Keep breaking universal joints

[kuchie]

Hi

Was wondering what people do to strengthen uni joints or some particular brand i should be getting?

I have a 7M-GTE on a toyota crown and since boosing it slightly the last uni joint thats just before the diff keeps wearing out and breaking.. the bearings turn into a nice grease/metal mix, roughtly every 3-4 weeks and thats driving rather sensibly. im not one to do burnouts n smoke it up or drifting.. but something needs to be done.

Most of the tailshaft is still original crown, just the yoke and a bit on the front was modified to fit the turbo box!

I really thought the diff would be gone already but 6 months of being on the road its still doing fine, but hopefully a torsen will help it stay on the road a little more. need to fix the tailshaft first

Michael

[30psi 4agte]

How many have you been through?
Who replaces them?
Is the alignment of the tail shaft to the diff o.k I.E the uni dosent sit on an angle when the cars on the ground?

Checked all the bushes in the back? diff not moving around?
Sorry for million Qs but strange to go through unis so quick! something major must be wrong.

[oldcorollas]

what angle is the uni joint on?

there is an ideal angle, above which wears really wuickly, and below which, wheres quickly in one spot.... i forget the angle tho...

that would be first thing to look at

[takai]

I believe it is like +/- 10* or so, from memory. Then again im quite tired/tipsy and could be wrong.
Besides, jsut replace it with a single piece.

[rolleraction]

Excuse my ignorance, but it it leaf of coil sprung rear?

[kuchie]

Well i had new genuine toyota bushes put in the back on the control arms.

It has coil springs in the back.

All this started when i boosted the car, it has a tremendous increase in power but yeak this problem is annoying. if i run it stock all is fine.

Attached are pictures.. both are at different times that i have replaced them.

Anyone i could take it to? or should i get a stronger tailshaft?

It is at an angle when it is on the ground as the tailshaft goes up towards the centre bearing.

http://www.users.bigpond.net.au/mkuc.../unijoint2.jpg

http://www.users.bigpond.net.au/mkuc...s/DSC01409.jpg

http://www.users.bigpond.net.au/mkuc...s/DSC01411.jpg

[oldcorollas]

dumb questions..

each time, you replace bearing cups AND pinion (whatever you call the cross bit )
i assume you did cos they come as a kit..

when they failed, you replaced the yoke that you show pictured??
i assume you may not have...
the problem could be that the yoke is bent, and so the bearing surfaces are not parallel to the pinion and thus bearing dies in arse quick.

check the angle at each uni joint, when installed in car and check that against the ideal angle... too little and too much are both bad..

other possibility is that the yoke you picture is twisting and binding the bearings.. perhaps it has a crack in it somewhere?

Cya, Stewart

[Earlyrolla]

Has the centre bearing ever been replaced?

Agree a one-piece tail shaft would be better.

Was the front of the tail shaft properly modified and the tail shaft re-balanced?

[YelloRolla]

the relationship between the uni joints is more important than the angle it is working on - unis will work at varying work angles (within limits) without failure. As the rear has not been modified (from what I can gather), and assuming Toyota knew what they were doing, then I wonder if the rear tailshaft has been twisted.
If it were twisted, then the clocking of the joints will be out, meaning that when the shaft rotates the unis don't roll smoothly.
As an expansion to what Earlyrolla has written - there must be some vibration or associated noise that gives clue to the problem existing prior to the failure (possibly the centre bearing).
I have only replaced my first unis at Christmas - over 5 years of service and I replaced them for piece of mind.
FWIW I use Spicer - the solid ones that are for "LSD equipped vehicles" or some such sod.

If I were you, and I couldn't locate the problem, then I would take it to a driveline shop; the associated cost would probably be cheaper than numerous unis.

[kuchie]

Hi,

Well the last pic i DID replace the joint from my spare crown.

The original yoke on the gearbox side had been changed and rebalanced by a tailshaft specialist with all new joints and a new centre bearing, as well as being balanced. Done 2 years ago but only been on the street since october.


Any ideas on the recommended angle?

Failure is usually assoctiated with a rattling / vibrating noise about a day or 2 before hand.
Problem at the moment is that it is my daily driver and trying to keep it on the road till i can afford time without it.

I replace the cups and pinnon thingy as a set and regrease it with the supplied grease nipple and that

[Earlyrolla]

The angle of the diff should match the angle of the motor. The universal joints allow the rotation to be transferred along two parallel planes that are offset by some amount. Does that make sense?

When looking at the car from the side the engine and gearbox will slope down towards the back of the gearbox and in turn the front of the diff will be pointing slightly upwards. So if you drew a line through the centre of the diff along the car and the same through the gearbox you should find they are parallel but some distance apart from each other.

The pinion angle may be varied slightly to account for loading of the diff, which when loaded the diff should end up on the parallel plane to the centreline of the crankshaft/gearbox.

[Earlyrolla]

It could (only speculation here!) be the case that under high load the tailshaft flexs the centre bearing enough to create some funny angles on the tailshaft, putting it out of alignment in two planes, i.e. left to right as well as up and down. This would kill uinversal joints...

[YelloRolla]

The tailshaft modifier may have f*cked up somewhere. When you say that "it has been on the road since October", has it been experiencing the short universal life from day 1? (failed at Uni!?)
If that were the case, then I would be taking the whole shebang to another driveline place and asking them to look over the shaft and offer any reason for why it keeps failing.
Has the centre bearing been installed up side down? This still shouldn't kill unis as quick as you're experiencing.

It could (only speculation here!) be the case that under high load the tailshaft flexs the centre bearing enough to create some funny angles on the tailshaft, putting it out of alignment in two planes, i.e. left to right as well as up and down. This would kill uinversal joints...

Again it still should not kill unis that quick.

[kuchie]

Well the bearing was put in the wrong way first time and the way its been made it wont bolt up casue it has a flange bit on one side and doesnt make it fit,

Been on the road since october, and there has been no problem until i boosted it. broke it the first night was trying to calibrate the boost controller.. only problems since then.

well im running it standard boost until something works out.

[YelloRolla]

It won't "work out" and the problem is not boost related. You will need to systematically go through the suggestions above. Going well until you boosted it? This is a little hard to quantify - if it were going well since October 1995 then this may be a point. I really think that you need to take it to a driveline place - and maybe NOT the one that did the job initially.

I am assuming that the diff pinion bearing is o.k or the diff would have shat itself by now, but it's worth a look.

I don't entirely understand what you've said about the centre bearing?