1959 Driveshaft

[1959chevybr]

I am new so please forgive if I am doing things incorrectly. I have read over the last two weeks every thread on this site about 2 piece drive shaft woes and have tried every suggestion. I am not an expert but have done over 25 frame up builds but nothing has ever kicked my butt like these vibrations. So the basics, 59 Belair, 1995 LT1 Corvette engine, 4L60, thus shortened the front drive shaft accordingly, had it balanced and a trial run. Pulsing at low speed strong vibrations around 60. So bought an Inland Driveline unit all balanced together, etc. Still the same issue except worse, talked to them about the issue they suggest the 3/8 trim off the center bearing, no help. I bought another drive shaft, had it balanced still the same issue. Then came the angle process and have moved trans, center bearing (up and down), pinion all over, used Spicer's site to calculate angles, no help. Went back as close to the factor angles as possible, no help. I doubt there is an angle I have not tried (except maybe the correct one). I really do not seem to be able to affect the vibration by moving any angle, better or worse. I am looking for someone that really has fixed this issue, is it possible after cutting the shaft and mild modifications to the car (2 inch front spindles) is it impossible to ever get the car to operate correctly? I have thought 1 piece driveshaft with advice pro and con. It looks like without really massaging the frame about all that could be used is a 3 inch shaft and the driveline shop says not large enough for the length and doubt the success. I am looking for real life answers as I have been banging my head against this drive shaft for 6 months. Can not really use the car and as all of us have dumped a lot of money. I apologize if I have gone about this thread thing incorrectly and realize there are many threads on here about this very issue, they just did not fix mine.. Please HELP!!

 

[La Hot Rods]

Is there a chance that your vibration is your torque converter and not your driveshaft.

 

[1959chevybr]

Thanks for showing an interested in my vibration issue. At this point I can not be negative to any input so, sure it is possible. It is a newly rebuilt transmission with a new torque converter. The thing that might make me feel this might not be the right path is that sitting still and running the engine thru all RPM ranges there is no vibration and of course the torque converter is turning during that time. Maybe I am not approaching this correctly and if you have more reason to think converter push those points to me. Thanks, BR

 

[1959chevybr]

Still thinking about your torque converter suggestion, from a slow roll the more pedal you give it the more feedback you get.. Idle off slow from a stop and not much vibration but give it say half throttle and the vibration increases, so the more throttle always give more vibration and then of course it vibrates steadily at 60 MPH. thanks, BR

 

[La Hot Rods]

If your lockup is set to work like factory you can get the car up to speed in overdrive and whit one foot on the throttle to hold your speed then apply just enough pressure on the brake pedal to make the brake lights come on.
Now doing this will make the torque converter unlock the lockup clutch.....I have found converters that would vibrate when in lockup mode and would stop vibrating when unlocked.
Not sure how you have the lockup feature hooked up.

 

[La Hot Rods]

Are you torquing the center support mount bolts when you have the car at ride height?

 

[1959chevybr]

Totally agree with the torque converter lockup, this is all operating factory specs, computer controlled. The vibration stays the same with foot on the brake, also it stays the same whether in OD or DRIVE. This is all great checkout issues when rolling 60 or so but on takeoff around say 5 MPH or so it is not in lockup and still has significant vibration. Also failed to mention I have bolted on 3 different sets of tires and wheels. I really appreciate your thoughts, I have been working on this so long I have gone totally brain dead, I almost always have something else I can try but on this I have exhausted my toolbox.

 

[1959chevybr]

Oh,, forgot, yes, center bearing bolts torqued while on drive on lift.. ride height. Thanks..

 

[La Hot Rods]

It is always good to have an outsider take a crack. at a problem.
So is the front drive shaft u joint crosses lined up parallel or 90 degrees off?

 

[1959chevybr]

This answer will be more complicated than it should be but here goes.. Today the answer is no, not out of phase.. BUT we just recently changed it from the "factory out of phase" to the more traditional "in phase",, same vibration issue both ways.. Now, not to say some other thing may have been "off " at the time I had it out of phase. Inland Driveline Service was adamant it had to be back in phase so that is the direction I have gone recently.

 

[La Hot Rods]

Guessing this has the billet center support.
Is your car lowered?

 

[61BUBBLE348]

I had a slightly similar problem nearly 40 years ago, chased my tail for weeks, MKIV and TH400, end up putting a 1 piece shaft in and it was smooth to 140. Models has some nice pics on the chassis mod to do this.

Not with standing this lots of guys have solved this problem and it would appear you have tried most of the fixes, now a dumb question, have you tried running the car with the wheels of the ground, i understand you won't have any load but if there is still a vibration this will eliminate tyre balance. La Hot Rods has a good point about the alignment of the universal joint, you should check this. Re the Torque converter this will also need to be checked.

1 other thing, not sure whether or not this applies, do you have the correct flex plate / flywheel, are the LT1 externally balanced like the 400 sbc, if so it may pay to check.

good luck with your hunt,

just a side note I also chased a vibration on a 1956 Ford years ago, changed angles, replaced universal joints, found that one of the diff tubes was out of alignment, fixed all this and still a vibration, replaced the uni's for another brand, the vibration magically disappeared.

 

[1959chevybr]

It does not have the billet center or the telescoping drive shaft any longer, it was worse than the regular driveshaft. Right now I am running a OEM 59 shortened front shaft, NAPA center support bearing (factory height) and OEM rear shaft. The car rides on original GM springs front and rear in stock form with 2 inch lower spindles in front.

 

[1959chevybr]

There seems to be a lot of disagreement on the driveshaft phasing. Factory "out of phase" versus the norm, "in phase", I have no clue where the real fact is on this point..

 

[La Hot Rods]

Try this..... loosen the center support while the car is at ride height now move the center support forward about 10 mm to preload it then tighten it down and try it.

 

[La Hot Rods]

Factory is 90 out.

 

[1959chevybr]

Yep,, when I saw that it was factory 90 out, it defied all driveshaft protocol I had ever been involved with. I contacted Inland Driveline who is supposed to really know this stuff and they said put it back in phase.. so I did. I might need to find another front shaft and start over again with it 90 out. Originally 90 out is where I started with the vibration but there could have been something else wrong at the time. I appreciate all your input.. I really feel like I am on a deserted island.

 

[61BUBBLE348]

I have my 61 lowered in the order of 3" all the way around trans is 700R, so tailshaft had been shortened when I got the car some 10 years ago, when I first got the car I lowered it and got the angles close enough for most driving but I had a slight vibration with this at around 90, I had the tailshaft re-done and balanced recently as I went on a 2,500 mile trip, the previous owner had shortened the shaft and used the 700R yoke and part of the shaft and welded it to the much smaller diameter original front shaft, this caused the slight out of balance.
I suppose what I am trying to say, is if you get your angles close to spec, and you still have a major vibration something else is going on.

 

[1959chevybr]

You might be right on something else going on, just cant find that gremlin.

 

[La Hot Rods]

Can we get the full history of your build to give us eyes to these word.