Driveshaft bolts keep loosening and clunking noise

[p0l1wrath 10]

Recently my VR started making a clunking noise when going on the power and slowing up, I had a good look around underneath and seen that some of my driveshaft bolts onto the gearbox were loose!

 

Got the car up and took them both out, repacked the cvs and put them back on the car and torqued them upto 40nm (found that torque in another thread) but some of them snapped as I was doing them up, I drove it home from my mates workshop and the clunking had stopped but halfway home the clunking started again

 

Plan is to buy 12 new bolts from vw (hopefully not discontinued) and torque them up again!

 

Anyone had this problem before?

Am I doing the bolts up to the correct torque?

 

Cheers

[MattPc 0]

Bolts should be a stock item as they're still used on current models. Make sure when you re install and torque the bolts up that there is NO grease in the threads, The correct torque is 45Nm (33lb-ft), and if you really want to be anal you can also lock wire them, but make sure that is done correctly.

 

Matt

[Stonejag 10]

I've snapped all the bolts off one side before. The noise it makes when they let go is the stuff of nightmares! :eek: You can't even limp it anywhere as the diff sends all the drive to the disconnected wheel...

 

Attempting to tighten a dodgy bolt will either strip the head or snap it, as you've found. Garage had no trouble ordering more, VW tend not to discontinue nuts and bolts with quite the same fervour as other Corrado bits. Lockwire's a good idea, wish I'd thought of that before refitting them...will be replacing them all every time they're removed though, just for peace of mind. Think they're about a quid each.

 

My theory is that the loose ones rattle around for a while (making the noise) before falling out (making them go quiet). When mine were first found there were only 3 of 6 left on some side - the remainder had heads so mangled they couldn't be tightened. The last three went while the bolts were on order :shrug: I'd had three instances of horrific rattling noises before so that must have been it - I was quite pleased as I was saving up for a gearbox rebuild which turned out not to be needed!

 

Stone

Edited May 27, 2013 by Stonejag

[p0l1wrath 10]

Cheers for the help guys, ive got 12 new studs and going to put spring washers on there with them, lock wire's a good idea but hopefully this will do the job, yeh then this dreading clunking noise will go!

 

Cheers

[Jim Bowen 1]

Do the 3 little plates that go between each pair of bolts help with this? or are they just for the hell of it?

[p0l1wrath 10]

Thats the thing, i dont even know what they are theyre for? they will be staying there on mine though, i order bolts with 3mm more length on them to account for my washers

[vw rule 19]

The plates that the bolts go through these are to make sure there is even pressure distributed over the inner CV joint when tighted up,

plus they act like a washer as well as the head on those bolts is small.

 

I've used lock tight also known as thread lock and never had a problem.

 

 

Hope you get it all sorted.

 

Si

[p0l1wrath 10]

The plates that the bolts go through these are to make sure there is even pressure distributed over the inner CV joint when tighted up,

plus they act like a washer as well as the head on those bolts is small.

 

Ah right assumed it was that,

 

Anyway replaced them over the weekend and still getting the clunk, although the new bolts have helped reduce it, which leads me to believe it is still a driveshaft problem?

What's inside the outer cv boot? Could lack of grease cause a clunk to come from here?

 

If anyone got any suggests that would be great wanna get this sorted!

 

Cheers

[vw rule 19]

The outer CV joints have a inner carrier which hold large ball bearings which rotate in reinforced recesses,

so only allow the outer joints to move roughly around 45 Degrees when going from lock to lock on the steering,

plus any movement with in the front suspension.

 

The inner CV joints have similar carrier and ball bearings but this joint slides in and out,

as well as a similar movement to the outer joint.

 

Normally when the joints wear out the ball bearings become smaller due to wear or the reinforced recesses loose there hardened lining,

making the joint rattle or knock when going from lock to lock when driving.

In some cases it can crack the inner carrier due to excessive play.

 

Knocking from lock to lock when driving is normally the sign of outer CV joint wear,

you should be able to hear this if you drive in a circle clock wise or anti clock wise in a large car park,

and constant rattle or knock when driving in a straight line is normally inner joint wear.

 

You can regrease the CV joint but it really depends on how warn they are,

don't use normal EP grease that you use for wheel bearings as this in CV joints will not work well,

as it's a thinner grease and won't take up all the play with in the CV joint.

 

What you need to use is the black Lithium grease this is really thick grease,

this is the proper stuff for CV joints.

 

Most people don't do this but I believe you are ment to remove the CV joint off the drive shaft,

and completely clean it out and re-pack with fresh new grease.

You can try to pack the CV joint with it still attached to the drive shaft,

but you won't be able to fill the joint up correctly it'll just fall back in to the CV boot.

 

Most garages do it this way as it's quicker but like I say you won't be able to fill the joint correctly with grease.

 

Also remember to release the pressure from in side the CV boot or it could pop off at a later date.

You do this once the joint is reattached to the drive shaft and the CV boot is fully fitted to the CV joint,

simply slide a flat ended screw driver between the boot and joint and lift slightly,

and you should hear a slight hiss as the trapped air is released, plus you may see one of the boots ridges pop back out.

 

 

Hope this helps.

 

Si :thumbleft:

[p0l1wrath 10]

Ok thanks that's all useful to know although neither of those seem to match my problem, my problem seems more load related, when I power on, I get a clunk, then when I slow, not always instantly on power off, I get a second clunk, there are always in pairs as if something moves out of place then back into place

[vw rule 19]

That could be a inner CV joint but it would have to be really warn out though to course that kind of noise,

plus it normally is a clicking / knocking sound.

 

What you have by the sounds of it is a engine / gearbox mount warn ?

Anti roll bar bush clamp lose ?

(I've had this, had to replace the bolt as the clamp had sriped the threads and fit a heli coil in to the chassis leg)

 

Sub frame bolts lose or bushes warn badly ?

Front lower ball joints warn badly ?

 

Has the car been lower at all or is it standard ?

It's just that you can get clunking noises from the lower wish bone arm bushes,

but this is normally when cornering or very agressive driving.

 

Also have you still got the balance weight on the O/S/F drive shaft,

as these can oftern work lose as they are only bonded to the drive shaft.

Mine worked lose so I cut it off as it was making a noise.

 

 

Si

[p0l1wrath 10]

I changed my gearbox mount a year ago, and checked/flipped the other two mounts 2weeks ago, I've got drop links ordered in ready for the weekend as I can't find them anywhere in the service history so I will check the other bushes and clamps then I crowbarred the subframe mounts also two weeks ago and they seems perfect, and same with the lower ball joints, yes the car is lowered, but the wishbones were changed last month for mot and have no memory of a balance wieght on the drive shaft? What does it look like and where is it? Deffinately nothing mo being about on it though.

[vw rule 19]

I think it acts as a counter weight and as a anti vibration damper,

normally they are fitted to the longest drive shaft of the two.

 

On some cars they are bonded and on others they are clamped and bolted on.

I think on some of the French cars like Renault & Peugeot they have a support bearing in the centre of the drive shaft,

which is attached to a bracket which is bolted to the engine block to keep the drive shaft central and balanced.

 

On the Corrado it's bonded to the O/S/F drive shaft,

it's roughly about 3 inches in diameter with a 3mm to 5mm thick outer steel ring sleeve,

the centre is made of rubber,

the whole thing just slides over the drive shaft and is bonded to the centre or just off centre on the O/S/F drive shaft.

 

What happens on the Corrado is the rubber in the centre of the damper splits,

which in time courses the whole thing to break off from the drive shaft,

the damper then is free to spin and move along the drive shaft which can sound like knocking / clunking,

as it's able to hit against the sub frame or chassis leg when your at 70 MPH,

or can happen when you throttle off and on when driving.

 

---------- Post added at 12:19 AM ---------- Previous post was at 12:17 AM ----------

 

I know you've said that you have checked the sub frame mounts,

but have you actually checked that the bolts are tight,

because there can be a lot of pressure or load on some of these bolts,

which when lose which doesn't have to be much, in some cases the bolt may only need a 1/4 of a turn or less.

 

What I mean is a slightly lose bolt can still allow slight movement with in a component when it's under full load,

but may still feel ok when being checked by hand.

Remember that there is a lot of weight that the front sub frame is supporting ( Engine, Gearbox, Steering Rack )

 

Did you also feel for any play with in the inner CV joints when you were bolting them back up ?

 

 

Si :thumbleft:

[Jim Bowen 1]

Never seen this damper on my driveshafts tbh

[Kevin Bacon 5]

VR6s never had them. You tend to only get them on 4 cylinder engines.

 

The driveshaft bolts shouldn't ever come loose and certainly not snap! Something seriously wrong there. How low is the car? Sump scrapers exert massive loadings onto the inner CVs which can quickly see off the diff bearings.

 

How much backlash does your box have? I.e jack it up and turn the road wheel back and forth. That'll make a nice clunking noise! Also check to see how far you can rotate the wheel before the driveshaft starts to turn. Check at the gearbox end too.

 

I think you have an external influence causing the bolts to come loose. As I say, on mildly lowered (~30mm) or standard cars, it's never a problem, or shouldn't be at least.

[p0l1wrath 10]

Well it used to be a sump scraper maybe a year and a half ago, before i bought it, then previous owner then raised it to an acceptable height, i dont know how low it is as ive never measured it, this weekend, its new drop links, check ARB mount bushes, and subframe torque settings, and repack out cv boots, if none of this does the trick then i really am stumped and maybe time for a new gearbox, or driveshafts, obviously ill check them first, no noticable pitting or damage to inner cv bearing though.

another thing to point out, when i removed the old bolts from the driveshafts they were all different, some had shrouds, some didnt and some shrouds were different lengths, not even sure if all were high tensile, so i can only assume this was the problem with them snapping and coming loose

 

Thanks for all the help so far, need to get this problem sorted!

[Kevin Bacon 5]

Ah, your last comment is making some sense now. Were they even proper VAG bolts being used? I kind of assumed they would be the correct bolts as it would take a grade A numpty to use any old random bolts that were laying around the garage!!

 

Did you say you're fitting new bolts at the weekend? If so, that may even sort your problem!

 

If not, I'm suspecting the sump scraping ride height might have left a last impression on your gearbox! Maybe the inner CV flanges not quite running true, which could eventually shake the bolts loose over time. It's hard to explain what a mean, but imagine a mexican wave of force being shunted down the bolts as the CV rotates. Hope that makes sense!!

[p0l1wrath 10]

I have already fit the new bolts, and it did make the clunk a lot less harsh, but it is definitely still there!

Yep im with you on the mexican wave, and would be awful it it is the gearbox :( so now i have a few questions concerning this damage

How are the gearbox cups held in?

Is the inside the same setup as push in driveshafts?

Can i remove the cups, and check the splines? (assuming the answer to the previous question is yes)

What would give way first male drive shaft cup splines or female gearbox splines?

Cheers

[Kevin Bacon 5]

IIRC, the gearbox output flanges tap onto the diff shafts over circlips. I would say the flanges are harder as driveshaft steel is designed to have a bit of give in it, so the shaft would wear first I reckon. With the inner CVs disconnected, try and wobble the flanges up and down to see if there's any play. If the diff bearings are worn out, there might also be oil dripping from the flange seals. If everything seems OK, there could be some internal damage.

 

Are the threads in the CV flanges clear? The bolts aren't binding or bottoming out are they?