Diff Trouble - I Think

[Man3 0]

A few weeks ago my car started making a knocking noise that sounded very much like a CV joint, I was a little suprised as neither shaft is particularly old but none the less i thought nothing of it thinking i'd get a new shaft sorted out once i'd established which one it was. Then the noise stopped.

 

The next time the noise resurfaced it was quickly followed by violent snatching of the steering, pulling the car to the left each time i backed off of the throttle, this was accompanied by a loud banging/clunking noise. Each time i backed off it didn't just snatch the once, it was more of a repetitive action which only seemed to stop once the throttle was depressed again. As soon as i got the car home i checked the transmission fluid level and it was a little low as it appears the casing has been weeping slightly. I topped up the fluid and it has been better since.

 

However, it is still not right, ever since the top up it has still occasionally pulled the steering hard accompanied by a loud bang when i manouver the car and over the last couple of days it has become more and more frequent to the point where it does it near enough everytime i manouver the car and it now seems to be accompanied by a rattling noise.

 

I'm thinking its something to do with the diff, anyone agree with me? Could it be knackered bearings creating play in the diff? Or is it something else?

 

Cheers

[welshpug 1,661]

sounds like shot suspension bushes or a balljoint to be.

[Man3 0]

Definately not either of those as it is repetitive knocking/banging/tugging when you back off the throttle. Bushes/balljoints would just cause it the once as they took up whatever slack they had present and it does it a really low parking speeds. When it happens there is a lot of force coming back through the steering. I'm 99% certain its transmission related.

 

Its a real loud metallic sounding banging/crashing noise.

[welshpug 1,661]

did you drain the oil in the box or just top it up?

 

if you drain it thatll give you an insight into whats going on in there, someone I know had a similar noise on his 306 but wasnt getting the odd driving.

 

if the oil comes out full of metal its quite likely that its going to die soon.

[steve@cornwall 100]

Definately not either of those as it is repetitive knocking/banging/tugging when you back off the throttle. Bushes/balljoints would just cause it the once as they took up whatever slack they had present and it does it a really low parking speeds. When it happens there is a lot of force coming back through the steering. I'm 99% certain its transmission related.

 

Its a real loud metallic sounding banging/crashing noise.

 

I've got similar on the cti when braking- track control end is fubar- allowing the wheel to wobble

[Man3 0]

Thats a possible, but i'm not sure it would explain the noises i get that are similar to a fubared CV joint. I've just been out in it and it seems to do it most when turning right. At the moment it makes a really loud bang and snatches the steering when turning at low speeds and at higher speeds i.e. roundabouts it soundmore like a cv joint and there's no kick back, but as i said, on occasion it will knock and bang at high speeds as well.

[axnutty 10]

I had a very similar thing on an old AX race car. It almost felt like someone was locking up a brake caliper on one side momentarily and snatching the wheel. I only drove the car for a couple of hundred meters trying to establish what exactly was going on. Was very strange feeling. It only seemed to happen randomly and for some reason at low speeds was a lot more pronounced - but that could of been as I was only feathering the throttle...

 

I was doing a lot of work on the car anyway and just replaced the gearbox when I was rebuilding it, which sorted the problem. I would guess, as you say, something locking the diff through wear or debris I dont know. Ive still got the box kicking about somewhere but Ive never stripped it to diagnose it.

 

Dont know if thats the same thing youve got - but sounds like it could be similar?

[Man3 0]

That does sound a lot like what i have. I'll try and find some time to drop the diff out. Once its at speed and going in a straight line it seems to be fine at the moment. The only time its ever really done it in a straight line was when it was low on fluid a few weeks back. Some of the internals are tting on a bit now, the 1.9 ratios and casing have done approx 75k but the diff and cwp is unknown but i'd say they've done at least 115k. Does anyone have the part numbers for the diff bearings? I don't really want to pay through the nose at pug if i can go elsewhere.

[steve@cornwall 100]

May be worth pulling back the gaiter on the inner c/v joints and checking the grease has no swarf in it, as your later description also sounds like a deteriorating roller race on the "tripod"- a two year old c/v I dismantled for a recent mot had all the (sparse) grease baked onto the rollers, gaiter was fine. after cleaning,greasing and re-assembling I now have a noise like a dry wheelbearing coming from that side, although I also replaced with a s/h hub/bearing..... and the characteristic knock on full lock. (not the cti)

[Man3 0]

Ok, i'll look at that too. I'm gonna get the diff out and change the bearings anyway i think, so i look at the shaft while its out as well.

 

Can anyone confirm the part numbers for the diff bearings? I've done a search and have come up with 2 numbers:

 

LA Timken JL69349A

SKF JL69310

[Man3 0]

I've just checked both the SKF and the Timken websites and the bearings seem to be the same size and spec.

[B1ack_Mi16 67]

This sounds like my 405 Mi16.

 

A tooth had broken off the final drive, and fell into the diff.

This had made the diff gears get _very_ worn. And at last it would slip and made loud banging noises and pulled hard in the steeringwheel.

 

This is the missing tooth from the final drive:

http://cortex.fa-s.ntnu.no/~kristian/knekt.jpg

 

And this is how the small wheels in the diff looked like!

http://cortex.fa-s.ntnu.no/~kristian/difftannhjul.jpg

 

More or less 3-4 teeth completely gone on each of them, no wonder it would make banging-noises when it slipped.

[Man3 0]

I'm not sure whether to thank you for showing me those photos or not!?! I'll get the diff out asap.

 

Cheers guys.

[Guest purpletoddy]

could it possibly be the strut top bearings???? just a thought......my astra derv does the same as what you have stated and just changed the strut top mounts today and its like a new car....well.....maybe not!!! lol

[Man3 0]

They're new, well one side is and the other side isn't that old. Fubared diff seems to be the likely culprit as i suspected. Brilliant!

[hengti 2]

When you say the CV joints aren't that old, have they actually been renewed on the old driveshafts?

 

I had very similar sounding symptoms after renewing an outer CV boot - I'd taken the CV off to fit the boot and had managed to damage the circlip whilst putting it back together - part of the circlip had snapped off and made its way into the CV joint.

 

I think that Steve has already suggested a similar possiblity - just adding a note of my own.

 

ed. just re-read - sounds as though you renewed the complete shafts - ? i'd say it's still worth checking before gearbox/diff surgery anyway

Edited December 28, 2006 by hengti

[Miles 331 1 Cars]

The sun & Planet gear's as in that pic do have a habbit of breaking up but normally do it in style and pay the road a visit along with a oil slick 50% of the time,

If you have any problems getting hold of bearings let me know as I keep them in stock, but they rarely wear out that much