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Adding for a couple things; mine is a little more track rat but to re-iterate some of the things;
For the suspension, look into VB&P's offset LCA bushings. It's really hard to get negative camber into these cars and that helps.
Also, lowering the front via removing spacer on the outer pads on the spring and then putting in some drop wedges will get the front fairly low (and it's fairly inexpensive)
Don't do an unsprung clutch disc - it's miserable, even at the track.
While the car had tons of hours on it, the only thing that changed between the previous race was the canton oil pan . . . Dunno if I'd blame it entirely on the pan, just something to consider.
And then this:
GL w/ the build, seems like a lot of fun!
Last edited by RandomTask; Mar 27, 2018 at 09:45 AM.
Even with a ZR1, you'd have to do everything you're planning save for the engine build. And your planned engine will be faster than a stock ZR1 motor. It also has the benefit of being considerably lighter, too.
Adding for a couple things; mine is a little more track rat but to re-iterate some of the things;
For the suspension, look into VB&P's offset LCA bushings. It's really hard to get negative camber into these cars and that helps.
Also, lowering the front via removing spacer on the outer pads on the spring and then putting in some drop wedges will get the front fairly low (and it's fairly inexpensive)
Don't do an unsprung clutch disc - it's miserable, even at the track.
While the car had tons of hours on it, the only thing that changed between the previous race was the canton oil pan . . . Dunno if I'd blame it entirely on the pan, just something to consider.
And then this:
GL w/ the build, seems like a lot of fun!
We are doing the wedge thing in the front with the bolt change in the back. I told him that I did not want a drastic ride height change...prefer to maintain as much travel as possible. I subscribe to the lower spring rate/high quality, aggressive damper theory of handling as long as everything is well controlled.
Pretty sure the clutch will not be unsprung. He knows I want to be able to drive this on the street as well.
Last edited by Jaye Bass; Mar 27, 2018 at 10:46 AM.
We are doing the wedge thing in the front with the bolt change in the back. I told him that I did not want a drastic ride height change...prefer to maintain as much travel as possible. I subscribe to the lower spring rate/high quality, aggressive damper theory of handling as long as everything is well controlled.
Pretty sure the clutch will not be unsprung. He knows I want to be able to drive this on the street as well.
I was running the '84 Z51 spring in the back - car was very twitchy under braking and power on. Mind you, I'm at 2800lbs w/ driver race weight.
From my research, cars like a little bit of stiffer spring up front, softer in the back, and a lot of sway bar on both ends.
So the rebuild starts. The word from the builder was that everything looked good. We are only reusing the a portion of the motor: block, intake, and a few other bits. Replacing the piston assemblies, crank, new heads, etc.
I can't believe how dirty and rusty that motor was. Good luck with the build. Just did the top end on my 93.
Yea it was pretty nasty. Not bad for the price though. The interior, the undercarriage, and most of the body is in remarkably good shape though I am replacing all of the wear items underneath, new brakes, etc. In one of the pictures, you could see a pine needle or two in the gunk.
Quick update. Parts are coming in. The builder changed pistons to Wiseco Pro Forged.
Also I went ahead and bit the bullet for a full Banski rear set up ( toe link, trailing arms, camber rods, and boots). Keeping the poly bushings up front.
When you order pistons I recommend you specify a .020" lower pin location (raises the top of the piston .020" in the bore). The reason for this is with a .005" block cut to level the deck surface, you will have a zero deck height. This is important when running high compression to prevent detonation. With a ,039" head gasket you will have .039" quench clearance between the top of the piston and the bottom of the head which creates good turbulence in the chamber and more complete ignition of the mixture. If you need more volume to keep your compression ratio pump gas friendly, get a D shaped dish in the piston. Believe me it makes a difference, I have an LT1 with 11:1 compression and a Vortech supercharger with 8 lbs boost and it does not detonate on 91 octane. I attached a good article which better explains the importance of tight quench
If you have the money buy a new Vette you will not forget my opinion. To big a project for a car thats uni body!
If I ever buy a new Vette it will likely be a base model C8. I'm thinking it will be a very quick car, that handles as well as a Cayman S for less than a highly optioned Cayman...but with less polish. I'll keep the C4 cause I want an analog driving experience with air con and cheap maintenance. I've paid 911 maintenance for the last 10 years.
Outside of PU's, the last American car I owned was a brand new Turbo T-Bird before that there was a 69 442 vert in 1976 (senior HS), and a slew of 307 Chevelles.
I'm about ready to buy the Forgestar CF5's in 18x11 for all four corners. Wanted to confirm that the offset is 50mm. Block went into the shop in April. Has just come out in the last couple of weeks. That did entail the builder partially assembling the rotating bits to get the measurements for zero decking the block. These old codgers can be difficult to deal with. My car might get finished by mid-September.
Originally Posted by MatthewMiller
For sure. My avatar is actually with 17x11.5 CCW wheels and Toyo 888s on a track (previous owner). But I can top that: last year I ran 315/35/17 Hoosier A7s on those same wheels at several autocrosses. That combo makes stupid amounts of grip, and it doesn't hurt anything. I would make sure to leave the roof on, but the suspensions on these things are pretty stout.
Most of my autocrossing is done on 315/30/18 BFG Rival S tires (Hoosiers aren't legal for my usual class), and I drive on them to and from events and occasionally other street driving when I get too lazy to swap them out. They actually pretty well on the street - better than worn-out Kumho Ecstas in the 315/35/17 size, for example. As always, it depends on the particular tire you choose. But there are cars coming from the factory these days with far shorter sidewalls than the 315/30/18 has.
My 11" wheels with 315-width tires (either 17s or 18s) all fit fine at all four corners, with 50mm offset (7.96" backspacing). That offset is the real key. Off the top of my head, I think the 10.5" C5Z wheels have more offset, and therefore may require a small spacer to avoid rubbing on the inside edges. That's not a problem, as long as you install longer ARP wheel studs in your hubs. Those wheels are a cheap and good-looking option, if you can find a set of four. Ideally for a 315 tire, you'd want 11-11.5". I got some Forgestar 18x11 CF5s, which look good, are easy to clean, and don't break the bank....just in case you're looking for options.
I've got a C4 with a Golen 396 LT1 (550-600 crank HP) with the converted clutch (Ram single disc with hydraulic throw out bearing). I love the motor, I hate the clutch! This is an AutoX and Track Days car. Any recommendations for a low weight, twin disc clutch for this application?
BTW, I run 18x10.5" OEM C5Z ( light!) with 315's Hoosiers or Rivals and love it. I've even run 335's on the rear with some CCW's (18x12) with no issues. I've kept the stock gearing to keep it a "4 speed" car at the track. Brakes are C5Z front (Hawk HP Plus) and stock rear (HP Plus).
Matthew, badass info as always.
