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TR4 severe vibration


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Hi everyone and a happy Bank Holiday WE.

Those that are not occupied with the festivities - can you help on this one?

 

Took my car on its first longish trip (250 miles - much on motorways) on Wednesday. Had previously only done about 170 miles locally, so not at any speed.

 

Problem is at speeds above 40-45 mph a severe vibration and noise sets in.

  • It is felt particularly through the gear knob (in and out of gear).
  • Seems to be related to road speed
  • Knock it out of gear at say 55, and there is not much difference - except of course, as the car quickly slows to the 40-45 mph region most of the noise and vibrations goes.
  • Seems the same with OD in or out.

All I've been able to do so far is check the UJ bolts which all seem nice and tight. However, the prop seems to be the wrong way round (ie the sliding part is to the rear, whereas the Part Manual shows it to the GB end). But I cannot imagine that would have any effect(?)

 

There is no noticeable play in the OD output and Diff input shafts.

 

But there is some play in the sliding part of the prop. Difficult to say exactly how much but side pressure to the prop at this point results in a total sideways movement of perhaps 1 mm (at the point of pressure).

I've had a good ol' search on this forum for similar complaints and found much helpful advice - except for any clear view on the spline wear aspect. It doesn't seem much to me, but perhaps its critical - so any learned comments most welcome!

 

Thanks for reading yet another of my trials and tribulations!

 

Norman

Edited by TRnorm
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I can't say I've gone out of my way to measure side to side play in the sliding prop joint but I've never noticed any play at all when putting it all together. Mine was refurbished by Proptech of Kidderminster and it sounds as though yours warrants it too. I wouldn't be happy with it being fitted back to front either.

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Norman

 

I had the same problem with a 68 Spitfire. Reversing the propshaft such the short end was close to the gearbox solved the vibration issue.

 

Robert

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Best bet would be to safely set the car up on rear axle stands so you can run the drive train without load and test for problems

My 4A had the prop shaft fitted backwards for years without me knowing it or causing vibration.

You need to know first whether the problem is related to road/wheel speed or transmission speed.

 

From what you say it could just be a single unbalanced wheel

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I would say that it's most likely to be the propshaft. Take it off and see if there's any obvious play in the UJ's. You might fix it by turning it around (as per Robert) but it's probably worth getting it balanced anyway (assuming there's someone close-ish to you who can do it.

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It doesn't take too much to throw a propshaft out of balance.

 

Even turning it through 180º can do it.

 

AlecP came up with a good test some time ago. Fix a jubilee

clip to the propshaft (may need a couple in your severe case)

and do a road test.

Then turn the clips through 180º and road test again.

The difference between the two tests should indicate if, and

maybe where, there is imbalance.

 

But for sure, first thing to do is refit the prop the right way, not

back to front.

 

AlanR

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An old Kerbside Autos Car Sales trick, when faced with a worn propshaft causing vibration, was to reverse the prop . . . . . which in the short term often reduces the vibration factor.

 

Quicker and cheaper than replacing even a UJ, let alone a propshaft.

 

It would generally be several hundred miles before the buyer noticed a problem, and out of what passed for 'used car warranty' . . . . . .

 

I'm familiar with the jubilee clip test that Alan mentions, and yes it is often helpful, but I think it was someone else's good idea to post the tip on here . . . . credit where it's due !

 

Cheers

 

Alec

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Hi Norm,

I've known many propshafts fitted the 'other' way round with no ill effects. It was a topic of discussion in February at the London Group meet.

 

Have you got ALL the wheels balanced correctly - wire wheels on a wire wheel balancing rig.

What are the dampers like.

Is ALL the suspension bolted down firmly.

Are the tyres in good order - no lumps or bumps.

 

If yours is a 4A have you got the balance lump on the back of the gearbox.

I have a 4A without the lump with no vibration but ST fitted because of a resonance.

 

Roger

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Hi

 

I think that possibly this could a number of things, so a few to check;

 

1. Flywheel and clutch cover - are all the bolts tight ? If they have come off a full turn or more the assembly will wobble enough to cause a big vibration. Generally this is revs related, but if you're not prone to going over 3,000 to 4,000 rpm in the gears might only be noticeable at motorway speeds.

2. Propshaft reversal, as above, all about the condition of the UJ's and splines - this has to be a favourite

3. Gearbox, either a bad balance which is what the later damper device was to deal with as above or the tail shaft bearing is going bad and the end of the shaft is moving about. This is related to final drive speed so consistent with your symptoms.

4. Gearbox mount - if this has sheared it often makes gearbox vibration worse

5. Differential - nose bearing or compression washer in the front has collapsed

6. Brake drums ... Are one if them loose enough to wobble on the hub / wheel bolts

 

I've experienced all of the above on a TR4 and all appear as a middle drivetrain vibration at first. You need to go through the driveline front to back to eliminate each moving assembly to find this Im afraid. If yiu leave it, something is bound to shake loose eventually.

 

Regards

 

Tony

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Thanks Guys - really good stuff.

 

The car is a 4, not 4A, and the GB & OD came from a 2.5 saloon (and seem to be OK as far as i am able to judge give the masking effect of the vibration). I should emphasise that it is far more than just vibration - its that in spades plus a real loud accompanying din.

 

The wheels and tyres were new and balanced etc say 12 months ago and have since just supported the car plus done a total of about 400 miles.

Front dampers are new and all the suspension was rebuilt with polybush and Revington's camber kit etc. Perhaps i should say that I stupidly did not renew the prop, just freed up up - we all learn, eventually!

 

The more I think about it the more I tend to suspect, like I think Peejay does, the play in the sliding splines. And being realistic- am I going to be happy doing various things like reversing the shaft, renewing the UJs, balancing the prop etc - with all the effort involved, if in the end i know i still have the play. .

Having said that, It would still be interesting to hear how others view the 1 mm play.

Thanks as always

Norman

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Norman,

 

As TR Tony says, your issue is about safety right now.

Harmonic vibration at certain revs, extra vibration above 5000 revs, and rattle through the gear lever are all symptomatic of TR cars, and even well set up ones.

Likewise, the source of an occasional clunk can be very difficult to locate.

 

Th symptoms you describe are none of the above.

 

You need to find a single source of the problem before you go very much further, and anywhere at all at any speed.

You should not need to buy any new parts before locating the problem (in fact it might be counterproductive to do so.)

 

Reversing the prop is a simple enough job. Do it first. If nothing changes it is not the problem (but it would be worth checking that all the UJ nuts and bolts are identical.)

Edited by Paul Harvey
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And thanks Tony - just seen your advice (no sooner does one push Post button than another helpful reply lands!)

 

You have reminded me that I did not (re)fit the tie bar that was certainly there on the original non OD GB extension. I can't remember why i didn't but it might have been because I wasn't sure how (or if) it was fitted to the OD and perhaps i thought the overall bulk of the OD itself negated the need for further support - but maybe it does(?)

 

I do hope it is not the clutch and flywheel scenario!

When bolting it all together I couldn't force myself to trust using just (stretched) bolts for the flywheel so went for the security, as I saw it, of using the turned-up tab washers. So I'm confident its shouldn't be a loose flywheel,

 

Trying to rock the diff input and OD output bearings by hand and with the prop attached doesn't seem to show up any play, but again, another reason i guess to get the prop out and replaced, and at the same time check the bearings.

 

 

Norman

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And Thanks Paul - I'm taking to heart the safety advice.

The engine was incidentally balanced as was the lightened flywheel (just 5 lbs off).

 

Supplementary question please...........

 

Am I likely to be able to get the prop out without removing (or at least moving) the rear axle? It certainly doesn't look possible and I'm sure i put it together in the order Engine>Prop>Rear axle.

Norman

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Norman,

 

From what you say, the vibration is related to road speed,

not engine speed, so I think you can rest easy over any

engine issues causing your vibration problems.

 

AlanR

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Thanks Alan - I like to think you're right :):)

Norman

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Maybe I am wrong in my assumption here. :mellow:

 

If the prop shaft is out of balance, then the frequency of said vibration would be 3.7 (diff dependant) times greater than road speed. Assuming 60 MPH, that would be around 3000 RPM prop speed giving a frequency of 50Hz, so that would be like a buzz on the gearstick. Roadspeed, again at 60 MPH would be around 13/14 Hz, so more of a shudder.

 

Any thoughts?

 

Graeme

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Norman,

 

You can drop the prop out without touching the diff, there is enough for and aft in the spline section to free it up and slide it back below the diff and onto the floor (or your chest!).

 

A quick job to turn it through 180 and try another road test.

 

Mike

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Norman ..." a real loud accompanying din"

What sort of din?

tinny? clunky?....

Where does it appear to come from?

Peter

Edited by Peter Cobbold
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Thanks Mike - emboldened with that info I'll reverse it this WE.

 

Peter, Its certainly not tinny or clunky.

Its more than a typical vibration - it feels and sounds more like a coarse, powerful higher pitched rumble, and you do fear that it will knock out the OD bearings. Not too dissimilar to an unbalanced washing machine but an octave or so up.

Following up Graeme's hypothesis, it could well be about the 40Hz mark (appropriate the speeds I was doing).

Like relatively low frequency sound in general it is difficult to pin point its source other than to say that it seems to originate from the prop/OD area.

Also, if you knock it out of gear, and at the same time blip the throttle you can hear the engine blip quite distinctly separate from the "vibration". Which again makes me lean towards the propshaft as the culprit.

I'm looking for an iPhone app that can read vibrational frequency as that might really nail it. Someone seems to be working on that using a transducer, but I haven't found the final version yet.

Norman

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Proptech will do you a completely new prop with massively uprated joints and flanges for about £160 https://plus.google.com/114932373192573447579/about?gl=uk&hl=en Well worth it. You did say that you "Freed up the prop" can you elaborate on what was seized?

Stuart.

Edited by stuart
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Not sure it was seized as such, more seriously glued-up that required lots of penetrating oil, hammer blows and levering to move it.

Current plan (at 07:40!) is to try reversing it this WE which may get me to my SU rolling road tune-up session this Thursday in more comfort and faster than a crawl. But after that source and fit a new prop as I'm now sure that 1 mm of slop ain't right, and is technically as Alec described.

 

The thumbs-up for Proptec from both Stuart and Peejay is a great help, although as I live in Hertfordshire I'm wondering if anyone has experience of the GKN HD one that the TR Shop feature (they say TR4A-6 but i guess its OK for a 4)? About halfway into their listing below.

THINK I'M READING THIS WRONG - LOOKS LIKE THE IRS HALF SHAFTS

 

http://www.trshop.co.uk/special.html

 

Thanks everyone - the mist is rising!

Norman

Edited by TRnorm
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Update

Reversed the prop and Lo and Behold the really severe vibration has gone. Certainly up to 60 mph.

Not tried it higher as the GB/OD cover has not yet been refitted and sideways glances at the prop rotating at 60 mpg is alarming enough (even though, for safety, I'd refitted my heavy duty prop strap).

 

The UJs confirmed as very smooth and no play - but there is spline wear.

I remain frankly quite surprised that such a severe imbalance can have been largely rectified by just this reversal. Although I'm wondering if it has something to do with the bulky part of the prop now being more closely "coupled" to the axle, rather than the OD.. Can't think through the possible dynamics, but............

 

Anyway, I'm now very happy about my trip to the rolling road SU tune-up on Thursday, and now have the time to talk to the potential replacement prop suppliers as kindly suggested here.

 

Thanks to everyone for their valued input.

Norman

Edited by TRnorm
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