Lets talk Autocross

-
zhandfull

zhandfull

Well-Known Member
Joined
Mar 8, 2006
Messages
2,987
Reaction score
102
Location
Rancho Cucamonga
With this years MATS coming up I will admit it! I have been jealous watching the autocross guys having a blast going around cones in Vegas. So I'm thinking about maybe taking the budget Dart this year and participating in some of that fun.

I have already made a few handling and braking improvements to the car like bigger wheels and tires, 1.03 torsion bars, rebuilt front suspension, 11.75" disc brakes. The Dart also has another modification that may hurt cornering. The rear leaf springs have been relocated under the frame.

So whats the deal with autocross suspension set up? Seems like at the slower speeds the setup wouldn't be as much a science as say road racing but I'm sure I'm wrong.

What transmissions are the autocross guys running auto manual or both? Are they shifting or setting it up to basically run in one gear?
 
I would think a rear sway bay will compensate for the relocated springs some. The ride height of the car is very important especially in the rear. If the back of the car sits high it won't go round corners fast.
 
I'd think selected 2nd would do it. Good springs level car will help a bunch. Also make sure your thrust angle is on point. Most A bodies seem to be short on the passenger side.

Did you happen to install offset bushings?

I took some straight as possible 1x4's and put them in front on the front wheels, and behind the rears and took a measurement, mine was off almost 1/2". Shimmed them out with some 1/2" nuts. :D
 
zhandfull said:
With this years MATS coming up I will admit it! I have been jealous watching the autocross guys having a blast going around cones in Vegas. So I'm thinking about maybe taking the budget Dart this year and participating in some of that fun.

I have already made a few handling and braking improvements to the car like bigger wheels and tires, 1.03 torsion bars, rebuilt front suspension, 11.75" disc brakes. The Dart also has another modification that may hurt cornering. The rear leaf springs have been relocated under the frame.

So whats the deal with autocross suspension set up? Seems like at the slower speeds the setup wouldn't be as much a science as say road racing but I'm sure I'm wrong.

What transmissions are the autocross guys running auto manual or both? Are they shifting or setting it up to basically run in one gear?
Click to expand...

If having the ability to tune for an Autox is what you want, throw on a Hellwig E-body tubular rear bar. Its 3 way adjustable, about $175 and clears a spring relocate if you mount the dogbones on the inside of the bar eyes. The upper mount needs some reinforcement still in the pic, this was just the first mock up.
 

Attachments

  • 008.jpg
    44.8 KB · Views: 694
  • 007.jpg
    55.9 KB · Views: 752
mischiefdart said:
I would think a rear sway bay will compensate for the relocated springs some. The ride height of the car is very important especially in the rear. If the back of the car sits high it won't go round corners fast.
Click to expand...
I have the car low enough that will not be a problem. I was thinking the same about a rear sway bar and the relocated leaf springs
PoisonDart74 said:
Did you happen to install offset bushings?
Click to expand...
I did install the offset bushings and the stiffener plates on the lower control arms.
72BBSwinger said:
If having the ability to tune for an Autox is what you want, throw on a Hellwig E-body tubular rear bar. Its 3 way adjustable, about $175 and clears a spring relocate if you mount the dogbones on the inside of the bar eyes. The upper mount needs some reinforcement still in the pic, this was just the first mock up.
Click to expand...
Good to know that rear bar will fit with the relocated springs. Did I read somewhere you weren't running the rear bar because it made your car tail happy.
 
After watching multiple youtube videos of past Mopars at the Strip in Vegas. I think its important to point out the course is very short, tight and looks pretty smooth. The one thing I notice is the average cars roll around like the Queen Mary in rough sea's. The Hotchkis cars seem to be pinned down with very little body roll. Even the big old Road Runner doesn't look like it has any suspension movement at all. Looks like the cars are strapped down on the bump stops on all four corners or at least the fronts, not saying they are just pointing out how they look compared to the average car at the event.:scratch:

I guess I need to find a old parking lot with no lights or curbs to hit and do some initial testing. :-D

[ame="http://www.youtube.com/watch?v=xasTfEoRdt0"]Mopars at the Strip, Hotchkis Autocross with the Magnum - YouTube[/ame]
 
It made my car tail happy for a road course, but IMO I would have the thing at least in the trailer if I went Autox'ing just in case. On a tight course, tail happy can be faster.
 
That is a tight course compared to a what you'ld find at most SCCA events.
I've not run MATS or Goodguys, just SCCA or equivalent so my answers will reflect that.

Autocrossers run both automatics and manual transmissions. Advantages to both.

Which gear to use depends on the course and your car. If you can keep the throttle inputs super smooth, and there's enough tire grip, the gears that get you the most torque and the least amount of shifts is the best. I'll recommend you try to keep it in 2nd until you get a feel for things.

Always remember that the goal of autocross is least time on the course. Often this is not the same as highest speed on the course. Extra motion and extra distance can cost more than extra speed can make up for. This leads to the very best thing you can do to prepare is take a 'class'. Your local sports car club may offer one of their own or sponsor an Evolution school. If you get nothing else out of it, with an Evolution Phase 1 class you'll get a lot of seat time. For most people, the concepts and instructors are very helpful too. I thought it wasa great bang for the buck. Link=>http://www.evoschool.com/

Back to the car. I agree that a soft rear sway bar could help make up for the inboard relocation of the leafs. Dedicated autocross cars are often setup with a the tail a bit loose. That's fine when you get multiple tries and have a very low chance of hitting something solid when the car slides or spins.

Roll by itself is not a problem, its the side effects. When its excessive it can bring the suspension geometry into an unfavorable range, and driver tolerance for it also varies. How much spring needed depends on how well the tires stick. Just use what you have - at least to start. It's not like your on /6 springs with a big block. Also, as you learn to take a better line and use smoother inputs the car will roll less. I've been more than guilty of working the car harder than necessary on course.



Autocross is all about transitions so shocks are very important. They are key to controlling the motion. They can also be big bucks. Might want to just go with what you have for now.

Definately go with an alignment more agressive than the factory in negative camber and positive caster. Set toe just in or zero. If it follows ruts on the highway, toe it in a little more. Bring a tire pressure gage, measure all four cold, and then hot. Often a little more air in front reduces rollover and a little less in the rear can help induce some oversteer and get the rear tires hotter faster.

PS. If you have an passenger, tell them to hold on to the seat bottom, not the rain gutter. Hands out the window will earn a DSQ if not a red flag at an SCCA event.
 
Mattax thanks

Yeah the Vegas deal is not real serious just a fun event that I believe is sponsored be Hotchkis to showcase their products. Down a little closer to home they have a little more competitive events occasionally at California Speed Way in Fontana. The courses are much faster and longer.

I don't know the car is just suppose to be a cruiser and it does that nicely. I always enjoy watching the autocross cars and was just thinking it might be a fun change. I'm definitely not going to dump a bunch of money in the car, it is after all the budget Dart. It does need sway bars and shocks though.
 
Are you saying no front sway bar right now, or just the stock one?
Honestly, even without, you'll still have fun at the MATS autocross. But if your going to take a school (I added Evo School link above), you'll get more out of it with a front sway bar. Do not add a rear sway bar until you've added a front sway bar, specifically a large aftermarket front bar.

Shocks. Nowadays there's a lot more options. Just run what you have until you're ready to buy (unless they are not working or making you unhappy). Just don't waste your money on KYBs - especially on a street cruiser. Not enough high frequency damping. Although on a full rubber suspension maybe it wont be so noticible.

Oh. There is one possible issue. The typical power steering pumps can't keep up. I dont know the details as I use a manual box. Steve Wall can fill you in on that if it doesnt show up in a search.

One more. I like to run a fairly full fuel tank. Keeps weight from sloshing around and puts weight where its needed.
 
gold66cuda said:
http://www.youtube.com/watch?feature=player_detailpage&v=63dAEd7BPic

Here is my 66 cuda from last year, it has all the hotchkis stuff but 14" BFGs on the front and 15" BFGs on the rear, as you can see it was really tight. My advice is get a good set of low profile sticky tires and don't over drive it. Have fun.
Click to expand...

Come down again and hit Spring Fling the weekend before (Thurs April 3rd) the Vegas show and really run your car all day and get some serious seat time at SPEED!

We only ran this close for this video. Most of the time we are more spread out for safety.

[ame]http://youtu.be/ij9HK2GNTbQ[/ame]
 
gold66cuda said:
http://www.youtube.com/watch?feature=player_detailpage&v=63dAEd7BPic

Here is my 66 cuda from last year, it has all the hotchkis stuff but 14" BFGs on the front and 15" BFGs on the rear, as you can see it was really tight. My advice is get a good set of low profile sticky tires and don't over drive it. Have fun.
Click to expand...

Yes your car was one that I enjoyed watching. Your car actually handled very nicely. Don't remember everything you had done but definitely remember your car and the other early "A" think it was maroon and a little more of a stock Formula S car.
 
Mattax said:
Are you saying no front sway bar right now, or just the stock one?
Honestly, even without, you'll still have fun at the MATS autocross. But if your going to take a school (I added Evo School link above), you'll get more out of it with a front sway bar. Do not add a rear sway bar until you've added a front sway bar, specifically a large aftermarket front bar.

Shocks. Nowadays there's a lot more options. Just run what you have until you're ready to buy (unless they are not working or making you unhappy). Just don't waste your money on KYBs - especially on a street cruiser. Not enough high frequency damping. Although on a full rubber suspension maybe it wont be so noticible.

Oh. There is one possible issue. The typical power steering pumps can't keep up. I dont know the details as I use a manual box. Steve Wall can fill you in on that if it doesnt show up in a search.

One more. I like to run a fairly full fuel tank. Keeps weight from sloshing around and puts weight where its needed.
Click to expand...

Currently I don't have any sway bars

Funny you mentioned the power steering pump. I remember back in high school sliding My early "A" Mopar around in the rain and having problems with the power steering getting hard and losing power intermittently. It was the old style pump with the large cap. This Dart I think has the saginaw pump and box out of a 74 Valiant I also put in the washer to lower the pressure in the pump a little.
 
Overdriving is definately siren's call with high hp cars. Since we're posting videos, a bit embarressing but a good example. AbodyJoe took this video of my first run of 2013 with his phone.[ame="http://www.youtube.com/watch?v=eEgUVLCSNtU"]Auto cross cuda - YouTube[/ame]

Around 20 second mark is a good example of overdriving into the turn. It starts at least one cone back with too much speed and slightly late steering input, and then way too much speed into the 180.

Much better driving is the decreasing radius finish (helped by my o/c hidden by the region's truck). Both the off course and overdriving probably would have been avoided if I had arrived early enough to get in more course walks.

Based on other people's on-board videos, average speed on this course was 40 mph.
 
zhandfull said:
Currently I don't have any sway bars

Funny you mentioned the power steering pump. I remember back in high school sliding My early "A" Mopar around in the rain and having problems with the power steering getting hard and losing power intermittently. It was the old style pump with the large cap. This Dart I think has the saginaw pump and box out of a 74 Valiant I also put in the washer to lower the pressure in the pump a little.
Click to expand...

The Saginaw (oval neck) power steering pump is the one to get. In later years it was squared neck. You can also drill out the spool valve hole 1/64" larger than original to get more flow.

The Federal units do not keep up with sawing the steering back and forth quickly in an autocross.

If you can, later plastic Saginaw filler caps have a rubber baffle in them. I've even seen them at the parts store in the HELP section. You may have to mark a new fill level spot to match your original one. The quick turning in an autocross can get the P/S fluid to splash out of the cap. Sometimes even foam, so your good quality P/S fluid.

If you car has a Federal pump on it, I wouldn't let that be the only reason not to run the car. The course is super short. It's not a show stopper for what you are doing. BUT if you have one laying around...
 
autoxcuda said:
The Saginaw (oval neck) power steering pump is the one to get. In later years it was squared neck. You can also drill out the spool valve hole 1/64" larger than original to get more flow.

The Federal units do not keep up with sawing the steering back and forth quickly in an autocross.

If you can, later plastic Saginaw filler caps have a rubber baffle in them. I've even seen them at the parts store in the HELP section. You may have to mark a new fill level spot to match your original one. The quick turning in an autocross can get the P/S fluid to splash out of the cap. Sometimes even foam, so your good quality P/S fluid.
Click to expand...

Looks like I have the squared off neck. Do they use same bracket?
 

Attachments

  • 1972 Dart 053.jpg
    78.8 KB · Views: 600
The Saginaw is better but my federal has hung in for several track events and autocrosses. Don't let Steve scare you out of your old federal. 😄
 
zhandfull said:
Looks like I have the squared off neck. Do they use same bracket?
Click to expand...

That's a saginaw pump. Lots of parts store pumps come with the square can (resivour can). The can just pops off the O-ring around the pump when you take the rear bolts off.

I think the early '70 up brackets will work with the later pump. Those look like early 70's brackets you have. Not sure about brackets from something like a Diplomat?

The direction of the low pressure inlet nipple on the back of the can is what you have to watch. That seems to change through the years and the nipple can interfere with all kinds of stuff and point the wrong direction.
 
That MATS course is so short and slow I'm thinking just some sway bars and I could be having some fun

Any recommendations on sway bar sizes I'm running 1.03 torsion bars up front some old stock leaf springs rear. I was looking at 1-1/8 Addco bar for the front maybe that E body adjustable rear bar shown above. That should make it ride like a truck. Not running any HP so just need this thing to corner nice and flat.
 

Attachments

  • college 12.jpg
    75.9 KB · Views: 570
That looks like a great time, thanks for the video. We might take you up on that, just now planning to go to Vegas again this year but that video might change the plans a bit. I am waiting for my direct fit 5 speed to get here before I do anything with this car.

Sorry zanfull didn't mean to hijack the thread!

A quicker steering box like the Borgesen unit would be a great help to for a short course like Vegas.
 
GMachineDartGT said:
The Saginaw is better but my federal has hung in for several track events and autocrosses. Don't let Steve scare you out of your old federal. ��
Click to expand...

I agree it's not a show stopper.

Mitch Lelito and John Sandburg are SCCA Nationals competitive autocrossers. They had problems with Federal pumps years ago and switched. They ran lot of events and at a high level of competition and speed (time).

Some of their problems will not be problems for most everyone else.

I personally DID have a issue with the Federal pump in my 68 Dart conv. I could feel it not keeping up doing quick maneuvers. But that doesn't mean it was in great shape though and not worn out.

I had another Federal in my 67 Fury conv go bad, so I swapped the Dart's Federal unit over to it and put a Saginaw in the Dart conv and spent about $10 for brackets for it. I didn't have that issue in the Dart with it not keeping up. And the switched over Federal unit worked fine in the Fury, but I don't do quick maneuvers in that barge!
 
You must log in or register to reply here.
-

Back
Top