Got a strange vibration between 80 and 110 - any ideas?

[The Red Baron]

Gave the car a hard day on an advanced driving day and since then I've noticed a vibration when cruising at speed. It certainly didn't do it before.

Following the course day I replaced the front tyres, had the rear tyres balanced and had the wheels aligned, but the vibration is still there. The only thing that hasn't been changed are the rear tyres, which were just balanced.

It isn't a constant vibration, but a sort of pulsing vibration that I can feel through the car rather than the steering wheel. It also feels like it starts at the front of the car and moves through the car to the rear, before another wave starts at the front.

It is only apparent when cruising between 80mph and 120mph, (German autobahns ) but the frequency of the pulsing doesn't change with increasing speed.

I'm stumped as to what could be causing this vibration. It has to be as a result of the driving course, which IMO was quite tough of the tyres and suspension. But having changed the front tyres and realigned the wheels, I don't know what else it could be.

Can anyone help?

[Johno]

Probably the prop shaft. Try greasing the UJ's making sure you see fresh grease appearing from each of the pin/crown bearing ends . . .
Can take some moving and twisting and if you an't get new grease through it may time for a change . . .

[ESDavey]

I had a similar problem that could be felt throught the car on a an Audi & turned out to be the rear wheels had not been balanced correctly and / or they had thrown a poorly fitted balance. It wrecked the rear wheel bearings.

[yellowgriff]

don't rule out tyre wall letting go.. Had this a few times on cars. Get them balanced again but don't let the fitter pull the cover over the balancing machine, if its miss shaped you see it straight away...

[450Nick]

I'd check your tyre pressures first.. I sometimes get this when I've had tyres changed and I forget to check what pressures have been put in them. A difference left to right of around 3psi or more can cause said vibration in my experience...

[griffith400]

Ian,

I had this on a Cerb I had. Car had service & new tyres fitted (and therefore balanced) before a trip to Italy. Had major vibrations for the whole trip. Thing was, like you it only happened above 75-80 (you normally think of wheel balancing starting at 55-60). It too felt like a vibration through the whole car, not just through the steering wheel...felt like a prop shaft imbalance to me?

However, on return, I took the car in and they found it to be just poor wheel balancing!!! I was fuming .... And this was a main dealer!

[steve-V8s]

As you say the frequency doesn’t change with speed I would have thought that rules out wheel balance or UJs. Having said that, before I changed the Diff mounting bushes the drive shaft UJs became quite noisy for a few miles after really loading the diff with some enthusiastic driving. I think the diff twisted in the bushes and caused the drive shafts to sit at an unusual angle until it all settled back into place. That however doesn’t fit with the not speed related symptom. So how about engine mounts ? If they were past their best and you gave them a hard time could be that one or both of the exhaust headers is now clattering against the chassis and that is what you can hear. Also is the bolt that clamps the exhaust to the block still there ?

[coetzeeh]

My Griff suffered from a vibration between 60 and 80, admittedly felt through the steering wheel. No amount of balancing fixed the problem, neither did changing the tyres.

Turned out to be one front estoril alloy that was out of round due to a pot hole or something similar.

[Rob_the_Sparky]

One of hte chaps here at work has had similar (not on a TVR) where the inner edge of hte alloy had gone out of true on his alloys (furthest from the wheel spokes). He has had this happen twice now and on chatting to the tyre fitter after the second time he was told it is not that unusual, although I'd never come across it before.

[350Matt]

Another vote for the prop,

I'd recommend these guys for re-balancing work

http://www.davemacprops.com/dmphome.html

[The Red Baron]

Thanks for all your advice. I'll start with the simplist and work up from there. I'll get the wheels balanced, rear tyre walls checked. Get the wheels checked for 'roundness' and then start looking at engine mounts, prop shafts, diff alignment etc.

Drove it last night (90 miles). Seemed it was worse when it (engine and tyres) had warmed up a bit. It was midnight and the motorway was clear and I had the chance to open her up a bit. The vibration was quite bad at 130mph and is worse the fast I go. (I'm not in the UK!)

Something is out of balance - just got to find out what.

Winter is coming quick, so don't think I'll get the chance to drive it much until next year - so have found myself a winter project.

To change the subject...

My oil pressure guage always reads around 35 to 40 psi when cold, and maybe 30 to 32 psi if hot. However, I noticed when I'm driving and accelerate really hard, the oil pressure guage will show a decrease in oil pressure, down to 15 psi, while I've got my foot down; recovering when I button off.

Has anyone else noticed this too? Is this normal?

Thanks again.

[davep]

The Red Baron said:

Thanks for all your advice. I'll start with the simplist and work up from there. I'll get the wheels balanced, rear tyre walls checked. Get the wheels checked for 'roundness' and then start looking at engine mounts, prop shafts, diff alignment etc.

Drove it last night (90 miles). Seemed it was worse when it (engine and tyres) had warmed up a bit. It was midnight and the motorway was clear and I had the chance to open her up a bit. The vibration was quite bad at 130mph and is worse the fast I go. (I'm not in the UK!)

Something is out of balance - just got to find out what.

Winter is coming quick, so don't think I'll get the chance to drive it much until next year - so have found myself a winter project.

To change the subject...

My oil pressure guage always reads around 35 to 40 psi when cold, and maybe 30 to 32 psi if hot. However, I noticed when I'm driving and accelerate really hard, the oil pressure guage will show a decrease in oil pressure, down to 15 psi, while I've got my foot down; recovering when I button off.

Has anyone else noticed this too? Is this normal?

Thanks again.

Possibly an engine vibration, oil gets warm and thinner allowing movement in bearings, piston slap, and so on. There's some vibration analysis systems out there that are worth a look:

http://www.vibratesoftware.com/html_help/html/Diag...

Good luck.

BTW If you're in Germany on a regular basis, here's some contacts for garages with TVR experience:

Gehrke, Hagen, Germany

Bornemann, Braunschweig, Germany

ACS Pro, Neu Anspach, Germany

Sautter, Dachau, Starnberg, Germany

Hr. Pulfer at TGE Autotechnik, Embrach, Switzerland

Edited by davep on Saturday 17th October 12:36

[bigdods]

I had similar on the chim, turned out to be a combination of the following:

1. Popshaft UJs dry - they are supposed to be greased at every service but never had been. Packed with grease , vibration reduced by about 80%
2. Poor wheel balancing. Had the wheels balanced , but when checked found they were 25g out ! They had put the weights in the wrong place and made a small imbalance a lot worse. This sorted about another 10% leaving me a small vibration that seemed to be coming from the front
3. Engine mounts - um...didnt have them really. Discovered that 1 mount had disintegrated, bolt missing so engine just resting on the mount. The other mount was in 1 piece but only 1 turn of thread holding the nut on so it was loose. New engine mounts and all vibration sorted.

So if I were you as a starting point I'd grease your joints and check the engine mounts. Virtually cost free and quick to check.