How do you stop your Griff taking off !
Discussion
Do you know how much lift there actually is? I measured it on the V8S and it was a tiny amount. If you have a stability problem it may be related to suspension settings, geometry or tyres? Worth checking before you go too far down the aero route. If you do eventually come back to aero, then it would be worth changing the rake of the car to give it a nose-down attitude as the first step. This makes quite a significant difference to the aerodynamics. However, it will also affect the geometry and not necessarily for the better, so small changes and check the geometry and handling as you go.
Had Nitrons fitted. Now the Griff is already low, but after the fitting, it was set an inch lower again. While this is a pain in the ars@ with both my driveway and the sleeping policemen, it has made a world of difference to high speed stability. Of course, some of this may also be down to the new springs and shocks themselves, but at 150 on the autobahn everything was rock steady.
Lots and lots of rear lift is the answer! Currently saving for a Griff so a colleague dug out some aero survey results for me; can't obviously post many figures but the rear lift coeff was 0.247 (roof down) which is apparently about the highest ever seen and certainly won't help with high speed stability. A little strip of something across the back of the boot would sort it straight away.
But hey, they look great.
Ruari
But hey, they look great.
Ruari
Hello, Ruari! Thought I recognised your name from the Sylva mailing list! Why on earth are you considering something as slow as a Griffith?!
I'd be interested in more detail on the aero results you have, if you could either post them on-forum or mail them to me via my profile.
I'd agree that a Gurney tab on the boot might help (perhaps something along the lines of the one fitted to the Saggyarse, combined with a front splitter?), but I suspect that the air in that region is so turbulent that it wouldn't make a massive difference.
Having said which, I've had mine up to about 155 mph on a couple of occasions, roof off, and found it to be reasonably stable at speed.
I'd be reluctant to do anything which destroyed the car's lines, too - unfortunately the Griffith's trademark is the complete lack of any unnecessary external 'blemishes'.
...oh, and if you do get one, for heaven's sake don't try to take it round corners as quickly as a Sylva/Fisher!
>> Edited by Mutant Rat on Wednesday 3rd August 13:24
My 500 is welded to the floor at high speeds with no problem. As it is one of the last 100 built, there is a splitter added to the front, just under the rad. Seasider has retro fitted a home made one (much better than it sounds) and now his too is welded to the tarmac at speed. There was a thread on here some time ago with pics of his. Mail him, he may be able to help!
reeso said:
My 500 at high speeds
reeso said:Thank you sir
Seasider has retro fitted a home made one (much better than it sounds)
Still hasn't fallen off reeso said:www.pistonheads.com/gassing/topic.asp?f=13&h=&t=133787
There was a thread on here some time ago with pics of his.
richb said:And alot have lost them
If you are refering to the piece of aluminium screwed underneath, just behind the lower air intake all Griff 500's had these. Rich...
Yes I have the front splitter on my car ,its been knocked off twice but I have stuck it as well as screwing it on and have been ok since, the car seems to run about 5c hotter without it so it must work,but I thought this was to do with cooling,not ground force.
I was in my friends Griff and and the boot catch was broken,anything above about 50mph and the boot was sucked up to the fully open position,perhaps you could strap some weights to it to see how much lift there is!.Iam sure I saw a picture of a rear under tray ala SEAC 450 fitted to a Griff.
I was in my friends Griff and and the boot catch was broken,anything above about 50mph and the boot was sucked up to the fully open position,perhaps you could strap some weights to it to see how much lift there is!.Iam sure I saw a picture of a rear under tray ala SEAC 450 fitted to a Griff.
a company called Newlun Designs have designed front and rear splitters for the Griff as well as Tuscans, Chimps etc.
can't post the pics, but they're on the Monster Web as are their contact details.
www.ballisticbanana.co.uk/tvrmonster.htm
those cars will be at the event, so come along and have a look.
I also have a home made splitter at the front, which also improves cooling. rather the acting as a splitter proper, it prevents the air being pushed past the radiator, below the car, causing lift. forcing it thru the rad improves cooling.
rear lift is apparent, via the boot lid effect, a guerney style lip will reduce this drastically, but where do you put it? to have the desired effect it needs to be quite a way "up" the bootlid (bout 7" which frankly looks crap.
My cars fine at 160+
andy
>> Edited by Guillotine on Wednesday 3rd August 16:39
can't post the pics, but they're on the Monster Web as are their contact details.
www.ballisticbanana.co.uk/tvrmonster.htm
those cars will be at the event, so come along and have a look.
I also have a home made splitter at the front, which also improves cooling. rather the acting as a splitter proper, it prevents the air being pushed past the radiator, below the car, causing lift. forcing it thru the rad improves cooling.
rear lift is apparent, via the boot lid effect, a guerney style lip will reduce this drastically, but where do you put it? to have the desired effect it needs to be quite a way "up" the bootlid (bout 7"
which frankly looks crap. My cars fine at 160+
andy
>> Edited by Guillotine on Wednesday 3rd August 16:39
Interesting talk of front splitters, but while my Griff driving experience to date hasn't quite been enough to make a valid assessment (about 300 yards!) I thought I'd post some more numbers which might be of interest....
Certainly you'd imagine that it's the rear end that needs attention re. stability, and while a splitter at the front will certainly help with cooling it'll also make the front/rear lift balance even worse (unless you do something even better at the back too of course!)
1992 Griff, 2-up, full fuel, ride height (measured to top of wheel arches) 624mm front 655mm rear. It does actually appear to have a small splitter across the underside of the nose - just a little vertical strip.
With roof up:
Cd 0.344
C fr lift 0.024
C rr lift 0.247
So the front is actually pretty well stuck down compared with the back.
Put the roof down, drag increases to 0.377, front lift zero, rear lift 0.229
With solid panel removed and rear section + windows up, drag increases to 0.382, front lift 0.008 and rear 0.225.
Interestingly, at 30 degrees of yaw (roof up) the rear lift increases to 0.430, which is huge, but the front also goes up (to 0.379) so the balance isn't too bad.
Conclusion? Drive sideways everywhere - should be much safer!
Ruari
Certainly you'd imagine that it's the rear end that needs attention re. stability, and while a splitter at the front will certainly help with cooling it'll also make the front/rear lift balance even worse (unless you do something even better at the back too of course!)
1992 Griff, 2-up, full fuel, ride height (measured to top of wheel arches) 624mm front 655mm rear. It does actually appear to have a small splitter across the underside of the nose - just a little vertical strip.
With roof up:
Cd 0.344
C fr lift 0.024
C rr lift 0.247
So the front is actually pretty well stuck down compared with the back.
Put the roof down, drag increases to 0.377, front lift zero, rear lift 0.229
With solid panel removed and rear section + windows up, drag increases to 0.382, front lift 0.008 and rear 0.225.
Interestingly, at 30 degrees of yaw (roof up) the rear lift increases to 0.430, which is huge, but the front also goes up (to 0.379) so the balance isn't too bad.
Conclusion? Drive sideways everywhere - should be much safer!
Ruari
Interesting stuff...The roof-up Cd is pretty good, considering! Don't suppose you have figures for the frontal area and the Cd with hood/rear section and windows down, do you? Also, off topic, but have you had your Fisher Fury in the wind tunnel? If you have, what were the figures on that?
>> Edited by Mutant Rat on Sunday 7th August 20:36
Gassing Station | Griffith | Top of Page | What's New | My Stuff