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Vitesse 2 liter - intermittent resonance / faint "grinding" between 2500 and 2750 rpm


James H

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Hi all, I have a 2 liter Vitesse with a five speed Ford Type 9 gearbox and there is an intermittent resonance / faint "grinding" between 2500 and 2750 rpm, not audible only felt and honestly not worrying, it is fairly subtle but its there and perhaps most importantly to emphasise that its intermittent, maybe 25% of the time.

Any ideas ?? pointing towards engine, gearbox, dynamic timing, I have no idea what to suspect. Its something I can live with but would prefer to understand and/or remedy !

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58 minutes ago, Iain T said:

Is the resonance in all gears ie irrespective of road speed?

Iain

Iain hi, yes it is and it is pretty much spot on 2500 revs when it begins, 2750 roughly when it fades out. What are you thinking ? My only thought was dynamic timing but I've had the distributor apart,checked and fully lubed plus verified advance on the pulley markings at higher revs, alls ok...

Edited by J Hobbs
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If it's not speed but engine rev related it could rule out diff and prop shaft. I had a vibration at around the same engine revs at it turned out to be a crap alternator. It sounds crazy but the alternator caused so much vibration it rattled the exhaust! Take the fan belt off and run up to the offending revs for a (very) short time to see if the vibration magically disappears. Mine did! I then bought a Brise alternator.

Iain

Edited by Iain T
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1 minute ago, Iain T said:

If it's not speed but engine rev related it could rule out diff and prop shaft. I had a vibration at around the same engine revs at it turned out to be a crap alternator. It sounds crazy but the alternator caused so much vibration it rattled the exhaust! Take the fan belt off an run up to the offending revs for a (very) short time to see if the vibration magically disappears. Mine did! I then bought a Brise alternator.

Iain

Interesting, was it intermittent too ?

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6 minutes ago, Iain T said:

Not really, it depended on road surface etc. The problem was always there it just noticed more on smooth quiet surfaces. It was more of a seat of your pants vibration than audible.

Iain

Thanks I'll look into it and may well be the case, I would never have thought of that but do wonder since its intermittent that its something else, its either there or not at all. Frustratingly its really tricky to describe but its like a faintly grinding gear or such felt mostly through the pedal...

The previous owner rebuilt the car and put the gearbox in and his work unfortunately isn't the best, I cant remember if it did it when I got it or developed since. As I'm writing this I also just remembered discovering almost no oil in the gearbox shortly after I got it, topping it up with GL4/5 before later realising it needed good old GL4 but if any damage had been done surely it would not be intermittent ??

Edited by J Hobbs
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No gearbox oil, never a good idea, but as Iain says, rev related excludes gearbox.   Except for the input shaft.  Does the noise go away at the said revs if you coast out of gear or just press the clutch?

If you can adjust the throttle or recruit an assistant to keep the revs in range, try listening via a broomstick between various parts of the engine and your ear.  Or, a mechanic's stethoscope.  Might narrow it down.

John

 

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3 minutes ago, JohnD said:

No gearbox oil, never a good idea, but as Iain says, rev related excludes gearbox.   Except for the input shaft.  Does the noise go away at the said revs if you coast out of gear or just press the clutch?

If you can adjust the throttle or recruit an assistant to keep the revs in range, try listening via a broomstick between various parts of the engine and your ear.  Or, a mechanic's stethoscope.  Might narrow it down.

John

 

I was going to mention I'd started a new thread you might be able to help out on but you're already here !

Ok so gearbox is ruled out (still works flawlessly so got away with that then) but havnt tried coasting or clutch, will do and get back to you...

Also forgot to mention it only does it on the road, cant get it to do it revving when stationary.

 

Edited by J Hobbs
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With a T9 conversion I believe it's possible to have an issue with the input shaft being too short hence wearing out the crank spigot bush. Mine seemed ok but to belt and brace I machined out the flywheel and fitted a standard Sierra needle roller bearing as well as keeping the spigot bush.

Iain

Edited by Iain T
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Take the rocker cover off and see if there is a slow oil drip from each of the rockers. Triumphs are susceptible to rocker assembly oil starvation but let's not go down the remote oil feed, that's another can of worms 🐛 

Iain

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1 minute ago, Iain T said:

Take the rocker cover off and see if there is a slow oil drip from each of the rockers. Triumphs are susceptible to rocker assembly oil starvation but let's not go down the remote oil feed, that's another can of worms 🐛 

Iain

That ones easy as I happen to know oil supply at the top is ok, the crank spigot bush sounds serious but I'm clinging to the intermittent nature of it to hopefully find something less so... a less than ideal conversion job wouldn't surprise me though !

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It depends what plonker used whatever adapter plate and thickness. I'm sure the cause is something more easily rectified. On a new 1980s BMW I had a similar niggling vibration which turned out to be a batch of faulty oil pumps.

Iain

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You said it not me, lol, I've been in France too long and have missed the english language !

I've got to do a better job of explaining this, its not so much a vibration but more of an engine rpm whirring/grinding felt seat of the pants and through the pedal only when moving not stationary.

Anyway will take her for a run now, do the tests mentioned before and get back to you :)

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Another cause of vibration which caused me 3 years of anguish was caused by 'the experienced Triumph specialist' not fitting the correct oversize location bolt on the bell housing. There is a dowel at 12 o'clock then all the other bolts are 5/16 apart from one which is 3/8 at about 5 o'clock. This misalignment of the crank to gb input shaft can cause anything from nothing, if you're lucky, to severe vibration. My vibration at about 25 thou off centre resulted in not being able to drive over 45mph. Worth checking, I just love laying under the car....

Iain

Edited by Iain T
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1 hour ago, JohnD said:

No gearbox oil, never a good idea, but as Iain says, rev related excludes gearbox.   Except for the input shaft.  Does the noise go away at the said revs if you coast out of gear or just press the clutch?

If you can adjust the throttle or recruit an assistant to keep the revs in range, try listening via a broomstick between various parts of the engine and your ear.  Or, a mechanic's stethoscope.  Might narrow it down.

John

 

Right I'm back and can be more precise...

So its actually a slow and relatively subtle pulsating grind or whirr felt through the car and not the pedal that starts at 2250 rpm and stops at 3000 rpm and only when moving.

Its intermittent in that under acceleration after each gear change it will either do it or it wont meaning that if I back off and then accelerate again it wont suddenly appear if it wasn't there before but after the next gear change it may or may not be there.

It can happen in any gear at said revs under any condition including when coasting downhill or accelerating uphill, however it vanishes when dropping the clutch and/or putting it in neutral.

I'm wondering if Iain is onto something with the input spindle as the intermittentness (if thats a word) might be explained by the chance of everything synchronising properly on every gear change being random ??

Also 2250 is roughly where I would change gear 99% of the time if thats relevant, obviously the issue is only present when driving beyond that.

Edited by J Hobbs
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If it is the input shaft it might just be another thing to put on the "pretend it doesn't exist list" along with the slight lean on the drivers side, the slow gearbox leak (I do top it up though) and the blowing exhaust (which sounds great) :)

I'll see about the alternator but hesitant about running at those revs without a water pump...

Iain if you've got a T9 in your Vitesse do you know what sort of mpg you're getting ?

Edited by J Hobbs
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16 hours ago, J Hobbs said:

Iain if you've got a T9 in your Vitesse do you know what sort of mpg you're getting ?

On the variable speed run up to Shuttleworth I think it's around 30mpg but the 7B needles I use run rich at low revs.

Iain

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16 hours ago, J Hobbs said:

I'll see about the alternator but hesitant about running at those revs without a water pump

The problem was identified by Vibration Free at Bicester and even though the engine was already hot they ran the engine for a good minute. If your engine is coldish running for a couple of minutes should be fine.

Iain 

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2 hours ago, Pete Lewis said:

clutch hub damper springs can make some awful vibration or noises if they are too hard/soft/broken 

Pete

Thanks Pete, yep looking more and more like clutch or input shaft...

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2 hours ago, Iain T said:

On the variable speed run up to Shuttleworth I think it's around 30mpg but the 7B needles I use run rich at low revs.

Iain

Thanks I was keen to know as someone on the other thread mentioned getting 35ish with a non overdrive original gearbox so my 25ish even with the T9 seemed low, on the other hand my research online hasn't found anyone else getting as high as that but if you too are managing 30s I'll try to get some more out of it.

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2 hours ago, Iain T said:

The problem was identified by Vibration Free at Bicester and even though the engine was already hot they ran the engine for a good minute. If your engine is coldish running for a couple of minutes should be fine.

Iain 

My concern is because I cant test it stationary as the issue never occurs then, instead I have to run it on the road between 2-3000 revs until it occurs which may well take several attempts, risky... I might try to find a way of getting a makeshift belt over just the water pump and crank pulleys, "something" would be better than nothing.

Edited by J Hobbs
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