Long history of vibration

[DanDanTheGardeningMan]

Hi,

I've a noticable vibration between 38 - 44 and 65 onwards. Felt through the seat, not the steering wheel.Speed not revs related. I've done all the obvious, but am now out of ideas.

I've changed the tyres and wheels from Minatour to standard Stag wheels, vibration was worse ( heavier wheels in the equation?).

I've changed the propshaft to a brand new one. Slight improvement.

Changed the driveshafts to brand new. Slight improvement.

New outer subframe bushes (rubber). No difference.

New gearbox mounts (BW65). No difference.

New diff mount bushes, changed from poly to rubber. No difference.

Replaceddiff front nose, with good quill shaft & new bearing. No difference.

I changed the diff oil to 80W/140, hoping it would reduce the diff whine ( it did ), unfortunately it has made the vibration worse. No idea why.

New rear springs and rubber isolators.

Changed the rear drums for different drums, all it did was slightly extend the vibration to 44 - 46mph

Rear wheel bearings changed - no difference

Front wheel bearings and disks, calipers etc changed, no different.

Front strut bushes changed - no difference.

Gearbox was reconditioned 15K miles ago, I assume they replaced the necessary output bearings.

Diff was also reconditioned about 20K miles ago, before my ownership.

Am now out of ideas.....any suggestions?

Thanks

[Guest]

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Hiya Dan, you certainly seem to have gone the extra mile with this. My guess is thewheels, the centres are not always in the middle ! when new they were not of the best quality, and after decades of use they only get worse. If you have someone close to you with known good wheels and tyres, see if they'll swap the rears, thenall four as a test. Good luck. Martin.

[DanDanTheGardeningMan]

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Hi Martin, Unfortunately I get the problem with two seperate sets of wheels and tyres. The only difference is the vibration is worse with the Stag alloys, which weigh more than the modern Minator wheel and tyre set.

My car has a longer than norm wheel base, 102.5" on one side and 101" on the passenger side. Somebody suggested maybe the extra length was causing "propshaft whip", a problemTriumph also had with the 2000 Estates.

Somebody else said maybe the flanges from the gearbox or on the diff were no longer "true", so was causing a wobble in the drivetrain. No idea how to check this.

Also been suggested is the propshaft UJ working angles......

Thanks

[Dieter H. Marschall]

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Hello,

Is it possible that vibrations are conveyed from the engine via the exhaust system to the body? Is have this in my Stag and thus I will cut the exhaust pipes behind the manifold and put in a flexible, braided piece.

Just a thought.

Kind regards, Dieter.

[Guest]

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I'm sorry to hear that Dan, but I would still try it, even if just for elimination.

I wonder how you wound up with differing wheel bases ? Martin.

[DanDanTheGardeningMan]

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Dieter H. Marschall wrote:

Hello,

Is it possible that vibrations are conveyed from the engine via the exhaust system to the body? Is have this in my Stag and thus I will cut the exhaust pipes behind the manifold and put in a flexible, braided piece.

Just a thought.

Kind regards, Dieter.

Hi Dieter,

Thats an interesting modification, I've wondered about the exhaust before, I've checked its not rubbing anywhere, but I'll certainly try your suggestion.

Thanks

[Kevin Garrod]

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DanDanTheGardeningMan wrote:

My car has a longer than norm wheel base,

Is this what Clarkson means with the 'Staaaag'?

http://www.youtube.com/watch?v=TGJty_Rdp1U

[DanDanTheGardeningMan]

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Martin Stevenson wrote:

I'm sorry to hear that Dan, but I would still try it, even if just for elimination.

I wonder how you wound up with differing wheel bases ? Martin.

Hi Martin,Stag been restored at some point, in the early 90's I think, sills replaced etc, maybe they didn't do a good job.

[tonyh]

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[ams]

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Have you tried havingall fourwheels balanced ON the car. (balanced while wheels still on the vehicle)

Had an old Volvo years ago used to have similar trouble and this cured it..

Hope this helps

Andy..

[V Mad]

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There must be no play in the rear bearing of the gearbox otherwise this will cause the propshaft to vibrate. Check for any movement of the flange where it bolts to the propshaft.

[Andy Rundell]

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I'd start by getting the propshaft professionally balanced, then all the wheels.

Asmentioned earlier, phone round to find a tyre place that still has the equipment to do the balancing on the car

.......Andy

[DanDanTheGardeningMan]

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Thanks for all the replies.

Tony - It was a brand new propshaft with UJ's. The retailer describes it as a "solid shaft" with no elastomer/rubber joint. It is a bit heavier than the one I took off.

Andy (ams)& Andy , yes I've had wheels balanced on the car. Not really made alot of difference.

V-Mad: I'll have a check on the gearbox flange this weekend.

I guess I need to whip off the new propshaft and get it dynamically balanced, as suggested. I've not done that yet, as I assumed a new prop would come balanced. More cost, the wifes gonna kill me.

[flying farmer]

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I had this same vibration problem on a 2.5PI saloon with stag alloys. Try jacking the car up one wheel at a time so the tyre just clears the ground. Make a pointer to run very close to the rim then spin the wheel. You may well find that the entire wheel is going up and down as a result of studs not being in the middle of the wheel! my worst wheel was three sixteenths of an inch out. Do not assume that the hubs will be any better I only had one out of four without a wobble. The secret is to turn the rim on the hub one hole at a time and see if you can reduce the problem. If this works put a dollop of paint on the drum or hub next to the valve so you always put the wheel back on in the same place.

[DJT]

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Dan,

Have you tried slackening off all the exhaust clamps and shaking it about a bit to settle it? It may be putting too much strain somewhere. Might need some WD40 and a rubber mallet to loosen some of the joins. Worth a try. Better done on a proper ramp or from a pit so that the weight is on all four wheels and the suspension settled.

Dave