The Stovebolt Site Forums The Shop Area Engine Shop Vibration on 53 flatbed

I install a matching 400 engine and tranny in my 53 stakebed. runs really smooth up to 2500 rpms, if i go any faster i get a vibration in the drive train. i had a driveshaft made and thought it was that so i had another one made and put new ball joints in. could it be the rear end. it shifts good, no noises just a virbation, used tires but they were spin balanced and wheels are not bent, any suggestions. i plan to put a 301 ratio in in the future, also if i do put the 301 in the truck should i have any problems, would it be geared to low?thanks for any help. i think it gets up to about 40 or so before it vibrates.

A friend of mine totaled his 3/4 ton pickup because he tossed the two piece driveshaft and went to one loooong shaft. He pole vaulted off the freeway coming down a long hill. I'd talk to the folks at the driveshaft shop, may need a two piece.

is it drivetrain or wheel / tire related ?

i have said it before, from experience, an out of round tire will shake the heck out for your car / truck at speed.

leonard

the drive shaft came out of the donor truck and all we had to do is put a 350 yoke on it. i dont know if it vibrated before i removed the old drive train or not. it jacked the front up and rotated the wheels and they look like they turn true.i jacked the rear up on put on jack stands, ran the motor and tranny in 1st and it vibrated when it got up to 3000 rpm. the wheels looked like it rotated trul.i looked at the drive shaft turning and it looked truei forgot to mentioin that it vibrated when coasting down a hill at what i think is 40 mph or so.

the whole truck dont vibrate, you can feel it trough the shifter when you get up to above 3000 rpms.if you go under 3000 the whole truck and drive train is reallly smoooth

sounds like drivetrain for sure...
how about motor and trans mounts ?
just a suggestion..

leonard

Is the drive shaft in proper phase?
Scott

I own a driveline shop here in So Cal, and what you are describing sounds like a classic driveline issue.

What series is the chassis? If it is a 3/4 ton, then you would likely need a hybrid u-joint to attach a T350 yoke to the existing shaft, and there are something like 7 or 8 different types of 350 slip.

Also, you say all you had to do was put the slip on? I find it highly unusual that you did not need to modify the shaft.

Something else to look at engine wise, are you sure you have the right flexplate? The 400 is an externally balanced engine, all other smallblocks are internally balanced. Put the wrong flexplate/flywheel on and you got yerself a 4 wheeled paint shaker. Don't ask me how I know.

phase?

the motor came out of a 78 chevy truck. the motor was a 350 and was replaced with a 400 out of a car. my best friend was given the truck and said that he just parked it. the motor and tranny were all one assembly when i got it. i used the exsting drive shaft and cut i think about 2 inches of of it and welded the old 3/4 ton yoke, so the yoke that goes with the tranny is the one that came from the factory. tell me more about the hybrid u joint,thanks

There are a variety of U-joints that will let you convert from one series to another, and in some cases, I can swap caps around and make even more combinations.

Did you cut the shaft yourself? and how exactly did you do it? Can you take a picture and post it or email it?

If you just cut some tubing out of it and butt welded it together, I suspect that is your problem. And phasing means that the u-joints are all lined up with one another. Very important.

Going home now. I'll check in tomorrow.

Mike

the guy took the drive shaft from the donor truck and cut it to length. i alreday had the 350 yoke on it. he took my 3/4 ton drive shaft and cut the diff end yoke off and slipped it in the end of the donor shaft. he then measured yoke to yoke on each side to make sure it was the same measurement and he then welded it. i would have thought that it needed to be put on the lathe and centered it on both ends and then welded it, but that is not what he did.he told me that he has never had a problem with any that he did that way. i think it may be the problem to but dont know. thanks for any help.

i check and it is in phase.

If I understand correctly, you had two shafts, and I'm assuming they were different diameters, and your guy slid one inside of the other and welded them together? If this is the case, that is most likely your problem. Yes, it should have been done in a lathe or specialized driveshaft machine. I have seen many jobs done this way. Sometimes they work, but more often than not they have issues.

I would suggest you find a professional driveline shop in your area and at the very least see if they can balance the shaft. If it's a 2 pc, you will need to balance both pieces together.

i talked to a friend that i know that works at a hydaulic shop and told me that he could put in a lathe and make it true- but could not balance it. what do you? they have a nice machine lathe with a 20' span.

There has to be a driveline shop somewhere near you. It looks like you are in or near boston. That is a large urban and industrial area. TAKE IT TO A DRIVELINE SHOP. Not to someone who knows someone that saw someone work on a driveshaft once 5 years ago.

Sometimes you just gotta pony up and pay someone knows what they are doing and are experienced in a specific area of expertise.

i removed the driveshaft and took it to my friend that is the manager at the machine shop. he said it was 1/4" out of round, and that he needed to put a new yoke in sized for the drive shaft. he has to order it and will find out tommorrow. I covered up the tail shaft of the tranny and started the motor and put it in drive. ran it up to 3500 rpm and no vibration.it starting vibrating at 3000rpm before so, im hoping it is the drive shaft.

Well, that's a start. But how is he going to know if the rear yoke is welded true? On the slip end it's easy, you can clamp the slip in the chuck and run the tube in a steady rest. How is he going to tool up the rear?

OK, I'm new here and I don't want to come off like a jerk. I just deal with this literally several times a week, every week for the last 30 years or so. If I can help with any part #'s, or advice, drop me an email and I will help anyway I can. If you know the tube diameter and wall, I will know the part number off the top of my head. I just don't want to be accused of spamming.

Mike
[email protected]

If it was 1/4" out of round I'd say its time to throw it in the trash & spring for a new driveshaft. You could get away w/a single large tube driveshaft since your truck isn't that long(lots of 70's/80's long wheel trucks used a 1 piece shaft). But personally I'd go w/a 2 piece shaft..Joe

72" center to center and 3.5" diameter is my cutoff for length, I won't make them any longer than that as a steel one piece. The new aluminum stuff they are making as long as 80".

mine is 62" end to end. anyway the machine shop installed the new yoke. looks professtional. they remove the yoke and it was 30" long, and that was also one of the major problems. reinstalled it and it runs smoothe and feels like a babys behind. thanks for everyones help. my friend had about 1.5 hours of labor and didnt charge me anything except for the new yoke