Another Tailshaft Woe....Please Help

[Surfin Alec]

Since the Surf had its SAS and the rear got lifted to 4" over standard. It has a bad tailshaft vibe that I can't get rid of.
I had another shaft in the shed so I got a fully rebuilt double cardin put in and ballanced (twice).
Its length is about 1150 ish.
Under acceleration untill about 50 ks it vibrates (enough to let you know its there) but then at around 110 - 120 k its terrible.
Want to do a raod trip around Easter to QLD and its killing me.
I got new tyres and rims this week cos I thought that might help, no different.
The double cardin gets quite hot after driving and now the spline has got a small amount of play (I think its worn due to the vibe that wont go away).
Any help appreciated as the missus is giving me hell as its her daily driver. Is there a tail shaft wiz that I don't know about in Sydney?

Cheers ,

Alec

[bogged]

gearbox/transfercase spacers like they do on GQ"s??

[Busiboy]

got a side shot of it?

what the hell is SAS? I don't know

Offroad industries in Silverwater helped me out with mine.

EDIT:

isn't it on arse about?

take that purple thing off, it won't be helping either

[Surfin Alec]

gearbox/transfercase spacers like they do on GQ"s??

I have packed the box down with spacers by 20mm allready at the g/box X-member. Forgot to mention.
How low can you go?

Thanks,

Alec

[Surfin Alec]

got a side shot of it?

what the hell is SAS? I don't know

Offroad industries in Silverwater helped me out with mine.

SAS is solid axel swap.

Alec

[Busiboy]

thanks been driving me mad!

[bogged]

Are the uni's in good shape, were they replaced??

[Surfin Alec]

Are the uni's in good shape, were they replaced??

All new unis. The double cardin was totally rebuilt (allmost $300).

Cheers,

Alec

[bogged]

has it happened since the SAS, or sicne the 4in lift, or was done together.


maybe get on a hoist, and in gear, see if you can see it out of wack, maybe the union join of the shaft and diff is bent?

[Surfin Alec]

has it happened since the SAS, or sicne the 4in lift, or was done together.


maybe get on a hoist, and in gear, see if you can see it out of wack, maybe the union join of the shaft and diff is bent?

SAS and lift was done together.

Whats the union join?

Alec

[shorty.mqute]

i would have said it was on back the front to mate, ?? but i know kuf all bout this, only that mine on the lux has the extender bit closer to the top end i think, cheers

batesy

[bogged]

Whats the union join?

Im not sure what its called, btu the plate that the tailshaft bolts to thats actually on the diff.

Everythign is aligned up correctly isnt it? EG The Diff is in straight? if its out of line, theres your problem.

Makes it a little harder with the lift and SAS done at one time :( so you dont know which one is the issue.

[RUFF]

Your pinion is too low. If you are running a DC joint you need to point the pinion straight at the back of the Double Cardan. Otherwise remove the double cardan and from the looks in those pics it should be fine.

[Surfin Alec]

i would have said it was on back the front to mate, ?? but i know kuf all bout this, only that mine on the lux has the extender bit closer to the top end i think, cheers

batesy

Correct, until you get a doublle cardin joint, then the extender bit (spline)goes at the diff end.

Cheers,
Alec

[RUFF]

To fix the pinion you need to either lengthen the uper arms or shorten the lower.

[DaveS3]

Have you looked at getting a high pinion diff centre?

That would lessen the angles on the uni's.

Dave

[Busiboy]

what ruff said,

still reckon you have it on back to front though

and ditch the pruple bit it isn't helping

[RUFF]

Alec trust me ignore anything others have said here and try what i have said.

A High pinion diff wont make any difference to the vibes if the pinion is still pointing lower than the DC joint. And the high pinion Diff will most likely fail in the rear in any case.

[Surfin Alec]

Your pinion is too low. If you are running a DC joint you need to point the pinion straight at the back of the Double Cardan. Otherwise remove the double cardan and from the looks in those pics it should be fine.

When I replace that shaft with my old standard shaft (no DC) the viration changes (as in what speed it vibrates) but is still there.

When the SAS was done the top trailing arms where extended to try to point the pinion higher.
Is it enough or do the top arms need to be longer, or how can the pinion angle be changed without cutting off the spring mounts and re-welding?

Cheers,

Alec

[RUFF]

what ruff said,

still reckon you have it on back to front though

and ditch the pruple bit it isn't helping

The shaft is in back the front but if it was the other way the DC joint would be exposed to rocks so it needs to be fitted this way. I always fit tailshafts this way wether they have a DC joint or not as the slip joint usually handles rock impacts better than the Tailshaft Tube.

[DaveS3]

A High pinion diff wont make any difference to the vibes if the pinion is still pointing lower than the DC joint. And the high pinion Diff will most likely fail in the rear in any case.

Cool, Didnt know that.

now i know (No HP rear)

[Dozoor]

Yep you can just make it out in the pics , Ruff is Right Alex .

[RUFF]

When I replace that shaft with my old standard shaft (no DC) the viration changes (as in what speed it vibrates) but is still there.

When the SAS was done the top trailing arms where extended to try to point the pinion higher.
Is it enough or do the top arms need to be longer, or how can the pinion angle be changed without cutting off the spring mounts and re-welding?

Cheers,

Alec

The pinion may actually be too high then for just 2 unis. But its still too low for a DC joint. But i do see what you are saying about the spring perches. But im sorry there realy is no other way to fix this. Other than lowering the Tcase more but they you will have more trouble with the front shaft.

[Guy]

In those pics, to me it looks like the shaft may be a few splines out, so your Uni joints are out of phase, before you spend a cent make 110% sure that this is not the case, even one or two teeth out can cuase you big vibes ..

[Surfin Alec]

In those pics, to me it looks like the shaft may be a few splines out, so your Uni joints are out of phase, before you spend a cent make 110% sure that this is not the case, even one or two teeth out can cuase you big vibes ..

Checked and double checked.

Thanks,

Alec

[dave]

Is the purple rubber boot off a shock absorber because if it is that will cause major vibes to, they are made of to softer rubber and fling around.
Ruff is also very corect with the pinion angle. If running single unis at either end 10 degres at either uni is recomended as a max angle.

[pjhsv]

The pinion may actually be too high then for just 2 unis. But its still too low for a DC joint. But i do see what you are saying about the spring perches. But im sorry there realy is no other way to fix this. Other than lowering the Tcase more but they you will have more trouble with the front shaft.

I know bugger all about this, but i'll have a crack anyway..... If the angle is too big for no DC joint....but too small for a DC joint...would taking the xfer case spacers out and raising it back up again increase the angle a bit, and make it not vibrate with the DC joint?

Like I said..I know absolutely bugger all about tailshaft and universal joint physics, so ignore me if i'm way off track.....

Paul

[Wendle]

you most definitely need to take the angle out of the uni at the pinion end. it looks like the spring mounts will be fine. you only need a few degrees of change. the car will probably look a bit better if you do this by lenghtening the top links. with 4" lift and short links the rear wheels probably already look tucked forward.

EDIT: just noticed your shocks mount behind the axle. make sure the bodies of your shocks still have room to move after you do this..

[roadrunner]

It may be just me but I don't think your T-case and rear diff are aligned properly

When you adjusted your control arms, was the diff alignment checked afterward?

[Surfin Alec]

Well today I swapped the old shaft back in and went for a drive to reassure myself that it still vibrates. It vibrates less at low speed then the DC shaft but over 100 holy cow hang on. My 1 yr old could hardly keep his eyes open as he was shaking that bad in the back.
So as I was swapping the shafts back I decided to check the flange plate on the transfere by putting it in drive and spinning it. There is a about a 0.25 - 0.5 mm wobble in the plate when spinning. I tested this with a screw driver on the edge to the plate.
I had the flange plate made up out of 2 (1 the original and the second the front flange of a tranfere) to bolt up tp the double cardin shaft as the double cardin is wider than the original shaft.
The flange was all welded then machined but I guess you cant laithe the whole face plate flat because there are holes in it and how do you machine a plate with holes??
BUT bear in mind that the reason I had this flange made up is to fit the DC shaft as the vibration was that bad before I went down that road.
So I guess I will have to get the top trailing arms lengthened to correct the pinion angle first then see where I stand.
And yeah I did take my purple boot off the slip jpint...no difference unfortunately.

Thanks for your replies guys as I have to sort this out. Its doing my head in,

Alec