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Vibration at 45+ mph


NevSpit
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Spitfire Mk4 1971 O/D

 

I have all of a sudden developed a vibration from the rear of the car (was fine on the outward leg of a journey but seemed to appear on the way home the same day) at around 45 mph and over. I have admittedly not taken it much over that as it does not appear to go away. It is not engine speed related as the problem still occurs at the same road speed irrespective of gear.

 

I have swapped the wheels front to back and the problem still persists. Having trawled through a small portion of the web the symptoms seem to point to the prop shaft so off to the garage this morning to extract it. Any tips on removal or is it simply a case of removing the nuts / bolts and dropping it down? It is a non sliding one prop and when I had to drop the front end to replace the overdrive last year it was not that simple given part of the OD output protruded into the prop. Hopefully the back end is 'flat' so that will just drop down and give me the movement to take the front off - if you follow me.

 

Any other tips or pointers to look for whilst I am under the car or indeed once the prop is off would be most welcome!

 

Cheers.

 

Paul.

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there has to be some telescope effect be it a slide or strapped coupling

 

propshaft vibration is rapid, its same speed as engine in top gear , so vibration is high frequecy,

 

most likely is one of the drive shaft  UJ has failed or has some joint float,  this is road wheel speed and can be worse on cornering

 

can make some awfull vibrations as the cross pin moves in the journals... get a pry bar you dont want any shift in the cross pin

 

do this with the wheels at road height , ie jack up on stands but support the wheels.

 

Pete

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The Universal joint is in the "dotted box" on the diagram it's labelled GUJ115. They're quite cheap, around £10. If it was me I'd do both sides even if the other side seems OK. It's quite an easy job, I remember doing one on the road under the Hammersmith flyover!

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This interests me because although I do not get the vibration, the rear of my Herald is noisy above 45mph. I had assumed it was a worn diff or worn bearings in the diff and have been trying to pluck up the courage to remove it for reconditioning.

 

Would it be worth changing the UJs first, in case that is the problem rather than the diff itself?

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There some simple clues about how to on bills www.rarebits4classics..co.uk

 

the drive shaft universal can make some unbelivable noises and vibrations

its less problem on rotaflex but on spit herald mk1 vitesse and gt6 this little unit takes awhole lot of load

as it rotates the journals on the crosspin must not have any lift or end float the caps under the circlips must be a neat tight fit, a prposhaft is self centres and less of a problem

 

thicker circlips are about to make these little sods a neat fit

You must get the shaft as in its running position and stick a strong lever through the cross pin and attempt to lever the yoke , the slightest lift will give you noise vibtration and or clicking on corners at low speed,

you cab change the circlips on the car , they must ,,, reallymmust be

cleaned and fully located in their shallow groove

believe me you dont want one to pop out on test

 

got that Tee shirt.

 

Bearing caps can and often pitch and jam

it goes with the job , never force a new cap , if it stops

when pressing in then you probably have a needle roller

dropped out , stop look start again

 

pete

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A propshaft U/J can suddenly go from being "tolerable" to shaking the car apart in a few hundred miles, and the vibration can be very severe.

 

It's well worth jacking the car up and checking the to see if one has failed - probably the rear one.

 

Relatively easy repair, although it may be easier to buy a new (balanced) prop shaft and fit that - less phaffing with the bearing caps.

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Brief update, driveshafts looked ok as far as I could tell (that's not to say they are guilt free at this stage) so extracted the props shaft - after the swear box was suitably topped up removing the rear nuts / bolts...

 

Looking at the rear UJ it was 'sticking' on one plane so a replacement UJ was sourced.

 

Once on the workbench I used the over and under sized socket plus big hammer method and after quite some persuasion managed to separate everything and this is what it looked like:

 

UJ

 

As can be seen three sides are shiny and one is not and this is what the a couple of the caps look like:

 

Caps

 
Now, the one on the right I may have mangled more than it was in trying to get it out but as for the needle rollers I have no idea where they are (and yes that was on the 'dull' side of the UJ). It was not loose when it was on the prop and I have not found them on the workbench or floor so no idea what happened there. Hopefully this is the cause of my problems but if not then it needed doing anyway!
 
 

 

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  • 2 weeks later...
  • 1 month later...

Just by way of closure it worked!!

I was fairly confident given the condition of the old UJ but you can never be certain that there is not some other dark force at play...

I know it has been a while since I raised the original thread but there have been demands of everyday life to deal with and whilst the car was up I sorted out the other jobs I had been meaning to do such as painting the floor / chassis, a healthy dose of cavity wax, greasing, trunnion oiling, painting the exhaust with VHT paint (now that does smell when it cures!) etc.

I'm ready now for some more sunshine!

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