RallyCross tough on drivetrains?

I've been reading all the RallyCross threads and builds during the shutdown.  I am getting very interested!

Looking to pick up a Fiesta ST.  Hoping to play with it a little, possibly RallyCross it, and then use the engine and transmission in a project in a year or two.  Don’t care if I damage the body, but I want the engine unaffected.   How could RallyCrossing the car affect my plan?  

thanks, Justin

As long as your engine mounts are good so you don't get into any wheel-hop scenarios on course, it shouldn't really be any harder than autox and should be easier on it than track events.

edit:  also not sure robust a Fiesta ST diff is, but some cars are pretty sensitive to low-traction conditions for one wheel and it can cause diff problems.  I have not heard anything bad about the ST.

In that specific situation I'd be most concerned about overheating. But generally speaking aside from mounts and temperature concerns rallycross is generally fairly easy on the drivetrain itself. We ran a car for a full season on a partially broken clutch disk before it finally gave up completely. Fiesta is open diff so I'm sure it'll be wheel spinning all over the place, but shouldn't really cause any issues.

I know the guys that run subaru's locally are always talking about being on their 4th-5th engines but the miata guys are fine, the guy with the mustang is fine, the golf that runs blows up every other time but that is apparently driver related.  The main issue would be dust intrusion past the air filter, just run a good air filter/airbox and that should solve that issue.

I've been running ~30 year old engines for a decade of rallycross (only reason I say engineS) is because I swapped to a bigger one. Never had engine issues, transmission issues, or drivetrain issues other than a couple LSD diffs (also 30 years old) burning out their clutches eventually. Maintain the car well, especially the cooling system, and make sure all drivetrain mounts are in good shape. We have few people having drivetrain DNFs at our rallycrosses (other than Subarus), and if they do it's usually a motor mount breaking. Suspension DNF is more likely for the cars that are driven hard. 

Comparing engine longevity to the Subarus...not a good data point.  As a former WRX owner (who blew an engine at 9k miles), it's not rallycross that's killing Subie engines. It's the engine being turned on.....lol. 

Some courses involve downshifts into first gear or lots of time in first gear at the rev limiter.  Either plan on losing time on those sections by staying in second or manage the downshifts carefully. 

If you live in a hot climate, add coolant and oil temperature gauges.  Locally, a bigger radiator is one of the common reasons people bump out of stock class.

Otherwise, avoid full throttle at full lock and you should be fine.

It's a fwd turbo car with short gears and an open diff, pretty sure first gear (and honestly probably second gear too) is just going to be a wheelspin fest, not sure going between gears is going to be necessary or helpful.

From speaking to people who ran these cars, the main engine mount (on the passenger fenderwell) is a liability.  I forget if the mount broke a lot or the bracket broke a lot, but apparently it happens in street trim too.

Any time you have a front driver with motor mounts that allow a lot of drivetrain motion, you will break CV joints at full lock.  All the cyclical loads times the CV at its weakest point makes for rapid failure.  After I shattered my first CV joint in my Golf, I started a policy of never using more than a half turn of steering while on course.  My times started to suck but I also never broke another axle.

I love what Leon Drake did to do an end run around this problem on his infamous VW Caddy.  He basically made slapper bars for the drivetrain!  There was a big plate boltd to the engine with slapper bar snubbers that torqued against the strut bar (I think, it was like six years ago) to keep the drivetrain from doing the lambada.

The FiST has been lowered on it's stiff suspension from the factory.

Probably not the best for a dirt course.   Maybe the stock Fiesta springs would work better.

The quasi limited slip through brake application might help. Forget what it is called.

I found my FiST to have very good forward traction in snow/ice.  Of course the 3 yr old Blizzaks helped.

I agree with dps 214,s comment on gearing.

In reply to iceracer :

Stock height Fiestas are a rollover liability, I'd want to keep it as low as possible IMO

Never had any issues rallycrossing a 1st gen Neon with 390,000 miles on it.  Motor mounts broke, but they did that in 10,000 miles of street driving also.

Pete. (l33t FS) said:

In reply to iceracer :

Stock height Fiestas are a rollover liability, I'd want to keep it as low as possible IMO

Yeah, that's a real catch 22. I wouldn't want to lift it very for rollover and alignment concerns, but I've also never seen one compete that didn't seem like it was actively trying to destroy its front fenders.

The "front" (passenger side, ford calls it front because it's the front of the engine I guess) motor mount is a weak point. Not sure how long it would last in rallycross use, mine made it 80k miles of street and mild autocross use with an aftermarket rear mount before it started making noise. Normal failure mode is just the rubber wearing out, not sure if it would be different with rallycross use. Replacement part is only like $70 and there's a ton of moderately cheap aftermarket options though.

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

Because the SCCA forgot the mazda2 exists? Honestly I think even the ST is a rollover risk, for autocross anyway. They two wheel all the time and at least a couple have been rolled, though nobody's done it recently to my knowledge. If we're talking 100% rallycross use only I wouldn't be afraid to lift the fiesta a little bit, but not with base model springs (which probably wouldn't do much anyway because the ST is heavier than the base model) but something stiffer and higher.

dps214 said:

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

Because the SCCA forgot the mazda2 exists? Honestly I think even the ST is a rollover risk, for autocross anyway. They two wheel all the time and at least a couple have been rolled, though nobody's done it recently to my knowledge. If we're talking 100% rallycross use only I wouldn't be afraid to lift the fiesta a little bit, but not with base model springs (which probably wouldn't do much anyway because the ST is heavier than the base model) but something stiffer and higher.

Doubtful, since the outgoing rallycross chair rallycrosses a.....Mazda 2  :)

He (steve hyatt) isn't particularly fast since he doesn't do it much any more, but there is another local guy who runs with DC/Susquehanna, runnign a prepared class Mazda2 (bright green!) and he pretty much beats everyone except Andy Thomas. I've never observed his car to look as if it was a rollover risk, even on off-camber-downhill speed turns (where my worker station was at the last rallycross, as it happens). 

irish44j (Forum Supporter) said:

dps214 said:

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

Because the SCCA forgot the mazda2 exists? Honestly I think even the ST is a rollover risk, for autocross anyway. They two wheel all the time and at least a couple have been rolled, though nobody's done it recently to my knowledge. If we're talking 100% rallycross use only I wouldn't be afraid to lift the fiesta a little bit, but not with base model springs (which probably wouldn't do much anyway because the ST is heavier than the base model) but something stiffer and higher.

Doubtful, since the outgoing rallycross chair rallycrosses a.....Mazda 2  :)

He (steve hyatt) isn't particularly fast since he doesn't do it much any more, but there is another local guy who runs with DC/Susquehanna, runnign a prepared class Mazda2 (bright green!) and he pretty much beats everyone except Andy Thomas. I've never observed his car to look as if it was a rollover risk, even on off-camber-downhill speed turns (where my worker station was at the last rallycross, as it happens). 

Maybe I'm off base, but I thought he was referring to autocross, where the base model fiesta is specifically illegal because of rollover concerns, but not the mazda2.

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

Interesting, I thought Mazda2s were lower than Fiestas.

irish44j (Forum Supporter) said:

dps214 said:

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

Because the SCCA forgot the mazda2 exists? Honestly I think even the ST is a rollover risk, for autocross anyway. They two wheel all the time and at least a couple have been rolled, though nobody's done it recently to my knowledge. If we're talking 100% rallycross use only I wouldn't be afraid to lift the fiesta a little bit, but not with base model springs (which probably wouldn't do much anyway because the ST is heavier than the base model) but something stiffer and higher.

Doubtful, since the outgoing rallycross chair rallycrosses a.....Mazda 2  :)

He (steve hyatt) isn't particularly fast since he doesn't do it much any more, but there is another local guy who runs with DC/Susquehanna, runnign a prepared class Mazda2 (bright green!) and he pretty much beats everyone except Andy Thomas. I've never observed his car to look as if it was a rollover risk, even on off-camber-downhill speed turns (where my worker station was at the last rallycross, as it happens). 

We have a local with a prepped Fiesta.  It looks and sounds badass.  It also is probably a foot wider than a stock ST.

Pete. (l33t FS) said:

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

 

Interesting, I thought Mazda2s were lower than Fiestas.

the factory bilstiens are the same part number iirc

In reply to MrChaos :

Maybe it's a visual thing or something because all of the 2s that I have ever seen were hatches (was there a trunked 2?  Not counting the Toyota) and all of the Fiestas I see, if I ever see any, are trunk cars.  Very rare to see an ST.

Its like everyone said "The Focus is bigger and costs the same, I'ma get a Focus"

Pete. (l33t FS) said:

In reply to MrChaos :

Maybe it's a visual thing or something because all of the 2s that I have ever seen were hatches (was there a trunked 2?  Not counting the Toyota) and all of the Fiestas I see, if I ever see any, are trunk cars.  Very rare to see an ST.

 

Its like everyone said "The Focus is bigger and costs the same, I'ma get a Focus"

trunked 2 is called the scion iA, yaris iA or yaris sedan

dps214 said:

irish44j (Forum Supporter) said:

dps214 said:

MrChaos said:

so why are stock height fiestas a roll over risk while stock height mazda 2's arnt? same suspension down to the stampings.

Because the SCCA forgot the mazda2 exists? Honestly I think even the ST is a rollover risk, for autocross anyway. They two wheel all the time and at least a couple have been rolled, though nobody's done it recently to my knowledge. If we're talking 100% rallycross use only I wouldn't be afraid to lift the fiesta a little bit, but not with base model springs (which probably wouldn't do much anyway because the ST is heavier than the base model) but something stiffer and higher.

Doubtful, since the outgoing rallycross chair rallycrosses a.....Mazda 2  :)

He (steve hyatt) isn't particularly fast since he doesn't do it much any more, but there is another local guy who runs with DC/Susquehanna, runnign a prepared class Mazda2 (bright green!) and he pretty much beats everyone except Andy Thomas. I've never observed his car to look as if it was a rollover risk, even on off-camber-downhill speed turns (where my worker station was at the last rallycross, as it happens). 

Maybe I'm off base, but I thought he was referring to autocross, where the base model fiesta is specifically illegal because of rollover concerns, but not the mazda2.

oh, perhaps. I must have missed the topic change. 

In reply to irish44j (Forum Supporter) :

I was asking about rallycross, but if you guys had told me no, I would have switched the plan to autocross.  So all the answers have been super helpful.

thanks everyone.  Still thinking about it, but very happy with all the replies.  If I do buy one I have no problem getting and installing heavy duty engine mounts.  And likely an LSD!

In reply to Jah29 :

The guy I was talking to at Nats in 2016 said something to the effect of everyone with a FiST breaks X component.   I am assuming "everyone" means "everyone on the owner's forum" and the rule of thumb a friend mentioned about RX-8s: "Being on the Internet makes your car break".  He worked at a Mazda dealership and was not seeing the horrible problems people were having with RX-8s except for people who were on the forums, you see.

Personally if the brake assisted diff works, I'd use that.  All the advantages of an open diff without the disadvantages.  Assuming that it does not cut throttle at the same time, but the pictures I have seen of melted brake pads from track days suggests that it does not.

dps214 said:

In that specific situation I'd be most concerned about overheating. But generally speaking aside from mounts and temperature concerns rallycross is generally fairly easy on the drivetrain itself. We ran a car for a full season on a partially broken clutch disk before it finally gave up completely. Fiesta is open diff so I'm sure it'll be wheel spinning all over the place, but shouldn't really cause any issues.

Overheating is definitely an issue with the Fiesta ST in autocross and rallycross, low speed high load is not good for cooling.  My stock Fiesta ST overheated during an autocross, upgraded the radiator to a mountune/CSF unit and no more overheating problems.  Another Fiesta ST at the last rallycross (in cold Feb weather) overheated during its second run.

Some cars seem to handle heat better than others, there was theory about radiators with flaws from the factory that was addressed in later years.  Best bet is to give it a try and see if you have issues.

Fiesta STs are quite fun in rallycross once you figure out left foot braking.  There is a way to disconnect the brake switch in the pedal area to allow left foot braking without power cut.  Basically tape the brake light switch actuator at top of travel to trick it into thinking you never hit the brake, also this doesn't disable the brake based "LSD" (it would be disabled if you pull ABS fuse).