Anti roll bars
Discussion
The C of G is so low that the gains are minimal. The factory fitted front and rear bars to their track day demo car last year. I think that someone said that they did improve the laptimes but only by a few tenths.
If you were going to race the car and lower it enough to get some serious ground effect then you would need to add anti-roll bars. The Masters Motorsport British GT car has full bars front and back....but it runs *very* close to the ground.
If you were going to race the car and lower it enough to get some serious ground effect then you would need to add anti-roll bars. The Masters Motorsport British GT car has full bars front and back....but it runs *very* close to the ground.
I was wondering the same thing. Ted said not needed unless racing all the time. After driving the car now for 5000 miles, I agree there are not needed, the car corners amazingly!
jeff
www.worksstand.com/jeffs.htm
jeff
www.worksstand.com/jeffs.htm
Now that Ive finally seem a GTR in the flesh (still waiting to drive one though..), from what Ive been told and what Ive read (I know, its only hearsay, but here goes anyway), the car doesnt have any anti roll bars as the springs are very stiff.
Have a look at Jays site www.europeancarparts.ca
I think what he says make alot of sense.
I also believe (anyone ready to shoot me down in flames...) that the high spring rates is why the chassis has not has any development as far as chassis stiffness is concerned.
Andy
Have a look at Jays site www.europeancarparts.ca
I think what he says make alot of sense.
I also believe (anyone ready to shoot me down in flames...) that the high spring rates is why the chassis has not has any development as far as chassis stiffness is concerned.
Andy
Whilst Jays site makes for interesting reading, it doesn't take into account the fact that the chassis stiffness can only really be assessed with the body on!
Whilst he did a great (and scientific) job of it, it would be interesting to see if the chassis ended up any stiffer than a standard car?
Whilst he did a great (and scientific) job of it, it would be interesting to see if the chassis ended up any stiffer than a standard car?
Stig,
Do you think that the addition of the body would make that much of a difference....after all, it is supposed to be non load bearing.
Certainly, the centre section would make a difference, but a measureable increase in stiffness?
I suppose that the front and rear clips would also increase the stiffness, but I think that would depend on the hinges/catches and surely would be marginal at best.
Again, I dont actually own a GTR as yet, so if any one has a valid reason to shoot me down...feel free to do so
Andy
(Edited cause I spell like a 3 y.o.)
>> Edited by doc_fudge on Friday 18th July 11:19
Do you think that the addition of the body would make that much of a difference....after all, it is supposed to be non load bearing.
Certainly, the centre section would make a difference, but a measureable increase in stiffness?
I suppose that the front and rear clips would also increase the stiffness, but I think that would depend on the hinges/catches and surely would be marginal at best.
Again, I dont actually own a GTR as yet, so if any one has a valid reason to shoot me down...feel free to do so
Andy
(Edited cause I spell like a 3 y.o.)
>> Edited by doc_fudge on Friday 18th July 11:19
As Jeff and many others with Ultimas has experienced,
the GTR does not need ARB,s to go around corners fast.
However the same cornering speeds and role stiffness can be achieved using softer springs and anti roll bars combined. This is the route choosen by every race car and street car manufacturer worth noting regardless of C of G height.
This method should give a softer more compliant ride.
Its also worth noting that the more powerful cars
like the Mac1 or any F1 car designed by Gordon Murray,
has no rear ARB, this to improve rear traction on corner exit. A high powered car set up this way will have a low speed understeer, it has to be or it would be too tail happy on corner exit. This is why an Ultima understeers, it has to to be safe at high speeds
and with power on (remember the first gen audi TT; no low speed understeer, lots of high speed oversteer and cars leaving the road backwards at 130 mph).
The Ultima frame as supplied has a stiffness of 3300 ft lb deg. If Porsche work on the 904 and 906 is any indication the body, if bonded on, should add another 500 to 1000 to this. I will measure this in about one week and send a note in.
the GTR does not need ARB,s to go around corners fast.
However the same cornering speeds and role stiffness can be achieved using softer springs and anti roll bars combined. This is the route choosen by every race car and street car manufacturer worth noting regardless of C of G height.
This method should give a softer more compliant ride.
Its also worth noting that the more powerful cars
like the Mac1 or any F1 car designed by Gordon Murray,
has no rear ARB, this to improve rear traction on corner exit. A high powered car set up this way will have a low speed understeer, it has to be or it would be too tail happy on corner exit. This is why an Ultima understeers, it has to to be safe at high speeds
and with power on (remember the first gen audi TT; no low speed understeer, lots of high speed oversteer and cars leaving the road backwards at 130 mph).
The Ultima frame as supplied has a stiffness of 3300 ft lb deg. If Porsche work on the 904 and 906 is any indication the body, if bonded on, should add another 500 to 1000 to this. I will measure this in about one week and send a note in.
It seems like some here are calling “body” the ally panels, whilst others are calling it the fiberglass (but it could just be me ;-) ). So, Jay, for clarity, I’m taking it from your last post, that not even the alloy panels were on when you measured 3300 lb*ft/degree, since that's how the chassis came from the factory?? I’d think that the ally would help torsional stiffness greatly (in a monocoque sort of way), whilst the fiberglass would help just slightly more than wet paper. ;-)
Jay, great job stiffening the chassis (in some cases, with parts so light and at low Cg elevations that I’d plan to do them myself); I think the factory might learn something from that.
For the issue of springs vs. ARB’s, note that soft springs with stiff shocks is thought to help cornering OVER BUMPS and TRANSITIONAL cornering (as well as ride-comfort), so the Ultima's lack of ARB's -- nor whole TENTHS of a second on most tracks -- is not something to sneeze at, performance-wise. I wonder if progressive springs would help the Ultima, and be able to substitute for not adding an ARB, or if the soft-section of a progressive spring would allow too much camber-change on an Ultime even if it only added 1/2”-1” of wheel-travel?(See next paragraph regarding camber-change.) Or if not, where'd ya git (or how'd ya make) your ARB, Jay? :-)
Insofar as oversteer at high speeds when you’re setup to be neutral at low speeds, though, adjustable wings (and/or suspensions whose toe-in changes with speed) were created for the very purpose of correcting for that (so that you can be neutral at any speed), whether your car has a rear ARB or not. ;-)
So these short A-arms (which was another issue detailed on Jay’s site)... Has anyone noticed large camber changes?
- e.g. #1, on a car used on the street only, but with the standard method of getting three temps across the tread-width to make sure your outside tires are set to zero-camber when nearly skidding thru a corner, Do you tires wear unevenly when you’ve been doing more highway driving than cornering?
- e.g. #2, If you race a lot, on a high-speed course (i.e., during high downforce, with a car whose suspension was setup properly for zero-camber at LOW speeds), do you find that at these high speeds, your tires wear unevenly or give you temperatures that are no longer equal, across the tread-width?
Jay, great job stiffening the chassis (in some cases, with parts so light and at low Cg elevations that I’d plan to do them myself); I think the factory might learn something from that.
For the issue of springs vs. ARB’s, note that soft springs with stiff shocks is thought to help cornering OVER BUMPS and TRANSITIONAL cornering (as well as ride-comfort), so the Ultima's lack of ARB's -- nor whole TENTHS of a second on most tracks -- is not something to sneeze at, performance-wise. I wonder if progressive springs would help the Ultima, and be able to substitute for not adding an ARB, or if the soft-section of a progressive spring would allow too much camber-change on an Ultime even if it only added 1/2”-1” of wheel-travel?(See next paragraph regarding camber-change.) Or if not, where'd ya git (or how'd ya make) your ARB, Jay? :-)
Insofar as oversteer at high speeds when you’re setup to be neutral at low speeds, though, adjustable wings (and/or suspensions whose toe-in changes with speed) were created for the very purpose of correcting for that (so that you can be neutral at any speed), whether your car has a rear ARB or not. ;-)
So these short A-arms (which was another issue detailed on Jay’s site)... Has anyone noticed large camber changes?
- e.g. #1, on a car used on the street only, but with the standard method of getting three temps across the tread-width to make sure your outside tires are set to zero-camber when nearly skidding thru a corner, Do you tires wear unevenly when you’ve been doing more highway driving than cornering?
- e.g. #2, If you race a lot, on a high-speed course (i.e., during high downforce, with a car whose suspension was setup properly for zero-camber at LOW speeds), do you find that at these high speeds, your tires wear unevenly or give you temperatures that are no longer equal, across the tread-width?
Gassing Station | Ultima | Top of Page | What's New | My Stuff