Is my diff fubar'd ?

[bigdods]

Last 2 years I have had occasional knocking noises from the back , usually only when moving very slowly forwards (say in a traffic jam) . Noise is a clonk and repeats in time with the speed being travelled. Usually got to hear this clonking once every few hundred miles. Now it does it a lot more , on a 25 mile journey yesterday about half the time when i pulled up at a roundabout or set of lights it was clonk, cloknk, clonk, clonk. And one time it decided to do it at about 20mph , sounded like a machine gun (well a quiet one anyway). It seems to come from the n/s rear . I kept hoping it was just a driveshaft UJ but they've been checked a few times now and no fault found so I reckon I am heading for a diff refurb.

Also there is some slack in the drivetrain on take up , not much but enough to feel when pulling away.

Comments anyone ? Whats the likely cost of a diff refurb ?

Cheers

Dodsy

[thegman]

could be your suspension - what makes you think it is the diff?

[bigdods]

thegman said:

could be your suspension - what makes you think it is the diff?

Good point, I just assumed it was the diff. Excuse the stupid question (Im not the most mechanically minded person!) but which part of the suspension should I be looking at ? I can try adjusting the dampers to see if that makes a difference (I've got the rears set at 10 out of 12 clicks right now).

[GreenV8S]

Regular clonking/tapping noises that vary in frequency proportional to your speed, and come and go as you accelerate/corner, points strongly towards a damaged CV joint. These can't always be found statically as the damage may be on a part of the race that is only loaded under specific conditions.

[bigdods]

Am I correct in thinking replacing the CV joints on both sides would be a lot cheaper than having the diff refurbished ? Or are they part of the diff. See how little I know, without my bible in front of me I am a dunce !

ETA: Just trying to get an idea of the work involved and impact on my wallet before i call my favourite indie

Edited by bigdods on Tuesday 11th December 14:04

[That Daddy]

bigdods said:

Am I correct in thinking replacing the CV joints on both sides would be a lot cheaper than having the diff refurbished ? Or are they part of the diff. See how little I know, without my bible in front of me I am a dunce !

ETA: Just trying to get an idea of the work involved and impact on my wallet before i call my favourite indie

Edited by bigdods on Tuesday 11th December 14:04

Yes,cheaper than refurbed diff,as Green v8s said and certainly in my findings the joints dont always show play but the joints balls and tracks can be damaged,they are only Ford and are not megga money to fit or replace,renew the gaiters while your at it,your symptoms sound like a faulty joint/s to me.

[bigdods]

Thanks for the advice, I'm hoping it will last a bit longer as I dont drive her much during the winter (just enough to keep her running nicely) and I'm a bit skint due to christmas! Looking at a new clutch in march plus a fix to an oil leak at the back of the engine so I will add CV joints to the list....

[Else]

before you go ripping the diff out try slight pressure on the brake pedal when its making the noise, could just be the brake pads. I've got a very slightly buckled rear disc and i get a slight knocking noise when moving slowly. It disappears if i rest my left foot gently on the brake pedal.

Else

[steve-V8s]

As well as the universal joints, could be worth checking that all the flange bolts between the Diff and drive shafts are tight, perhaps that is where the play is. Presumably you have checked the wheel nuts are tight!

The “Buckled disk” mentioned may simply not be seated correctly. Had that on mine where a bit of rust had fallen between the hub and disk.

[Chimtastic]

bigdods said:

Last 2 years I have had occasional knocking noises from the back

is it the wife in the boot?

[spend]

Chimtastic said:

bigdods said:

Last 2 years I have had occasional knocking noises from the back

is it the wife in the boot?

No, hes' just driving too slowly

Check for dents in the bumper

Dave

[bigdods]

Chimtastic said:

bigdods said:

Last 2 years I have had occasional knocking noises from the back

is it the wife in the boot?

aha, I had wondered why my dinner hasnt been on the table when I get home recently...

[bigdods]

I think the CV's are it - not the brakes it does it regardless when they are being used or just coasting. Knocking stops when power is applied (sometimes accompanied by a clunk). Yes the wheels are on tight, that was my first thought ....

all good advice thanks team PH !

[Slacey]

I had similar symptoms and it was indeed the CV's - definitely cheaper than the diff for a first try at fixing it.

[nawarne]

I had a 'regular' clunk on my V8S,,,turned out to be the prop shaft rear UJ.
Nick

[RumbleBee]

To check the discs, ride the brake slightly at a low speed. If you feel the pedal pushing back, they are warped. I had a daily hack with a terrible noise. Was diagnosed by an indie as CV joint failure. Turned out to be a loose road wheel. Lesson: check everything first and start with the simplest and cheapest option. Lash in the diff can cause a clunk when travelling slowly and taking up drive. You feel it more in the Chim because the diff is big and right behind you, if you think its that, its nothing to worry about, maybe a change of diff oil is all thats needed.