Old track car project - new update
 

Some of you may remember that I have been working on a 56 Corvette track car ----- forever. A few months ago I finished fabricating an all new, high travel, low roll front suspension. I built several lower control arm mock-ups to work out all of the tire clearances with the 335 front tires, deep backspacing, high travel, lots of caster gain, etc. Anyway, I finally sent the chosen mock-up to my son Ryan to finish the fabrication - chrome moly, Sutton inboard bearings, Howe ball joints. He built fixtures and even built special bender shoes to get opposite direction bends very close together. He sent me these photos as he gets ready to start Tig welding. They are car porn!

Pappy

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For those going through the same drill putting wide, deep backspace wheels on their projects, I thought I would post a couple of pictures of the wheel mock-up I built to verify clearances. By raising and lowering the car, turning the wheel to 30 degrees, and rotating the mock-up I was able to locate all of the areas of interference. It is amazing how much the wheel moves around in the wheel well when you go through lots of compression, especially with a good bit of caster gain. A "static" check of fitment at ride height won't catch all of the possible areas of interference.

Pappy

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Looks great Pappy, you and your son both have loads of talent! Looking forward to seeing this one done.
:thumbsup:

Thank you. I got wrapped up in a couple of other projects, but I got them under control so I am back on the Vette - should make faster progress! Ryan's work is superb. He is becoming one of the best fabricators I have seen - puts me to shame.

Pappy

Looking Good Pappy !

It's been a year, but I'm back on this project with a vengeance. Finished the high travel/low roll front suspension (thanks Ron), but decided the rear suspension wasn't going to be strong enough for what I have planned, so I bought a complete Detroit Speed Decalink which I am in the process of adapting to the C1 chassis. I decided to stay with a non-traditional big block (for a road race car), so I am having a 515 inch, Brodix all aluminum motor built (3.875 stroke, 4.6 bore). Brodix heads, T&D shaft rockers, Hogan fabricated sequential injection manifold, Motec ECU, Comp Cams solid roller, Calles crank/rods, 13:1 JEs, and a Dailey Signature dry sump system. All of the parts are in except the intake and wiring harness. I purchased a Tilton triple disk carbon clutch with bellhousing, flywheel, and reverse-mounted starter. I am having to move the motor back another 5 inches (for a total of 15 inches) because the dry sump pump wouldn't clear the back of the lower control arm mounts - LOL. Pics to follow soon - I hope.

Pappy

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Short stroke big block! Yes please! :bigun2:

Very cool.

That motor setup has me drooling! What a setup....

It's good to see that your grandchildren's grandchildren will have a car to drive. :D

A few new parts
 

DecaLink and Tilton 7.25 inch triple disk carbon clutch. Motor is progressing - should get the Hogan intake next week and Shane Tecklenburg is doing all of the Motec integration (computer, harness, sensors, tune).

Pappy

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Ron Sutton gave a good response to questions about an IRS versus an offset 3-link in Greg Weld's Track Warrior project thread. I have been messing with the IRS for 40 years and have stumbled on most of the "issues" that Ron points out. However, I think I am getting close to a solution that solves a lot of the problems.

Background: I first tried an old C-3 Corvette IRS. Lots of issues, the most significant of which were that the half shaft acted as both a drive shaft and a suspension link, and as the suspension compressed it caused toe out roll steer which is why you see C-3 corvettes with the rear hanging out most of the time - fun, but not very fast. Then I went to a C-4 Corvette-based suspension. Better, but the half shafts were still part of the suspension, and the forward links are too short causing fore-aft movement of the tire with suspension travel. This contributes to roll steer, but GM made the toe links long so the rear would toe in with compression (for road safety reasons). Then there are the C5 to C7 Corvette-based systems with upper and lower control arms like a front suspension. If you don't use the Corvette transaxle then you need to fabricate a system for a differential. We did that using a Camaro differential and Corvette control arms in an old Jag. Works okay, but you better get the geometry right the first time because there isn't much provision. for adjustments, as Ron points out.

I prefer (and designed) a multi-link IRS much like the old CanAm cars and some other open wheelers. The multi-link applies drive and braking forces parallel to the car's longitudinal axis (like a 4-link), can be adjusted for bump-steer like a front suspension, and is easier to build in roll center and anti-squat/anti-dive adjustment capability. I was struggling with connecting the forward links to a C6 upright, when along came Detroit Speed's DecaLink. This gave me all the features I was looking for in a multi-link plus the Hammerhead differential is plenty strong and the 1250 HP axles shouldn't give any problems. I purchased the Decalink and will be installing it in the next few weeks, which will cause a little "surgery" since it wasn't designed for my chassis. Nothing a chain saw can't handle. LOL

Pappy

C-3 Suspension
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C-4 Suspension
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C6 Suspension w/Camaro Differential
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Multi-link Mock-up
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DecaLink
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Old Track car
 

Wondering what you have heard about the CV joints
vs old spicer/u-joint shafts.... one of my Pantera buddies
states the harmonics are better on the CV joints... I have
seen one of the big block cars tear up a set of CV joints
but u-joints can also fail

Also been told the CV joints need to be maintained
I am toying with changing out the shafts on my Pantera

By the way the Big block Pantera has a C-5 suspension
adapted to his car.. Thanks to you an Ron for all the info

Bob

Hey Bob,

If you are referring to the u-joint shafts with splines to absorb the length changes during suspension travel, there are some problems with spline friction/binding with high horsepower applications. Friction in the splines causes inconsistency in suspension geometry. The newer CV joints are very strong - in fact some drag and standing mile cars are hitting them with 2000+ WHP. I ordered the "1250 HP" CV joints/shafts from Detroit Speed - should be plenty good for a track car with 8-900 HP.

Pappy

Old track car
 

Thanks for the info
Yes was talking about cv joints

Bob

Great discussion!!

I'm not a suspension "guy" --- frankly -- I could care less about it. I have a guy that knows a guy that knows a thing or two about that stuff.... so I can keep my pretty little head as empty as possible....

My many many years of experience with C3 "stuff"...... I could always find the weakest link. Usually the little stub axle. Shear those little POS easy.


The setup Pappy has found is certainly NOT C3..... and Detroit Speed should know a thing or two about horsepower! Looking forward to updates when you finally hit the track with this!

Thanks Greg. Building it for NASA TTU/STU, so maybe we can get together on track - figuratively, not literally. Got the intake today - nice piece. Moving the motor down 2 more inches (small flywheel and Tilton bell housing and shallow dry sump), but will still have to have a 4 inch cowl hood to get plenty of room for airflow.

Pappy

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Old Track Car
 

Hogan's manifolds are always a work of art
Thought about just having one in my office
to smile at on a bad day

Looks like your vette has all kinds of great items

Bob

Getting on track with friends..... YOU BET PAPPY!!! Let's do this!!!

A little progress. Motor is almost done and ready for the dyno. Hogan is doing a little more on the manifold and the harness for the Motec is in work. Ron Sutton just spec'd the front sway bar and will soon get the JRI shocks for a little "secret sauce". That finishes the suspension. Sorry for the quality of the cell phone photos.

Pappy

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Hey Pappy, any updates on this?

Motor is finished. Just waiting on the harness for the Motec ECU so I can go to the dyno. Got the Forgeline GA3Rs (18X12 inch front/18X12.5 inch rear) and mounted a set of Hoosier 335/345 scuffs. I went with 8.5 inch backspacing on the front to get .375 inch of scrub (left a little to account for tire squirm under load), and everything cleared including the inner inside of the barrel (control arms, tie rod, sway bar, etc.) and the tire thru full suspension travel up to 30 degrees of turn. Whew. I've still got to move the firewall and motor back 5 more inches to get the dry sump pump to clear the aft pick-up point of the lower control arm. With the smaller Tilton bellhousing I will also be able to lower the motor another inch or more. I also got the Tilton 900-series pedals so I will complete their installation when I move the firewall. Still lots to do, but getting there.

Pappy

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Jewelry......

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That looks great Pappy.

I don’t know what your plan is for the water pump bypass, but I don’t see a port in the intake. I tried to run mine without it and it almost always developed an air pocket and belched out my over flow. I’m talking about each drive cycle.

Thanks Todd,

In the past I drilled a couple of holes in the thermostat base circle and that seemed to work fine. I guess my other option is to drill and tap a hole in the face of the thermostat housing boss (below the thermostat) and add a small bypass line from there to the pump. Thanks for the observation.

Pappy

I don't think I tried that and I don't recall why, but the coolant from the factory returns to the pump under/before the t stat.

Decided that the C-4 Corvette based suspension was not going to be strong enough, and I wanted to get the half shafts out of the suspension business, so I took this out:

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I am in the process of installing the Detroit Speed Decalink with a 3:73 Hammerhead differential. It was designed for a C-2/C-3 Corvette, but with some minor modifications it is going to fit the C-1 chassis fairly easily. Luckily the forward four-link provisions I had for the previous suspension fit perfectly (width and vertical placement with adjustment capability), so the conversion is going smoothly. I watched the DSE Corvette company car with the Decalink at last week's Goodguys autocross in Scottsdale, and I really like the way the rear was planted.

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Pappy

Short update. The DSE Decalink install is almost complete. Even though it was designed for a C-2/C-3 Corvette, it went in the C-1 chassis fairly easily. Modified the cross member to fit the C-1 frame rails, added a front hoop to carry the front of the differential, and added 4-link-style, adjustable pick-up points for the forward links. The 345s on 12.5 inch Forgelines fit perfectly. The motor is done - just waiting to get it on the dyno.

Pappy

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Wow, that's awesome! Glad it's working well for you, Pappy. Good luck with it in this new year.

This looks interesting. So a C4-type suspension is also called a five-link, I think, and the DSE setup is called a "decalink," which sounds like a Bruce Jenner-style update (the Olympics version, not the modern one). It's hard to tell via DSE's site, but is there now some semblance of an upper control arm? Aside from that, it looks very similar to the C4 setup (with batwing!), which I recently learned was largely pirated from early Indy car-type setups (makes me feel better about my C4 stuff) . . .

Nice stuff!

It has an upper link, a lower link, a toe link, and two forward links - so you could call it a true 5-link. The axle shafts are free-floating with CV joints and are not part of the suspension like the C-4 set-up. The C-4 uses the axle shaft as the upper suspension link, but the Decalink does not. The C-4 is, therefore, a 5-link with the axle shaft serving as the fifth suspension link. I had a C-4 based rear suspension in the car earlier, but I pulled it in favor of the true 5-link (post 26 has a photo of the C-4 based system in the car). If you look carefully at the picture I posted of the DSE unit mocked up in the car (post 27) you can see the upper link. The axles are not installed in that photo. I debated going to upper and lower control arms, but I am fond of a multi-link that applies driving and braking forces through the forward links that are parallel with the car's axis - much like the old CanAm cars. The forward links also give you a much better range of anti-dive/anti-squat adjustments than control arms, and the lateral links (upper and lower) provide for a wider range of roll center adjustment. Thanks.

Pappy

Finally got the motor on the dyno. 852.71 peak HP @ 7100 rpm, 685 peak torque @ 5900 rpm. Should be enough.

Pappy

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Jesus, that is outstanding. :bigun2:

Not bad for an NA motor. The AFR was a little fat, especially 3500-4500 rpm, and the timing was only at 34 degrees, so there was a little more to be had with tuning. I will do that when I get it on the chassis dyno.

Pappy

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Wow!

Bruce jenner fanboi
 

So...Paul.....
"deca" being the Roman prefix for "ten"......i.e. 5 links per side.....q.e.d.

Thank God for the Romans....

Bruce Jenner...not so much :buttkick:

Goodness gracious!!!

Haven't posted in a while. Finished up the Decalink rear suspension and rebuilt the trunk where I cut it up to do the rear suspension install. Added a fuel door in the deck lid so I didn't have to open the trunk (with the wing and supports that run through to the frame) every time I refueled. Cut the firewall out to move the motor back 6 more inches (for a total of 15) to get clearance between the dry sump pump and the lower control arms. Turned out to quite complicated since I had to modify the x-member to get clearance for the rear mounted starter motor and so I could pull the transmission from below the car instead of out through the cockpit, but I'm getting it done. Looks like my driveshaft will be 19 inches long - LOL

Pappy

The open 3 inch holes get air hoses that bring air from the side scoops to the differential and fuel coolers.
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Firewall before the cut
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Tilton Bellhousing
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Reverse mounted starter
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I also got the fuel cell from Fuel Safe. 19.7 gallons, 1.76 gal sump with trap doors, Aeromotive 1000 pump.

Pappy

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Need to get over and see this in person sometime Pappy. Looks great!!!

Well, that should be FUN!