High speed vibration.

Technical advice Q&A

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Austinspace
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#1 High speed vibration.

Post by Austinspace » Mon Jul 05, 2021 2:12 pm

Hi, I have an E type series 3V 12 oh and had it converted from automatic to manual using the Getrag five speed gearbox.
The work was done professionally by Watjag.

When I got the car back everything seemed fine except when driven aggressively beyond 70 miles an hour at this point you would feel vibration and if you continued with the speed the vibration would get worse it did not seem as if it was coming from the engine and the vibration could almost be felt literally around the rear of the car particularly underneath the passenger seat and in that floor area.
I am lucky enough to be involved with the classic car restoration company who have been really helpful in attempting to investigate this problem and I’ve made other enquiries to ask if anyone has come across anything similar. It seems to be pointing to the drive shaft and perhaps when altered to accommodate the gearbox was either not balance correctly or the balance and has come off. At this point we are going to do further investigation and remove the prop shaft to have it balanced. When I spoke to the company doing this work I asked them if they could check whether the prop shaft presently was out of balance and they said they couldn’t they could only rebalance it. The reason I would like this done is that it would determine whether the problem was the prop shaft. Does anybody have any experience or similar problems in this way that would make them think that it may not be the prop shaft or that I am heading in the right direction?Of course any help is much appreciated

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christopher storey
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#2 Re: High speed vibration.

Post by christopher storey » Mon Jul 05, 2021 2:30 pm

The symptoms may be associated with the prop shaft and the rebalancing is certainly worthwhile. However, any imbalance in the rear wheels could also produce this sort of vibration . The two sources can sometimes be distinguished by the fact that wheel imbalance is usually purely speed sensitive, whereas propshaft vibration is often throttle sensitive as well, with the amplitude of vibration varying markedly depending on whether the throttle is open or trailing . Another potential source of vibration is worn or seized UJs on the driveshafts i.e transmitting drive from final drive to wheels

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abowie
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#3 Re: High speed vibration.

Post by abowie » Mon Jul 05, 2021 8:42 pm

It might well be the prop shaft but that's impossible to check on the car.

As they have said they need to take it off and put it on the balancing machine to check and fix it. This involves removing the IRS to get the prop shaft out.

As Christopher has said, while it might be the prop shaft it also might be other things. I would be asking WatJag to find and fix the problem.
Andrew.
881824, 1E21538. 889457. 1961 3.4l Mk2. 1975 XJS.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Austinspace
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#4 Re: High speed vibration.

Post by Austinspace » Mon Jul 05, 2021 9:22 pm

So the work was done by Watjag while Derek was the owner and sadly while my car was there he suffered a heart attack & his wife wisely got him to sell the business & retire. A lovely guy while I am on .
Still employing great guys one of them also being called Derek my car was finished then the business sold to some other Yank who probably not a bad guy but less interested in the cars and people than profit in my opinion. That said when I got the car back I didn’t have much chance to drive it at speed.
Then another manager from Watjag left and started his own business doing the same Jag specialising. I followed but it wasn’t the same and sadly just by timing and misfortune I now have spent a good bit on the car but really don’t have a come back.

On a positive note I now have all my work done by Tim Robinson who is really the best and most helpful engineer I have met since being an apprentice myself. He has really solved so many issues on both my cars I have total faith. As we all know though Is worth a lot and we will solve this issue I just wanted to throw it out there as 2 heads are better than one.
I will keep you all updated on progress and maybe this will help others.

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Austinspace
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#5 Re: High speed vibration.

Post by Austinspace » Mon Jul 05, 2021 9:34 pm

Ps. Thanks for all the input.

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abowie
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#6 Re: High speed vibration.

Post by abowie » Mon Jul 05, 2021 10:01 pm

Good luck and keep us updated.
Andrew.
881824, 1E21538. 889457. 1961 3.4l Mk2. 1975 XJS.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Series1 Stu
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#7 Re: High speed vibration.

Post by Series1 Stu » Tue Jul 06, 2021 3:08 pm

Hi

I'm puzzled by the balancing company stating that they couldn't tell you whether the propshaft is out of balance. They would have to determine the state of balance before starting the re-balance, therefore they can tell you whether they had to add/subtract weight when they return the properly balanced propshaft to you.

We have recently had some very exacting balancing operations carried out on high mass rotors and received detailed reports as to where, and how much, material was removed (addition was not an option in this case).

Regards
Stuart

If you can't make it work, make it complicated!

'62 FHC - Work In (slow) Progress
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109
'94 X300 XJR basket case

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abowie
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#8 Re: High speed vibration.

Post by abowie » Tue Jul 06, 2021 11:06 pm

Series1 Stu wrote:
Tue Jul 06, 2021 3:08 pm
Hi

I'm puzzled by the balancing company stating that they couldn't tell you whether the propshaft is out of balance.
I think they're talking about assessing it when it is on the car.
Andrew.
881824, 1E21538. 889457. 1961 3.4l Mk2. 1975 XJS.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Austinspace
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#9 Re: High speed vibration.

Post by Austinspace » Tue Jul 06, 2021 11:19 pm

I spoke on the phone with North West Propshafts in Manchester and I said I would bring the prop shaft to them and he clearly said they couldn’t tell me if it was already out of balance. Seemed strange to me that he could as well but it’s what he said!
After all they have to find out of balance to correct it so spinning as it is makes no difference I would have thought.
I may ask another company to get a second opinion.
If I can have it checked as is it will either determine or iliminate the problem being the prop shaft.

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vee12eman
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#10 Re: High speed vibration.

Post by vee12eman » Wed Jul 07, 2021 12:14 am

Hi.

I don’t know where you are based, but several years ago I fitted a prop shaft to my S3, which was also a conversion to Getrag. I have had no problem with balance or vibration, so I can’t help much with that, but I had my prop shaft made up by Bailey Morris in St Neots. I got fantastic service, and it was surprisingly cheap. My car probably differs from yours, as I have a bell housing which mates the V12 directly to the gearbox rather than using an adapter plate, and some Getrag conversions use a spline output (like mine does), whilst I believe some have a bolt on yoke adapter. I had to do all the measurements myself, but very happy about 13 years on.

Regards,

Simon
Regards,

Simon
Series III FHC

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abowie
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#11 Re: High speed vibration.

Post by abowie » Wed Jul 07, 2021 7:19 am

Austinspace wrote:
Tue Jul 06, 2021 11:19 pm
I said I would bring the prop shaft to them and he clearly said they couldn’t tell me if it was already out of balance.
So if he can't determine if it out of balance I wonder how he can balance it....

Sounds like asking someone else is a good move.
Andrew.
881824, 1E21538. 889457. 1961 3.4l Mk2. 1975 XJS.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Series1 Stu
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#12 Re: High speed vibration.

Post by Series1 Stu » Wed Jul 07, 2021 10:15 pm

Austinspace wrote:
Tue Jul 06, 2021 11:19 pm
I may ask another company to get a second opinion.
If I can have it checked as is it will either determine or iliminate the problem being the prop shaft.
I don't know where you're based but I would recommend Wilkinson Dynamic Balancing in Halesowen. They are up there with the best of them.

You will definitely have to take the shaft to them so they can set it up on a machine but they will tell you whether it was out of balance and by how much. I think the cost will be the same whether they have to correct it or not but at least you'll know for sure.

First though, check your universal joints for wear.

Regards
Stuart

If you can't make it work, make it complicated!

'62 FHC - Work In (slow) Progress
'69 Daimler 420 Sovereign
'78 Land Rover Series 3 109
'94 X300 XJR basket case

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Austinspace
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#13 Re: High speed vibration.

Post by Austinspace » Wed Jul 07, 2021 10:36 pm

Thanks Stuart,
Good advice. I plan to have the car in the workshop & on the 4 post checking all drive joints for play & wear.
I’m based in Manchester and have emailed another company already regards checking the driveshaft before the rebalance it to determine if this is the issue.
I will post progress and any positive companies I work with for reference.
I’m taking the car to Goodwood Revival and hope to have it corrected by then.
It also has an issue with the Rev counter over reading on its Luminition ignition. I have read previous post on this and hope to look at that using the wiring diagram posted.
Have found that they are very unresponsive to customer support!
Best insight has been on this group 😀

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Fspp369
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#14 Re: High speed vibration.

Post by Fspp369 » Thu Jul 08, 2021 1:05 pm

For any work involving rotating shafts especially prop-shafts try Dave MAC in Coventry.
They are the go to guys as far as lots of car friends and I are concerned, they are realistically priced and the job always comes back sorted.
(I have no ties with the company or workforce)
Peter
Peter {XKE V12HE efi}
XKRS
RR Phantom 3 1937 Sedanca de Ville.

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MarkS
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#15 Re: High speed vibration.

Post by MarkS » Fri Jul 09, 2021 7:36 am

I had exactly the same problem. Vibration at around 70mph that left if I pushed on thru 90mph. I went through the process of checking wheel bearings, wheel balancing (especially as it had been standing for a while, like yours...). Changed the UJ's. I had the prop and driveshafts balanced at Congleton Propshafts (cheap and cheerful, and near you). They found that the propshaft had been molested before, so it had been an ongoing problem with the previous owner. Still the vibration persisted. Eventually, when I was returning from Le Mans, it developed a ticking noise noise in time with the vibration. We thought it was inside the gearbox, but it turned out to be a distorted driveplate, that had eventually fractured. Chester Automatic Transmissions (also near you) found a way of changing the driveplate without removing the gearbox.
I realise yours is not an automatic. But I would suggest that if balancing doesn't fix the problem, then look more upstream. Especially because of the work you have had done changing the gearbox. Maybe mountings even....?......Balance of probabilities ('scuse pun) is that the issue is connected with the recent work

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