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Our A-1 ITB Rabbit has a large front bar. Most other racers said they don't have one. Why? Most of the time we were the fastest A-1 and finished well for a rookie driver and crew. Can we go faster without the bar? Any help would be appreciated.
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a front sway bar in a car that already understeers? go to www.srsvw.com and read dick shine's rap on sway bars. i run only a rear bar in my 85 golf gti. check out dick's site you will learn a lot
enjoy
daveparker
itb#13
Here's some of my thoughts on anti-roll bars and what is the best choice.
Anti-roll bars do two things, transfer weight and reduce body roll. Dick's rap is very accurate when he states that anti-roll bars do tranfer weight off the inside wheel. But is that really bad? It's going to depend on your tire loading. All tires have an optimum loading point, anything less and you won't get maximum performance. Sometimes we need to have an anti-roll bar to get some extra loading during cornering to get maximum handling. There's actually some very simple matrixs that can determine how much extra loading you want to get the best handling car by knowing static corner weights, load trasfer, some tire info from the manufacturer and some other misc info depending on how indepth you want to get.
The other important relationship is spring rates versus anti-roll bar size. Obviously to get the desired body roll we'll have to up the spring rates to compensate for the loose in body roll. Having higher springs rates makes for a car that is more 'skateboard' like and will mean less control over bumps or transitions. We have to remember that the absolute best spring rate is the softest spring that will prevent the vehicle from botteming out. This is very important on any A1 or A2 chassis where the MP suspension limits a lot of suspension travel.
Personally I'd rather have a very small front bar and a big rear bar then no front bar with higher spring rates. It's more driveable and easier to control plus makes better use out of the tires.
Unfortunately I'm not sure that's the best way with an A1 or A2 VW yet. I'm really liking the car with no front bar but there seems to be an advantage on higher speed turns with a front bar. In autoxing the no front bar definitely has an advantage for getting the car to rotate but gives up a lot of driveablity. I'll know more when I get my better suspension (Truechoice phase 3s) installed.
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1999 Honda Civic Si #71 STR (2002 DSP)
1984 VW Rabbit GTi (nearing ITB completion)
1983 VW Rabbit GTi (getting an Audi 1.8T swap)
1967 Olds 442 W-30 Convertible (completely stock)
Quote:
Originally posted by dave parker:
daveparker
itb#13
Hey Dave, it's me, Glenn...ITB #07 (silver Rabbit GTI). I need to ask you something but your e-mail address isn't available. Drop me an e-mail at [email protected]. Thanks!
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Glenn
MARRS ITB #07
I don't run a front bar on my car, and I still have wheelspin problems on hard r/h turns, even w/ a Quaife. I can't see doing something which would increase the upward pressure on the inside tire. I run 2 rear bars on my car as well. I like the way the car handles, it's very stable in high-speed corners and handles fast transitions well. I will be increasing the rear spring rate on the car in an effort to keep the front more planted.
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MARRS #25 ITB Rabbit GTI
Thanks for the info. What you all said confirms what I was thinking. We are running the car as we got it and making improvements as time and money allow. Working with spring rates and corner weights is next. The car handles great except for a bit of front wheel lift in hard right turns. We might try a small stock front bar next.
I would recommend you trash the front sway bar altogether and spend the $55 on one of Shine's Lower Stress bar.
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Sam Rolfe
TBR Motorsports
#85 VW Rabbit
We already have a lower stress bar.Will probably try a selection of springs of different weights.
A welded diff should take care of the wheespin issue (and present new maintenance/driveability issues).
I have run with no front sway and with stock front sway on my Scirocco street car at autocross and track events. While it rotated a little better at the autocross without the bar, it didn't seem to help in the high speed stuff. The body lean was noticeably greater. I now run the stock front bar. Oh and trailing throttle oversteer becomes more abrupt, which I didn't want in a year round daily driver.
My wifes 90 GTI has bigger front and rear swaybars and really corners well, for a street car. It does not have the same quality shocks as the 'roc (boge vs. Bilstein Sport), but handles better. Of course the digi 8v doesn't make enough power for wheelspin to be a major issue, but my lap times at Gingerman are just as good or better in the Golf when compared to the Scirocco.
On my ITB project (target Feb 2002 completion !!! I just need the wife to not shut down the funding) I hope to be able to dial back some of the front spring rate in the used suspension I bought(from 550) and use a swaybar. When I get the time, I want to run stock bar, stock bar with poly bushings and upgraded bar setups to get a feel for how they each react to my driving style. After all, compatability with your driving style is what really matters, and some guys will be fast with no front bar while some guys will be fast with a big front bar.
If I were you, I would try it both ways. Especially since it is so painfully easy to pull the bar off a mk1 car.
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Chris
Dean,
Make sure it's a triangulated one, ala the 16v Scirocco.
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MARRS #25 ITB Rabbit GTI
With our front-wheel drive VWs, we need to get the proper balance of roll couple distribution between the front and the rear of the car. In other words, the roll stiffness between the front and rear need to be compatible with each other. This can be accomplished with the right springs and anti-roll bars. A front anti-roll bar is not necessary bad if the springs and bar work together to provide the proper amount of roll stiffness. Regards, Ryan.
Excellent point Ryan!
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MARRS #25 ITB Rabbit GTI