tailshaft centre bearing probs

[wildss]

mods, please dont delete or move this right away cos i need an answer quickly thats why its here.

ok this morning the vn did yet another centre bearing in the tailshaft, this is the third one in under 20k, maybe even 10-15k.
notthing has changed inbetween bearings either.
i marked the shaft before i split it and its all good for a bit then bam....gone again.

this morning was an unuaual one, it started going off its head then came good every now and again.

im about to order one along with sme new uni's but i was wondering wtf is causng these bearings to let go?
bad batch? is there a certain brand bearing/uni's i should be buying?

ive had enough of thsi **** with bearings and diff probs (and its not like i fang the living **** out of it anyway) and ive started seriously contemplating a 9 inch/one piece shaft setup but id like to avoid it if possible right noe cos funds a tight

any help appreciated
cheers

[Calaber]

Is there any chance you have a bent tailshaft, front or rear? Do you encounter any sort of vibration through the car when the bearing is in good condition? Is the centre bearing mounting bracket bent or out of alignment? What condition is your rear transmission mounting in?

[Emackulation]

Is there any chance you have a bent tailshaft, front or rear? Do you encounter any sort of vibration through the car when the bearing is in good condition? Is the centre bearing mounting bracket bent or out of alignment? What condition is your rear transmission mounting in?

Thats what I was thinking.

[wildss]

not sure about shaft being bent, car hasnt got massive hp so i doubt it, not sure about the gearbox mount though.. could that be the cause of my poblems?
spoke to ailshaft joint just then and for 220 ill get a one piece shaft made up using my yolk, new unis etc.
is that a fair price?

edit: yes there is a light vibration when bearing is new

[DANNY8]

I'd grab a 2nd hand tailshaft ($50-$100 I rekon), which should come with a centre bearing and uni's anyways.....then if it kills that one u know it's not the uni's, centre bearing or shaft itself. I got a 1 piece shaft in my VB and it's a bitch....I got lowered springs all round, and I can only have 2 people in the car, even if a midget gets in the back I can't go anywhere coz the tailshaft scrubs on the floor. Even with just me and my bro it scrubs going over bumps. Chances are ur not as big as me or me bro tho so ya might be ok with it.

[Reaper]

As the others have said - something is amiss. I pieced a centre bearing together using the bits from 3 tail shafts and it has no vibrations at over 200 km/h. Dead centre bearing might be the symptom but something else may be the cause.

Reaper

[Emackulation]

My old VN sufered from a busted flex joint, but under further inspection we also found the tranny mount was vertuly non existant and causing vibrations to stuff the tailshaft.

[fnlow1]

Yep gearbox mount sagging will change the alignment of the driveline and put extra stress on the centre bearing. Lowering the car will compound the problem usually. The tail shaft yolk and diff yolk should have the same axis with the tailshaft essentially linking the difference between the two.

[fnlow1]

http://www.drivetrain.com/driveline_angle_problem.html

[ephect]

check where your putting the centre bearing mount spacers.. u can change the geometry of the tailshaft by placing them between the body and centre mount, or between the bolts and centre mount.. make sure u get it right.. this could be the cause also.

[Not_An_Abba_Fan]

Misalignment of the two halves putting the shaft out of balance is my bet. Not only do you have to get the 6 bolts back in the same position, but you also have to have the splines back in the exact same position as well. Just put a new bearing in and then get the whole shaft balanced. A cheaper option may be to just get another tailshaft and fit new uni's and a bearing making sure that the spline and the casing are all marked.

[wildss]

cheers for all the replies fellas but ive gone ahead and told a guy to make me up a 1 piece shaft.
ill have to mod the floor but im ok with that.

i think the cause of failing centre bearings was a fuct centre cv joint, it was dry and the bearings had notched into the casing causing heat spots etc.

edit: i priced a cv joint and that was $246.84 and new unis would have been about 60 and balancing about the same.
new shaft is going to cost me 220 with new unis and a bit of my time to mod the floor and make up a tailshaft loop