Rear Drum vs. Disc for racing purposes

[WTFestiva]

Hey guys got a quick questions or two, well I'm more looking for recommendations. We are currently going to do an aspire brake swap. I've seen threads on here about converting the drums to disc. I've also read that the capri discs can swap into the festiva as well. I know discs have a better stopping power, and there will be a lot of braking with this BP in now. Let's just say if you were in my position, which would you rather have, and how would you go about it?

[TominMO]

The Aspire brake swap gives you better brakes front and rear, and the ability to use 13" wheels in the more-common 4x100 bolt pattern. Aspire front rotors come off the front, a nice advantage.

The Capri front swap keeps the 4x114.3 pattern, gives you even stronger front brakes, but you must use minimum 14" wheels. Capri rotors are mounted from the rear, like Festy rotors. They can be converted by Rocketman to Mitsu front-mounted rotors, tho. Also, you need to use Aspire LCAs with the Capri front swap.

To me it's just personal preference, in the long run. I like the look of the huge Capri rotors.

Edit: note that Charlie/Advancedynamix changed from Capri to Aspire front, and kept Festy rear, with its different bolt pattern. That suited his needs best--lightest brake components and trailing arm, and the ability to use the lighter 13" wheels/tires. This is on his raceFesty Tweak.

[Movin]

Go with the lightest weight, suspension performance ..if you are racing you are probably going to over heat your shocks long before you over heat your brakes.. but you are a better judge of your racing than me.

[Advancedynamix]

Honestly, Stock drums can out brake a z06 Corvette being driven by a professional driver on a road coarse. If all the parts are in good working order there is not much need for anything else, however in your case it depends on what you want out of your handbrake. You may want to switch over to hydraulic hand brake, by tapping into the stock rear lines. In FWD rally, the handbrake can be a life saver, but my stock one will spin the car quite easily, even on asphalt. A hydro hand brake with better lever positioning would be more comfortable though.
The big thing you have to consider is weight bias. On a FWD car, the more rearward weight you have, the less speed you'll be able to carry through the corners. Weight in the back does nothing but aggravate the chassis as a pendulum force. With that said, any brake changes that you make that add weight to the rear of the car will be counter productive from a performance standpoint. I actually turned my stock drums on a lathe to remove as much material as possible to subtract weight from the rear.
Also, in rally, unsprung weight is one of your worst enemies. Most commonly available drum and disc upgrades will add weight to your rear suspension. However, if you put a hydraulic hand brake on you'll actually be able to remove a little weight.

One big reason that a BP engine swap doesn't negate the need for more rear brake is because you are hanging more wight over the front of the car. The rear of the car now weights less under braking, not more. Think of your front wheels as the fulcrum of a teeter totter. you used to have a skinny korean kid on that end, now you have a fat sumo wrestler. so the back is more likely to raise up. Less weight over the rear means less need for stronger brakes. At Firebird Main road coarse here in phoenix AZ I accelerate to 140mph and bring the car back to about 70 once every minute and 12 seconds with several hard slow downs in between. This goes on for about 20-30 minutes at an ambient temp of over 100 degrees F. When I bring the car in off the track, my rear brakes are warm, but I can actually touch the drums. They are only doing about 15-20 percent of the braking. My front Aspire brakes on the other hand, can't go near those for almost an hour without loosing skin.
Hope that helps.

[WTFestiva]

I figured you guys would have something meaningful to say on the topic. I'll likely just change to the aspire front and rear to get the 4x100 bolt pattern, I wasn't thinking that the rear brakes would be much of an issue but my brother says the latter and wants to go ahead with a disc swap... I don't want to make it any more complicated since i've already screwed up our suspension trying to modify stuff myself lol.

As for our E-brake, I haven't put hydraulic in, but i did replace the pivot pin with a removable pin so i can take the lock out, It's not like what the pros have, but its the Free way of having a fun unlocked e-brake, while being able to put the pin back in to have a working parking brake as well.

Since we were talking a little bit about weight distribution, I'd like to ask your opinion charlie. I know you've been around rally in the past. With 2WD rally are you sure about the whole keeping weight in the front is safe? I've had people telling me I'm going to need more weight in the back. I'm a physics student and I was seeing the angle you were giving, that weight in the back is counter-productive and will spin the car more making it hard to control. I read your racing thread post (festiva advantage i think) but was wondering how that would translate to rally or gravel conditions. thoughts?

[Bert]

It was either GM or Ford that used rear discs on their pickups for a year or two and then suddenly abandoned the whole idea. Mud and debris is much more a problem with rear discs than with drums and I suspect that was why this was discontinued. If you're rallying this car (as in your picture and videos) you might take that into account, plus realize that having rear discs, plus a good working handbrake, is not going to be so easy to accomplish.

[Advancedynamix]

Since we were talking a little bit about weight distribution, I'd like to ask your opinion charlie. I know you've been around rally in the past. With 2WD rally are you sure about the whole keeping weight in the front is safe? I've had people telling me I'm going to need more weight in the back. I'm a physics student and I was seeing the angle you were giving, that weight in the back is counter-productive and will spin the car more making it hard to control. I read your racing thread post (festiva advantage i think) but was wondering how that would translate to rally or gravel conditions. thoughts?

I'm very sure about this. The techniques I use to embarrass sports cars on a road coarse in a FWD econobox, I learned in the dirt. If you want to pitch the car at slow speeds then put weight in the rear (makes slow drivers feel like they are driving fast, and makes a sportier feeling car) if you want to pitch the car at high speeds, then you need weight over the wheels that are most important and you don't want pendulum weight that will encourage excess oversteer and make it hard to control on the limit. With FWD and front biased AWD you trail brake into an early apex (set the direction of the car early) and then power out. The more weight you have in the rear, the more likely the car is to want to keep rotating while your accelerating. "Push" is a result of driving a FWD car like it was RWD, if you want the car to rotate more, then brake later and harder (without locking up the front) then dive into the corner while still slightly on the brakes, while the back end is light. If this isn't causing the car to pivot then your front is too stiff or your alignment is off (too much toe in will ruin your turn in). Soften the front spring rate or and/or lower the front of the car. You need more weight on the front wheel to get traction for the initial turn in, not in the rear. Most importantly, you must realize that 99% of the chassis tuning and driving advice you'll get from people will not apply to a short wheelbase FWD car, unless your circle of friends speak french and have a room full of WRC trophies, lol.

[Advancedynamix]

Side note: Most of todays top WRC drivers perfected their skills while driving front drive cars. Search for videos of FWD FIA rally drivers and watch the dynamics of the cars. They dance these cars on the front wheels, and rotate the car with braking, not power. They use power to pull the cars out of the drift. This is possible because of a drastic frontward weight bias on these cars. It's no fluke that Audi dominated rally in an era where most other teams were putting high HP engines in the rear of little tiny cars. If you look at the 5cyl audi platforms (4000/5000) you'll notice one very important feature. A huge, heavy iron block inline 5 hanging out in front of the front axle. They just shortened their lightest chassis and utilized a front biased AWD system, which was very simple compared to what the other teams were trying in order to keep up. We haven't seen serious mid engined WRC cars since everyone figured out why audi was so damn fast. Front weight bias.
What car would you feel more comfortable driving on a snowy road, an el camino or a Festiva? Then why turn your Festiva into an el camino? Instead, focus on improving what makes FWD superior in stability and traction.

[jdobbs86]

I've gotta say, this thread has really help me with Gran Tourismo 5.

[Movin]

Knowledge will usually get a serious whupping from lots of experience. But when the two come in one package the videos are fun to watch!!

[standard235]

I know one thing for sure, my Rio/Aspire swapped Festy rotates under braking on the street... I need to get a GoPro clip of this car so people can see the difference this swap makes!

[Charlie1717]

WTFestiva, call meeeeeeeee your aspire stuff has been in Rolla for almost 2 weeks! They are getting pissed at me haha.

(812)350-8342

I pm'd you a few times too