Noises from the rear, and yes I know its a Triumph

[MJH2454]

Hi guys, I've had a read through previous posts and feel that there may not be a conclusive answer to this but here goes any way.

Spitfire MKIV 50,000 documented miles, started to hear a noise on the overrun, sounds like the exhaust popping, however in the last 100 miles the noise has got steadily worse and displays classic signs of UJ's. Switched the engine off and coasted downhill just to make sure it was not the exhaust.

Been under the car and the NS drive shaft UJ has been changed very recently, Propshaft UJ also looks like a recent change if the modern circlips  are anything to go by, OS UJ looks original again going by the old style of retaining clips. Can not see or feel any obvious wear in any of the UJ's, Grasp the prop shaft and drive shafts and I get about 1/4 inch of movement before the diff gears lock in, again not excessive if previous posts are anything to go by.

Had a good tug and rattle at everything else and nothing is moving, wheel bearings seem OK as well and wheels are on tight.

Any ideas on where else I should look.

Many Thanks

[NonMember]

Unless the wear is really bad, you won't see or feel it in driveshaft UJs without relieving the spring tension (e.g. by taking the drive shaft off). Even a tiny bit of play in them will make them clonk.

[Gary Flinn]

Could very well be the OS UJ Making the noise, its normally very difficult to find any play because everything is under tension (Unless things have got really bad!)

Worn UJ's can make knocking or ticking noises relevant to road speed and the halfshaft ones are normally the first to wear, its important when replacing them to ensure the correct thickness circlips are used to ensure no end-float (Is that the right word?) in the new UJ Cups.   

 

[dougbgt6]

Sadly newness doesn’t let UJs off these days. There’s a lot of rubbish spares about.

I generally adhere to the “if it ain’t broke don’t fix it” rule, but I change UJs on both sides even if only one is troublesome. Same with the prop shaft. Others may have different ideas, but UJs are cheap enough.

The problem is getting reputable spares, I would trust the club shop ones, but others who’ve done the job recently may know of other suppliers.

Doug
 

 

 

 

[Pete Lewis]

yes because of how the two systems work a prop uj will self centre , gives vibration rather than noises

the drive shaft is under serious load all the time and must have absolutley no end float , as said best take it off if its slack and floppy  its going to click and clack 

often more so on tight corners when loads are swapped , and a prop does engine speed a drive shaft does 4 time less being at road wheel speed so the frequency of whatever is very different between the two problems 

a decent pry bar stuck thro the uj will sometimes show up some small lift in the cross pins 

 

Pete

[MJH2454]

Thanks guys all very helpful, guess I'll have to bite the bullet and change the UJ's shame the PO didn't do both sides when the NS one was done. Brakes on the OS side also seem to be binding a bit so lots of spannering to do. Any helpful tips on how to stop the drums turning whilst trying to take the wire wheel hub adaptor off? For those with wire wheels you will be aware of what precious little room there is between the adaptor and the nuts!

[johny]

I've never heard them sound like the 'exhaust popping' though and not had them deteriorate in 100miles either. If they did I would expect them to be pretty shot and have lots of play.....

[Pete Lewis]

are you sure the exhaust is not close and makes contact with the chassis or elsewhere as the torque changes from drive to overrun

Pete

[NonMember]

1 hour ago, Pete Lewis said:

are you sure the exhaust is not close and makes contact with the chassis or elsewhere as the torque changes from drive to overrun

That reminds me of a 1500 Dolomite I had which developed the most horrible piercing brake screech under just certain light braking. After some significant investigation it transpired that the combination of soft engine mounts and soft suspension meant that, under just that degree of braking, the exhaust was making gentle contact with the propshaft and resonating like an organ pipe.

[Nick Jones]

You can get a clicking or light knocking from the driveshaft UJs if there is any end-float between spider and cups. It’s quite common and is cured with thicker circlips or shims under the circlips.  More likely to be the new one doing it.

Nick

[GT6M]

is this noise a sort,v clonk,n noise

which is accompanied by  a slight jerkiness in 4 th gear or top OD at low revs on over run

an a clonk on power tek up.!!