Hi Lads,

maybe someone has a bit of advise here

some of you might remember that I have some bad vibration at ~50mph and wanted to balance the driveshaft myself.
I had the car jacked up at rearaxle yesterday so I was able to 'drive' on the pit.
One little things I found was the header touching the bellhousing at alternator, so we bent that in a bit which helped generally, but the rest of vibration is definetly speed related.
It's at ~50mph no matter what gear. 5th gear at around 1700rpm and 4th at ~2200.
So what I've done was to use a piece of chalk under the rotating driveshaft. if the shaft is out of balance you will have those chalk marks going about the quarter of the circumference.
I did that front and back. I taped nuts to the shaft at the exact opposite side where I had the marks (half a rotation).
Even though it seemed to get better under the car: I made a new chalkline under the rotating shaft and it got almost 3/4 of the circumference and moved a bit (which kinda tells me its more stable).
Buit my pal sitting and driving the car advised it actually got worse.

So I removed all my temporary weights again. drove again to see how that goes and then I rotated my shaft by 180 degrees. which again made matters worse.

I inspected the shaft itself and found that I have a little play between the 'ears' of the shaft.
What I mean with that is that the u-joints are using inside snaprings and I can move the joint from side to side (only a tiny bit). Lets say 1/64" ? couldn't measure. it's not much but you can feel and see it
This I have front and back.

The main question I have is: if i rotate the shaft by 180degrees then shouldn't this rather indicate that the u-joints bad rather than the shaft itself?!

Any advise on what to try next?
I have the following options:
a) take the u-joints out, whack the driveshafts ears a bit so u-joints will be a tight fit in there
b) i found a shop in Dublin that would balance the shaft for 120USD!!!! (insane money for this work). go for that and get new joints
or
c) forget about it. call dennysdriveshaft.com and get a new aluminum shaft with front yoke. balanced and all for 400USD not including shipping to europe.

I don't really want to go for a new shaft since I had ordered already several u-joiunts and even got a used shaft from eBay (the one I'm driving now). But i'm just sick and tired of it ..
the amount of time I spend on this problem is unreal and I don't want to brake my new gearbox or rear axle with stupid vibrations. SIGH!

 

I don't think that any movement should be seen. It would be nice if you had another drive line to swap with and see if it ran smooth. Not only does the driveshaft have to be in balance, it needs to be exactly straight, or it will wobble. The shop I use when cutting or making a drivshaft do both (they do work for a NASCAR team). When straightening, they heat an area up with a tourch and apply a wet rag. The tube will move. They may do this several times to get it straight. Once they do that, they will spin it on a balancer and apply weights where needed. So far their work has been perfect. One other issue may be something in the tranny out of balance. You can easily check that by not hooking up the shaft (make sure the yoke don't fly out). Heres some info I copied off the net.
1) Before pulling a suspected out-of-balance driveshaft, check to
make sure the u-joint is properly positioned in the yoke. Some
yokes have small tabs that the u-joint caps must be indexed
behind to hold the driveshaft in the center of the yoke. If you
removed the u-joint caps for any reason, did one of the needle
bearings fall over when you put the cap back on? This little
oversight WILL cause a bad vibration (I have had this happen).
2) Before pulling a suspected out-of-balance driveshaft, check the
runout of the shaft with a dial indicator. If runout is ok (about
.012”) at the front and not the back, it could mean that you have
a bent yoke or pinion. To check this, record the runout amount
and mark where it is high and low. Now remove the driveshaft
from the rear yoke, rotate it 180 degrees, re-install it and recheck
runout. If it is the same amount and it is high and low in
the same locations, the driveshaft is the problem. If it is the
same amount, but the low and high spots have changed places,
you have a bad yoke or a bent pinion.
Good luck.

 

Over the past 8 years or so of trying to help people over the internet I generally state that solving noises and vibrations via a discussion forum or email is at best very difficult but usually impossible.

In this case it has seemed possible because you are obviously a savvy and determined guy. You have described things very well in all your posts. One thing that you did not mention in the above post was if you were doing this with the wheels off? If you were then I am completely convinced that the problem is in the driveshaft.

Now, the 1/64" play that you speak of, does this mean that the cups move easily back and forth in the yoke? If so, that is NOT good and is very likely at least part of your problem. Driving the "ears" closer together is a bad solution.

Due to the number of front engine, rear wheel drive cars in the US, most every town of any size has at least one good driveshaft shop that could replace a yoke, check balance or whatever and could pinpoint the problem and correct it in short order.

I have done at least as much European car work over the years as domestic. It shouldn't take too much imagination to know which brand Euro car by looking at my moniker. That said, I know that the typical European driveshaft has many differences from the heavy, US counterpart. I expect that there are not a lot of driveshaft shops in Europe that would find much familiarity in this driveshaft.

All that said, it sounds as if you are faced with getting a known good driveshaft from the US. I know that you probably feel that you are throwing good money after bad, but I think it's your most effective way to deal with this problem and get it behind you.

Good luck,

 

thanks a million for info. great idea. friend of mine drives a 66 stang with auto trans. That's the shaft I originally bought on ebay. So maybe I can convince him to borrow me his shaft (which is good) and put that into my car.
On the other hand: the T5 is rebuilt by someone who actually does know what he's doing and every single part in the rear axle is brand new (bought brand new diff). The only parts that are not new are the u-joints and shaft ... so I guess that really must be it.
Maybe this is a good excuse to buy a dial indicator (don't have one ...) and thanks for your response. I see exactly what they meant with high/low measurement. as well I'll recheck on my u-joints (for any lost needles or similar)

can tell you i'm quite sick of it ... it's a neverending story. spend so much money on the car and it actually drives worse than before. performs great but the vibration destroys all fun you might have driving it

Kalli



Kalli

 

I COMPLETELY understand how you can get sick of a car in such a situation. Driving a car like this requires a certain mindset. You must realize that you are dealing with a 40 year old vehicle. That means 40 year old technology and no abundance of parts availability at your local parts store. That one is compounded for you being on a continent where such cars are not common.

My advice is to be patient, do what you need to do and you will be enjoying the car again.

You have already exhibited a massive amount of patience so hang in there.

 

i can't spend much more work on that. i have so many little projects going on for it. I have a new set of pony seat upholstery that a friend got at a swap meet to go in, i have to fix internal door issues (i have the parts for it) as well as parts for front suspension. it's all work i'm looking forward to do but have to postpone until I have the vibrations fixed.

My rear leaf springs are fried and I have a set of nice 5leafs to go in. So i will put them in, measure all distances etc and order a new fantastic alum driveshaft.

I know hat I could sort it if I hang in there, but if I'd charge myself 30$ an hour this would have paid for 2 shafts already. disgusted with a failure to recognise problem straight away, but don't care anymore. I rather eat porridge for a month then having to go back to that problem again ;-)

so I'm putting the leaf springs in, doublecheck pinion angles and then I'll order.

mbdiag: i'm very very positive I'll enjoy driving that car again. It just seems the more new parts I put in the more old ones **** up. thanks for your words.

 

Hi guys I havent been on here from a while, but given winter is over here in Australia, its time to get the stang out from under cover again.
I had what sounds to be a very similar issue to you, where I was getting a vibration at about 59 Mph. mine seems to resonate in and out somewhat.
Anyway, i went down the path of repacing the yoke, and both uni joints, ans getting the whole assembly balances, but this did absolutely nothing to fix the issue.
I then read on this forum ages ago, that often when your rear trans mount is shagged can cause enough misalignment of the driveline, to give you this vibration. (the gearbox drops in relation to the engine mounts so in effect, the output shaft is pointing down.
I replaced mine, ($25) and bingo, no vibration.
Give it a go, for about $25 its woth a shot.

 

Hi fast, thanbks a million for that idea as well.
Gearbox is professionally rebuilt and the crossbrace the t5 is sitting on is brand new as well

what you indicate seems to be related to wrong angles of gearbox to shaft and shaft to pinion but i have measured mine over and over again. the spring perches were welded in wrong angle when I received it (pinion was pointing 4degrees down instead of up). So I cut the old ones and welded new ones on.

my leaf springs are 40+years old so I cannot drivbe with passengers in back. I bought new set of 5leaf mideye springs and I'll put them in on Saturday. I am convinced that the pinion angle will be different again after this swap.

So I'll wait until I have that finished, then re-check, re-measure and either:
- re-adjust pinion angle or
- order new driveshaft

I have 3 pints on lager that I will end up ordering that shaft ... unless a friend is willing to lend me his shaft to check

anyway. leaf springs first now

Kalli