Differential or wheel bearing, LSD?

[Timmygti1.8t]

Hi guys, i need your knowledge and expertise please, i'm a member of quite a few VAG related forums and nobody seems to be able to shed any light on this so a fellow VwAudiforum member suggested i try here :Blush2:


I have a mild problem with my Golf mk4 1.8t at the moment, i'm taking it to the Nurburgring in a few months and want it all sorted for that abuse.

When accelerating and turning right at the same time i get a kind of hollow rumbling/grinding noise, its very obvious when going round roundabouts, it also does it a little when turning right in gear and decelerating.
.
I can however hit the same right hand bend/roundabout as fast as i like without having it in gear and it makes no noise, i did think it might be wheel bearings and have replaced 1 front left and both rears so far but now i'm thinking its not wheel bearings, especially as it only happens when in drive/gear.

Gearbox and dogbone engine mounts have been replaced, all the suspension is new, shocks, springs, arms, bushes, roll bars all new. i even replaced the outer CV Joint on the front left just incase (the corner under load when it happens) i also tried a different set of wheels/tyres and i cannot see any rubbing anywhere.

So i'm thinking the only possibilities now are,
The last wheel bearing not replaced yet on the right hand side?

The CV joints, both inners and the right outer? left outer already replaced, but normally CV joints make clicking noises.

The Differential? or gearbox? bearing in mind it does not happen when accelerating in a straight line or accelerating and turning left. it also does not happen when out of gear. If it is the diff atleast i could put an LSD in there to make it worthwile.

Any ideas please? i'm pulling my hair out and i didn't have much to begin with http://www.vortexmediagroup.com/images/banghead.gif

[Crasher]

Is it lowered and what year is it?

I doubt it is the diff itself but it could be the diff side bearings.

[Timmygti1.8t]

Its 1999 year and It is lowered ,30mm on Eibach with Eibach Roll-bars and Koni shocks.

[Crasher]

Is the Eibach front bar the normal uprated version or the one for lowered cars?

[Timmygti1.8t]

Good question

Its part number E40-85-005-01-11 front and rear kit, i was under the impression they changed the design years ago and made the hoops bigger, so if you had the old kit, small hoops, hit driveshaft, new kits, big hoops, clear driveshafts. i bought mine end of 2007

[Crasher]

No, you can still buy both and that is the deep hoop kit BUT I have still had instances of that bar rubbing on the drive shaft but only on the left side on cars with the thick left shaft which yours should not have. It is easy to check for this, the bar leaves marks on the shaft. Also I have seen the shafts rub the inner wing chassis leg just behind the forward sub frame mount and this was especially a problem on lowered cars built before 2000 when they appeared to have altered the construction method. The rub point is very small and often only a few millimetres in diameter so needs a close look to spot. The only cure is to grind the welds back and then, err-adjust-the area with a large tapping stick and big bar!

[Timmygti1.8t]

I was quite pleased i managed to find the reciept, i thought it was the bigger hoop bar.

I do have the large left hand driveshaft though, its huge and varies in width in various places, i have had a good look around when it was on a ramp and couldn't see any rubbing marks, i might have to have another closer look just to make sure, especially if you think the mark it makes could be that small. I hope its something that simple, Differential problems sound expensive :mad:

[Crasher]

I think I have a pic of the impact point on my work PC so I will look tomorrow. If you look at the drop down section from the chassis leg which is the pickup point for the front subframe mount, the weld for this pickup to the leg can be rather big where it ends and this is exactly in line with the shaft and even a slight rub makes a terrible noise.

[Timmygti1.8t]

Thanks for that, a piccy would be ideal if you can, then weather permitting i'll have another look tomorrow, hopefully i'll find something because that would be a nice easy fix in comparison, but i have had a good look around already for rubbing marks and didn't see anything, although my last look was not quite this specific, otherwise its back to the drawing board.

[Timmygti1.8t]

Would you still think the driveshafts could be rubbing only when in gear and accelerating? surely the driveshafts turn regardless and would rub based on just the steering turning and cornering force rather than power being applied? i'm just thinking theoretically but you may have 1st hand experience that it happens?

[Freakydeaky]

Have you fitted new engine and gearbox mounts? It could be pushing the drive shaft onto something whilst under load.

[Timmygti1.8t]

I have replaced both the dogbone and gearbox mount but not the main engine mount on the cambelt side, that mount seems ok though, i have tried putting it in 1st gear with the handbrake on and seeing if it moves excessively and it looked fine, could be the next thing i replace just to rule it out as there relatively cheap.

[Timmygti1.8t]

Come to think of it i do get a little vibration from the engine when stationary at idle but not all the time, maybe it is that engine mount gone, although i thought it might be the DMF but it does it regardless of clutch being pressed or not, so maybe not that, hmmmmmmmmm!

[Crasher]

No, not under acceleration, I thought it was only during cornering. Has the box been out or the timing belt changed recently? I can’t find the shaft to body rub picture.

[Timmygti1.8t]

Gearbox never been out, infact its on original clutch, turbo, engine and gearbox and its done 130k, timing belt done at 103k together with auxillary belt and all tensioners, pulleys and waterpump.

[Crasher]

Get hold of the inner CV’s and see if there is any play in the cups.

[Timmygti1.8t]

The inner CVs feel pretty tight, a tiny amount of movement yes, like 1mm, the Inner CVs are definately still a possibilty but i thought CV joints made clicking noises when they are worn.

I have just dropped the car down to VW for wheel alignment as it needed doing, not had it done since literally all the suspension has been replaced so it must be out, plus it will exclude tyre noise due to incorrect wheel alignment which has been suggested to me as a possible cause.

I also asked them to look into the noise, you never know they might work it out but its unlikely :zx11:

[Crasher]

Not from the perspective of the inner CV’s but from for play in the cups themselves which are supported by the diff bearings.

[Timmygti1.8t]

Not from the perspective of the inner CV’s but from for play in the cups themselves which are supported by the diff bearings.

Good point, i'll check that soon, noisy diff bearings could be the answer, would a molyslip additive help? or would it be pointless?

Its come back with its 4 wheel alignment done from the dealer, was way out, drives much nicer with the steering feeling better weighted and much more solid, the noise however, continues to persist, they said they couldn't get it to do the noise when they tested it and i should go out with a technician and show them, maybe its just the way i drive lol

Normally i would just keep driving it until it became blatantly obvious whats causing it but because of going to the Nurburgring again and knowing how much it stresses components i'm worried the problem will get worse very quickly, where i cannot fix it and it would make the trip a total waste, during normal driving and if your not trying to get it to do it the noise only appears every so often, but track type driving really highlights it.

[Crasher]

I have used Slick 50 trans oil additive and Red Line MTL for about 15 years as it actually seems to work. The 02J box (the same as yours) on my Octavia VRS was clunky and noisy when I put the new engine in and I was annoyed as had I known (I bought it blown) I would have converted it to 6 speed when the lump was out, even though the clutch/flywheel are a lot more. It has been perfect for the last 12K, now on 132K.

[Timmygti1.8t]

An additive has got to be worth a go then, its a cheap fix if it works and not much wasted if it does not, i'm pretty sure from our discussions its Diff bearing related but its pretty mild at the moment, maybe an additive can help it along for a bit longer :approve:

So many to choose form though, slick50, X1R, Molyslip to name a few

[Timmygti1.8t]

Well the additive made no difference.

Now i have had my tracking and camber etc done if i replace inner CV joints does that mean i have to undo the ball joints on the wishbones (3 bolts)? i can never get the ball joint off the hub itself, i dont want to put it out of line now i have spent £60 getting it done.

So can you do the Inner CVs out without undoing everything else on an AGU 1.8t 5 speed? whats the process? My inner CV boots are nearly perished so will need to have them off sooner or later.

Thanks

[Crasher]

Avoiding dropping the bottom ball joint out of the wishbone would be a real pain when doing CV’s, it is the way you do the job. Scribe around the bolt heads but you MUST use new bolts and preferably replace the lock plate as well.