CadVetteStang

I want to find complete Corvette C4 Z51 front and rear suspension for an upgrade. Do all Z51s have 13” rotors? Do all Vettes with 13” front rotors also have 13” rear rotors? If I call a salvage yard, what year range do I ask for to get what I want? What codes do I look for on a salvage car to know if I have found what I want? Is there a year model to avoid?

My 70 model Cadillac 500 engine makes 550 lbs. of torque@ 3700 RPMs and 440 HP @ 4400 RPMs. I know I need a Dana 44 and not the Dana 36, however the Dana 36 has the tall gears I want. Does the Dana 44 come in a higher gear than 3.01:1? Does it come in a 2.73:1 or a 2.50:1? I want to stay away from overdrive if possible, so I am looking for the tallest gear avail.

I have heard that I do not want Z51 because of the quick steering ratio; can I go with complete Z51, but use a non-Z51 rack? My car has a 13" longer wheel base: does that create a problem? I will not need to modify the width of the suspension because the 72 Mach 1 is 4" wider than the C4 Vette. The Caddy big block does weigh 35 lbs. more than a cast iron 350 Chevy, but the 72 Mach 1 is 600 lbs. lighter than the C4 Vette so I won't have to change the front spring rate either. I still have less weight on the front wheels.

Do all Z51s have 1.25” front sway bar? If not what cars have them? Are there any bigger sway bars? If I add late model suspension to a non-computerized car, what do I need from salvage to add the active suspension feature? (Not traction control or ABS, I’m referring to street to race settings on the shocks) If I want to use coil-overs in the rear in stead of the leaf springs, does anyone make them for the C4 rear?
This car will spend 90% of the time being street driven because it gets over 20MPG, but it will see plenty of autocross and road race time.I know this is a lot of questions…

Thanks in advance,
Cody

Red Guts

Lots of good information in the Tech "sticky" post at the top of this forum, including a handy suspension chart. You can do Z51 springs, shocks, and sway bars without the Z51 steering rack. All of this stuff is available aftermarket through the usual Corvette vendors.

96GS#007

No. Until '88 (IIRC) all had 12" in the front including Z51. Rears are 12" in all cases. '88 -'90 had 13" fronts with Z51. '91 & up had 13" with Z07. '95 and '96 had 13" standard regardless of suspension. All '90 - '95 ZR1s had 13" front rotors as well.


No C4s had 13" rear rotors from the factory. What year....lol...depends on what spring rates you want which depends on your specific car. Oh by the way....front suspension geometry changed in '88 vs the earlier cars so you'll need to research that too.


Dana 44s came with 3.07s. 3.33s, 3.45s, and a very few came with 3.54s.

You can do that. Not sure why the Z51 rack is bad for your application. I'd rather have quick steering than feel like I'm driving a school bus.


I find it hard to believe the Mustang is 600lbs lighter than a C4 unless you put it on a serious diet. Early C4s tipped the scales at just over 3,000lbs. Later ones were 3200-3400. You're saying your Mustang is 2,400 - 2,800?

Later Z51s have 30mm front sway bars. The aftermarket sells 32mm. The only thing "active" on the suspension were the shocks in the FX3 and F45 ('96 only) cars. It had nothing to do with springs or anything else. If you want to add RPO FX3 or F45, you need a list of stuff waaaaaaaay longer than I feel like typing here. A few of the bigger itmes would be the controller, switches, wiring harness, various connectors, etc. Not worth the hassle and if you go the coil over route you won't use the shocks anyway. Several companies sell coil-overs including Doug Rippie Motorsports and Exotic Muscle.

whalepirot

U sure? My engine makes that kind of power and the expert rear end shop made me comfortable with a cryo treated, later design D36 when finding a 44 was tough. He also selected a 3.54 gear set with more contact area, which I realize is above your desired ratio.

racebum

the z51 spring rates also change over the years. the 1996 spring setup is no where near as stiff as the 1990 model. I actually have a 1990 front FHA 530/lb spring i will sell for any reasonable offer. This is stiffer than the late z51 but not as stiff as the 1990 z51. it is OEM FX3 in 1990.

xrcrx

Z51 springs and anti-swaybars were changed from year to year as the C4 got softer. See here:
http://www.corvetteactioncenter.com/...usp_chart.html

rodj

Must be a good salesman.
See what happens when you start dumping the clutch on the start line.

CadVetteStang

Thank you all for the good information! I stand corrected about the weight of the C4. One website listed the weight at 3850.... I just looked at another site that lists the 84 at about 3085. According to my title, my Mustang was 2950 with AC and a 351C 2BBl. The car had a 302 in it when I got it. Oh, and the Caddy's wight I listed at being 35 lbs. heavier than 350 is assuming the Cad has an aluminum intake. I put the battery in the trunk to shed the overage. My guess is the rollcage added 125 lbs. I think the finished car will tip the scales at 3150 with the heavier 20" wheels and added gear.

VIN_#_00521__Z-51_C4

I have an '84 with the RPO Option Z51 I do have 13' cryoed Drilled and slotted rotors up fron and in back too ( I changed this out last July when i bought the car, i also bought the some Grand Sport 2-piston calipers and ( 2)13" cryoed rotors for the front/11.5 D/S rotors for the rear from the owner .... my car was already lowered and it handles better after the brake upgrade and the proper alignment

you can do a brake upgrade with rotors/calipers and the proper brackets through VB&P ( I only had to buy the SS hoses and brackets and Now they are on the car like they came with it

rfn026

I love my Z51 steering rack. I can't imagine have the slower rack.

Richard Newton

101 Projects for Your Corvette 1984-1996

Autocross Performance Handbook

CadVetteStang

I do want quick steering, and as long as a Z51's ratio is not so quick it prevents you from relaxing on long road trips, I would like to have it for auto crossing and road racing. I eventually want to drive the car coast-to-coast in the Hot Rod power tour. Right now I have no time limit on how long it takes me to build the car, my wife just started 7 months of chemo, and everything I make is going to medical bills. I want to learn and plan as much as possible for this project that will start in the Fall.
Thanks again,
Cody

CadVetteStang

Body: The car in the picture is like my car, but is not the actual Mustang. Mine has had the Caddy motor in it for 17 years and has been parked behind a friend’s house for 15 years waiting on a roll cage, body work and paint. The suspension is worn out. The fenders had been cut out years ago for the 15 X 10 wheels under all for corners. It looks kind of like a dirt car. The car in the picture is the same color as mine and has the same style wheels I want for the finished ride. For years I could not afford to have the work done, but that has changed since I went to work at Falcon Jet. After the medical obligations have been met, I can finish the car.

Suspension: I doubt any of you here would question why I want to put a Vette suspension under and old Mustang; it is simply the most cost effective way to get the car to corner and stop the way I want it to. And since I will be working with a budget, It sounds like I can bargain-shop for the best deal on a C4 suspension that I can find regardless of year model and weather it’s a Z51 or not. That way, I can spend my money on the suspension’s installation, the roll cage, the engine overhaul and the body & paint. Assuming all years between 84 and 96 have interchangeable components, I could upgrade to the Z51 handling pkg. and 13” rotors after I get the car on the road.

Transmission: Because of my medical / financial obligations, I wanted to avoid the overdrive trans because only the 480LE will hold up to the Cad 500’s torque in the long term (In the previous post, I quoted only the stock rating of the 10:1 compression engine with a 10% increase in HP.) I would like to start with a Dana 36 with the 2.59:1 ratio, but I doubt even a modified diff. would handle the actual torque of my engine with a moderate build up. It would be difficult to resist an acceleration test since I will be driving the car daily for my 66 mile round trip to work and back. I would, however, like to find out just how strong a Dana 36 can realistically be AND how much it will cost to modify it. I eventually want a 480LE and I think it would work well with the wiring harness and computer from a 454SS truck that will control the 670 TBI that I plan to use as a gas mileage/performance compromise to keep the car a daily driver that I can afford to buy gas for.

Engine: (Gas mileage and power numbers) The stock engine’s power numbers were obtained with points ignition, 0.035 gap plugs, a single 2” exhaust, quiet muffler, solid fan spacer, stock cast iron intake, and AC hooked up and running… I reported numbers based a 10% HP increase and left the Torque numbers alone because I learned years ago that I must understate and never exaggerate the performance numbers if I expected anyone to believe what I was saying about a Cad 500. However, I am “slandering” the Caddy somewhat. If anyone wonders why I would put a Caddy 500 in a Mustang, well…… The factory obtained the stock numbers without a performance tune. It had low voltage points ignition, 0.035 gap plugs, single 2” exhaust, a quiet muffler, an additional exhaust resonator, a solid fan spacer, a stock restrictive cast iron intake, very inefficient exhaust manifolds, restrictive air breather, and the AC hooked up and running.… A 70 Eldorado was my first car. It got 13.5 miles to the gallon on the interstate due to these inefficiencies and the fact that the stock Caddy thermostat is in the 200 degree range and the engine was breathing under hood air that was insulated by fiberglass insulation under the hood to reduce noise. The mid 70’s 500s got 15 mpg because of a fan clutch and electronic ignition. However, these cars were over 5,000 lbs. shaped like a shoebox and still breathing 200 degree under hood air. Their compression was also reduced to 8.5:1.
I put a 472 in a 3,680 lb. Eldorado and with fuel injection I recorded 20 MPGs @ 55 MPH and 16MPGs. @ 75MPH. I had not yet changed the 3.5:1 front diff, and the trans would not shift into overdrive. I was still working the bugs out of the car when the stock salvage yard engine began to knock. I never finished the project. I had fully expected a 27MPG car after changing the front diff. to a 2.43:1 and fixing forth gear.

In the Mustang, I will use an electric cooling fan, Edelbrock performer intake, a 50 horse street cam, Fuel injection, high voltage electronic ignition, 8.8 mm plug wires, try-Y headers and dual 3” exhaust with Flowmasters. This should be good for at least a 20% increase in HP. Conservatively, that would work out to 480 HP @ 4500 RPM. The torque would be above 610 lbs. @ 3800. Again, that’s a conservative estimate. The 670 CFM TBI from the 454 SS truck my cut those numbers down somewhat. When the time comes I may use a Holly 950 CFM TBI or a tuned port injection. The 670 TBI is my low dollar, high gasmileage choice. I have included some links to show what a cad's true performance potential is. The secret to this engine's performance comes from the shape of the combustion chamber, the position of the sparkplug in relation to the top of the combustion chamber and the perfect 1:1 bore stroke ratio achieved by the 4.30 bore, 4.30 stroke.

So, I’m talking about an engine with about the weight of a 350, with the performance numbers of a 454 and the gas mileage of a 3.8 liter V6. Yes, I know it sounds to good to be true, but the numbers are very real and proven. That’s why I’m a fan of this motor. If it was called a "GM 500" in 1970 and was available in a 70 Vette as a Z06, everyone would know about the Cad 500 and I would not be able to afford one. I bought mine in running condition for $150 and will have less than $2,500 in it when I’m finished.

this is a copy of an add for a crate motor:

"POTTER AUTOMOTIVE
Potter offers complete Cadillac 500 crate engines from our standard 500hp /575-lb-ft, all the way up to 700-plus-horsepower engines on 92 OCTANE PUMP GAS! And those numbers are without a blower, NOS, or a turbo (and we sell those too!). Each engine is built to order and formatted to fit each individual need from the absolute highest-quality, badass, race-proven parts. This is the ultimate street rod engine and weighs 75 pounds less than a BBC (and that's without aluminum heads!). There is also a complete line of parts ranging from pro-type intakes, aluminum heads, blower kits, 52mm roller cams, and more. A stock-block and crank will handle over 1,000 hp with proper prep. Complete engines are priced from $6,900, with billet pulleys, an alternator bracket, T-6 valve covers, an aluminum intake, a distributor, and a carb! Trade in your core. In-house dyno-testing available! We got what it takes to take what they got!

Potter Automotive's Cadillac Performance Parts
P.O. Box 4514, Dept. KC
Chattanooga, TN 37405
(423) 332-7636
www.cadillacperformanceparts.com "

Here are some other links:

http://images.kitcarmag.com/techarti...uyers_09_z.jpg
www.eldocountry.com/eldo/links.html
http://www.geocities.com/MotorCity/P.../guide/Why.htm
www.cadillacperformanceparts.com
http://www.mtscadparts.com/

Cody

CadVetteStang

I live in central Arkansas: no "all Vette" salvage yards around. Some that have a Vette think they are made of Gold. Memphis and Texarkana are close enough to drive to. Anyone got the 4-1-1 on a good Vette grave yard? I'd like to find a Dana 44 with 3.07 gears.

pianoguy

Mojo and prayers for your wife's recovery.

Curveit

Heck of a combination you got going there. I'd think the body would be heavier than that, but maybe it's lightened up a bit. I'm somewhat familar with the big Caddies; never got into one, but i did some research back in the 80s. They do have lots of potential; the 500" CI has what, like a 4.30-35" stroke stock? Should freak the Mustang guys out too. Good luck to you and your wife.

CadVetteStang

Thank you

CadVetteStang

Thanks for the good luck wish.
I remembered my title saying my weight was 2,985… In actuality, my fastback weighed 2,995 with the 351C 2bbl and AC. My guess is with the cage and extra gear, it will be race ready at less than 3,150lbs.
http://www.mustangsetc.com/f_cars/1972.html

The Cad 500 has a bore of 4.300 and a stroke of 4.304, giving it close to a perfect 1:1 bore/stroke ratio even with mildly oversized pistons.

One of the Cadillac performance forums, I’m talking to a guy who has a 540 inch stroker rated at 700 HP and 700 lbs of torque.

Car Guy 88

On my 88 with Z51 suspension the specs for Z51 specific equipment are as follows:
-Dana 44 rearend
-3.07 gears (performance axel ratio)
-26mm rear sway bar
-30mm front sway bar
-stiffer shocks + spings
-Quick ratio steering
-17x9.5 aluminum wheels with 275/40 ZR 17 good year Eagle non-directional tires
-Power streering cooler
-Heavy Duty radiator
-less restrictive exhaust worth 5 hp
-Radiator boost fan
-LArger front air dam
-13inch front with H.D 2 piston calipers
-4+3 Trans
-(H.D wheel bearings???)
-you don't need to use the quick ration steering rack to use the rest of the components

-I don't think any stock C4 had 13 inch rear brakes, I'm not sure but I think the rears are either 11.5 or 12 on all C4's with single piston calipers

-Look for the factory 17inch wheels in 87-88 models, that means they are either a Z51 or Z52 suspension, only difference b/w Z51 and Z52 is how stiff the shocks and springs, Plus all Z51 had to have a manual trans but not all Z52's did, but the rest of the equitment is the same and you probbaly want to get new shocks and springs anyway since the ones on any junkyard car will be well worn and not as stiff as they used to be anyway and you probbably won't be using a 4+3 or ZF trans anyway.

-Thier was a suspension geomtrey change in 88 for better control under hard braking conditions + plus 88 and up got thicker rotors plus I thik only 88 and up models had 13 inch brakes with the H.D 2 piston calipers(87 and prior Z51's had 12inch rotors with non-H.D 2 piston calipers), 88 and later have different backspacing than 87 and prior models, 88 had the biggest anti roll bars of any C4 exept for the 96 Grand sports witch were the same size roll bars, also an 84 Z51 suspension had the very most stiff shocks and springs and they got progressivley softer year after year, after 84.

-in my original sales brocher the performance axle ratio (3.07) is listed as part of the Z51 package however it is listed as a seperate feature from the dana 44, so mabey an odd-ball Z52 with auto might have had a different ratio, but no Z51 would have. Also I think in 89 and 90 the dana 44's had something like a 3.54 or 3.44 rear gears, also all ZR1's came with Z51 suspension.

-you asked about anti-roll bars you can get a 32mm front anti-roll bar from mid America motor works, this is larger than any front C4 factory anti-roll bar.

-Hope all this helps good luck

CadVetteStang

Thank you all for the information.....

xrcrx

A Z52 car had the quicker steering rack with the softer suspension settings. They also got the base rear axle-2.59 unless optioned out otherwise. Great info 88