the reason i ask is that my '55 has an m420 4 spd truck box instead of the stock 3 spd and above 40mph or so it vibrates real bad but it feels like its the trans itself. i know for sure its not the steering or tires/wheels. may be bad ujoints but they feel solid. have to do some head scratching and figure it out
Terriffic looks do not equal being right. I would be checking ujoint angularty ,sounds to me it has something to do with the drive shaft. Is this truck a short or long bed. If long you may need to go to a 2 piece driveshaft. With suspension loaded as it would set on the ground check the ujoint angles with a angle finder/protractor.
Lots of info hear, but still a problem. One more ideal to rule out the driveshaft is to remove it and have someone tow you at speeds that cause your problem. If no problem occurs its either your drive shaft or your pinion angle to trans. angle. If still there than look at your rearend or tranny or what ever else might cause it.
it's a long bed. i've thought about the two piece shaft option and will talk about that with my mechanic tomorrow. i'm running out of time though and he patience. nutajunka: the truck was fine before the trans swap.
Just had another thought, was the imput shaft measured to see if it even reached the pilot bushing? The fact that the problem seems to get better and worse keeps leading back to the clutch disk somtimes when you shift it might end up centered, other times not, another thing you might try, get up to speed when you have a bad vibration shift into neutral, lift your foot off the clutch, let engine idle and the truck coast now rev the motor is the vibration related to truck speed or engine rpm? Engine = clutch, Truck = driveline good luck
The symptom of a bad pilot bushing is clutch chatter on takeoff. This is a driveline vibration... Tim, I finally got a look at your videos. They are too coarse and jumpy to tell anything for sure, but assuming certain things, I'd still think you have some driveshaft "whip" going on at the front yoke. There seems to be alot of play at the yoke, but where exactly I can't tell from the video. How much of the yoke is inside the trans. in the video? is the yoke fully splined? When under load (accelerating) the problem is better than coasting in neutral. This sounds like driveshaft whip to me because when under load, the yoke is at the initial point of the force application, but when you push the clutch in, now the force is being applied by the rearend, and the yoke is at the tail end, sort of "like playing crack the whip". Does that make sense to you? I would say that if that is how much yoke is out of the transmission when going down the road, then it's out too much. Combine that with not enough spline overlap and a long heavy driveshaft and you may have your problem. Balancing the driveshaft will not mean anything regarding this issue. If the outside of the yoke was ever "surfaced" to clean up seal marks, and they took too much off, then that could be adding to your problem, even with a new tailshaft bushing. Disconnect the rear u-joint and push the yoke in farther and see if that helps with the slop. If not, try a different yoke all together.
snarl: thanks again for your help..... the truck was up on the lift with the rear wheels hanging so the yoke will go further into the tailshaft with the truck resting on the ground. having said this, this vibration seems to be in the driveshaft somewhere but i could be wrong. replacing that tailshaft bushing didn't do much to take out the slop and the slop in my old trans (which is sitting on the shop floor with the yoke attached) is non existent. there's no movement there what so ever. like you, i was wondering if the yoke itself is worn. tomorrow morning, i'm going back down there . we're going to do some tests with another mechanic to get a new perspective. if we can't figure it out, i'm going to drive it to a local trans shop and have them look at it. i called the trans shop today and gave them the low-down and they said that they'd look at it. thanks to everyone for their comments and help.
About time the little light in your head came on. You may get by with a one-piece shaft on a short bed, but the longer wheelbase accentuates the balance problem. I can't think of how many trucks of that era that I threw together with mix-n-match junkyard parts that rode as smooth as silk compared to what you describe. I've had Muncie 3 and 4-speed in them, the big SM420 boxes as well. 6-bangers, built up big blocks, it didn't matter. As long as the center hanger bearing didn't go blooey, they always cruided nicely, never a vibration. Bob
my gut tells me that this is a driveshaft vibration. going back down there today to discuss a split shaft. also going to take it to a local trans shop that i called yesterday. he said he'd put it on the lift and look at it. i still think that there is too much slop in that output bushing but it's new....
I have an 94 F250 extended cab Long Bed and the drive shaft in that sucker is like 12 feet long!!! I don't have any vibrations - Except from the Stereo HAHAHA
we jacked up my truck and ran it while he looked underneath. he sees a vibration but doesn't know why. my mechanic is a dunce. i then took it to a trans shop and he believes that it's the driveshaft AS DO I. the front and rear u-joints are not in phase which can be seen visually. they need to be within 3º. if we can see that they are not in phase just by looking at it, then they are out by at least 15º. this has GOT to be the problem. my mechanic thinks he's a goddamn genius though and he did the driveshaft. gotta call him...
Hopefully this takes care of it!!!! Sounds to me like he was trusting of the mechanics capabilities, which is not neccesarily a bad thing! But it sounds to me like this mechanic just lost a customer and got some bad press or at the very least anything else he does will be heavily scrutinized!
the trans man measured the driveshaft at 66" and recommended that we get one from the junk yard that length and install it and see if that solves the problem. he ruled out the trans as a suspect. if i can see that the u-joints are not in phase just by looking, this MUST be the problem. that driveshaft has to be cut and put back together with the right tool to make certain both the front and back are totally in line. if we aborted this trans swap and put the old trans back in, we'd have the same vibration problem. this is incredible....
#### one easy way to see if the joints are in phase is to lay the shaft on a flat surface. Quick, simple, and effective !!! >>>>.
Way cool, a picture is worth 1000 words. In my basic "Driveshaft Shortening 101" tutorial (between my ears) I always scribe a line on the flange and tube. Take it apart, shorten it, put it back together and line up the marks! Not exactly rocket science, is it? Bob
Success teaches you nothing, at least you now know your ass from your elbow, more than some professional whose judgement you used to trust. Keep us posted. Bob
#### Yep !! "A wise man Knows When He's In Over His Head" but a "Genius Knows When To Admit It" >>>>.
i haven't been able to contact the mechanic to let him know what we have determined. since i have NO TRUCK, i've had to use my motorcycle as sole transportation and it's storming right now so can't ride down there. a guy who does as many driveshafts as he, should have a special tool to measure exactly the driveshaft phase. if not, he could put it back together wrong again....
had a so called expert do a driveline 30 years ago for me and it ended up being junk! needless to say it ended up being returned. thats how i learned how to do drivelines one $35 lesson.
dirtbag54 gave me some very useful info on drivetrain alignment and pinion angles. i absorbed what he said and called the mechanic. he said that he checked the pinon angles with a dial caliper and they were within two degrees of each other. i'm not sure i believe him. in fact i don't believe anything he says. he also told me that the driveshaft shop checked the phase but the guy at the shop said that he only balanced the driveshaft. today another mechanic was supposed to look at the truck at my mechanics's shop. i went out there and he was not there. we jacked the truck up and ran it through the gears and my mechanic threw up his hands. i then said that i could take it to the trans shop and he said, fine. so i did that and posted the results above. my mechanic dismissed it. he then tells me tonight that the other mechanic who was supposed to be there called to come look at the truck while i was out. somehow that was my fault. he didn't tell me that we were waiting on him. i'm dealing with fucking pricks. that's the problem....
Finally,you realize you are being too damn nice to an idiot that calls himself a mechanic,with all the headaches and bullshit this guy has put on you you could have had the truck towed to a driveshaft specialist and been driving the truck.Being nice can just go to a certain point and you have finally found yours,Good Luck man.
getting angry at him won't do anything to make him smart. i do not know if i can limp the truck to a driveline specialist because i don't know if one exists in this area. i can't drive the truck over 30mph. i'd have to have it towed. regardless, tomorrow, i'm going to ask him what he's going to do to fix my truck. if he says he doesn't know and wants more suggestions, i'm not playing that game. he's the mechanic. he has to tell me what it will take to get my truck running properly. if he can't and i incur expense elsewhere then i will have to sue him in small claim court. he's had the truck for two months. but, i'm not going to get angry because they will just use that against me. i'm going to be sweet as pie. he keeps saying that it must be the transmission but that's a cop-out. the trans guy said he thinks the trans is fine. there isn't much that the trans can do to create this bad a vibration and not have self destructed.
You can see if he'll give some of your hard-earned $$ back, but since you've added other specialists (real mechanics!) into the equation, he has a quasi-out, at least in his mind. I really like the truck though and they're great to learn on, although the T5 swap is a little beyond what most people can tackle... even the "pros"! Bob
i do not know how much this has cost me. i may just tell him to put in the old trans. this is insane. if i have limp it to another idiot redneck, it will be more expense and i may not have a reliable vehicle to move all my worldly belongings across the country. i'm worried that even if we get this vibration figured out, that when i put a load in that truck, it will come back. then what? i made a mistake by allowing this idiot to work on my truck. after i move, maybe i'll revisit this trans swap. right now though, i need a truck upon which i can count. i wouldn't feel good about driving that truck long distance with that T5 disaster job.
" i may just tell him to put in the old trans." Don't do this, your problem is 99.9% driveshaft. Have the phasing done right. even if you have to have a new shaft made. " i'm worried that even if we get this vibration figured out, that when i put a load in that truck, it will come back. then what? " Once you solve the problem it's solved. You gonna love the T-5. I put a T-5 in my C-30 with a V-8, Sometimes the gross weight is over 7500 lbs. empty is 4800. I've put a lot of miles on it. No problems. The trans gets warm, but not hot. THe OD is worth it for highway driving. Frank
frank: thanks for that info. i contacted a local "off-road" guy who said; "sounds like you have a driveline problem." and i'm going to limp the truck over to him tomorrow, hopefully.... i'm feeling better about it now because the guy who installed the T5 was over his head. he said that he used a "caliper" to align the driveline. that's BS. he never even tried to align it.