Griff stability
Discussion
During my journey today (motorway use), I have noticed that at "ahem" some speeds, the griff kind of "vibrates".
I was told by a service centre that the rear requires rebushing , so I am going to do the whole car over winter, including the diff mounts.
I have never driven any other griffs/chims, so cant really compare my car to others , but it dont feel right.
Also the steering can get a bit , twitchy.
Just wondering if its common , and if there are any common failures.
All the wheel bearings were changed when wheel conversion was done and it had new Avos fitted last year.(Hence the tale of the rear bushes)
The diff is whining, but has done so since I have had the car.
I have a spare awaiting rebuild and fitting.
Any thoughts?
I was told by a service centre that the rear requires rebushing , so I am going to do the whole car over winter, including the diff mounts.
I have never driven any other griffs/chims, so cant really compare my car to others , but it dont feel right.
Also the steering can get a bit , twitchy.
Just wondering if its common , and if there are any common failures.
All the wheel bearings were changed when wheel conversion was done and it had new Avos fitted last year.(Hence the tale of the rear bushes)
The diff is whining, but has done so since I have had the car.
I have a spare awaiting rebuild and fitting.
Any thoughts?
tony,
Not that I am a griff expert by any means (still a relative newbie!!) but I was having similar problems above 70mph (of course I never drive more than 71mph) and when I put the car in for the interval service at Austec mentioned it. Car had 2 x new toyos on rear then four wheel re-balance and laser alignment
Seemed to do the trick for me, maybe would be worth this as an intial cost saving measure?
Might help!
Not that I am a griff expert by any means (still a relative newbie!!) but I was having similar problems above 70mph (of course I never drive more than 71mph) and when I put the car in for the interval service at Austec mentioned it. Car had 2 x new toyos on rear then four wheel re-balance and laser alignment
Seemed to do the trick for me, maybe would be worth this as an intial cost saving measure?
Might help!
If it is definite vibration at certain speed ranges only, it will almost certainly be one of three things:
1) Wheels need balancing
2) Propshaft needs balancing (possible wear in UJ's too - get them checked when you have the prop balanced).
3) Bodyshell resonating.
Worn bushes will certainly exacerbate the first two, because they will allow the effected components more freedom to vibrate.
The cure for the first two is pretty obvious.
Not much you can do about the third; it is a characteristic of fibreglass bodyshells to some extent, though TVR's are not usually as bad as old Lotus' in this respect. In theory, if you can find which panels are resonating, you could apply 'bituminous' type sound deadening sheet to cure the problem (or simply lay up another layer of glassfibre onto it, to change the stiffness), but usually not worth the effort.
The steering sounds pretty normal to me - not one of the Griffith's strongpoints; they have a reputation for a certain amount of tramlining and kickback. If you are used to a car with good steering precision (eg. a Lotus, or your Clio 182), or a 'normal' production car with steering and bushes tuned for a high degree of stability, it will take a little getting used to.
I don't know if the Spider wheels have a slightly different offset to the standard wheels - perhaps someone else on the forum will be able to tell us? - but if they do, that will effect the steering feel and stability, too.
1) Wheels need balancing
2) Propshaft needs balancing (possible wear in UJ's too - get them checked when you have the prop balanced).
3) Bodyshell resonating.
Worn bushes will certainly exacerbate the first two, because they will allow the effected components more freedom to vibrate.
The cure for the first two is pretty obvious.
Not much you can do about the third; it is a characteristic of fibreglass bodyshells to some extent, though TVR's are not usually as bad as old Lotus' in this respect. In theory, if you can find which panels are resonating, you could apply 'bituminous' type sound deadening sheet to cure the problem (or simply lay up another layer of glassfibre onto it, to change the stiffness), but usually not worth the effort.
The steering sounds pretty normal to me - not one of the Griffith's strongpoints; they have a reputation for a certain amount of tramlining and kickback. If you are used to a car with good steering precision (eg. a Lotus, or your Clio 182), or a 'normal' production car with steering and bushes tuned for a high degree of stability, it will take a little getting used to.
I don't know if the Spider wheels have a slightly different offset to the standard wheels - perhaps someone else on the forum will be able to tell us? - but if they do, that will effect the steering feel and stability, too.
some garages are a little commercial when it comes to balancing. The rears would have to be well out of balance and/or bushes badly worn for the resultant vibration to be noticeable, but I'd always get them balanced, regaqrdless.
As old64er says, just because the fronts have been balanced, don't assume that they have been balanced correctly. Plenty of the muppets employed by tyre fitting centres either don't know how to use the equipment properly or don't give a
. Would you, if you were being paid minimum wage to do a mundane, dirty, physical job?
Also, remember that tyres can go out of balance pretty quickly as they wear, especially when new.
As you say, you could also have other tyre problems which have caused them to go out of balance:
1) Flat-spotting due to brake lock up?
2) Distorted carcase, due to car standing on its tyres for a long period in storage, without moving?
3) Damaged carcase? - Visually check for bulges or distortion of the sidewalls.
As old64er says, just because the fronts have been balanced, don't assume that they have been balanced correctly. Plenty of the muppets employed by tyre fitting centres either don't know how to use the equipment properly or don't give a
. Would you, if you were being paid minimum wage to do a mundane, dirty, physical job? Also, remember that tyres can go out of balance pretty quickly as they wear, especially when new.
As you say, you could also have other tyre problems which have caused them to go out of balance:
1) Flat-spotting due to brake lock up?
2) Distorted carcase, due to car standing on its tyres for a long period in storage, without moving?
3) Damaged carcase? - Visually check for bulges or distortion of the sidewalls.
Yep, that sounds like pretty shot to me...if they are that bad, it should be visually obvious if you jack up the car and inspect them. Look for obvious splits, distortion or damage in the rubber of the bush and, particularly, any where the bolts passing through the bush appear to be off-centre. Rear geo can be very critical to stability (rear toe-out will result in scary and potentially life-threatening behaviour). Get them sorted, like now, before they kill you!!
If you do a search through old treads on this forum, you'll find plenty of reports of crashes caused by 'unpredictable' behaviour. The usual quote is 'it just went sideways, without warning'.
Many reasons for these accidents, but the bottom line is that the Griffith is quite dangerous enough without having handling/suspension related defects!
Sorry if this sounds
, but if you have any doubts about brakes, tyres or suspension components, you really shouldn't ignore them...if you can't afford to have them fixed right away, you shouldn't be running the car! 
Yes, there will be plenty of adjustment designed into the suspension either side of the recommended 'tolerance' settings, so if you can't achieve them, there is something seriously amiss.
Who did your geo, and what were their comments, exactly?
Obviously, I don't know which setting is out of tolerance and by how much. Too much rear toe-in probably isn't too critical (though it will wear your tires quickly), but if you have toe-out at the back, the car will tend to be directionally unstable (which may be the 'twitchy' steering you mentioned earlier) and very unpredictable at the limit. It can just take a bump or ridge in the wrong place on a corner or under hard acceleration to find yourself pointing the wrong way. If this happens to be in the path of an oncoming artic, it's Game Over, I'm afraid!
>> Edited by Mutant Rat on Wednesday 31st August 22:02
Who did your geo, and what were their comments, exactly?
Obviously, I don't know which setting is out of tolerance and by how much. Too much rear toe-in probably isn't too critical (though it will wear your tires quickly), but if you have toe-out at the back, the car will tend to be directionally unstable (which may be the 'twitchy' steering you mentioned earlier) and very unpredictable at the limit. It can just take a bump or ridge in the wrong place on a corner or under hard acceleration to find yourself pointing the wrong way. If this happens to be in the path of an oncoming artic, it's Game Over, I'm afraid!
>> Edited by Mutant Rat on Wednesday 31st August 22:02
Getting the rear tracking done can be a bit of a bar steward, Guglielmi told me that un-seizing the components and getting it within tolerances can take quite a while and a lot of people dodge the job, he toes in 10" generally I believe.
I would get a second opinion on the tracking if I were you and maybe get the rear end checked out at the same time.
I would get a second opinion on the tracking if I were you and maybe get the rear end checked out at the same time.
Mutant Rat said:
If it is definite vibration at certain speed ranges only, it will almost certainly be one of three things:
1) Wheels need balancing
2) Propshaft needs balancing (possible wear in UJ's too - get them checked when you have the prop balanced).
3) Bodyshell resonating.
It will not be the propshaft, the prop will not be out of balance, they do not lose their balance, after being balanced at the factory of manufacture, CV's would have to be excessively worn to give vibration and then it would be during low speed / high torque.
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