vwcorvette

Seems to be few folks using these, but it's what I have. So I'll ask away...

Mods include Bilsteins, poly bush f control arms and trailing arms, VBP radius rods, EBC Greenstuff pads, stock L48 (intake, carb, exhaust changes including headers), TH400. Stock aging springs and front sway bar only. Been fairly reliable. Just added 93 Sawblades with Hoosiers. Now it's somewhat competitive at the local AX level. However it ROLLS a bit and sits too high IMOP.

Haven't been to a track in 8-9 years and then it was with FWD VW purpose built for these situations.

I am thinking of doing COM in the Northeast. So that means NHMS, Mont Tremblant, etc.

Was thinking 360# rear composite spring. Stiffer fronts (though not sure of rating--500 maybe?) and sway bars front and rear.

Want to install a roll bar (not a full cage)to stiffen chassis and provide anchors for harness. I was thinking a main hoop with two rears bars and two door/side bars.

Brake upgrades have me confused/intimidated/unsettled. Stock is pretty good with the EBC pads for autocross and street, but have the dreaded soft pedal after a while. Most likely due to rotor run-out pulsing pistons. Would sleeved and o-ringed calipers be adequate for the occasional track day? Wilwoods would be dandy but pricey. Seen a few upgraded to C5s, but wonder about master cylinder capacity and ability.

Power steering is stock mostly new (save for the pump and box). Has the factory "free play" built in! Am looking at Grand Prix rack conversion for feel and price.

Can't do all things at once. Am thinking the brakes should be my first consideration, then steering.

Any thoughts on the TH400 for the occasional track day? Has aftermarket trans cooler in front of radiator. Shifts firm at the autocross.

As an aside, I do have a 95 Lt1 in pieces in need of rebuilding on the bench and the 4L60e that goes with it for future considerations.

Any suggestions? Thinking next year mostly. I'd like to do at least one track day.

Thanks,

George

txoutlaw55

First of all, welcome back from the Dark Side--FWD cars can be fun to autox, but nothing like a Corvette!

I have been running the SS, O-ringed calipers for a long time and I like them a lot. For the money, if you are not going to make your C3 a permanent track/autox car, you can't go wrong with them.

If you plan any serious high speed stops, go to a bigger kit. I have been considering hydraulic assist for my '69, because the big block doesn't provide enough vacuum to run power brakes efficiently.
With new brakes, you will have to be careful of locking up and sliding front tires. Flat spots suck!

Also, if you buy a weld together cage, be careful of stray sparks--old carpet and fiberglass burn easily!!

Good luck!

vwcorvette

Thanks outlaw.

Don't see myself going to a big block. Booster was new 3 years ago and that hasn't been a problem. I find that the brakes need bleeding more than I would expect. I always bled the brakes on my Rocco every year as precautionary.

By bigger kit, you mean fronts I assume? Certainly have the room inside the rims with the 17s. Would that mean adapter/spacer to locate same caliper further from hub to allow larger diameter rotors? That's how it's been done on VWs right from the factory.

Are your calipers new aluminum or the oem heavy units converted by SS?

I would not like to make the car a permanent ax/track car, but could see doing up to 3 track events annually and as many as 5 autocrosses a year.

Any more pics of your car?

What's the suspension like?

Thanks,

George

txoutlaw55

I ran it with NCCC for many years in the stock class (Group 1A). Now I play with my C5Z since 93 octane gas is cheaper than the 110 octane leaded race gas we run in the '69.

The suspension was stock, heavy duty from '69. We updated the bushings to poly a couple of years ago. The brakes are SS sleeved OEM with O-rings from Vette Brakes. Its an L88 big block, so with that big cam, we have a problem creating enough vacuum to run the power brakes, but I've been too lazy to do anything else to it in recent years. I have found that the pedal goes soft if it sits for any extended period of time. I would consider going to newer style C5 or Wilwood brakes if it would cut out all the bleeding time every spring.

The torque thrusts on it are 17 x 8 fronts running 245/40 and 18 x 12 rears with 295/30 Michelin PS2s.

The roll bar is rear braced and I installed C4 seats to keep me in the car while going around a corner.

Locke

If rotor run out is causing the brakes to go soft, fix the problem.
If the brakes brakes are going soft in a few autocrosses or in six months, well that sounds pretty normal to me. I would bleed the brakes before each autocross running the C-4 and did the same with a pressure bleeder back when I ran the '69. In NCCC events we usually make between five and fourteen autocross runs in a day so the brakes are really worked over hard.
I was using Motuls but have been successfully using Valvoline Synthetic to save a bunch of money in a year.
For track day use, you will need to consider brake ducts in the front of the C-3. A change in brake pads may be wise too. I plan on going to Hawk HP Plus for dual duty but am no expert in pad choice.
A roll bar will help the chassis a little, will give you a great place to attach a full harness and make things a little safer.
Before taking on that track day, pack the wheel bearings.
Keep an eye on your fluid in the tranny, maybe a switch to a synthetic fluid would be a good idea.
I'm in the process of starting a NCCC Group II, C-3 and have had 550 front and 330 rear springs recomended.
Txoutlaw55, your car is beautiful. I hope mine can get there some day. As you can see by my avitar, I need to start with CCWs. These C-4 wheels are just wrong on a C-3.

Locke
North Florida Corvette Assn., NCCC
Buccaneer Region, SCCA
Jacksonville, FL

AU N EGL

From our NCM event at VIR

txoutlaw55

Locke, are you gonna run it in IIB? Lets see some pics! Its good to see the Dinosaurs still running around.

vettehardt

I have a blue 73 and a yellow 76 both I run NCCC 2D autocrosses with.

The 73 isn't pretty, but it runs very well. It is a 4speed with hooker sidepipes. It has a 275hp 71 motor in it with an aluminum intake. It has the 550lb springs in the front, and a 420+lb VBP composite spring in the rear with adjustable strut rods. It has the KYB gas-a-just shocks all the way around. It has 1-1/8" bar up front and a 3/4" bar out back. I haven't run this one in over a year now because of a fuel starvation problem I haven't tracked down yet. I hope to have some time to work on it over Labor Day weekend.

The 76 has the same shocks, bars, strut rods, and front springs on it as the 73, but it has a 360lb VBP compsite spring in the rear. This one is an Automatic with a TH350 in it and the L-48 with 71 heads and aluminum intake. It has stock exhaust manifolds for now with tiny dual pipes. I have some under-car headers to put on but just need to be able to afford the rest of the exhaust. This one handles as good as or maybee a little better than the 73, but it definatly has less power.

I run 16X9.5" C4 wheels on both using 3" adapters. I normally use Kumho Victoracer V700 tires in a 265/45R16 size since they are the cheapest, longest-lasting race tire out there that fits.

I included this picture since someone said it was the only time they had seen the car shiny!!!?


In this picture I am making a fairly hard left hand turn so that is why the front is so high.

69autoXr

The roll bar with any forward bracing is going to stiffen the chassis significantly. I have a five point bar with two rear braces and a single, diagonal "Petty bar" and I was was amazed at how much stiffer the car felt after installing it.

I've been using the VBP o-ring calipers for several years for both autocross and track use. I use the ones with the insulators on the pistons. On a track with Wilwood 570 fluid and Hawk HT-10 pads, on a cool day I had no issues. On a hot day at my local track eventually the fronts would get a little hot and I'd loose some stopping power in the front, and the increased rear bias would make things interesting. I recently cut out some stainless steel insulating shims that go between the pads and pistons and at the same track on a similarly hot day, I had no problems running 20 minute sessions. The only other issues I've had with the calipers are that the piston insulators fall apart after a while and need to be replaced. I run HP+ pads for autocross but change to the HT-10's for track lapping days; for single or two-lap time trial runs on tracks I use the HP+.

The mods you mention above (rack and pinion, C5 brakes) are going to put you into a highly modified class at autocrosses, consider how serious you want to be at the events you run at before performing these mods. Stock-type brakes are plenty capable to be competitive, and the steering is a bit slow compared to newer cars but it just means we have to work a litlle bit harder.

vwcorvette

I'm beginning to get that clue.

Thanks for all the advice and input. So I think I'm gonna get new front calipers and look into pads. Cooling ducts will be on the list as well. Front and rear roll bars for sure with 500ish springs up front and the 360# composite in the rear. Anymore opinions about sway bars. My front end moves as much as any I've seen in all the posted pics (friends are joking that I need a set of 33s to go mudding with that clearance!). I don't want to move to a very uncompetitive classing so I will keep the steering as is and look to rebuild the box.

Great pic of everyone's cars. I like your paint Outlaw. Would do similar with blue instead of red on mine cause i like metallic blue and white combinations.

Keep the conversation going!

Thanks,

George

vwcorvette

69 autoXr: how close to Farmington Hills are you? My inlaws are there. We come out to MI every Thanksgiving. Would love to see your care.

69autoXr

Not far at all. Drop me a line when you're in town.

My experience has been to avoid too large of sway bars. I run a 1-1/8" front bar and stock 7/16" rear bar. I had bought a large aftermarket (3/4 or 5/8) rear bar and it lasted all of about two runs before I disconnected it, way too much oversteer.

Locke

There is a really valuable piece of information in the prior posts which applies to anybody who is new to the sport.
Before you start making modifications to the car, check out the sanctioning body, or bodies, you intend to run with and see what their rules are.
Often the cool mods we want to do (like the steering box that includes the power steering actuator I want to replace my worn out box with) will take the car into a higher ($$$!) class than I want to run with in NCCC or SCCA were NASA may not mind it at all.
Of course this applies to competition events were we are classed, if it's a track day or PCA Driver's Ed, run what you brung and enjoy the increased grip or reliability of the modifications.
In NCCC we can change to poly suspension bushings in the Stock class because rubber are no longer available for a C-4. Those bushings and brake ducts allowed in NCCC would make me a cheater in Stock class with SCCA but running in Street Prepared or Prepared would result in a whooping.
Take the time to see were and with whom you want to run and then make a goal and plans.

TXOUTLAW55 there are a few pictures of the new car on my photobucket page:
photobucket.com/albums/tt146/vettelocke/

Locke McCormick
North Florida Corvette Assn., NCCC
Buccaneer Region, SCCA
Jacksonville, FL

Mike P

Everyone has great advice. I'll second everything said so far.

You could use the stiffer springs. These cars like stiffer.

The sway bars are more of a personal preference, but you should find that the tinyest rear bar or even NO rear bar works very well. I, too, have a 1 1/8" front bar but no rear bar.

The bushings, strut rods and headers already place you in BSP or SSM in SCCA autocrossing. Changing springs won't move you. Changing to rack-pinion will bump you out of BSP (not sure about SSM).

Adding the roll bar, door bars and Petty bar will just about double the chassis stiffness. Obviously more effective on a convertable. The Petty bar has more effect than the door bars, so if you have to choose, go with the Petty bar.

Lower is better, too. Looks like you're at stock ride height right now. You'll need longer spring bolts in the back, and might have to cut a coil or two up front. Take your time when cutting springs, cut a little bit at a time, be methodical. Measure the ride height, cut 1/2 coil, reinstall, measure the ride height, cut 1/2 coil, measure the ride height, reinstall, etc..... I had to cut about 2"-3" from the front fender openings and about 1/2" in the back.

Agree on minimal brake upgrades for now. I run stock style capilers and rotors and Carbotech pads and my car STOPS!! No road course experience, so I defer to those guys on heat build-up.



Mike P

Locke

Chris, Mike ect....
Are you guys running 17" or 18" wheels? What back spacing and are you using notched trailing arms?

Mike, will your convertible top work with the roll bar? Is your forward diagional removable, if so how did you do the ends? I'd do a six point if NCCC allowed me to cut the dash in Group II but it's not an option.

When thinking about upgrading the brakes, unless you're going to add a bunch of horse power and run alot of laps, it does not seem like one of the most important things to do. I realize the new pads work better than the stuff of the 70's and 80's but back in those days the endurance racers ran fairly stock calipers and stock rotors. We did have the dual pin, metallic pads, insulated pistons and spacers to run the wide pads from Delco but still on stock calipers.

Locke

69autoXr

I run 16's or 17's; all are 11" wide.

The 16's are 4.25" bs (4" advertised) Real Racing Wheels and I use a spacer in the rear to clear the calipers. 275/45-16 A6, R6 and old bias plies. This Saturday I'm trying some 25x12 Hoosier R35 slicks in group 3. These tires are old and pretty well used so I'm mainly just trying them to test the fitment. If they're fast it will be a bonus.

My 17's are 4.5" front and 3-7/8" rear bs, no spacers necessary. Team III LTIII. 315/35-17 A6

No notched trailing arms, not allowed in Group II. Besides I've got a lot of flare to fill up in the rear, so I'd push the wheels out regardless.

Mike P

Complete Custom Wheel (CCW) 17" x 12" with 4.5" backspace. I use a 1/4" spacer on the rear to clear the parking brake cable/bracket on the outside of the control arm. No offset arms for me, either (that would put me out of BSP).

The factory hardtop does fit over the roll bar, it hits the inside of the top on the outside corners. I don't have a convertable top, but I'd assume it clears that, too.

My Petty bar is not removable. It runs from the center of the main hoop down to the inside face of the frame rail, just below the passenger floor pan. There's a nice flat section on the inside of the frame under there. I know the SCCA allows bars and cages in all cars/classes (I think) and allows the resulting holes in the car for installation. Are you sure NCCC doesn't allow their installation, since they are a safety item.

The Petty bar gives the passenger a nice place to hang on, and has room for one foot on either side. You'd HAVE to put a 4 or 5 point harness on the passenger side.

Mike P

vwcorvette

When I mentioned new calipers I meant stock other than going with sleeved and o-ringed. I'll just have to experiment with the pad choices.

So the consensus is no door bars but the Diagonal bar. Do you have pics of the install?

I am running C4 Sawblades with 3 inch adapter/spacers. OE trailing arms. Clears the e-brake okay by about 1/4 inch.

I was wondering about cutting the springs. I've done this on my VWs in the past so I am familiar with the process.

I would need the 10 inch spring bolts then for the rear if I went to the 360# composite rear spring.

Thanks for all the information. The articles posted are great too, just skimmed them for know. Will go thru them when I have more time. This season is almost over anyway and I've picked up an exhaust leak that appears to be at the header to head gasket.

Keep the pics coming!



Here's mine.

vettehardt

I do use the stainless lined calipers, but I don't use the O-ring style. I use the lip seal style. According to a paper that Duntov wrote, the brakes were designed with the lip seal for a reason. The shop, duntov motorsports, has that paper on their website.

For header gaskets, don't use the paper kind. Get the copper or aluminum gaskets. My dad and I had problems with gaskets blowing out on our hooker sidepipe headers. We put the copper gaskets in and haven't had a single issue since. I can't remember when they went in, but it was around 1998-1999. I just installed a new set of headers (the old ones rusted out) with the same gaskets.

I just looked at the rules. You are able to put in a 6 point cage, but (you are right) you can not cut the dash in groups 1s, 1, 2, or 3. You can cut the dash in RP or RPAF.

Locke

I just looked at the rules. You are able to put in a 6 point cage, but (you are right) you can not cut the dash in groups 1s, 1, 2, or 3. You can cut the dash in RP or RPAF.[/QUOTE]

Captain Jack has a full cage in his GpII B car and it was installed in the door opening to clear the dash. I intend to use my car alot more on the street (or I would have gone III R/P with a different car) so want the room in the door opening and footwell. My old Gp III R/P car had a diagnoal bar from the center of the main hoop and it wasn't very comfortable for a passanger so if I do one of those it will be removable again.

Here's a question for you GP II B guys:
The z-28 / LT1 intake which we can run has become rather costly even if you can find one not ported for racing. Since the GM Performace book touts the new LT1 manifold as being a replacment for the old one, only lower to promote hood clearance, can we use it? It's only $250 from my local Chevy dealer. I don't think it's legal but feel it should be. For that matter, I'd vote for using any dual plane manifold.
I've been approached to be the RCD for the Florida Region, maybe I should do it.

Edit: Oooo, I'm not speeling very well this morning! Why doesn't this thing post my signature when I check that box????
Locke McCormick
Jax FL