looked at by a reputable shop if you haven't already. As the one piece rubber element shafts have a tendency to "twist" the rubber with age. Also check that the u-joints have no movement from side to side, clips are on all the caps especially at the rear end yoke and little or no axial movement. The trans slip yoke will go into the trans if the diff hangs and will come outward when on its wheels. Its the arc of the four link suspension. A good rule of thumb is 3/4 but no more than 1 in. of yoke showing with the rear axle in a riding position. The diff pinion nut being loose indicates a problem that probably won't be solved by just tightening it as MONZAZ indicated and again probably should be looked at by a reputable shop. You could rule out the wheels and drums yourself by running the Bucamino up on stands without them but be very careful and don't touch the brake pedal or you'll blow out your wheel cylinders! Doing this will also alow you to observe the axle flanges for run-out. Basically the loose pinion and yoke could cause the problem or a bad driveshaft could've caused the pinion to loosen. I am firmly aware that most of us "car guys" are do-it-yourselfers and don't want to spend the money to take it to a professional when its something we can repair ourselves so just take one thing at a time and arm yourself with the useful information thats given and Good Luck with it!
Ok,,, Tim, apology accepted.... As an old ford mechanic, [certified in 1962] I know that there are limits to how far the factories will go in tolerances, balance, ect, on the parts that are put into cars.... and when I see Buick telling mechanics to ''balance'' driveshafts by opposing hose clamps, I am not impressed by them.... no doubt that a custom hand built shaft is better than the stuff that the factory puts out.... Then there is the old saying that you cant argue with success,,,, the shafts that the local guy has built for me have held up and not viberated.... so he cant be too far off.... nuff said.
Thank you for accepting Doc. As a Ford mechanic i would guess that your knowledge of Fords is probably greater than in the other makes domestic or foreign. So is my knowledge of doing one thing repetitivly six days a week for years which was repairing and building all makes and models of driveshafts. I've seen factory shafts that were well made and others that weren't even close. I've also seen custom shafts that were well made and others that were not. I've even posted in another question a story of how Ford came to my old shop to repair and balance an entire palet of aluminum E-series van shafts they were having problems with in which we cut them apart at the worse end, installed the cardboard tube they wanted and reassembled and balanced them until about two o'clock in the morning on a Saturday. Maybe some companies don't balance to as close as a tolerance as the company i worked for did, that i can't say but i just wanted the majority to know that what looks straight doesn't always mean balanced to perfection. As you stated...Nuff said. :TU:
Guys please do not fear me...I am just hear to help. The more opinions we get the better the out come. I really do not think anyone hear is out to irritate each other. We all work to the same goal TO SOLVE THE PROBLEM at hand. I DO NOT claim to know ever single thing on rear that is for sure...lol. I always appreciate a different view especially from OPH. I learn from actual experience and the experience of other builders and guys that have physically torn done diffs also...even you guys that find something new I have never seem before....EVERYDAY...we learn. So back to it... The GM yokes are also balanced. Check that. they are usually on the dust flange I have seen so of these spin on the yoke and cause imbalance also. Far as the drive shaft issue. My point of view is limited as every shaft I have ever had build has been balanced and from a logical stand point I would say the weld will be inconsistent along with the tube material and there is also a seem with the material of the shaft that will also throw the balance off. I do not know the material that was used by your shaft maker so it is very hard to say . We will just have to take words for it that it is true. If kcombs did have drive shaft work done and is unsure of the quality it is best to find second drive line shop and have it double checked. Good luck with the subject and remember as long as your disagreement is brought up intelligently and and not abusive or abrasive we can all agree to disagree....:laugh: :grin: :beer
