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CLONK!....Have now run out of things to check


Big Brother

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Help needed......I have now run out of things to check

 

 

Symptom

 

I get an intermittant "clonk" from the rear of the car when pulling away and sometimes when cornering although this is less common.

This seems to be from the rear of the car and can be "felt".

It feels like the rear axle (or something big) is moving a short distance.

This "clonk" has also happened when starting to move off in reverse.

 

History

 

About a month I had the rear A frame bush (under diff) fail. This was caused by oil contamination due to the cars old open breather set up. (now fitted with a catch tank)

The bush was replaced and this is now fine, as is the diff bracket and outer a frame bushes.

Changing this bush stopped the previous symptoms (clonk when getting on and off the power) but the "new" clonk was noticed shortly afterwards

 

The car

 

The car is a short cockpit 7 with a factory fitted Ford live axle.

The rear of the car is completely standard and has Ford drum brakes.

 

Things checked so far

 

Propshaft U/J's and security

All rear suspension bushes and bolts

Radius arms (bushes and bolts)

Rear axle and Diff (for excessive play, oil level and end float)

Rear wheel bearings

Hand brake operation

Wheel nuts!

Shocks and springs

Fuel tank location and security

Rear gearbox mounting

Engine mounts

Exhaust mountings

 

My theory

 

Only thing left I can think of (but won't explain the odd clonk when cornering) could be that the rear brakes are sticking slightly and pulling away releases them with a clunk. (once had a tin top do this)

 

Any ideas appreciated.

 

Cheers

 

Steve

(clutching at straws)

 

 

 

Edited by - steve motts on 26 Aug 2002 13:54:35

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Kev,

I have checked the seat mountings and boot.

The clonk seems to jar (sp?) the car as you move away.

 

Hoopy,

The car is a live axle but I had a look at the clearance around the prop this morning.

All looks OK with no signs of any contact.

all bolts have been checked for torque and all "moveable" bits at the rear have been checked (by eye) for contact with each other. Nothing looks out of place.

 

Steve

 

www.Se7en-Up.co.uk

One day, all cars will be made this way!

 

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Steve,

 

I have a 1990 deDion, so am not familiar with the live axle set up. My "A" frame is two separate links with no cross member. Under braking (and to a lesser extent acceleration) the base of the A frame wants to change width. When I had a clonk (under braking) it was due to the pressed in bush at the base of the A frame moving in the tube.

I hope that makes some kind of sense.

 

Ian

 

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I have a 96 live axle car and I was getting a clonk, particularly when I went around left hand corners. My brother checked my car for end float but there did not seem to be much movement at all.

 

Even so, on inspection by Caterham Midland, it proved to be a 1/2 shaft moving in its bearings. Caterham did a great fix for me for about £125 in April and since then it has been through 7,000 road miles and two Curborough sprints with no more clonk.

 

Hope this helps.

 

Ade *smile*

 

Make the world a better place, hug an estate agent

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Worn splines on one of the halfshafts maybe? Have you pulled the half shafts out to check the bearings or did you just do an up & down, side to side check for play? I have known the cage break up on these type of bearings causing odd noises.

It is always good to get a fresh opinion on a peculiar noise so is it worth one of us coming out with you for a short ride at the Phoenix this week to see if a diagnosis is possible.

Is it more likely to happen when you pull away very quickly ie drop the clutch or is it the same when pulling away gently? (actually have you ever pulled away gently?) *wink*

Finally do you know if you can you hear/feel the clonk more if you were to try and move off with the handbrake on?

Oh I do love a challenge! *thumbup*

 

Brent

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Brent,

The main problem is that I am unable to replicate the fault at will.

The last time I heard a clonk was on the way back from the Phoenix on Thursday.

The time before was as I started to reverse out of the wotton Hatch carpark.

 

I didn't pull the halfshafts but gave both rear wheels a hard tug in all directions.

No play too speak of. I also turned the rear wheels while watching the prop. I could see a very small amount of play but nothing that would worry me.

I am not sure if the Ford axles are prone to the same faults the Ital ones seem to suffer from.

 

The clonk does appear to be something heavy (big) moving though, as you can feel it as well as hear it.

 

 

Steve

 

 

www.Se7en-Up.co.uk

One day, all cars will be made this way!

 

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I hope this is not the problem but it has happened to me... in the diff the planet gear shaft came loose, in fact the pin holding the shaft in place came out. This allowed the shaft to float and catch the crownwheel but only occasionally, hence the clunk and a bit of forward drive hesitation. Eventually got worse and felt like the back end had seized up, but would free and behave normally. The axle is Ford Escort. Cannot check the problem from outside, sorry.
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Doesn't seem to be brake related (bang goes my latest theory).

It seems to be either when pulling away fairly gently from stationary or when changing gear, as you start to feed in the power.

I am now thinking that re-bushing the rear of the car will be the final step before pulling the axle and throwing money at it ☹️

 

bugger

 

Steve

 

 

Se7en-Up!

One day, all cars will be made this way!

 

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