Rallycross classing?

So my S10, which is very modified, is being prepped for Rallycross.

I am assuming I am going to be in MR class?

Tell me more and give me some hints on improving my chances.

Build thread is here

http://grassrootsmotorsports.com/forum/build-projects-and-project-cars/1996-chevy-s10-challenger/52505/page1/

MR seems to be a class of Miatas and BMWs and RX7s and such. As with all 2wd rallycross, big power doesn't mean that much, but getting traction for the power you have does. In general you want to be running the softest suspension that you can get away with to maximize tire on the ground time. A higher car isn't necessarily better, but the more droop travel you have the better off you'll be.
Mostly it's about driving. Because every run matters, you need to be able to run fast, but clean out of the gate. A cone here or there isn't a huge deal, but several cones every run will ruin your day. Locally it's not unusual for first and second to be 4 or 5 seconds apart after 800 seconds or so of runs. At the national challenge I took second by .3 seconds after 850 seconds of runs. You need to be looking for traction where it is available for your truck. This will be different than the FWD or the AWD cars. You probably don't want to be quite as sideways as you think. The fast guys are usually pretty tidy in their lines. Depending on the site, the course will change through the day as ruts form or the course otherwise breaks down. You need to adapt. The fast line at the beginning of the day may not be the fast line at the end. Again, you're looking for traction for both ends of the truck. It takes some time and riding with someone who is fast in your type of car can be a big help. Mostly, like all other motorsport, the more you do it the better you get.
Remember to smile, it's a lot of fun.

What spring rates would you think would be a good starting point for a reasonably front heavy 2800lb truck

BTW it is rear coil overs with 4 link and panhard

$2010

General rule of thumb for cars goes something like this - for stage rally it's something like double stock. For snow/ice rally it's stock rates. For rallycross, it's somewhere in between. All of the stock class cars are running.....wait for it.......stock rates, and they do well. If I had to start from scratch I'd probably run something like 125% of stock rate and see how it feels. Maybe 150%, but not more. Sway bars are another point of contention. I think a mild front bar is appropriate for most cars, but others like more spring and the bar off.

I have no rear bar, but have the ZQ8 front bar which is pretty big, but I can downsize that whenever.

Stock S10 front springs are 410lb, I was working on Camaro fronts around 580, I have G body at 790 now, they are going away.

Looking at 200lb coilover springs on rear, does this sound like a fair starting point

No bars, stock springs, rock on

You have more weight in the front than your run of the mill S10 right? I suspect that No bar and the 580's are going to be the best of what you have listed. And do rock on. Absolutely rock on.

Yes the engine will be a fairly stock 5.3, but the truck is fairly race prepped, aluminum dash, boxed frame, aluminum radiator, battery and fuel cell relocated into bed.

Take a guess at your front weight. If you're close to stock, run stock, if you're heavy, run heavier. I personally don't think front bar removal is as beneficial as others. I think trying to get the truck pretty close to stock operating a and feeling suspension is a good starting point.

I was going to throw some advice, but mazdeuce literally covered every single thing I would have said.

My advice would be to "not worry about winning" but go try it with what you have, then make adjustments according to how the truck performs. To be honest, I would be surprised if the truck would be super-competitive if your MR class is fast. The weight balance (or lack thereof) is the real killer. As is "the weight" overall. 2800lbs would be heavier than every car in our MR class (12+ cars) by a good margin, other than perhaps the old Supra that runs at the back of the pack.

But it all also depends on what kind of courses your region sets up, what the surface is like, etc. Our courses are beneficial to cars that are "quick" handling-wise, good braking, and well-balanced. I've seen other courses where it looks like higher-power cars have the edge without traction being an issue.

I am going to develop it as we go, and I will remove weight as well, its not a high powered set up, but will have plenty of torque.

I am working on balancing the truck more as well, it isn't as front heavy as you might think but it need about 300lbs off the front, or moved back.

I really do not expect to win, I just want to have fun and get back on the dirt

Plus RWD and a V8 always rocks

One of the most important things are tires. I don't know what your MR competition will be in your region, but I'll tell you that street tires suck, snow tires are ok but wear out way too quick. All terrain tires are ok as long as they have nice square shoulders. Rally tires are, of course, the tits. But, rally tires are very expensive (think $700-1000 new), and very hard to find used, especially in the larger sizes that your truck will require. Rally tires can make a crappy car fast, so sadly, if you're running against a bunch of cars in MR with rally tires and you don't have any, you'll have a lot of catching up to do. On a V8 S-10, you're gonna need some serious side bite on the front to get it to turn in.

Also, with the front heavy weight bias of your truck, you'll for sure need an LSD or a spooled or welded rear diff if you want to be competitive.

As you say, a V8 and rwd will be fun, but not necessarily fast. When we did the turbo conversion on my 300zx, the extra power actually slowed it down until we re-learned how to drive the car. Just like autocross and road racing, grace and smoothness often wins more trophies than power and flamboyance.

I also notice your through-hood exhaust, which is very cool, but it may become a problem at tech. I don't have my SCCA rulebook handy, but if memory serves, I believe it states that the exhaust must exit rearward of the driver

Aeromoto wrote: I also notice your through-hood exhaust, which is very cool, but it may become a problem at tech. I don't have my SCCA rulebook handy, but if memory serves, I believe it states that the exhaust must exit rearward of the driver

Definitely correct on that count. I noticed that too but forgot to mention it.

Guess he could just get some steel flex tubing and run it over the roof or something, lol.

Different engine going in, exhaust will be underbody.

Already has an 8.8" LSD disc brake rear end

Tire search begins

mazdeuce wrote: Remember to smile, it's a lot of fun.

I was going to try to add a few tidbits in if I could, being in MR myself (even before it was modified). But this is the best advice I could come up with.

Aeromoto wrote: As you say, a V8 and rwd will be fun, but not necessarily fast. When we did the turbo conversion on my 300zx, the extra power actually slowed it down until we re-learned how to drive the car.

+1. For a while, I had a problem with one particular coupler disintegrating due to heat from the exhaust and turbo. For the first few events that I had that issue (and the car was actually running well otherwise), I would actually turn faster times without boost than with.

Personally, I wish they would outlaw rally tires in SCCA Rallycross. I believe it goes against the low-budget theme of the program. But, you know how racing is- if one guy springs for the high dollar advantage, it forces everyone else to do the same.

Aeromoto wrote: I believe it goes against the low-budget theme of the program.

When did they institute this "theme"?

Where I run, we have people running antilag, race gearboxes, buying sets of tires from different manufacturers to see which is best, etc.

If you want low-budget crap cans putzing around where you're not allowed to do anything but play dress-up with your four wheeled dolls, there's always Lemons.

Besides, banning rally tires would make it more expensive, not less. I've been running the same pair of Michelin medium-compound tires for seven years. I get two events out of new snow tires before they're scrap. I paid $50/ea (maybe it was $60) for the rally tires, the snows I buy are $80-130 a piece. What's more expensive?

Aeromoto wrote: Personally, I wish they would outlaw rally tires in SCCA Rallycross. I believe it goes against the low-budget theme of the program. But, you know how racing is- if one guy springs for the high dollar advantage, it forces everyone else to do the same.

Might as well outlaw racing slicks in SCCA Autocross while you're at it.

Knurled wrote: If you want low-budget crap cans putzing around where you're not allowed to do anything but play dress-up with your four wheeled dolls, there's always Lemons.

Wow dude, really? I don't know why you'd want to turn this into yet another combative thread, I don't know where your statement fits into what I'm doing, and I'd say my 2011 and 2012 points championship trophies add up to a little more than "playing dress up" and "putzing". AND, God forbid someone advocate reducing racing costs on a GRASSROOTS racing site, but anyway, good luck with all of that. I'm glad we don't have anyone with these attitudes in our region.

So why don't you run in stock of you are too cheap to buy used rally tires?

E-thugs on GRM, this world IS going to E36 M3 now

Stock can be just as expensive though, since you're not allowed to change anything, which can prevent you from making repairs with cheaper parts. Say you have a car with a one year only engine and you hurt the thing, now you have to find a replacement engine for that... And say you drive over your fender liner and don't replace it, or mud rips the 5 pound plastic bumper cover off... by the letter of the rules your car is now only legal for Modified.

The less restrictive the rules are, the cheaper it is to compete. Which is probably why HALF of the field last year in Tulsa was in a modified class, requiring them to split Modified into two different run groups.

Nobody says you have to run rally tires. Snow tires of the proper type can be just as fast, trading some ultimate grip for lower rolling resistance. But they're more expensive than rally tires.

mazdeuce wrote: Take a guess at your front weight. If you're close to stock, run stock, if you're heavy, run heavier. I personally don't think front bar removal is as beneficial as others. I think trying to get the truck pretty close to stock operating a and feeling suspension is a good starting point.

This truck will never be anywhere near stock again, boxed frame, welded and owner made crossmembers, coilovers, 4 link and panhard make that impossible. The front end is not as radical, I have 2" drop spindles, QA8 Bilsteins, QA8 front anti sway bar and G body springs now.

Aeromoto wrote: Personally, I wish they would outlaw rally tires in SCCA Rallycross. I believe it goes against the low-budget theme of the program. But, you know how racing is- if one guy springs for the high dollar advantage, it forces everyone else to do the same.

Almost all of our MR class runs them this year, and virtually all of us bought them used off stage rally teams. I have 2 sets, both of which I got for <$200 (the price of new snow tires). I would not call them "high dollar." You just need to do some legwork to find them. Used rally tires come up all the time on our local rally board (guys from Black River, Rally WVA, Sandblast, etc. selling them after events). And they last several seasons (albeit they get less effective the more they wear), so even if you bought new ones it would be a virtual push compared to buying new snows every year or two.

Sure there could be some rich dude who goes and buys a brand new set every year, or rolls up with multiple compounds to suit conditions...., but that's no different from the autocross guys who are dropping $200-300 per tire for AD08s or RE11s in monster widths or R-Comps in "stock" class.

Really though, the tires are less of a factor in rallycross than in autocross. In autocross a car on RE11s will crush a car on all-seasons 99% of the time. In rallycross, cars with snow tires can be just as fast or faster depending on the surface. The rally tires just let you be more reckless because of less debead threat, IMO. The traction itself isn't necessarily superior.