After 9 months my Sag is nearly right

[Jappo]

So, after an interesting 9 months with my Sag I finally appear to have it right (paint matches, Dash ECU works, Warranty in place, ventilation blows cold when I want it to) with one big exception - high speed vibrations.

I am convinced it is not wheel balance or tyres (been done and brand new SSRs fitted). It starts to kick in around 85 and it's a whole car fairly high frequency vibration. It gets worse as I go quicker, and particularly under hard acceleration and also during cornering (long fast sweepers). It also varies as I go round a long sweeper - getting worse, then fading a bit, then getting worse again (e.g. on the namked left hander at Rockingham or the slip onto the M1 from the M6).

I strongly suspect drivetrain somewhere but it's only 2K miles ago that I had the propshaft balanced (didn't make any difference) so I suspect somewhere else (CVs, drive shafts, diff, engine mounts, etc).

In effect it's like a built in speed limiter that keeps me below 80mph - very, very annoying.

Any ideas?

[zooooom]

Hi Wayne
I was currently having a similar problem around 80-100mph with my T350c, though mines been made worst by hitting a pothole recently.
I notice that you’re not running the car on the problematic spider wheels as I am.
So all I can suggest is that you get a four wheel geometry set up check and while there get them to check wheel bearings and engine mounts.

[Jappo]

Just got back from TVR Power having had a full geo check. Haven't looked anywhere else yet, trouble with this process is that it could lead to a very expensive diagnosis based upon trial and error component replacement (1st the driveshafts, no that didn't work, now replace the wheel bearings, nope, that didn't work either, now replace the engine mounts, etc, etc, $$$$$$$$$$$).

[NCE 61]

I had a similar problem with my Tuscan 2. Have a look at this Topic there is another link on there that explains road force balancing of wheels. I had this carried out on all four wheels at Racing Green along with a 4 wheel alignment, totally transformed the handling of the car and the vibration is no longer noticeable on most roads.

[Jappo]

INteresting - do only Racing Green offer this?

[TGJR]

I notice a slight vibration kick in at about 90mph in my Sag, though nothing too severe. I think this is quite typical and recall the Jeremy Clarkson Top Gear test when he said that the whole car 'tingles with anticipation and feels like the engine wants to escape from the bonnet!'. One would assume the press car to be as good as it gets.

Must say it does'nt dilute my enjoyment and I did have wheel balancing checked recently. My car still cruises comfortably at 90mph but probably lacks the smoothness of some of todays highly engineered cars.

[Jappo]

TGJR said:

I notice a slight vibration kick in at about 90mph in my Sag, though nothing too severe. I think this is quite typical and recall the Jeremy Clarkson Top Gear test when he said that the whole car 'tingles with anticipation and feels like the engine wants to escape from the bonnet!'. One would assume the press car to be as good as it gets.

Must say it does'nt dilute my enjoyment and I did have wheel balancing checked recently. My car still cruises comfortably at 90mph but probably lacks the smoothness of some of todays highly engineered cars.

I'm talking serious vibrations here, the sort that make you think something's gonna give if you don't slow down.

[VARLEYHYD]

Well well

I have SSR's recently fitted and no issues.

Geo- Think that would make it feel scary/like on ice not vibes

Drive train- That's it for me;
Prop seems the favourite (do a swap with one from breakers yard?)
Or
Very worn upper ball joints? (replaced mine at sub4k miles & drop link)
G box & Engine mtgs?- (all torn replaced at sub4K)

G

[Jappo]

Hmmm, I feel some wallet attrition coming on again.......

I'll start with the Racing Green idea and then take a deep breath. If you had to replace all that @ 4K them at 12K, and given the hard use my car has endured, I'm knackered.

[Jappo]

VARLEYHYD said:

Well well

I have SSR's recently fitted and no issues.

Geo- Think that would make it feel scary/like on ice not vibes

Drive train- That's it for me;
Prop seems the favourite (do a swap with one from breakers yard?)
Or
Very worn upper ball joints? (replaced mine at sub4k miles & drop link)
G box & Engine mtgs?- (all torn replaced at sub4K)

G

btw - issue was just the same on my Goodyears previous to the SSRs. What pressures to you recommend for general road use on the Dunlops?

[hollowpockets]

If its any comfort to you iv had numerous problems, one after another for the last 16 months of ownership!

[VARLEYHYD]

Jappo said:

btw - issue was just the same on my Goodyears previous to the SSRs. What pressures to you recommend for general road use on the Dunlops?

Ala John 'daftlad'

23,5psi front 24psi rear
Use nitrogen if offered; keeps pressure rise to a minimum when tracked.

PS Plan to do geo checks vs tyre temperature plots at Croft and will update

G

[s6boy]

You mention at the top of you're post that the warranty is now in place, what's stopping you going back to the dealer and telling them to fix it? Surely even after 9 months a not fit for purpose claim would be valid especially if the vibration makes it feel like the car will fail somewhere.

[Daftlad]

Most likely cause is a bent rim (inside and not visible) and probably a rear.

[sportie]

Daftlad said:

Most likely cause is a bent rim (inside and not visible) and probably a rear.

Agreed, it has happen to me twice, flat spot on inside of rear wheel.

[Jappo]

s6boy said:

You mention at the top of you're post that the warranty is now in place, what's stopping you going back to the dealer and telling them to fix it? Surely even after 9 months a not fit for purpose claim would be valid especially if the vibration makes it feel like the car will fail somewhere.

It's worth a try isn't it, if only to test it out.

[Jappo]

Update on the situation for those of you that are interested. TVR Centre have run it on a different set of wheels/tyres - no difference. They flipped the prop through 180degrees - vibration now apparently kicks in at around 90mph rather than 80mph but after that - no difference.

As I suspected this could start to get extremely expensive as one thing after another is eliminated. Anyone had any experiences of this sort of thing being caused by the Diff? And also whether, if I had it replaced/refurbished, whether or not I should bite the whole bullet and get a lower ratio Diff but without changing the gearbox (in other words would it be worth it without the low ratio gearbox as well)?

Thanks as ever guys!

Jappo

[Maxx-Waxx]

Jappo said:

Update on the situation for those of you that are interested. TVR Centre have run it on a different set of wheels/tyres - no difference. They flipped the prop through 180degrees - vibration now apparently kicks in at around 90mph rather than 80mph but after that - no difference.

As I suspected this could start to get extremely expensive as one thing after another is eliminated. Anyone had any experiences of this sort of thing being caused by the Diff? And also whether, if I had it replaced/refurbished, whether or not I should bite the whole bullet and get a lower ratio Diff but without changing the gearbox (in other words would it be worth it without the low ratio gearbox as well)?

Thanks as ever guys!

Jappo

sorry to hear of your continued woes. Hope things get sorted.

WRT diffs and CR boxes check out this thread
http://www.pistonheads.com/gassing/topic.asp?h=0&a...

personally i went for changing to a CR box and diff upgrade at the sametime, so cant comment on just changing the diff with a standard box, but changing both certainly made the car feel more eager in 3rd and 4th, and dont have to drop down to 4th as often on the motorway to make btter progress.
£2.5k all in

N

[D_G]

Is the vibration through the seats, not the steering wheel?? I would definately suspect the propshaft, balancing doesn't always fix the problem. Get them to swop this over with a donor car if possible.

HTH

Dave

[Jappo]

D_G said:

Is the vibration through the seats, not the steering wheel?? I would definately suspect the propshaft, balancing doesn't always fix the problem. Get them to swop this over with a donor car if possible.

HTH

Dave

The argument was that turning the prop through 180 would have significantly changed the nature of the vibration if an out of balance prop shaft was the cause. It didn't, it just moved its onset up by a few mph which in TVR Centre's opinion was not a significant enough change to point to the prop being out of balance. Diff would be their next line of investigation hence my question asking if anyone had suffered similar vibrations issues that turned out to be the diff.

The vibration feels like it's the entire car - it doesn't come through the steering wheel. It is often, but not always, accompanied by what I can only describe as a thrumming which has a frequency of about 1 per second or two - this fades in and out a bit on long corners. It feels worse under hard acceleration than it does at constant speed.