My 62 Ranchero is shaking the shit outta me....Heres the symptoms: The vibration starts at about 45 mph, and gets progressively worse until about 63 mph, at which point it stops immediately. It doesn't get gradually better, it just flat STOPS, at that speed. runs smooth as can be at 75-80 mph.... The weird part is that after it quits vibrating, I can slow down and drive at any speed above about 50, and its smooth. When its shaking, I can put it in neutral, and the vibration continues. It is most noticable in the shifter itself... Now, heres what I have done about it to this point.....New trans mount, clutch, wheels and tires, Hell, I even changed out the complete rearend...( I had a spare...) To make this even weirder, at one point I pulled the driveshaft, and the front u-joint seemed really tight, so I changed it....this cured the problem....for about 2 days. So, I pulled it again, but this time the joint was fine...So, the questions are..... Its gotta be something to do with the driveshaft, right? How much slip yoke is OK to have hanging out the back of the trans? I haven't measured it, but it looks to be about 1 3/4 inch... Could it be something in the trans? Output shaft maybe? Still does it in neutral, so maybe not? Right now, I'm thinking my next move is having the driveshaft balanced, but I hate throwing MORE money at it, I've been fighting this problem for about 2 months now... This was my daily, and will be again, if I get it fixed. I need any input you have...driving my lame ass f-150 every day has me on the brink of suicide......help please.....
make sure the universal joints are phased correctly if you had your driveshaft shortened they may not have put them in right also take a good look at your tires they may be showing some wear patterns check the transmission and rear pinion angle and make sure there close when did the vibration start? what did you change if anything ? bill
The driveshaft hasn't been modified at all, I switched from an auto to a 3 speed, but that's not when the vibration started. I put on new wheels and tires today, made no difference. It has been lowered with 3 inch blocks in the rear, whats a good number for degrees of pinion angle?
Since you lowered the rear 3", this has eliminated the pinion angle to the output shaft of the trans....so you need to tip the pinion down 3 degrees.
The angle of the trans to the driveshaft should be the same as the angle from the driveshaft to the pinion. You want the RELATIVE angles the same. That is a whole lot different than having them both at the same angle. All the car manufacturers very closely make sure the relative angles are the same. NONE put them at the same angle. You have to measure the angle at the trans and driveshaft and determine what the difference is.You then move the axle untill you can get this same RELATIVE angle between the driveshaft and the pinion. This may or may not solve the prob but is good info. Good luck
Its funny that you bring this problem up because I had the same problems as you were getting and thought it was my rear-end/driveshaft/bias tires, u-joints, tranny mount, all which I replaced or eventually I ruled out. It turns out that the bolts that held my motor mounts to the frame the nuts had fallen off and basically my motor was being held onto the frame by 2, 3/8 bolts on each side instead of 6 or 3 per side. Man I couldnt believe that was the problem it wasn't till I pulled my motor out till I realised the root of all my vibration problems. Now my car sails like a Caddy down the road with no vibration until I hit over a hundred,..... I think I can live with that . hope this helps you BRENT
The angle between the transmission output shaft and the drive line should be equal and opposite on the drive shaft to the pinion. Example: the engine is sitting 4degrees up in the front and the drive shaft is level, your front drive line angle is 4 degrees. The rear pinion should be 4 degrees up to balance out the driveline. More likely your case is 4 degrees on the engine and 1 or 2 down toward the front on the drive shaft. If this is the case you have 5 to 6 degrees of angle in the driveline, which going by the book should be matched at the rear. BUT most driveline manufacturers would suggest only 2 degrees of angle MAX. You can get wedge shims to change your pinion angle and you can space the trans mount up a bit. But be carefull that shift linkage, exhaust and your fan don't interfere if you do decide to shim the trans up. I would also look at the rear leaf springs for a worn out bushing or broken leafs. If you have a dial indicator it would be helpfull in learning the condition of the drive line. I check the runout at the tube next to the weld and in the middle of the shaft. If it's out at all, replace it. Ford was pretty bad about balancing driveline components, part of the reason you see huge bob weights on pinions and hanging off transmissions. Even to go so far as to put vibration/harmonic dampener on the drive shaft yoke. Some drivelines are two tubes, some are visible with an elastomeric bond between the two like a dampener and others have a cardboard tube inside to silence the "ring" sometimes heard and for harmonic dampening. Over time the heat cycling, road miles and abuse just breaks them down and can cause the driveline to go out of phase or out of balance. You can check the phase with the driveline out of the car. Place a file across each u-joint cap and sight them, they should be paralell.
I dissagree with the rear needing to be angled up. ALL manufaturers angle them down to minimize the total of the angles involved. As the rear would move and rotate under load the rear angle would decrease and the front increase. That would cause a vibration due to the veriation of the angles and is the wrong way to do it.
I think I may have found something....I pulled the driveshaft, and it looks as though the front yoke is off center....barely, but off center. I'm taking it in tomorrow to have it checked. Pray for me, this vibration may be the end of me....
I find a lot in that article confusing and some contradictory. This is the most important, and misunderstood part of the essay; "...Pro Stock chassis builder Jerry Bickel assures us, there is no mystery to pinion angle. ... The goal is to create a straight line from the back of the crankshaft through the transmission, driveshaft, and the pinion of the differentialunder load. ..." but he shouldn't have included driveshaft...as long as the driveshaft/transmission and pinion are parallel to each other, under load, all is good. I suspect you are getting some serious spring wrap and the pinion is pointing up too much while accellerating to 80(?) and at that point it settles back down to "normal" and aligns itself once again. If you have removed spring leaves or put a tall lowering block in it could be twisting a lot, or if the rear Ubolts are loose, or thespring pads come loose it might change on you. could be shocks or broken shock mounts too
Your slip yoke hanging out could be the problem. I measured a couple of T-400 yokes I have, one was 3 3/4" long on the machined outer area, the other was 3" long measured the same way. This is the area where the yoke rides against the plain bushing bearing in the tailshaft housing. I don't know how long Ford yokes are, probably similar, but keeping in mind the usual set-up for a yoke has them sitting 3/4" - 1" from bottoming out on the tailshaft. Put another way, insert yoke into trans until it bottoms out. Pull yoke back 3/4" - 1", measure from horizontal front U-joint cup center to center of pinion yoke where the rear U-joint cup sits. That gives you the driveshaft length. If your yoke is 1 3/4" out and Ford yokes are similar in length to GM yokes more than likely you've worn the tailshaft housing bushing beyond limits . . . and it may have been overly worn to start with. The tailshaft bushings are easily replaced, at least they are on GM's and I'm guessing Fords are the same.
The yoke is about 6 inches long, so its quite a bit longer than the GMs..I'm taking the driveshaft over to a guy this morning to have it spun up and checked....
I want to address this missinformation right now. Show me and I will let your statment stand, but to say that ALL manufacturers angle the pinion down is a gross lie. And to prove my point: Check these out from the guys that should know best. www.iedls.com and www.4xshaft.com/driveline101.htlm and www.4x4now/gt0899.html and www.drivetrain.com/driveline_angle_problem.html If you really want to go further with take a look under any production vehicle made with a solid axle rear driver. The only guys that use pinion down are drag racers. Hardly ALL manufacturers. DrJ's explanation of spring wrap may be possible in the situation at hand. Lowering blocks will add more leverage against the spring pack and if it's old and weak or if leafs have been removed this situation may be the source of the vibration.
I'd say leave it in and see how much slop there is. The yoke centers the rear of the tailshaft in the tailshaft housing bearing and if the yoke is out there's going to be quite a bit of play present. Was the possibility of a bent driveshaft mentioned? That happens now and then, specially if it's a junkyard shaft that's been mistreated. You may find that once the shaft is spun up, found straight and then balanced that your problem goes away. Did that one with a 50 Ford coupe that had a shortened driveshaft. Used to vibrate when going through the traps at San Fernando running 100 mph. The balance job cured that. In any event, lete us know what happened.
I just returned from dropping off the driveshaft. He sighted down it and says it has a slight twist to it. I couldn't see it, but the guy I took it to has done a LOT of driveshaft work, and I trust his opinion. This is the solution: Since I believe the shaft is a bit too short, I took him another shaft that is a bit too long. He's going to shorten that one for me, so I will have the correct amount of slip yoke out the back of the trans...I'm gonna pick it up at 1:00 this afternoon, I'll post an update after the road test......Thanks for all the help!
FIXED!!!!!! The front yoke was spread apart slightly, allowing the u-joint to walk around when it was at speed....Fortunately, I happened to have a spare yoke. Thanks for everyones input on this.....I'm gonna go cruise now
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