Need help keeping up with C6 Z06 & Porsche GT3 on Road Course

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Uhcoog1

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I've been reading a lot of posts about great handling torsion bar cars, including autoxcuda's car, Tim's '68 Valiant, dusterbd13's low budget build, Mitch's '70 chally, and the Hotchkis 70 chally.

Anyway, I'm square in the middle of a 5.7 hemi, tk0600, Dana 60 swap into my '73 Duster. My goal is to run with (or run down) my buddy's on a road course (porsche GT3, C6 Z06). Big goal, I know. The hp will be there (prob 450 rwhp), so I need to figure out the rest.

The hemi swap is taxing my wallet, so I can't jump right into a full hotchkis TVS or similar. So far, I've picked up andyF's 11.75" viper kit, viper calipers, the appropriate 73+ drum spindles, and 1.04" (250#) mopar perf bars. So, I haven't really set a direction yet for the suspension. Oh yeah, I have stock replacement leafs from jcwhitney (10 years old), with caltracs set up with minimal pre-load for street. KYB shocks. And the Dana 60 that will be going in has the big drums.

I'm up to date on autoxxcuda's current build (Hotchkis TVS, 1.14" torsion bars), and his last set up (like dusterbd13's). The set-ups I don't know much about are Tim's '68 Valiant, and Mitch's 70 Challenger. I've seen it mentioned Mitch has done 1G+ in the skidpad, which really impresses me. Can anyone tell me a little about what torsion bars and sway bars these guys are running?

Also, Hotchkis has a great line about "geometry corrected" tubular UCA's, and "geometry corrected" leaf spring set up. I'm guessing they're just talking about UCA's that can achieve the ideal alignment, or have they adjusted the suspension geometry?

My current thought is to swap in the 1.04" TB's, get a hellwig front and rear sway bars (~$300), Moog offset upper ball joints, align as best as possible (maybe do spacers? need to know more here), and then fit sticky 275's on all 4 corners (been looking into 275/35 18 - need to do some measuring). QA1's or Bilsteins from Hotchkis at the same time or soon to follow (~$400).

I imagine I could use a bigger sway bar for a higher effective Roll Stiffness, but I'm guessing since I don't know the ratings of the Hellwig or Hotchkis sway bars. I'm not opposed to swapping torsion bars, either.

What am I giving up by not obtaining the tubular control arms, adjustable strut rods, and adjustable steering rods from Hotchkis? And on another note, will my factory replacement leafs with caltracs suck on the road course? I plan on finding out...
 
Uhcoog1 said:
What am I giving up by not obtaining the tubular control arms, adjustable strut rods, and adjustable steering rods from Hotchkis? And on another note, will my factory replacement leafs with caltracs suck on the road course? I plan on finding out...
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A few quick things before an expert steps in:

1) Seriously consider adjustable strut rods. Spend the extra $200 and buy from RMS. They will round out your front end with your already great suspension choices.

2) Firm Feel Stage III Steering Box. You want to have more fun than z06 guy right?

3) Don't waste $ on adjustable steering rods. Get 11/16" C-Body tie rods and PST solid sleeves

4) The center of gravity must change. Drop the car 3"

My apologies for not having the time to address a whole lot of your above questions. Good luck.
 
YoungBlood said:
A few quick things before an expert steps in:

1) Seriously consider adjustable strut rods. Spend the extra $200 and buy from RMS. They will round out your front end with your already great suspension choices.

2) Firm Feel Stage III Steering Box. You want to have more fun than z06 guy right?

3) Don't waste $ on adjustable steering rods. Get 11/16" C-Body tie rods and PST solid sleeves

4) The center of gravity must change. Drop the car 3"

My apologies for not having the time to address a whole lot of your above questions. Good luck.
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Thanks for the help! I'll research the adjustable strut rods and look into what I need to do for the C body tie rods. I have to run manual steering to fit the hemi, and eventually I'll look to a faster ratio box.

COG drop- how low do I want to go? I don't even know what "stock" height is, but I do have it high enough that the bump stops are still in. I've seen a number of guys with no bump stops and maybe a 1/2" before hitting where the bumpstop was. That okay?

1968FormulaS340 said:
There is your problem. Sorry for this but your goal is unrealistic for your budget.
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:booty:

HemiAlex said:
How about option V.


Put said Hemi in a Viper and profit.

:)
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Haha as fun as it would be, we'll save that project for a few years from now! I guess I should say I want the duster to fill a Viper's mirror as well...
 
I know moneys tight but if you want to keep up you probably have to go Alterkation for the best handling to realisticly have a chance of kickin there ***.
 
I thought long and hard about the AlterKtion, but I decided against it. The fastest road course mopars I've seen are all torsion bar cars. Have ya'll seen some impressive alterKtion cars on the roadcourse?

Shoot, the Hotchkis TVS 70 Chally finished fourth at the 2010 Motor State Challenge. Out of a field of 80. Including 2 XV cars (one level II XV car).
http://www.pro-touring.com/showthre...or-State-Challenge-OFFICIAL-Results-and-Recap

I'm going to stick to the torsion bars.
 
Subscribing to the thread.

Yes, his goal is lofty, maybe unreachable, but as long as this doesn't decend into a bunch of T-bar vs coilover bickering, some useful information might be generated.
 
Those cars are light, Vettes anyway, 2900 lbs and the newer ones are 600hp . You need to fit seriious rubber under your car to match what they are running. Just look at the size of there brakes! Plus alot of guy's supe them up more!
If you can put together something that even comes close and then have the cohoney's and skill to drive it-GOOD FOR YOU!!!!
If you can drive that fast My hats off to you. Suped up new Vettes are something to see when there driven by a skilled driver-Nothing that i have seen keeps up w them-Porsche included. I hate to say it but Vipers are tubs compared to them-Hurts me
Strange Engineering had a full tube frame race car(camaro) at road america w an AL 427, 355 x 17 tires 13inch Baer brakes and the Huge winged vettes were beating him
I am just glad Vettes are made in USA All Im saying
I have 5xxHP Primered Dart w lots of suspension mods and my plan is to have a 150 shot in the trunk for when a vette is behind me and getting ready to pass in a straight---FUN
 
I am building something very similar to your car. I would recommend ditching the heavy and expensive Dana and go with a 8 3/4. For handling purposes the car has to be as light as possible with an emphasis on unsprung weight. I can't stress this enough! Look at the supension on a newer Vette, Viper, Porsche, etc. and you will find spindly little aluminum arms and rods that look barely strong enough to support the the car let alone take 1+ g's in the turns.

Talk to Dick at Firm Feel. He knows his stuff when it comes to torsion bar suspensions in these cars. He built a setup for me that uses '73/up b-body LCAs and his tubular UCAs. I don't know much about the "geometry corrected" arms. What exactly are they trying to correct? Stock geometry in these cars is pretty damn good and doesn't need improving IMO. What does need improving is jounce travel. When you lower the car enough, you will use up your jounce travel (wheel moving up into the fender) leading to a potentially serious situation where the suspension goes solid. You definitely want to keep the bump stops! The b-body LCAs are curved rather than straight, giving you a little more travel. They also widen the front track by 2" requiring a wheel with a large offset.

As far as running them down, Vette owners are mostly mid-life crisis pussies that can't/won't push the car to it's full potential. Should be a piece of cake! :toothy7:

As far as Vipers being tubs compared to the 'Vette, remember the Viper OWNS the track record at the famed Nurburgring race track for production vehicles, beating the 'Vette as well as many other cars.
 
Uhcoog1 said:
Thanks for the help! I'll research the adjustable strut rods and look into what I need to do for the C body tie rods. I have to run manual steering to fit the hemi, and eventually I'll look to a faster ratio box.

COG drop- how low do I want to go? I don't even know what "stock" height is, but I do have it high enough that the bump stops are still in. I've seen a number of guys with no bump stops and maybe a 1/2" before hitting where the bumpstop was. That okay?
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Driving it 1/2" from the rail may be okay on the 'course (I really don't know), but taking grandma to the olive garden would be a nightmare.

I broke the bumpstop completely off and the first time that b-word hit I almost barfed. I thought the worst. It was a hell of a ride back to the shop to inspect what was going on... So if you're thinking it's gonna be a 90% street car, you might not dig it. Super stiff torsion bars be damned, a 1/2" travel can and will happen driving around in traffic.

On another note, I purchased a set of 1.03" bars knowing full well that lowering the car (as far as I freely could) the traditional way would be limited with that stiff of bars vs. the 318 bars that I could drop and stink-bug the car however I chose (this will limit your achievement of ideal COG obviously). You can get it pretty low with your 1.04" bars though still; watch those big 18's up front.

For the rear, with what you want to do, definitely replace your leafs w/ hotchkis geom. corrected and use the RCD Bilstein shocks (QA1 Adj. are friggin expensive).

Haters will hate. I say give this idea hell.
 
Lose weight, optimize suspension, stir in a bunch of torque and have fun.

If all else fail, swap some modified A-Body panels onto one of these and walk away from everybody.

Akins962C.jpg


962-051.jpg
 
Ask these guys , Challenger came in 1st or 2nd , Dart came in 9th out of 24 cars , lots of 67-70 Camaro , mustangs and one 1970 Javelin that won or was in 2nd place . 2 Penske Sunoco Camaros were there , Dart beat most of them . Dodge rules !
dartsummer2011022.jpg

Darts engine , over 500HP
dartsummer2011021-2.jpg



dartsummer2011027.jpg
 
Copy Tim Werner's 68 Valiant.

Mitch's 70 Challenger is purpose built for SCCA Autocross E-Street Prepared class. That is class racing in true competition; ie rules. Mitch's setup will hold you back for what you want; road course.

Tim Werner's 68 Valiant going off my memory. Hopefully AndyF will chime in with more details.

Motor

Suspension
  • 1.24" Torsion bar
  • bilstein shocks
  • Firm Feel tubular upper control arms
  • Firm Feel strut rods (but I think poly bushings. This was before people came out with spherical end strut rods)
  • road race leaf springs (I believe from Firm Feel. IMHO Hotchkis will be equivalent
  • AREngineering Brembo or Baer 6 piston conversion with 13" rotors and aluminum hubs. He currently runs the Baer caliper.
  • I think he just runs rear drum brakes

Tires/Rims
  • 275/40/17
  • 17x9 mustang rims

Chassis
  • 3130 lbs with a 55/45 split
  • full cage
  • front down bars tied to shock tower/inner fender
  • subframe connectors
  • 8 3/4 rear 2.94:1 ratio rear gear (I think clutch sure grip)

Notes: You need to baffle the center section to axle tube connection with Seals-It axle tube baffles. AND weld gate plates with holes in bottle to baffle the side ramps inside the round center section housing. You need to run a remote axle vent tube. Up at the top of the floor board or into the trunk compartment.

If you go 5.7 Hemi can you get the motor with same ground clearance as a stock motor? Meaning level with the bottom of the K-member. Will the header for the 5.7 Hemi (TTI's) has the same or less ground clearance as thier LA small block headers.

If you go 5.7 hemi does the oil pan have equal road race baffling as the Sm block and Big Block Milodon pans? Remember when Tim Werner tested his car with the new motor he could run easy with C5 Z06's, but the Charlie's oil pan couldn't keep up oil pressure and he had to put it back on the trailer. Now he has a Milodon SB road race pan.

pics of Tim Werner's car from 2007. Motor is different now.

2007-05-03_015.jpg


2007-05-03_016.jpg


2007-05-03_017.jpg


2007-05-03_038.jpg
 
Thanks for the replies guys!

Steve-

I'll have to do more research on the hemi pan. They say it's baffled- how baffled I don't know yet. The TTI motor mounts were designed with a 727 bolted to it to maintain stock engine location, so I'm guessing they also paid attention to the angle, and therefore it should be mounted in the same location. When I had the bare block in, it looked good to me. I do not have the pan yet, but the pictures show adequate ground clearance, probably even with the k member (I think it's a 6 or 7 quart capacity). I don't know the TTI ground clearance, but they're really the only option for headers right now. I appreciate the advice on the rear end oiling - I'll make it happen.

1.24" torsion bars - talk about some springs!!! What sway bars does he have with that? I found an article on Mitch's car - he runs the 1.24" torsion bars as well. I'm seeing a trend here... Has anyone tried lighter ~1" torsion bars with thicker sway bars? Or does that not have the same effect? I need to go read some of my suspension books again...

Jerry - do you have contact info for those drivers? I found some driver profile pages for them, but there was no contact info.

Mr. Ed - Dr Diff actually recommended I stick with the Dana - said the weight was negligible (30 or 40 pounds?). I'm sure the big drum brakes aren't doing me any favors, though. Also, I spent some time on firm feel's website last night - thanks for the recommendation to call Dick. I'm sure he'll be a great deal of help.

Youngblood- I'll be doing this, no matter what. With a video camera mounted in the car. So, you'll get to see it all ;)
 
Uhcoog1 said:
Thanks for the replies guys!

Steve-

I'll have to do more research on the hemi pan. They say it's baffled- how baffled I don't know yet. The TTI motor mounts were designed with a 727 bolted to it to maintain stock engine location, so I'm guessing they also paid attention to the angle, and therefore it should be mounted in the same location. When I had the bare block in, it looked good to me. I do not have the pan yet, but the pictures show adequate ground clearance, probably even with the k member (I think it's a 6 or 7 quart capacity). I don't know the TTI ground clearance, but they're really the only option for headers right now. I appreciate the advice on the rear end oiling - I'll make it happen.
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Sounds like the centerline of the crank is in the same location.

Who pan is it? What part number?

1.24" torsion bars - talk about some springs!!! What sway bars does he have with that? I found an article on Mitch's car - he runs the 1.24" torsion bars as well. I'm seeing a trend here... Has anyone tried lighter ~1" torsion bars with thicker sway bars? Or does that not have the same effect? I need to go read some of my suspension books again...
Click to expand...

You could try a soft spring/big sway bar/big shock combo. That's what we run in our Nacar Late Models. But you'll probably need a sway bar in the territory of 1 1/2" size. A splined Speedway Eng. unit would give you flexiblity. But those setups need pretty trick shocks ($$$). And most of all you'd need a lot of track time testing with some crew to make changes. Double adjustable shocks too so you don't have to buy tons of shocks. The shocks are what make those "big bar" setup work.
 
Regarding the Dana, most serious racers would give their left nut to save 40# of unsprung weight. You're not gonna blow up an 8 3/4 road racing. It also takes more torque to turn a Dana. Not tryin' to argue, just sayin'.

The TTI headers fit nice and snug to the bottom of the car with a little tweaking. The collectors come out perfectly through the t-bar crossmember factory " cutouts". Clearance to the left t-bar is very tight. I doubt a 1.24" bar would fit on my car without some serious header dimpling.

The trans may cause some issues. I got mine from Keisler and had to shim up the trans mount quite a bit because it made the back of the engine and therefore the headers, hang too low. It also screws up the front u-joint angle and engine clearance to the firewall. I have the trans as high as it can go without modifying the crossmember.
 
Mr.Ed said:
Regarding the Dana, most serious racers would give their left nut to save 40# of unsprung weight. You're not gonna blow up an 8 3/4 road racing. It also takes more torque to turn a Dana. Not tryin' to argue, just sayin'.
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I agree. And I'd run a True Track limited slip with that 8 3/4 too.

The TTI headers fit nice and snug to the bottom of the car with a little tweaking. The collectors come out perfectly through the t-bar crossmember factory " cutouts". Clearance to the left t-bar is very tight. I doubt a 1.24" bar would fit on my car without some serious header dimpling.
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I've got 1.14" with my TTI's with no dimpling. I've got room for more.
 
One of the most important aspects not mentioned yet is DRIVER EXPERIENCE........Gotta have the seat time.

If I remember correctly the owner of the red 68 Valiant above is a driving instructor, has a lot to do with how fast that car is.
 
rjsjea said:
One of the most important aspects not mentioned yet is DRIVER EXPERIENCE........Gotta have the seat time.

If I remember correctly the owner of the red 68 Valiant above is a driving instructor, has a lot to do with how fast that car is.
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Extremely true!

And the older cars are going to be tougher to drive as quick as the new stuff even is they are equal capable cars. Experienced driver in new sportscar might be as fast in older modified car. But inexperienced driver will probably be much faster in newer sportscar.
 
Sorry , no contact info , i posted on another thread car entrant , owners for event that's as much as I know . Spoke with the Mechanic for a while but that's it . Gary Underwood is listed on entrance form . Good luck , that Dart ran really well
 
I have minimal driving experience. I'm reading what I can get my hands on and I'm sure I'll probably watch some videos. The program these guys drive with is called the drivers edge, so everyone will have an instructor in the car for their first few times out. For now, I've got a CR80 shifter kart I'm running on our club track down here. If you've never driven a shifter kart, you're missing out!

I've been playing with the tranny output angles as well- I'm finding the same thing you're saying, I'll shim it as high as possible, and ill still want more I'm sure. But, it'll do according to my math.

The pan part number is 31000.
 
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